Document 6RzeQojjw2EVXoonoKV669eQg

DRAFT FOR PUBLIC COMMENT jSUsssaL...^,^.^ Am mb ient4 Fugfees^ ^nyl ChlorideT e Class of the BUfeK. La West Covinl^l December, 1995 Office ofEnvironmental Health Hazard Assessment California Environmental Protection Agency R&S145405 DRAFT ADDENDUM HEALTH RISK ASSESSMENT OF AMBIENT FUGITIVE VINYL CHLORIDE EMISSIONS FROM THE CLASS I UNIT OF THE B.K.K. LANDFILL, WEST COVINA, CALIFORNIA DECEMBER 1995 Principal Authors: David M. Siegel, Ph.D., D.A.B.T. Lillian J. Kelly, M.P.H. Robert L. Holtzer, M.D. Laurie E. Monserrat, B.S.N. Office of Environmental Health Hazard Assessment Hazardous Waste Toxicology Section 601 North 7th Street, MS 241 P. O. Box 942732 Sacramento, California 94234-7320 (916) 324-2829 R&S145406 ACKNOWLEDGMENTS The Hazardous Waste Toxicology Section (HWTS) of the Office of Environmental Health Hazard Assessment (OEHHA) expresses appreciation to its colleagues for their contributions to this project: From the Department of Health Services, Division of Environmental and Occupational Disease Control (DHS-DEODC) - Martin Kharrazi, Ph.D., Tim Lomas, and Rachel Broadwin for FIGURES 15,16, and 17; Rachel Broadwin for Appendix E-FIGURE 1; Michael Armstrong for assisting with the summary of the air dispersion model contained in Appendix F; Joel Swartz, Ph.D., formerly with DHS-DEODC, for the statistical analysis of the 1983-1990 ambient vinyl chloride monitoring data in Appendix D. From the Air Resources Board, Stationary Source Division - Lynton Baker for historical air monitoring and air modeling (Baker and MacKay, 1985) information about the B.K.K. Landfill; and together with Andrew Ranzieri and Anthony Servin for consultation during the development of the air dispersion model contained in Appendix F. This draft report incorporates comments received during a two-phased review process. The initial review was made by staff from OEHHA-Air Toxicology and Epidemiology Section, the Department of Toxic Substances Control, the Air Resources Board, the Department of Health Services, and the United States Environmental Protection Agency-Region IX. The second review was made by members of OEHHA's Ad Hoc Advisory Committee for Review of the Draft Addendum Health Risk Assessment OEHHA-HWTS expresses its appreciation to all the reviewers for their critiques, and in particular, wishes to acknowledge the contributions of the members of the Ad Hoc Advisory Committee: Nancy Adin, Ph.D., Resident Jean Ameson, Resident William F. Polich, Ph.D., Resident William Ketteringham, Ph.D., Representative for the City of West Covina Henry Moghtader, M.D., West Covina Physician Jack Yoshino, Representative for the City of Walnut John Froines, Ph.D., Representative for the B.K.K. Corporation Ed Avol, M.S., University of Southern California, School of Medicine Allan H. Smith, M.D., Ph.D., University of California, Berkeley School of Public Health Jay Beaumont, Ph.D., M.S.P.H., University of California, Davis Division of Occupational/Environmental Medicine & Epidemiology OEHHA-HWTS also wishes to thank Vincent James Cogliano, Ph.D., Acting Chief, Quantitative Risk Methods Group, National Center for Environmental Assessment, United States Environmental Protection Agency, Washington, D.C., for his always gracious discussions and meetings regarding young-age susceptibility to vinyl chloride. The authors express their appreciation to fellow staff members contributing to this report: Julio Salinas, Ph.D. for FIGURE 18; Ed Evans, for computerized data bases; and Sharon Davis, for patient and perfect word processing. R&S145407 D RAFT -i- DRAFT TABLE OF CONTENTS LIST OF FIGURES...................................................................................................................... iv LIST OF TABLES........................................................................................................................ vi FACT SHEET............................................................................................................................. viii EXECUTIVE SUMMARY.............................................................................................................. x INTRODUCTION.......................................................................................................................... 1 Objective, Methodology, and Scope of the Draft Addendum Health Risk Assessment.. 1 Previous Health Risk Assessments of the B.K.K. Landfill...............................................4 Organizational Changes in the Department of Health Services Since the 1990............ 5 Interim Report Appendices to the Draft Addendum Health Risk Assessment........................................ 6 HAZARD IDENTIFICATION..........................................................................................................9 Vinyl Chloride in the Class I Unit..................................................................................... 9 Vinyl Chloride Emissions From the Class I Unit............................................................10 Other Hazardous Chemicals Detected in Ambient Air...................................................12 Regulatory Agencies Involved With the B.K.K. Landfill..................................................13 TOXICITY ASSESSMENT..........................................................................................................15 Toxicity Values............................................................................................... 15 History of the Assessment of Vinyl Chloride Toxicity.....................................................15 New Unit Risk Value and Proposition 65................................................................ 19 Young-Age Susceptibility to Vinyl Chloride....................................................................21 EXPOSURE ASSESSMENT......................................................... 23 Ambient Vinyl Chloride Monitoring Data........................................................................23 Site Activities..................................................................................................................40 Odor Complaints Data......................... 44 Other Hazardous Chemicals Detected in Ambient Air.................................................. 48 RISK CHARACTERIZATION......................................................................................................50 Assumptions Regarding the Beginning of Exposures at Stations A, B, and MY.......... 50 Assumptions Regarding Ambient Vinyl Chloride Monitoring Data..................................52 Individual Excess Lifetime Cancer Risk Estimates..................................... 53 Exposed Population........................................................................................................56 Estimated Excess Lifetime Cancer Risks Using Different Assumptions and Methodology... 57 Limitations and Uncertainties......................................................................................... 61 Findings of the Draft Addendum Health Risk Assessment............................................63 REFERENCES........................................................................................................................... 64 R&S145408 DRAFT -ii- DRAFT TABLE OF CONTENTS (Continued) APPENDIX A............................................................................................................................ 72 Errata APPENDIX B.............................................................................................................................74 "B.K.K. Landfill, West Covina, California Fact Sheet, December 1990," California Department of Health Services-Environmental Epidemiology and Toxicology Branch, Emeryville, California APPENDIX C..............................................................................................................................82 Updated Toxicity Tables for Carcinogens Detected in Environmental Media Around the BKK Landfill, West Covina, California APPENDIX D..............................................................................................................................86 Statistical Evaluation of the 1983-1990 Ambient Vinyl Chloride Monitoring Data APPENDIX E..............................................................................................................................90 1990 Population Census Tract Data for the Vicinity of the B.K.K. Landfill, West Covina, California APPENDIX F..............................................................................................................................94 Air Dispersion Modeling of the 1983-1990 Ambient Vinyl Chloride Monitoring Data APPENDIX G...........................................................................................................................100 Updated Risk Estimate of the 1984 Indoor Air Monitoring Program Evaluated in the 1990 Interim Report APPENDIX H............................................................................................................................104 Department of Health Services-Cancer Surveillance Section Letter Regarding Review of Recent Tumor Incidence Data R&S145409 DRAFT DRAFT LIST OF FIGURES* FIGURE 1 LOCATION MAP, BKK LANDFILL, WEST COVINA, CALIFORNIA................................. 7 (Environmental Solutions, Inc.) 2 WASTE LOCATION INDEX MAP, BKK LANDFILL, WEST COVINA, CALIFORNIA.... 8 (Environmental Solutions, Inc.) 3 TONS OF HAZARDOUS WASTE DEPOSITED IN BKK LANDFILL............................. 11 WEST COVINA, CALIFORNIA 4 LOCATION OF SOUTH COAST AIR QUALITY MANAGEMENT DISTRICT'S ............ 25 AMBIENT VINYL CHLORIDE MONITORING STATIONS A, B, AND MY (CH2M Hill) 5 1981-1982 AMBIENT CONCENTRATIONS OF VINYL CHLORIDE NEAR ................. 26 BKK LANDFILL (Air Resources Board) 6 1983-1990 AVERAGE ANNUAL VINYL CHLORIDE CONCENTRATIONS (ppb)........ 31 NEAR BKK LANDFILL, WEST COVINA, CALIFORNIA 7 FREQUENCY OF VINYL CHLORIDE DETECTED AT OR ABOVE 2 PPB....................32 1983-1990, BKK LANDFILL, WEST COVINA, CALIFORNIA 8 FREQUENCY OF VINYL CHLORIDE DETECTED AT OR ABOVE 10 PPB..................35 1981-1989, BKK LANDFILL, WEST COVINA, CALIFORNIA 9 MAXIMUM MEASURED VINYL CHLORIDE LEVEL EACH MONTH, 1983-1990.......... 36 BKK LANDFILL, WEST COVINA, CALIFORNIA 10 BKK LANDFILL PROPOSITION 65 AMBIENT MONITORING STATION......................39 LOCATIONS (BKK Corporation - ENVIRON Corporation) 11 BKK SANITARY LANDFILL, OCTOBER 20, 1980.......................................................... 41 (United States Environmental Protection Agency) 12 BKK SANITARY LANDFILL, SEPTEMBER 2, 1983...................................................... 42 (United States Environmental Protection Agency) 13 BKK SANITARY LANDFILL, JUNE 15, 1984................................................................. 43 (United States Environmental Protection Agency) R&S145410 *A parenthetical notation in the title credits the source of the Figure. The full reference is given as a footnote on the Figure. DRAFT IV- D RAFT LIST OF FIGURES* (Continued) 14 TOPOGRAPHY NEAR BKK LANDFILL, WEST COVINA, CALIFORNIA...................... 45 (Department of Health Services-Division of Environmental and Occupational Disease Control) 15 ODOR COMPLAINTS NEAR BKK LANDFILL, 1980-1982 ..................... (Department of Health Services-Division of Environmental and Occupational Disease Control) 46 16 ODOR COMPLAINTS NEAR BKK LANDFILL, 1984-1985 ...................... (Department of Health Services-Division of Environmental and Occupational Disease Control) 47 17 TONS OF HAZARDOUS WASTE DEPOSITED, AVERAGE ANNUAL......................... 51 VINYL CHLORIDE CONCENTRATIONS (ppb) R&S 145411 *A parenthetical notation in the title credits the source of the Figure. The full reference is given as a footnote on the Figure. DRAFT -v- DRAFT LIST OF TABLES* 1 COMPARISON OF THE 1990 INTERIM AND 1995 DRAFT ADDENDUM HEALTH....... 2 RISK ASSESSMENT OF THE CLASS I UNIT OF THE B.K.K. LANDFILL, WEST COVINA, CALIFORNIA 2 RANK ORDERING OF ESTIMATES OF HUMAN RISK BY CATEGORY .....................20 (Office of Environmental Health Hazard Assessment-Air Toxicology and Epidemiology Section) 3 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY'S ESTIMATES......... 22 OF RISK FOR APPORTIONED LIFETIME EXPOSURES TO VINYL CHLORIDE AT VARIOUS CONCENTRATIONS (United States Environmental Protection Agency) 4 1981 VINYL CHLORIDE CONCENTRATION, PPM AT BKK VICINITY ........................24 (South Coast Air Quality Management District) 5 1981-1982 AVERAGE VINYL CHLORIDE CONCENTRATIONS IN .............................28 AMBIENT AIR (ppb), BKK LANDFILL, WEST COVINA, CALIFORNIA 6 1983-1990 AVERAGE ANNUAL VINYL CHLORIDE CONCENTRATIONS (ppb)........ 30 NEAR BKK LANDFILL (Ogden Environmental and Energy Services Co., Inc.) 7 NUMBER OF SAMPLES WITH NONDETECTABLE VINYL CHLORIDE......................34 . CONCENTRATIONS PER TOTAL NUMBER OF DAYS SAMPLED, 1981-1990 SCAQMD AMBIENT VINYL CHLORIDE MONITORING DATA, BKK LANDFILL, WEST COVINA, CALIFORNIA 8 BKK LANDFILL PROPOSITION 65 VINYL CHLORIDE MONITORING PROGRAM.... 38 (B.K.K. Corporation) 9 INDIVIDUAL EXCESS LIFETIME CANCER RISK FROM EXPOSURE TO ..................55 AMBIENT FUGITIVE VINYL CHLORIDE EMISSIONS FROM THE CLASS I UNIT OF THE BKK LANDFILL, WEST COVINA, CALIFORNIA, REASONABLE MAXIMUM EXPOSURE SCENARIO (30 YEARS) 10 ESTIMATED EXCESS CANCER RISK AT STATION A USING DIFFERENT................58 ASSUMPTIONS AND METHODOLOGY 11 SUMMARY OF HEALTH RISK ASSESSMENTS OF THE BKK LANDFILL....................60 WEST COVINA, CALIFORNIA R& S 145412 *A parenthetical notation in the title credits the source of the Table. The full reference is given as a footnote on the Table. DRAFT VI- DR AFT BLANK PAGE California Environmental Protection Agency Office of`EmrironmentafJ-Cealifi OCazardAssessment Hazardous Waste Toxicology Section Draft Addendum Health Risk Assessment B.K.K. Landfill, West Covina, California Fact Sheet DECEMBER, 1995 This fact sheet summarizes the Office of Environmental Health Hazard Assessment's (OEHHA) "Draft Addendum Health Risk Assessment ofAmbient Fugitive Vinyl Chloride Emissions From the Class I Unit of the B.K.K. Landfill, West Covina, California." The addendum report is an update of the 1990 interim health risk assessment conducted by the Hazardous Waste Toxicology Section (HWTS). In 1981, vinyl chloride was found in ambient air in residential neighborhoods adjacent to the B.K.K. Landfill. This is of concern because vinyl chloride is a known human carcinogen and is not normally detected in the South Coast air basin. Emissions of vinyl chloride are clearly associated with the Class I Unit of the landfill. Wastes containing vinyl chloride were deposited in the Class I Unit until June 1981. Emissions from the now closed Class I Unit are due to vinyl chloride-containing wastes deposited in the Unit and to the breaking down of other wastes containing chlorinated hydrocarbons. The emissions have been significantly reduced over time. OEHHA's health risk assessment is possible because there were monitoring data collected by a regulatory agency, in residential neighborhoods almost daily, for nearly a decade. The B.K.K. Landfill In 1963 the B.K.K. Landfill, opened on 130 acres in the San Jose Hills in the City of West Covina. In 1971 the B.K.K. Landfill expanded to its present size of 583 acres. In 1972 40 acres of the landfill were permitted as a hazardous waste (Class I) unit The Class I Unit was expanded to 140 acres in 1975. In November 1984, the B.K.K. Class I Unit stopped accepting hazardous waste and in March 1989, was formally closed. The closing process included an extensive landfill gas collection system and the placing a low-permeability soil cap over 170 acres. This cap covered the hazardous waste landfill and part of the adjacent Class III (solid waste) landfill. A separate Class III waste area of the B.K.K. Landfill is still permitted and is currently accepting waste. In 1985 the State of California committed to complete three health studies ofthe B.K.K. Landfill: a cancer study, a reproductive outcomes study and a health risk assessment. In 1990, the cancer study, an initial pregnancy outcomes study and the interim health risk assessment were completed. A more comprehensive reproductive outcomes study is currently being prepared by the Department of Health Services (DHS). At the time the interim report was being released to the public, the cancer potency of vinyl chloride was being reevaluated and a more potent value was expected. This would make the cancer risk estimated in the interim report an underestimate. The final addendum report plus the interim report will complete the health risk assessment of the B.K.K. Landfill promised to the residents by the State of California. Addendum Objective The addendum report estimatesthe excess cancer risk associated with exposures to vinyl chloride detected at three monitoring stations located south-east and south of ftie closed Class I Unit of the B.K.K. Landfill. Methodology The addendum report uses the four components of a health risk assessment: hazard identification, toxicity assessment, exposure assessment, and risk characterization. Hazard Identification Vinyl chloride is the chemical of primary concern. Although other chemicals have been detected at the monitoring stations, these chemicals are also found in the South Coast air basin. It is not possible to tell how much ofthese chemicals are from the B.K.K. Landfill and how much are from other sources in the area. Toxicity Assessment To estimate the ability of vinyl chloride to cause cancer, OEHHA evaluated data from studies in humans, exposed at factories that made or used vinyl chloride, and from studies in laboratory animals (rats, mice and hamsters). vui R&S145414 The cancer risk is estimated using the cancer potency value for vinyl chloride, 20 x 10'5 per part per billion (ppb). The cancer potency is an estimate of the probability of developing cancer as a result of daily exposure for 70 years to one ppb of a chemical in air. Exposure Assessment The vinyl chloride monitoring data were collected by the South Coast Air Quality Management District (SCAQMD) from June 1981 - March 1990, and by the B.K.K. Corporation from September 1993 September 1994. Station A was located at Marlena & Nogales Streets, Station B at Lynn Court and Station MY at Myra Court. These areas were exposed to the highest detected levels of vinyl chloride. Although other residential areas near the B.K.K. Landfill were exposed to emissions from the landfill, the levels were not as high or as frequent Risk Characterization Assuming that individuals lived near the monitoring stations for 30 years (1980-2009; a "reasonable maximum exposure scenario"), OEHHA estimates that there is an added 0.006 to 0.009 percent chance of developing cancer as a result of exposure to emissions of vinyl chloride from the closed Class I Unit of the B.K.K. Landfill. Addendum Findings There are four findings of the addendum report: 1. For individuals who lived near the monitoring stations during the 1980's, past exposures were higher than current exposures. The majority ofthe estimated excess cancer risk was incurred by 19831984. 2. The landfill gas collection system and the clay cap covering the closed Class I Unit have been successful in lowering vinyl chloride emissions to levels that pose little, if any, risk to nearby residents. 3. Regulatory agencies may want to include past exposures of vinyl chloride near the monitoring stations in subsequent health assessments of emissions from the landfill to ensure future risks do not add significantly to the past cumulative risk. 4. There is uncertainty associated with the assumptions used in the draft addendum report. The actual excess cancer risk is likely to be lower than these estimates and may be zero. Because the number of people who actually lived or are living near Stations A, B, or MY is small, it is unlikely that excess cases of cancer will occur. Each exposed individual may have an increased risk of developing cancer, however the added risk is small. Questions and Answers Q - What is the difference between the DHS Cancer Study and the OEHHA Health Risk Assessments? A - The cancer study investigated cases of diagnosed cancers for the years 1972-82. The health risk assessments estimate the theoretical probability, or risk, of developing cancer. Q - What is meant by "estimated excess lifetime cancer risk"? A - "Estimated excess lifetime cancer risk" is an estimate of the risk for an individual above the background risk of developing cancer during a 70-year lifetime. An individual living in the United States has a 40 percent (0.4) chance of developing cancer throughout a 70-year lifetime. An individual living from 1980-2009 near Station A, for example, may have an added 0.007 percent chance of developing cancer as a result of emissions of vinyl chloride from the closed class I Unit of the B.K.K. Landfill. Q - Has there been an increase in diagnosed cases of cancer since 1982? A - No, the DHS Cancer Surveillance Section recently reviewed the 1988-93 tumor incidence data for a one mile area around the landfill. DHS's review found no indication of increased cancer incidence. Ifyou have questions or comments about the addendum report described in this fact sheet, please contact: Lillian Kelly, M.P.H. Office of Environmental Health Hazard Assessment 601 North 7th Street, MS 241 P. O. Box 942732 Sacramento, California 94234-7320 (916) 324-2829 Copies of the cancer study, the pregnancy outcomes study and the health risk assessments are available at the West Covina, Walnut and La Puente libraries. Public Workshop A 60-day written comment period ends on Tuesday, February 13,1996. You are invited to a public workshop to review and discuss the draft addendum report: Thursday, January 11,1996 7:30 P.M., 1st Floor, City Hall City of West Covina Council Chambers 1444 West Garvey Ave West Covina, California R&S145415 IX EXECUTIVE SUMMARY This report i$ prepared as an addendum to the interim report, "Health Risk Assessment of the B.K.K. Landfill, West Covina, California, November 1990" (Department of Health ServicesHazardous Waste Toxicology Section [DHS-HWTS], 1990), and presumes the reader is familiar with the interim report. The format follows the four components of a health risk assessment hazard identification, toxicity assessment, exposure assessment, and risk characterization. This report is an addendum because at the time the interim report was being released to the public, the carcinogenic potency of vinyl chloride was being reevaluated, and a more potent value was expected to be derived. The interim report stated that an addendum would be prepared which would use the revised potency value and additional ambient vinyl chloride monitoring data. The objective of this addendum report is to quantitatively estimate the excess lifetime cancer risk associated with exposures to vinyl chloride near residential monitoring Stations A, B, and MY, located southeast and south of the closed Class I (hazardous waste) Unit of the B.K.K. Landfill. In May 1981, vinyl chloride was first detected in excess of the state's ambient air quality standard of ten parts per billion (10 ppb) at the landfill perimeter. The interim report and this addendum report primarily focused on exposures to vinyl chloride because vinyl chloride is a known human carcinogen, and it is rarely detected in ambient air of the South Coast air basin. Vinyl chloride has clearly been shown to be associated with the Class I Unit of the B.K.K. Landfill. The health risk assessment, conducted by the Office of Environmental Health Hazard Assessment (OEHHA), is possible because emissions of vinyl chloride reaching the residential community near the B.K.K. Landfill have been quantitatively studied since June 1981. The monitoring data were collected by a regulatory agency in residential neighborhoods almost daily for nearly a decade. Other hazardous chemicals are known to be emitted from the Class I Unit of the B.K.K. Landfill. However, no long-term monitoring of those compounds in air around the B.K.K. Landfill was undertaken, and so evaluation of any exposure to those chemicals is difficult. Those chemicals are also found in background air in the air basin, and it is not possible, with the available data, to distinguish between the amount of those chemicals emitted from the landfill and the amount found in ambient air from other sources. A summary of the sections of this report is given below. HAZARD IDENTIFICATION: The B.K.K. Landfill opened in 1963. Wastes were classified in statute as "hazardous" and "nonhazardous" by the State of California in 1972. From 1972 until December 1984, the B.K.K. Landfill served as the primary commercial hazardous waste disposal site for the Los Angeles area. The Class I (hazardous wast ) Unit of the landfill stopped accepting hazardous waste on November 30, 1984, and was closed in 1989. The B.K.K. Corporation has been operating a municipal solid waste landfill adjacent to the closed Class I Unit since 1987. Emissions of vinyl chloride from the closed Class I Unit are due to biodegradation of buried wastes containing chlorinated hydrocarbons and deposition of hazardous waste containing vinyl chloride. Other hazardous chemicals detected in ambient air are discussed in this section and in the exposure assessment section. R&S145416 DRAFT -x- DRAFT TOXICITY ASSESSMENT: Information is presented about scientific advances in the understanding of risks associated with exposure to vinyl chloride. Both epidemiologic (occupational) and experimental animal data are reviewed and used in this assessment. Vinyl chloride is classified by both the United States Environmental Protection Agency (USEPA) and the International Agency for Research on Cancer (IARC) as a known human carcinogen. Occupational exposures and doses in experimental animals were in parts per million (ppm). Residential exposures to vinyl chloride from the Class I Unit of the B.K.K. Landfill have been in ppb. (It takes 1,000 ppb to make 1 ppm.) Studies in experimental animals have shown evidence of greater sensitivity in the very young from exposure to vinyl chloride. USEPA interprets the sensitive period seen in animals as relating to children aged 0 to 5. Young-age susceptibility is discussed in this section and in the risk characterization section. EXPOSURE ASSESSMENT: Three sets of ambient vinyl chloride monitoring data are used in this addendum report: 1981-1982 data collected by South Coast Air Quality Management District (SCAQMD), with a detection limit of 10 ppb; 1983-1990 data collected by SCAQMD, with a detection limit of 2 ppb; and 1993-1994 data collected by the B.K.K. Corporation, with a detection limit varying from 0.005 to 0.010 ppb. SCAQMD's data were collected at three residential monitoring stations located southeast and south of the Class I Unit: Station A, located on the comer of Mariena and Nogales Streets; Station B, located on Lynn Court; and Station MY, located on Myra Court B.K.K. Corporation's data were collected at three locations in close proximity to the former locations of Stations A, B, and MY. The 1981-1982 data were collected for 16 of the 24 months, the 1983-1990 data were collected almost daily, and the 1993-1994 data were collected every 12 to 14 days. Data collected for less than a 12-month period were assumed to be representative of a 12-month period. Photographs of the landfill operations during the early 1980s show activities such as the changing working face of the Class I Unit and the proximity of residential development. Seventy-two percent of the total 3.4 million tons of hazardous waste accepted at the Class I Unit was liquid hazardous waste, and approximately 85 percent of accepted fluids were disposed of at the working face. Odor studies conducted between 1978 and 1981 show that the most number of complaints came from residents on "M" and "L" named streets, located southeast and south of the Class I Unit, respectively. Residential development near Station A was completed in 1977; near Station MY, in 1979; and near Station B, in 1979. Data on other hazardous chemicals detected at Station A in 1982 are discussed, as are data on the same hazardous chemicals detected in the air basin in 1985. It is not possible, with the available data, to distinguish concentrations of these other hazardous chemicals that are due solely to emissions from the B.K.K. Landfill. RISK CHARACTERIZATION: Assumptions regarding the ambient vinyl chloride monitoring data used in the risk calculations are presented. Exposures are assumed to have begun in 1980, since residential development in the area had been completed in 1979. A reasonable maximum exposure scenario (30-years) and an average exposure scenario (9-years) are calculated, rather than the worst-case scenario used in the interim report. A "reasonable maximum exposure" is the maximum exposure that is reasonably expected to occur, and is intended to be a conservative estimate, well above the average yet within the range of possible exposures. The unit risk value for vinyl chloride used in the calculations is the current California Environmental Protection Agency (Cal/EPA) R&S145417 DRAFT -xi- D R AFT value of 20 x 10'15 p*e*r*ppb, rather than the value of 0.69 x 1C5 per ppb used in the interim report. The unit risk is an upperbound estimate of th probability of dev loping cancer as a result of daily exposure over 70 years to 1 ppb of a substance in air. The Cal/EPA unit risk value was derived from a study in experimental animals (mice). Assuming the reasonable maximum exposure scenario of 30 years with exposures beginning in 1980, and assuming that individuals spend 80 percent of their time at home, the estimated excess (above background) lifetime cancer risk for an individual near the monitoring stations is as follows: at Station A, 7 x lO-5; at Station B, 6 x 10"5; at Station MY, 9 x 10'5. Assuming an average exposure scenario fora 9-year period beginning in 1981 (covering the years of highest average annual concentrations) the estimated excess cancer risks are: at Stations A, 7 x 10 , at Station B, 5 x 10"5; and at Station MY, 8 x It)'5. Excess lifetime cancer risks using different assumptions for time spent at home, the average annual concentration of vinyl chloride in 1980, the substituted value for samples with nondetectable concentrations in the 1981-1982 data, and the unit risk value are presented using Station A as an example. When values of 62, 76 or 96 percent time spent at home are assumed, estimates of excess cancer risk are between 5 and 8 x 10*5 at Station A. When the value of 5 ppb is substituted for the average annual concentration in 1980 and for samples with nondetectable concentrations in the 1981-1982 data at Station A, the estimate of excess cancer risk is 8 x 10`s; when the value of 0 ppb is substituted, the estimate of excess cancer risk is 6 x 10'5. When unit risk values derived from studies in male workers exposed to vinyl chloride are assumed, estimates of excess cancer risk are between 0.9 and 1 x IQ'5 at Station A. The population excess cancer burden (that is, the excess number of cases of cancer that may occur in a defined population who all have the same individual excess lifetime cancer risk) is not estimated because not all of the population around the landfill were or are exposed to the concentrations of vinyl chloride detected at Stations A, B, and MY, and it is not possible to obtain a reliable estimate of exposure to other residents. This addendum health risk assessment provides an assessment of past, present, and future risks for individuals living near Stations A, B, and MY from exposures to ambient fugitive emissions of vinyl chloride associated with the closed Class I Unit of the B.K.K. Landfill. There are four findings of this report: 1. From the available monitoring data, the single year of highest exposure to vinyl chloride was 1981. The maximum detected concentration of vinyl chloride at Station A in 1981 was 50 ppb, compared to 0.16 ppb in 1994. The average annual concentration at Station A in 1981 is estimated to have been 7.2 ppb, compared to an estimate of 0.05 ppb in 1994. For individuals who lived near Stations A, B, and MY during the 1980's, past exposures to vinyl chloride were higher than current exposures. The cumulative individual excess lifetime cancer risk suggests that for exposures beginning in 1980, the majority of the cancer risk was incurred by 1983-1984, and that there is little change (on the order of 15 to 22 percent) in the cumulative risk after 1986. R&S145418 DRAFT -xii- D R AFT 2. The landfill gas collection system, which was expanded over time, and the cap covering the closed Class I Unit have been successful in lowering the frequency and level of vinyl chloride emissions to levels that pose little, if any, risk to nearby residents. 3. Regulatory agencies with responsibility for remediation or control of the B.K.K. Landfill may want to include past exposures of vinyl chloride near Stations A, B, and MY in subsequent health assessments of emissions from the landfill to ensure future risks do not add significantly to the past cumulative risk. 4. In spite of using best available scientific knowledge, there is considerable uncertainty associated with the estimated exposures, the carcinogenic potency value of vinyl chloride, and young-age susceptibility methodology. The estimated excess cancer risks calculated in this addendum report are upperbound estimates, based on the assumptions, methodology, limitations and uncertainties specified. The actual excess cancer risk is likely to be lower than these estimates and may be zero. Because the number of people who actually lived or are living near Stations A, B, and MY is small, it is unlikely that excess cases of cancer will occur. Each exposed individual may have an increased risk of developing cancer, however the added risk is small. R&S145419 DRAFT Xlll- DRAFT INTRODUCTION This report is prepared as an addendum to the interim report, "Health Risk Assessment of the B.K.K. Landfill, West Covina, California, November 1990" (DHS-HWTS, 1990), and presumes the reader is familiar with the interim report. The format follows the four components of a health risk assessment: hazard identification, toxicity assessment, exposure assessment and risk characterization. This report is an addendum because at the time the interim report was being released to the public, the carcinogenic potency of vinyl chloride was being reevaluated by DHS and the Air Resources Board (ARB). The unit risk is a measure of carcinogenic potency and an upperbound estimate of the probability of developing cancer as a result of daily exposure over 70 years to one ppb of a substance in air. It was expected that the reevaluation would indicate vinyl chloride was more potent than previously thought, which would make the cancer risk estimated in the interim report an underestimate and out-of-date. The interim report stated that an addendum would be prepared which would use the revised unit risk value for vinyl chloride and additional ambient vinyl chloride monitoring data. This addendum report is not required by any state or federal statute, regulation, or agency. The original impetus for the health risk assessment of the Class I Unit of the B.K.K. Landfill dates from 1985. At that time, DHS committed to undertake three health studies in response to residents' concerns about potential health hazards associated with living near the B.K.K. Landfill. The health studies were: a cancer study, a health risk assessment, and a reproductive outcomes study. A cancer study investigates cases of diagnosed cancers whereas a health risk assessment estimates the theoretical probability (the "risk") of developing cancer. This addendum report plus the interim report complete the health risk assessment of the Class I Unit of the B.K.K. Landfill in West Covina. Objective, Methodology, and Scope of the Draft Addendum Health Risk Assessment The objective of this addendum report is to quantitatively estimate the "excess" lifetime cancer risk associated with exposures to vinyl chloride at residential monitoring Stations A, B, and MY. "Excess" refers to the risk above the background risk in the United States of developing cancer during a 70-year lifetime. Within the United States, the probability of developing cancer is 4 in 10, or 40 percent (Miller etai, 1993). This addendum report estimates risks above the background level. The methodology of this addendum report follows risk assessment guidelines set forth by the United States Environmental Protection Agency (USEPA) (USEPA, 1989a; 1989b; 1991a; 1991b; 1992a). These guidelines are used so that the addendum report will be consistent with standard methodology, and so that its findings can be compared to findings of other health risk assessments of the B.K.K. Landfill. Changes in USEPA's recommended guidelines followed in this addendum report include the use of reasonably maximum and average exposure scenarios, and use of half the detection limit for samples with nondetectable concentrations. The interim report had used a worst-case exposure scenario, and the value of the detection limit for samples with nondetectable concentrations. TABLE 1 highlights similarities and differences between the interim report and this addendum report. R&S145420 TABLE 1 COMPARISON OF THE 1990 INTERIM AND 1995 DRAFT ADDENDUM HEALTH RISK ASSESSMENT OF THE CLASS I UNIT OF THE B.K.K. LANDFILL, WEST COVINA, CALIFORNIA Section Hazard Identification Chemical of Primarv Concern Other Chemicals Defected in Ambient Air Toxicity Assessment Unit Risk Value Non-Cancer Health Effects 1990 Interim Report Vinyl chloride 7 known or suspected human carcinogens: vinyl chloride (known), benzene (known), trichloroethylene, perchloroethylene, chloroform, *1,1-dichloroethylene, and 1,2-dichloroethane 0.69 x 1Q'S perppb Estimated using Chronic Reference Doses 1995 Draft Addendum Report Vinyl chloride 6 known or suspected human carcinogens: vinyl chloride (known), benzene (known), trichloroethylene, perchioroethylene, chloroform and 1,2-dichloroethane 20x 10s perppb Not applicable Exposure Assessment Vinvl chloride monitorina data * South Coast Air Quality Management District (SCAQMD) * BKK Corporation Samples With Nondetected Concentrations Exoosure Scenariofsi Risk Characterization Individual Excess Lifetime Cancer Risk Population Excess Cancer Burden 1983-1987 Not applicable June 1981 - December 1982 January 1983 - March 1990 September 1993 - September 1994 Nondetected concentrations given a value equal to the detection limit Worst-Case (70 years) Nondetected concentrations given a value equal to 1/2 the detection limit Reasonably Maximally Exposed (30 years) Average Exposed Individual (9 years) Estimated at Station MY using 1987 ambient vinyl chloride monitoring data Estimated at Station A using 1982 - 1987 ambient vinyl chloride monitoring data Estimated for the 1962 Expanded Monitoring Program (ambient air) Estimated for the 1984 Extended Monitoring Program (indoor air) Estimated using the Air Resources Board model of 1987 vinyl chloride data Estimated for the population within 1 mile of the landfill (40,000 people) Estimated at Stations A, B and MY using SCAQMD and BKK monitoring data (1981 -1994) Discussed In Exposure Assessment section Updated risk calculation in Appendix G Modeling program discussed in Appendix F Not applicable * 1, 1-dichloroethylene is no longer classified as a suspected human carcinogen by the California Environmental Protection Agency no--- -2- DRAFT Typically, risk assessments required by regulatory agencies estimate current and future risk only. The methodology builds in overestimation of exposures to prevent underestimation of potential risks. Mitigation measures can then reduce current and future exposures if risk estimates are not acceptable. USEPA guidance for Superfund sites notes that "exposure assessments mav consider past, present, and future exposures. Current and past scenarios should be based on actual exposure conditions, future scenarios on potential exposure conditions. Typically. Superfund risk assessments focus on current and future exposures, but past exposures mav be important for selected sites" (USEPA. 1989b). The guidance recommends the Agency for Toxic Substances and Disease Registry (ATSDR) take the I ad in evaluating current health effects from past exposures. ATSDR, created in 1980, is the federal agency authorized to conduct public health assessments at sites subject to the Resource Conservation and Recovery Act (RCRA). ATSDR defines a public health assessment as "an evaluation of environmental contamination data, community health concerns, and health outcome data" (ATSDR, 1994). Of 69 public health assessments completed by ATSDR in 1994, approximately half were for sites with documented past exposure. The B.K.K. Landfill is not a Superfund site. The closed Class I Unit of the landfill is under RCRA permit. The Assistant Administer for ATSDR visited the landfill in 1984, when subsurface landfill gas migrated from the Class I Unit and triggered the emergency evacuation of 19 homes along the southern border (ATSDR, 1984). Because the duration of exposure to subsurface landfill gas was determined not to have exceeded seven years (the age of the affected homes) an epidemiologic study was not indicated at that time, and DHS continued as the lead agency for health issues. Of concern regarding the B.K.K. Landfill are the following: - Ambient air exposures are to vinyl chloride, a known human carcinogen; vinyl chloride is one of the few chemicals for which there are both human and experimental animal studies; - Vinyl chloride is clearly associated with the closed Class I Unit of the landfill; wastes containing vinyl chloride were deposited in the Class I Unit until June 1981; - Vinyl chloride is without detectable background contribution in the South Coast air basin. OEHHA's health risk assessment is possible because vinyl chloride was monitored in residential neighborhoods (Stations A, B, and MV) almost daily for nearly a decade. Monitoring in residential neighborhoods eliminates the uncertainty associated with extrapolating from onsite to offsite locations. As technology advanced, the detection limit of vinyl chloride was lowered, and the data consistently met internal quality control/quality assurance guidelines for the agency. The scope of this addendum report is more refined than was the scope of the iriterim report The refinement is due primarily to the iterative nature of risk assessments, and also to some changes in recommended guidance. The interim report was based on the exposure R&S 145422 DRAFT -3- D RAFT characterization (CH2M Hill, 1988), and estimated excess cancer risk for individuals living within a one-mile radius of the landfill, using data from four air monitoring programs (collected between 1982-1987) and one air modeling program, and a 70-year (worst-case) exposure scenario. Congruent with the iterative nature of risk assessments, this addendum report focuses on exposures associated with detections of vinyl chloride at Stations A, B, and MY because these locations, southeast and south of the closed Class I Unit of the B.K.K. Landfill, have been identified as the most impacted residential neighborhoods, and long-term monitoring data are available,. Exposures occurred at other residential locations around the landfill. However, detected concentrations of vinyl chloride at other residential locations around the landfill were neither as high nor as frequent as detected concentrations at Stations A, B, and MY, and long-term monitoring are not available for the other locations. This addendum report assumes exposures at Stations A, B, and MY began in 1980 because residential development near Stations A, B, and MY was completed in 1979. Long-term ambient vinyl chloride monitoring began in June 1981 Only ambient (outdoor) fugitive emissions from the closed Class I Unit are evaluated in this addendum report. Complete characterization of the air pathway would also include a simultaneous program of indoor air monitoring, reflecting exposure, if any, through subsurface landfill gas migration, and other effects that may make ambient and indoor concentrations differ. Subsurface landfill gas did migrate from the landfill in 1984, and a limited indoor air sampling program was conducted in selected homes. The limited indoor air sampling data is not included in the risk characterization of the long-term ambient vinyl chloride monitoring data because the short-term nature of the indoor monitoring is not compatible with the long-term monitoring. However, an updated risk estimate for the short-term exposure that occurred in 1984 is presented in Appendix G. At this time, there is no evidence that subsurface landfill gas migration is a problem for homes in close proximity to the landfill. Exposures to additional hazardous chemicals were documented in the first health risk assessment of the B.K.K. Landfill (DHS-ARB-South Coast Air Quality Management District [SCAQMD], 1983). These data and other data are evaluated in this addendum report. Previous Health Risk Assessments of the B.K.K. Landfill The first health risk assessment of the B.K.K. Landfill was conducted as a tri-agency study by DHS-ARB-SCAQMD and released in 1983 (DHS-ARB-SCAQMD, 1983). The study estimated excess lifetime cancer risk associated with exposures to concentrations of seven chemicals detected in ambient air at five locations around the landfill and one background location between July 19 to October 15,1982. Exposures were assumed to have begun in 1976, when the county building inspector began to approve dwellings for occupancy near the landfill (DHSARB-SCAQMD Appendix, 1983). The excess cancer risk for the limited time period was estimated to be approximately 5 x 10*5. The second health risk assessment conducted by the state was the interim health risk assessment (DHS-HWTS, 1990). In 1985, DHS initiated three health studies in response to residents' concerns: a cancer study, a health risk assessment, and a reproductive outcomes study. At a public meeting in December 1990, the cancer study, completed in two parts (Mack and Thomas, 1985; Mack and Pinder, 1988), the interim health risk assessment, and an initial pregnancy outcomes study (Rust et a/., 1988) were released. A fact sheet summarizing the findings of the two-part cancer study and the interim health risk assessment was made R&S145423 DRAFT -4- DRAFT available for residents (DHS-EETB, 1990). A copy of the fact sheet is contained in Appendix B. The two-part cancer study investigated cases of cancer diagnosed in residents who lived near the landfill between January 1972 through December 1982. The two-part study found no overall increase in the cancer rate among residents in the 11 census tracts studied, and no consistent pattern of occurrence to suggest that the B.K.K. Landfill was linked to individual types of cancer. Limitations of the study were explained in the fact sheet (se Appendix B). The interim health risk assessment estimated the theoretical probability of developing cancer for residents living near the landfill from exposure primarily to vinyl chloride in ambient air through 1987. The risk was estimated to be approximately 1 to 2 x 10"5. The study of pregnancy outcomes in the 1978-1984 birth cohorts found elevated rates for some pregnancy outcomes (very low birth weight [less than 1,500 grams] and neonatal mortality [death in the first 28 days of life]). The findings of the pregnancy outcomes study stimulated a more comprehensive investigation by DHS, and that study is currently in the process of being completed. The B.K.K. Corporation has completed three health risk assessments of the landfill, and is in the process of conducting one under the directive of the USEPA. The first two were prepared in 1986 as declarations filed in Superior Court of the County of Los Angeles on behalf of the B.K.K. Corporation. Those assessments recalculated the excess cancer risk associated with the seven chemicals detected in the 1983 tri-agency report, for the exposure period 19781985. In one report (Crump, 1986), the risk was estimated to be 0.25 x 10'5 (maximum likelihood estimate) and 1.1 x 10'5 (upper 95 percent confidence limit estimate); ip the other report (Bogen and Smith, 1986), the. risk was estimated to be 1.7 x 10"5 ("best" [50th percentile] estimate using a Monte Carlo analysis). A copy of each assessment was attached as appendices to the interim report The third health risk assessment, prepared by ENVIRON Corporation in 1991 in fulfillment of the Air Toxics "Hot Spots" Information and Assessment Act (AB 2588) of 1987, is being reviewed by SCAQMD (ENVIRON Corporation, 1991). The "AB 2588" risk assessment is a regulatory risk assessment, which means that its purpose was to estimate current and future risks associated with the landfill (California Air Pollution Control Officers Association [CAPCOA], 1991). As per the Health and Safety Code Section 44361, OEHHA-Air Toxicology and Epidemiology Section (ATES) reviewed the AB 2588 risk assessment and submitted its comments to SCAQMD (OEHHA, 1993). The current health risk assessment required by USEPA will be based on a one-year ambient air sampling program of 19 volatile organic compounds, including vinyl chloride, at onsite and offsite locations (B.K.K. Corporation et ai, 1994). Organizational Changes in the Department of Health Services Since the 1990 Interim Report In July 1991, Governor Wilson created Cal/EPA. HWTS, which prepared the interim report, was moved from DHS to Cal/EPA. The Health Hazard Assessment Division of DHS became OEHHA. This addendum health risk assessment is prepared by OEHHA-HWTS. The Environmental Epidemiology and Toxicology Branch (EETB) of DHS is now the Environmental Health Investigations Branch (EHIB), in the Division of Environmental and Occupational Disease Control (DEODC) of DHS. EHIB is completing the more comprehensive reproductive outcomes study. R&S145424 DRAFT -5- D R AFT Appendic s to th Draft Addendum Health Risk Ass ssment Appendices to this report contain the following: Appendix C, updated toxicity information for carcinogens detected in environmental media around the landfill and reported in the 1988 xposure characterization (CH2M Hill, 1988); Appendix D, statistical evaluation of the 1983-1990 ambient vinyl chloride monitoring data collected by SCAQMD; Appendix E, 1990 population census tract data for the vicinity of tbe landfill; Appendix F, an air dispersion mod I of the 1983-1990 ambient vinyl chloride monitoring data; Appendix G, updated risk estimates for the 1984 indoor air monitoring program evaluated in the interim report; and Appendix H, a copy of a letter from DHS-Cancer Surveillance Section regarding review of recent tumor incidence data. FIGURE 1 and FIGURE 2, from the interim report, show the location of the B.K.K. Landfill and the closed Class I Unit, respectively. R&S145425 DRAFT -6- \ DRAFT FIGURE 1 R&S145426 Source: Environmental Solutions, Inc., Figure 1.1, "BQC Landfill Site Assessment end Mitigation Work Plan. Book I. Subsurface: Site Characterization," March 15. 1988, p- 1*2. DRAFT -7- DRAFT FIGURE 2 S o u rc e : E n v ir o n a tn ta l S o lu tio n s , I n c . , F ig u re 1 .8 . "BKX L a n d f i l l S ite A eeeeaaant and M it ig a t io n Work F la n , Book I , S u b su rfa ce : S ite C h a ra c te riz a tio n ," March 15. 198B, p. 1*16. Z.SKHS'SU HAZARD IDENTIFICATION This section provides information about vinyl chloride disposal in the Class I Unit, vinyl chloride emissions from the Class I Unit, other hazardous chemicals detected in ambient air around the landfill, and regulatory agencies involved with the landfill. Vinyl Chloride in the Class I Unit While other chemicals are known to be emitted from the B.K.K. Landfill, vinyl chloride is the chemical of concern because it is a known human carcinogen and has dearly been shown to be associated with the landfill. Rarely detected in ambient air in the South Coast air basin, vinyl chloride was monitored almost daily by SCAQMD at residential locations south of th landfill between June 1981 and March 1990. Emissions of vinyl chloride from the landfill are presumed to be due to two processes: biodegradation of buried wastes containing chlorinated hydrocarbons, and deposition of hazardous waste containing vinyl chloride in the Class I Unit. The landfill opened in 1963, approved by the City of West Covina and the Los Angeles Regional Water Quality Control Board (RWQCB). In 1972, the State passed the Hazardous Waste Control Act. The Act required wastes to be classified as "hazardous" or "nonhazardous." From 1972 until November 30,1984, the B.K.K. Landfill served as the primary commercial hazardous waste disposal site for the Los Angeles area. Records of hazardous waste disposal at the landfill date from 1975 (CH2M Hill, 1988). An estimate of the total amount of waste containing vinyl chloride deposited at the landfill has not been identified. Four facilities in the South Coast air basin handled vinyl chloride, and all four disposed of waste containing vinyl chloride in the Class I Unit at the B.K.K. Landfill (ARB, 1982a). Opening years of operations for the facilities were: Keysor-Century in Saugus, 1958; Stauffer Chemical in Carson, 1959 (closed in 1982); B.F. Goodrich Company in Carson, 1960 (closed in 1985); and Union Carbide in Torrance, 1972. Stauffer Chemical produced vinyl chloride until 1982 (ARB Part A, 1990; SCAQMD, 1983). Stauffer Chemical sent wastes from its ethylene dichloride and vinyl chloride operations to the Class I Unit from at least 1975 to mid-1981; in 1979, Stauffer disposed of approximately 50 tons of waste containing vinyl chloride and larger amounts of waste containing other halogenated compounds (ARB, 1983). Waste from its ethylene dichloride plant contained on the average 45 percent ethylene dichloride and 30 percent 1,1,2-trichloroethane (ARB, 1982b). These two chemicals can biodegrade to vinyl chloride (Vogel et a/., 1987). Seventy-two percent (72%) of the total 3.4 million tons of hazardous wastes deposited in the Class I Unit between 1975 and 1984 was liquid hazardous waste (CH2M Hill, 1988). Liquids were disposed of at the working face, buried in drums, or injected into a total of 96 boreholes drilled into buried waste. Injection well (borehole) records identify truckloads of ethylene dichloride waste deposited in 1975, 1978, and 1979 (CH2M Hill, 1988). Approximately 85 percent of accepted fluids were disposed of at the working face and 10 percent in the boreholes (The Janes Network, 1994). R&S145428 DRAFT -9- D R AFT FIGURE 3 is a graphic presentation of the tons of hazardous waste deposit d annually in the Class I Unit between January 1975, when records became available, and November 30, 1984, when the unit stopped accepting hazardous waste. Explanations for the dips in the figure are as follows: The dip in the figure for 1981 is attributed to the prohibition in June of waste containing vinyl chloride following the detection at the facility perimeter of vinyl chloride above the California ambient air quality standard of 10 ppb; The decline in 1984 is attributed to regulatory restrictions on the disposal of liquid wastes, and to the halting of hazardous waste disposal (except for asbestos) on November 30,1984. Vinyl Chloride Emissions From the Class I Unit The landfill gas collection system is one of the ongoing site activities which has reduced the frequency and level of vinyl chloride emissions over time. Gas collection wells and a pilot gas burner and venting system were initially installed at the B.K.K. Landfill in 1975 (CH2M Hill, 1988). In 1980, the system consisted of 15 wells and 2 gas flares. An accelerated gas control program was started in July 1984 after subsurface landfill gas migration triggered evacuation of 19 homes along the southern border of the landfill (see Appendix G). By 1985 the landfill gas collection system included approximately 100 vertical gas extraction wells, 150 perimeter gas control wells, 198 perimeter gas monitoring probes, 4 horizontal gas well systems, and 2 flare stations with a total of 8 gas flares. As of 1994, the system consists of approximately 2,053 vertical gas extraction wells, 317 horizontal gas extraction wells, 170 perimeter gas monitoring probes, and the 2 flare stations with a total of 10 flares. Some of the wells and probes are located on the Class III (nonhazardous) portion of the landfill. The Integrated Waste Management Board (IWMB) and SCAQMD monitor the landfill gas collection system. Maintenance of the cap on the closed Class I Unit is another factor in controlling fugitive emissions of vinyl chloride from the landfill. In 1992, B.K.K. Corporation and the Departm nt of Toxic Substances Control (DTSC) reached a settlement agreement for violations of state hazardous waste laws and regulations found during a 1990 inspection (Cal/EPA, 1992). Failure to properly maintain the cap, designed to prevent rainwater from leaking in and landfill gas from escaping out, constituted one of the violations. On June 28 and 29,1994, a multi agency team consisting of 17 representatives from USEPA, DTSC, SCAQMD, IWMB, and the Local Enforcement Agency (LEA, City of West Covina) inspected the closed Class I Unit in response to the LEA's concerns about continuous detections of vinyl chloride in ambient air. Grid sampling on the surface of the closed Class I Unit over the two days found a total of fifteen samples with readings of total hydrocarbons in excess of the instantaneous total hydrocarbon limit of 500 ppm (SCAQMD, 1994). The total hydrocarbon limit was established under SCAQMD's "District Rule 1150.1," adopted in 1985 for the purpose of reducing gaseous emissions from active landfills (SCAQMD, 1985). SCAQMD issued two Notices to Comply to staff of the B.K.K. Landfill for the elevated surface emissions; reinspection by SCAQMD two weeks later found the surface emissions in compliance. Although the B.K.K. Corporation has been working toward improving the vegetative and clay cover of the closed Class I Unit, conclusions of the multi-agency inspection included a recommendation for routine and consistent maintenance activities (USEPA, 1994a). R&S 145429 DRAFT -10- DRAFT FIGURE 3 TONS OF HAZARDOUS WASTE DEPOSITED IN B.K.K. LANDFILL WEST COVINA, CALIFORNIA 800000 700000 -- /\ 600000 -- 0) % j 500000 <zasa 5No 400000 X 300000 c |2 200000 +-* X---- -* 100000 -- .x Vx X _|---------------- ]-----------------!---------------- I- 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 Year R&S145430 Figure derived from Table 1.4 "BKK Landfill Site Assessment and Mitigation Work Plan, Book I, Subsurface: Site Characterization," Environmental Solutions, Inc., March 15,1988, pgs. 1-22 and 1-23. DRAFT -11- DRAFT Ambient air monitoring at the perimeter of the landfill for concentrations of total organic compounds and any toxic air contaminant (such as vinyl chloride) in the landfill gas control system was also required under SCAQMD's Rule 1150.1. Semiannual monitoring was required of the B.K.K. Corporation. Based on the Rule 1150.1 monitoring, the B.K.K. Corporation published a Proposition 65 Warning for detections of vinyl chloride along the southern perimeter of the landfill on August 29, 1993, in the San Gabriel Valley Tribune (B.K.K. Corporation, 1993b). (Proposition 65 is California legislation [Health and Safety Code Section 25249.5 et seqr.] regarding exposures and discharges of known carcinogens and reproductive toxicants. For carcinogens, Proposition 65 requires a warning for exposures in excess of an individual estimated cancer risk of 1 x 10 s. For vinyl chloride, the 1 x 1CT5 risk level of 3 micrograms per day under Proposition 65 regulations [California Code of Regulations, Title 22, Section 12705] equates to a concentration in air of 0.05 ppb.) In September 1993, the B.K.K. Corporation began a voluntary ambient air sampling program to collect data that would be used to refine the Proposition 65 warning (B.K.K. Corporation, 1993c). B.K.K. Corporation's Proposition 65 monitoring program evolved to include additional perimeter stations, dilution (residential) stations, and collocated (duplicate) stations, and increased the frequency of monitoring to every 12 to 14 days. The B.K.K. Corporation also sought to lower the detection limit for vinyl chloride (B.K.K. Corporation, 1993a). Since 1993, the B.K.K. Corporation reports achieving a detection limit varying from 0.005 to 0.010 ppb. USEPA has stated that the analytical procedure appears to be acceptable to USEPA and SCAQMD for the purposes of ambient air monitoring at the B.K.K. Landfill (USEPA, 1994e). Other Hazardous Chemicals Detected in Ambient Air The earliest ambient air monitoring data of the B.K.K. Landfill is contained in the 1980 report, "Second Interim Report, Investigation of Odorous and Volatile Compounds for BKK Class I Landfill Site in the City of West Covina," prepared by the University of Southern California (USC) for the B.K.K. Corporation. Vinyl chloride was not among the more than 20 compounds analyzed; benzene and chloroform were identified as the carcinogens of concern (USC, 1980). The data were collected during active, open-face hazardous waste disposal. They were reviewed by CH2M Hill in the exposure characterization report and found to have limitations and uncertainties in laboratory analytical accuracy and quality assurance which precluded their use as a primary data set to assess human exposure (CH2M Hill, 1988). The 1982 ambient air program conducted by the three agencies (DHS-ARB-SCAQMD, 1983) was designed to monitor nine compounds known or suspected to be human carcinogens. In addition to vinyl chloride, the following chemicals were monitored: benzene (also a known human carcinogen), chlorobenzene, trichloromethane (chloroform), 1,1-dichloroethene (vinylidene chloride), trans-1,2-dichloroethene, trichloroethene, perchloroethene, and 1,2-dichloroethane (ethylene dichloride). Trans-1,2-dichloroethene and chlorobenzene were not detected. Vinylidene chloride is no longer considered a carcinogen by Cal/EPA (Standards and Criteria Work Group, 1994). The carcinogens detected in 1982 have been detected in landfill gas at the inlets to the landfill flares. Data from flare emissions and source tests were reviewed by CH2M Hill in the exposure characterization (CH2M Hill, 1988). Flare emissions data were determined to be inadequate for use in exposure assessment because of lack of replicate sampling, split sampling, and simultaneous ambient air sampling. The source tests data were found to be R & S 145431 DRAFT -12- DRAFT inadequate because of limited sampling time (3-hour tests), which may not reflect a full 24-hour period. The carcinogens detected at Station A in 1982 are among 12 selected volatile organic compounds monitored by ARB and/or SCAQMD in the air toxics monitoring program, begun in 1985 (SCAQMD, 1987). The air toxics monitoring program provides information on background levels for the selected compounds in the Los Angeles air basin. Data from ARB's El Monte Station were included in the interim report because the El Monte Station appeared to be more representative of ambient air conditions around the B.K.K. Landfill. However, vinyl chloride and 1,2-dichloroethane were not monitored at the El Monte Station. Monitoring in 1985 at SCAQMD's Azusa Station, located approximately 3.5 miles to the north/northwest of the B.K.K. Landfill, included the six carcinogens also detected at Station A in 1982. These two data sets are discussed in the exposure assessment section of this addendum report. Regulatory Agencies Involved With the B.K.K. Landfill Regulatory agencies involved with permitted activities of the landfill are: the USEPA, for corrective actions at the entire 583*acre facility; DTSC, for the closed 170-acre Class I Unit; SCAQMD, for control of gaseous emissions from the facility; RWQCB, for discharges from the facility affecting groundwater or surface water; IWMB and the City of West Covina, for solid waste issues at the facility. ARB provides technical support to the agencies, as needed. R&S145432 DRAFT -13- DRAFT BLANK PAGE R&S145433 DRAFT -14- DRAFT TOXICITY ASSESSMENT This section explains the toxicity values used in the risk characterization, and adds information on how increased knowledge has lead to changes in the assessment of the carcinogenicity of vinyl chloride. Toxicity Values Toxicity values are numerical expressions of a chemical's dose-response relationship, that is, the amount of a chemical (dose) that induces an effect (response). Toxicity values are developed for noncarcinogenic and carcinogenic effects. Reference doses (RfDs) are used when exposure occurs by the ingestion route. Since the 1990 interim report, USEPA developed Reference Concentrations (RfCs) for exposures by the inhalation route. Both RfDs and RfCs are used as measures of a chemical's noncarcinogenic toxicity. RfDs and RfCs are not expressed as probabilities or risks but rather as thresholds below which it is unlikely that even sensitive populations will experience adverse health effects from exposure to a specific chemical. A slope factor is the upperbound estimate of the probability of a response per unit intake of a chemical over a lifetime, expressed in the units "(milligrams per kilogram per day [mg/kg-d])'1." The unit risk is the probability of a response per unit concentration of a substance in the medium where human contact occurs. Both the slope factor and the unit risk are measures of a chemical's carcinogenic activity. For ambient air exposures, the unit risk is an estimate of the probability of developing cancer as a result of daily exposure over 70 years to 1 ppb of a substance in air. The unit risk is expressed as "(ppb)4." Updated toxicity information for carcinogens detected in environmental media around the landfill is contained in Appendix C. History of the Assessment of Vinyl Chloride Toxicity Understanding of adverse health effects associated with exposure to vinyl chloride, and the "dose" necessary to induce the effects, has advanced over the years. Vinyl chloride is one of the few chemicals for which there are both epidemiologic studies and experimental animal data. The following chronology is presented to show the change over time of awareness about acute effects, chronic effects, carcinogenic effects, and developmental/reproductive effects. Vinyl chloride, a synthetic organic chemical, is a gas at ambient temperature and pressure, with a density twice that of air. First prepared in 1833, commercial preparation of vinyl chloride in the United States began in 1939 (United States Department of Labor [USDOL], 1974). The primary use of vinyl chloride is in the production of polyvinyl chloride (PVC). The industry is divided into three segments: monomer production, polymer production, and fabrication. Production of the monomer is a large-scale continuous process, involving only a few firms. Conversion to the polymer or copolymer is an incomplete batch process in which not all of the monomer is reacted (Bames, 1976). Until 1974, high exposures to workers occurred during R&S 145434 DRAFT -15- DRAFT vacuation of the residual monomer gas, and during cleaning of the polymerization tank walls. Current regulatory standards and manufacturing processes substantially reduce or eliminate worker exposure to vinyl chloride. Little exposure occurred in the fabrication segment of the industry, where the finished PVC product is made by extrusion, injection molding, and calendering processes. Initially, vinyl chloride was regarded as a material of low human toxicity. In the 1930s, its use as a surgical anesthetic was considered, with narcotic properties being seen at levels around 8,000,000-10,000,000 ppb. However, its high flammability, and the cardiac and circulatory disturbances noted in animals and humans, precluded its use in surgical anesthesia (Patty, 1987). Acute, narcotic effects from exposure to vinyl chloride were the initial toxic end points of concern. The first occupationally associated deaths attributed to vinyl chloride were reported in the literature in 1960 (Danziger, 1960). The deaths were attributed to inhalation of vinyl chloride, presumably at levels above 10,000,000 ppb. In 1961, an indication of a chronic hazard was observed primarily in workers who cleaned polymerization tank vessels. They experienced a wide range of symptoms which became known as "vinyl chloride disease" and included: Raynaud's phenomenon (fingers blanch and experience numbness and discomfort upon exposure to cold), acro-osteolysis (resorption of the terminal bones of the fingers and/or toes), joint and muscle pain, enhanced collagen deposition (the major protein of the white fibers of connective tissue, cartilage, and bone), stiffness of the hands, and scleroderma-like skin changes (thickening of the skin with adhesions to underlying tissue). These symptoms were observed at exposure levels below 50,000 ppb. Studies in the 1980s identified a role of the immune system in workers with vinyl chloride disease, and determined that susceptibility to vinyl chloride disease was increased in the presence of specific genes; the immunologic effects of vinyl chloride were observed in mice exposed to 10,000 ppb (ATSDR, 1993). No case of vinyl chloride disease has be n reported since 1974 (ATSDR, 1990). In 1974, three employees from one PVC manufacturing company in the United States were identified as having died from a rare type of liver cancer, angiosarcoma of the liver (Creech and Johnson, 1974; Falk et a/., 1974). A fact-finding investigation by the Occupational Safety and Health Administration (OSHA) uncovered additional deaths due to angiosarcoma of the liver among workers in three similar companies. Between 1961 and 1977,23 cases of liver angiosarcoma were reported among approximately 20,000 vinyl chloride workers in the United States (ARB Part B, 1990). Studies were undertaken worldwide (Sweden, England, Italy, Japan, Germany, Canada, Norway, France, and Russia) to assess mortality among workers exposed to vinyl chloride. By 1985, at least 17 epidemiologic studies relating vinyl chloride exposure to the incidence of various cancers had been completed. Most of the studies were a retrospective cohort design in which cases were identified 15 to 29 years after first exposure. Since monitoring of vinyl chloride was not routinely conducted before 1975, exposure concentrations were estimated based on job classification and length of employment. A worldwide registry of histologically confirmed cases of liver angiosarcoma resulting from exposure to vinyl chloride identified 120 cases between 1974 to 1986, of which at least 44 percent (53/120) were employed as polymerization tank wall cleaners (ATSDR, 1990). The worldwide registry, although R&S145435 DRAFT -16- DRAFT incomplete, tabulates information about cases known to have occurred in men exposed to vinyl chloride that have been reported by individual manufacturing companies, trad associations, and occupational health organizations in Europe, North America, and Japan (Forman etal., 1985). Studies in the 1980s examined additional types of cancer and noncancer effects. "Other cancers that have shown a statistically significant increase in mortality among vinyl chloride workers, in at least some studies, included cancer of the brain and central nervous system, the lung and respiratory tract, and the lymphatic/hematopoietic system" (ATSDR, 1993). The earliest experimental animal study on the carcinogenicity of vinyl chloride was report d in 1971 in a study of rats exposed by inhalation (Viola et al., 1971). Subsequent studies hav shown that "vinyl chloride is carcinogenic in mice, rats, and hamsters when given orally and by inhalation. Vinyl chloride has been found to cause tumors in a dose-related manner at several sites, including liver, lung and mammary gland. The oncogenic response appears to be a function of the site, vinyl chloride concentration, tumor type, species of animal, and route of administration" (ARB Part B, 1990). In the liver, different types of tumors (liver angiosarcoma, hepatocellular carcinoma) have been seen following inhalation exposures. Hepatocellular carcinomas were observed only in rats, and the incidence of this tumor was significantly elevated when exposures started early in life (Maltoni et al., 1981; Drew etal., 1983; Cogliano and Parker, 1992). Hepatocellular carcinoma was induced in one study when exposures were begun at eight months of age (Drew et al., 1983). A study in newborn and adult rats on th effect of age on induction of pre-neoplastic hepatic lesions showed a well defined period restricted to the early lifetime of the animals (approximately day 7 to 21) during which the liver is most sensitive to carcinogenic effects of vinyl chloride (Laib et al., 1985a; 1985b). Cancer is considered to be a multistage process wherein a healthy cell is transformed into a malignant one by a series of somatic mutations. The mechanisms by which vinyl chloride exerts its carcinogenic effects have been elucidated from studies in both cultured cells and experimental animals; vinyl chloride is metabolized to 2-chloroethylene oxide, which binds covalently to deoxyribonucleic acid (DNA) causing mutations (ATSDR, 1993; ARB Part B, 1990). Mathematical models derived from the multistage theory of carcinogenesis assist in estimating which stages in the process of tumor development are affected by a particular chemical. Effects on an early stage suggest the chemical "initiates" the cancer process (that is, that the chemical causes the initial event), while effects on a late stage suggest the chemical "promotes" tumor development. Both the epidemiologic (occupational) and experimental animal data indicate that vinyl chloride affects an early stage of carcinogenesis. Epidemiologic studies have found that workers exposed to vinyl chloride before age 25 (Wong et al., 1991) and between the ages of 25 and 34 (Chen and Blancato, 1989; Pirastu et al., 1990) had a higher risk of liver cancer death than workers exposed after age 35. In animal studies, "across all the species and endpoints examined, the evidence consistently suggests that vinyl chloride primarily affects the initial stage in tumor development," and to a lesser degree, contributes to late-stage tumor progression (Brown and Hoel, 1986). Exposure to vinyl chloride in the workplace environment was not controlled by any regulatory program during the 1940s and early 1950s. The first recommendations for an occupational exposure limit in the United States were issued in 1955 at a level of 500,000 ppb (Wu et al., 1989). Concern about the narcotic effects of vinyl chloride and the risk of developing acroosteolysis caused reduction in exposure limits in England in the 1960s (Forman etal., 1985). R&S145436 DRAFT 1 -17- DRAFT One estimate of typical exposures to vinyl chloride monomer among the more highly exposed work rs at polymerization plants is: 1,000,000 ppb prior to 1955; from 300,000 to 500,000 ppb during 1955 through 1970; and from 100,000 to 200,000 ppb during 1970 to 1974 (Wu et ai, 1989). In 1974, OSHA promulgated a 1,000 ppb occupational standard (USDOL, 1974). In the late 1970s, several studies were undertaken to determine whether there were any cases of liver angiosarcoma in residential neighborhoods adjacent to vinyl chloride production or polymerization facilities prior to occupational controls (Doll, 1988): a study in Sweden and the former Yugoslavia found none; a study in Great Britain found 1 over a 12-year period but exposure was not attributed to the facility because the individual lived near the plant for only 6 years; a study in New York found 4 cases over an 18-year period in people who lived within 1 mile of fabrication plants or a polymerization plant The cases in New York were diagnosed between 1958 and 1975, and occurred after 15 or more years of residence, suggesting an association with the facilities (Brady et ai, 1977). Doll notes that 'This disease [angiosarcoma of the liver] is normally so rare that, in the absence of specific exposure to one of the known causes (vinyl chloride, thorium dioxide, and arsenic in pesticides and medicines), the annual incidence is on the order of 1-2 x 10~7. In these circumstances the discovery of even one case in a man living close to a factory in which vinyl chloride was used in the days before exposure was tightly controlled, may be regarded as presumptive evidence of the effect of environmental pollution." It is reported that concentrations of vinyl chloride within one kilometer of plants handling vinyl chloride in 1975 were on the order of 10 to 40 ppb, which is one-ten thousandth of the estimated concentration that caused the observed occupational incidence (Doll, 1988; Baxter et ai, 1977). "Epidemiological studies of families of vinyl chloride workers or communities having vinyl chloride processing facilities suggested the possibility of an increased incidence of birth defects and spontaneous abortions among people at risk; however, subsequent reviews of these studies have concluded that there is inadequate evidence to link environmental or paternal exposure to vinyl chloride with birth defects or spontaneous abortions in humans" (ARB Part B, 1990). "Vinyl chloride crosses the placenta of experimental animals. Some data indicates it may act as a transplacental carcinogen" (ARB Part B, 1990). Studies in experimental animals have shown developmental toxicity consisting of decreased litter size and fetal weight, delayed ossification, and dilated ureters; however, these effects occurred at levels which also produced maternal toxicity, so it is not clear if the effects on the fetus are due to maternal toxicity or to vinyl chloride (ATSDR, 1993). Reproductive effects reported in male workers exposed to vinyl chloride are decreased sexual function (androgen levels) and libido; exposure levels were not given and concomitant exposure to other chemicals could not be ruled out in those studies (ATSDR, 1993). A study by Bi et ai of male rats exposed by inhalation to vinyl chloride found a statistically significant increase in damage of testicular seminiferous tubules at concentrations of 100,000 ppb; decreased testicular- and increased liver-to-body weight ratios at 100,000 ppb; and no observed adverse effects at 10,000 ppb (Bi et ai, 1985). USEPA, DTSC, and OEHHA developed an action level of 25 ppb for indoor air exposures to vinyl chloride near Operating Industries, Inc., a Superfund site in southern California, based on no observed adverse effects in rats at 10,000 ppb (Hiatt et ai, 1993). ATSDR developed a Minimum Risk Level (MRL) of 2 ppb for inhalation exposures of 15 to 364 days duration, based on the increased liver-tobody-weight ratio in rats (ATSDR, 1993). Vinyl chloride has been identified as a mutagen in bacteria, yeast, and animal systems. Workers exposed to less than 15,000 ppb, however, did not show higher levels of chromosome breaks or aberrations than those in the control group (ARB Part B, 1990). R&S145437 DRAFT -18- DRAFT N w Unit Risk Value and Proposition 65 OEHHA-ATES reviewed epidemiologic (occupational) studies and animal cancer bioassays for the purpose of developing a unit risk value for ARB as required by the Toxic Air Contaminant Program (Health and Safety Code Section 39650 et seq.). The unit risk was derived using the linearized multistage model (described in detail in ARB Part B, 1990). TABLE 2 lists the 95 percent upper confidence limits (UCLs) range of cancer risk estimates for vinyl chloride derived by OEHHA-ATES. Three values are shaded: - The high end of the range estimate; the theoretical, upperbound, individual (human) excess lifetime cancer risk of 20 x 10-6 per ppb, based on studies in female mice that developed lung carcinoma; - The low end of the range estimate; the theoretical, upperbound, individual (human) excess lifetime cancer risk of 2.5 x IQ'5 per ppb, based on studies in male workers who developed liver cancer only (liver angiosarcoma and primary liver cancer); and - The middle of the range estimate; the theoretical, upperbound, individual (human) excess lifetime cancer risk of 4.5 x 10's per ppb, based on combined studies in male workers who developed liver, brain, or lung cancers. A unit risk based only on human studies would range between 2.5 x 10`5 per ppb, for liver cancer only (liver angiosarcoma and primary liver cancer), and 4.5 x 10 s per ppb, for liver, brain, and lung cancers combined. OEHHA-ATES stated the "Evaluation of animal tumorigenicity data indicates that vinyl chloride's carcinogenic potency is dependent on sex, tumor site, and age of exposure. Taking all these factors into account, staff conclude that the best estimate to use in order to assure the public health is the top of the range of the animal UCLs of risk, 20 x lO"5 (ppb)*1" (ARB Part B, 1990). By using default conversion factors (that is, assuming an individual weighs 70 kilograms and breathes 20 cubic meters of air a day) and assuming daily lifetime exposure, the unit risk is equivalent to a slope factor of 0.27 (mg/kg-day)'1. Low dose extrapolation models other than the linearized multistage model would likely produce lower or higher estimates of cancer potency, depending on the assumptions used in the model (that is, a sublinear model would yield a lower estimate of cancer potency and a supralinear model would yield a higher estimate). Preference for use of the linearized multistage model in estimating the potency of vinyl chloride is consistent with the generally recognized mechanism of action by which vinyl chloride exerts its carcinogenic effects. In December 1990, ARB adopted the unit risk value for vinyl chloride recommended by OEHHA-ATES, and identified vinyl chloride as a toxic air contaminant. In 1992, OEHHA established 3 micrograms per day (pg/day) as the no significant risk level (NSRL) for vinyl chloride under Proposition 65. Proposition 65 is California legislation regarding exposures and discharges of known carcinogens and reproductive toxicants. For carcinogens, Proposition 65 requires a warning for exposures in excess of an individual estimated lifetime cancer risk of 1 x lO-5. The NSRL represents a daily intake level over a 70-year lifetime that is calculated to result in a risk of 1 x 10*5. The NSRL of 3 pg/day was derived from the unit risk value adopted by ARB, and equates to an ambient air level of 0.05 ppb vinyl chloride. R&S 145438 DRAFT -19- DRAFT TABLE 2 {Office of Environmental Health Hazard Assessment Air Toxicology and Epidemiology Section) RANK ORDERING OF ESTIMATES OF HUMAN RISK BY CATEGORY Rank Experiment S1raina/Speclest Sex Tumor Individuals^ Unit Riskc PPb"1 if Orew . 2 BT-9,15d 3 Bi 4 Drew 5 BT-9,15 6 BT-1,2 :'7 Waxweiler 8 Bi 9 Drew 10 Drew 11 BT-1,2 "12 WSjp&ler ':W Iw/iilSiiii sd/rat, female wi/rat, male fi/rat, female sd/rat, male sd/rat. female wi/rat, male fi/rat, female fi/rat, female sd/rat, female :>oc/humanym liver angiosarcoma liver angiosarcoma liver angiosarcoma liver angiosarcoma liver angiosarcoma lung angiosarcoma hepatocellular carcinoma mammary .m...a..m.'mary '.vavav.v.v.v.v.v.v.v.; 18.X10'6 13X10'5 8.4X10*5 6.5x10*5 4.9x10-5 4.5x1 O'5 4.4x1 O'5 4.2x1 O'5 3.7x1 O'5 2.8x1$#- a: SW - CDI Swiss, sd - Sprague-Dawley, wi - Wistar, fi - Fischer, oc - occupational cohort, b: Number of all individuals entered in the analysis, exposed and unexposed. c: Calculated as an upper confidence limit with units (mg/kg-d*^) and converted to units of concentration (ppb-"*) using default conversion factors. The unit risk is an estimate of the probability of being diagnosed with cancer as a result of daily exposure over 70 years to 1 pg/m3 of a substance in air. d. BT - Maltoni's Bentivoglio (Bologna, Italy) project on long-term carcinogenicity bioassays of vinyl chloride. Source: California Air Resources Board, "Technical Support Document, Part B, Proposed Identification of Vinyl Chloride as a Toxic Air Contaminant," October 1990, Stationary Source Division, Sacramento, California, pages 8-11. DRAFT eet'sns'std -20- DRAFT Young-Age Susceptibility to Vinyl Chlorid In 1989, V.J. Cogliano of USEPA described in a memorandum a new assessment of th cancer risk from vinyl chloride (USEPA, 1992b). Cogliano identified a public health concern for young-age susceptibility based on a sensitive period seen in rats exposed by inhalation to vinyl chloride (Maltoni etai, 1981; Drew etal., 1983; Laib etal., 1985a, 1985b). The studies in rats showed that the carcinogenic effects from exposure to vinyl chloride depend on both age at initial exposure and duration of exposure, and therefore, suggest that children may face higher risks than adults for exposures of a given duration. USEPA interprets the sensitive period seen in rats as relating to children aged 0-5. The incremental cancer risk from breathing vinyl chloride throughout the susceptible period may be equal and in addition to the cancer risk from breathing vinyl chloride throughout adulthood. This means that an individual exposed during the first six years of life (age 0-5) incurs the full conventional (70-year) lifetime of risk, and an individual exposed from birth for. 70 years incurs double the conventional lifetime risk. Short term exposures for adults over 30, however, cany less than the conventional lifetime risk, according to USEPA's interpretation of the experimental animal data. TABLE 3 shows USEPA's estimates of risk for initial 6-year (age 0-5) and subsequent 4-year (age 6-9, etc.) apportioned lifetime exposures to vinyl chloride. The risk values in TABLE 3 are based on USEPA's slope factor for vinyl chloride of 0.29 (mg/kg-d)'1, which equates to a unit risk of 23 x lO"5 per ppb. (Note that the USEPA slope factor is almost identical to the Cal/EPA slope factor of 0.27 [mg/kg-d]'1). USEPA's 1991 interim guidance for Superfund includes a brief note on Cogliano's method of assessing apportioned lifetime exposures to vinyl chloride in the discussion of toxicity values for short-term exposures (USEPA, 1991a). In 1992, Cogliano published his interpretations of the experimental animal data for vinyl chloride (Cogliano and Parker, 1992). The report concludes that vinyl chloride provides an example of a chemical for which both toxicologic and pharmacokinetic evidence exists to override the default assumption of an equal risk over a lifetime under all age exposure conditions, in the 1994 edition of its Health Effects Assessment Summary Tables (HEAST), USEPA emphasizes that the slope factor and unit risk values for vinyl chloride do not reflect state-of-the-art science for vinyl chloride (USEPA, 1994b; 1994c), indicating that they do not reflect young-age susceptibility as identified by Cogliano. In 1993, USEPA, DTSC, and OEHHA co-authored a presentation which applied the young-age susceptibility methodology to action levels for relocation criteria at Operating Industries, Inc., a Superfund site in southern California (Hiatt et a/., 1994). While there is good evidence that young animals are more susceptible to vinyl chloride, the assessment methodology used by USEPA is relatively new and has not been fully evaluated or accepted for use in this type of health risk assessment. As mentioned, the unit risk value developed by OEHHA (20 x 10"5 per ppb) accounts for age specific susceptibility, and is used in this addendum report. R&S145440 DRAFT -21- DRAFT TABLE 3 (United Stat s Environmental Protection Agency) UNITED STATES ENVIRONMENTAL PROTECTION AGENCY'S ESTIMATES OF RISK FOR APPORTIONED LIFETIME EXPOSURES TO VINYL CHLORIDE AT VARIOUS CONCENTRATIONS Estimated Excess Lifetime Cancer Risk to Humans From a 4 Year Exposure: Apportioned Lifetime Risk Aae* 0 to 5 6 to 9 10 to 13 14 to 17 18 to 21 1 ppm 2.3 E-1 5.8 E-2 4.6 E-2 3.5 E-2 2.3 E-2 100 DDb 2.3 E-2 5.8 E-3 4.6 E-3 3.5 E-3 2.3 E-3 10.DDb 2.3 E-3 5.8 E-4 4.6 E-4 3.5 E-4 2.3 E-4 1 DDb 2.3 E-4 5.8 E-5 4.6 E-5 3.5 E-5 2.3 E-5 0.1 DDb 2.3 E-5 5.8 E-6 4.6 E-6 3.5 E-6 2.3 E-6 0.2 DDb 4.6 E-5 1.2 E-5 9.3 E-6 7.0 E-6 4.6 E-6 * Age range during 4 year exposure period. Source: United States Environmental Protection Agency (USEPA), "Cancer Risk Estimates for Vinyl Chloride." Memorandum dated September 28, 1992 from Jim Cogliano, Chief, Carcinogen Assessment Statistics and Epidemiology Branch, Office of Health and Environmental Assessment, Washington, D.C., to Arnold Den, Science Advisor, Region IX, San Francisco, California, with September 26, 1989 memorandum attached. Risk estimates are based on USEPA's cancer slope factor for vinyl chloride of 0.29 (mg/kg-d)'1. DRAFT -22- D RAFT R&S145441 EXPOSURE ASSESSMENT This section reviews the types, frequency, magnitude, and duration of residential exposures to vinyl chloride from the B.K.K. Landfill based on ambient vinyl chloride monitoring data, activities at the landfill, and odor complaints from residents around the landfill. In this section, the ambient vinyl chloride monitoring data are divided into four periods: 1981-1982 data, 1983-1990 data, combined 1981-1990 data, and 1993-1994 data. The data collected during the decade of the 1980s are displayed several ways (tables, line graphs, combined graphs, frequency graphs) in order to view exposures from different perspectives. Exposures to other hazardous chemicals detected in ambient air are also evaluated in this section. Ambient Vinyl Chloride Monitoring Data 1981-1982 Data In October 1980, odor complaints from residents living near the landfill prompted SCAQMD to monitor for organic compounds in the vicinity of the facility; in May 1981, vinyl chloride was detected above the ambient air quality standard of 10 ppb (DHS-ARB-SCAQMD, 1983). In June 1981, SCAQMD began monitoring at six locations. TABLE 4 shows the number of days the ambient air quality standard was exceeded at each of the six locations, the maximum concentration detected at each of the six locations, and the number of valid sample days p r month (SCAQMD, 1982a). Twenty-four hour integrated bag samples were collected and analyzed by gas chromatograph-flame ionization with a detection limit of 10 ppb (SCAQMD, 1982b; 10 ppb is equivalent to 0.01 ppm). Residence 1 became Station A, located at th intersection of Mariena and Nogales Streets, 450 feet southeast of the landfill property line. Residence 2 became Station B, located on Lynn Court, immediately adjacent to the southern property line. FIGURE 4, from the interim report, shows the locations of Stations A and B. Monitoring continued at Stations A and B in 1982. The detection limit for vinyl chloride was lowered from 10 ppb to 2 ppb during the 90-day monitoring program conducted by the agencies, DHS-ARB-SCAQMD. The 1981-1982 data were reviewed in the exposure characterization report and deemed not to be useful for exposure assessment because of the detection limit of 10 ppb (CH2M Hill, 1988). They were not included in the interim report because of the change in the detection limit during the monitoring period. However, this addendum report spans long-term monitoring data in which the detection limit for vinvl chloride continues to be lowered as technology advances. Detections at or above the detection limits are assumed to be real detections in each monitoring period. FIGURE 5 shows the percent of days during 1981 and 1982 when vinyl chloride was detected above the ambient air quality standard of 10 ppb at Station A or B (ARB, 1983). Average annual concentrations in this addendum report are calculated using the arithmetic mean, rather than the geometric mean used in the interim report. USEPA considers "the arithmetic mean is appropriate regardless of the pattern of daily exposures over time or the type of statistical distribution that might best describe the sampling data. The geometric mean of a set of sampling results, however, bears no logical connection to the cumulative intake that R&S145442 RAFT -23- DRAFT TABLE 4 (S uth Coast Air Quality Management District) 1981 VINYL CHLORIDE CONCENTRATION, PPM AT BKK VICINITY LOCATION MONTHS DAYS1 Suburban Water Company 163 May June July Aug Septc 0 0 0 0 0 MAX* <01 <01 <01 <01 <01 DAYS OF VALID DATA 1 26 30 29 3 Suburban Water Company 164 June July Aug Sept 0 <01 21 0 <01 30 0 <01 29 0 <01 3 Residence 1 June 10 .03 July 9 .03 Aug 8 .03 Sept 5 .01 Oct 9 .04 Nov 9 .02 Dec 12 .02 25 30 29 22 30 24 29 Residence 2 June July Aug Sept Oct Nov Dec 14 9 12 9 12 11 7 .05 .02 .02 .03 .03 .03 .02 ' 25 30 29 22 30 24 29 Residence 3 June July 3 .01 0 <01 25 5 Residence 4 July Aug Sept 3. .01 9 .02 0 <01 25 29 3 a) Days - Number of days exceeding state standard, VC .01 ppm, 24-hour average. b) Max - Single highest daily average in ppm. c) Sampling was discontinued on Sept. 3, 1981 at all locations except at Residence 1 and 2. R&S145443 Source: South Coast Air Quality Management District, "Vinyl Chloride in the South Coast Air Basin, May 1982,' El Monte, California, p. 18. Note: PPM = Parts per million; 1 ppm = 1,000 parts per billion (ppb). DRAFT -24- D R AFT FIGURE 4 (CH2M Hill) LOCATION OF SOUTH COAST AIR QUALITY MANAGEMENT DISTRICT'S AMBIENT VINYL CHLORIDE MONITORING STATIONS A, B, AND MY | FIGURE 7; Air Monitoring Programs, BKK Landfill, West Covina, CA (Based on CH2MHIII Rg. 5-21 and Plat 15)1 R&S145444 Source:' CH2M Hill, "BKK Landfill Exposure Characterization Report, West Covina, California,' August IS, 1988, Volume I, p. 5-165 (Figure 5.21) and Volume II, Plate 15. DRAFT -25- DRAFT FIGURE S (Air Resources Board) 1981-1982 AMBIENT CONCENTRATIONS OF VINYL CHLORIDE NEAR BKK LANDFILL Source: Air Resources Board, Figure 1 of'Developments in the BKK Landfill Situation,' Memorandum dated January 12. 1983 from James J. Morgester, Chief, Enforcement Division to James Boyd, Executive Officer. Taken from BKK Landfill files, Stationary Source Division, Sacramento, California. DRAFT -26- D R AFT R & S 145445 would result from long-term contact with the site contaminants, and it may differ appreciably from - and be much lower than - the arithmetic mean" (USEPA, 1992a). Calculating average annual concentrations when a certain portion of the data are below the detection limit requires exchanging samples with nondetectable concentrations for a value. USEPA recommends substituting half the detection limit for samples with nondetectable concentrations (USEPA, 1989b). When more than half the data are samples with nondetectable concentrations, assigned values may result in biased or imprecise estimates (Homung and Reed, 1990). There is uncertainty associated with the substituted value since nondetected concentrations could range from zero to just below the detection limit. The "true" level cannot be known. TABLE 5 gives the monthly and annual arithmetic average concentrations of vinyl chloride at Stations A and B during 1981-1982. The data were collected for 16 of the 24 months. SCAQMD's detection limit between June 1981 through September 1982 was 10 ppb, and between October through December 1982, 2 ppb. Results of the data collected between October 16 and December 31,1982, were reported in terms of the ambient air quality standard (10 ppb) rather than the detection limit (2 ppb). Consequently, the number of samples with nondetectable concentrations in this portion of the data are likely over-reported. Approximately 60 percent of the data in 1981 and 80 percent of the data in 1982 were samples with nondetectable concentrations. Substituting a value of half the detection limit (that is, a value of 5 ppb) for samples with nondetectable concentrations in this data set may result in estimated average concentrations that artificially reflect the detection limit. When a value of 1 ppb (half the detection limit for the 1983-1990 data) is substituted in the 1981-1982 data, the estimated average annual concentrations for 1982 are more consistent with the 1983 averag annual concentrations. This suggests that 1 ppb is a more reasonable substitution valu for the 1981-1982 data. This assumption may underestimate exposures since some samples may have had concentrations of vinyl chloride below 10 ppb but above 2 ppb. In the 1983 data, the percent of samples with nondetectable concentrations at the detection limit of 2 ppb decreased to 53-56 percent. The average values in TABLE 5 were calculated using 1 ppb for samples with nondetectable concentrations. r &S 145446 DRAFT -27- D RAFT TABLE 5 1981-1982 AVERAGE VINYL CHLORIDE CONCENTRATIONS IN AMBIENT AIR (ppb) BKK LANDFILL, WEST COVINA, CALIFORNIA Station A Annual Average Station B Annual Average January February March April May June July August September October November December January February March April May June July August September October November December 1981 _ - -- 10.S 4.4 7.0 7.0 8.2 9.2 4.1 7^ '= -- -- -- 7.5 4.7 6.0 3.1 6.9 8.4 6.6 6.0 1982 2.0 2.5 2.5 -- -- -- 8.1 4.9 3.2 3.1 1.7 2.8 3.4 3.3 3.1 3.4 -- -- -- 1.0 2.2 1.9 3.5 2.1 5.0 2.8 Source: Letter regarding South Coast Air Quality Management District's continuous sampling and analysis project for vinyl chloride monomer. Letter dated April 9, 1982 from Edward Camarena, Director of Enforcement, Headquarters, South Coast Air Quality Management District, El Monte, to Mr. Joseph Pantalone, California Air Resources Board, Research Division, Sacramento, California. A value of 1 ppb was substituted for samples with nondetectable concentrations. Detection limits: 6/81-9/82, 10 ppb; 10/82-12/92, 2 ppb. R&S 145447 DRAFT -28- D R AFT 1983-1990 Data SCAQMD continued almost daily ambient air monitoring for vinyl chloride at residential Stations A and B with a detection limit of 2 ppb beginning in January 1983. On June 27, 1984, SCAQMD established Station MY, located on Myra Court, 150 feet southeast of the B.K.K. Landfill property line (FIGURE 4). SCAQMD continued monitoring for vinyl chloride at these three residential stations through March 1990. The detection limit for vinyl chloride changed during that period as follows: between 1983 through 1987, the detection limit was 2 ppb; from January 1988 through September 1989,1.4 ppb; and between October 1989 through March 1990, 2 ppb. Although SCAQMD's laboratory could achieve a lower detection limit in 1988, the time to process the analysis increased. SCAQMD considered the advantage of a quicker processing time outweighed the small increment in sensitivity, and so returned to using the 2 ppb detection limit. The three residential monitoring stations were dismantled after March 1990 because vinyl chloride was not detected at or above 2 ppb at any of the three stations for two consecutive months. Beginning in 1987, the frequency of samples with nondetectable concentrations was more than 50 percent at all 3 stations. Substituting the value of half the detection limits for samples with nondetectable concentrations beginning in 1987 may over estimate the average annual concentrations. TABLE 6 presents the average annual and maximum concentrations of vinyl chloride det cted at Stations A, B, and MY between January 1983 through March 1990. Average annual concentrations ("means") were calculated using three different values for samples with nondetectable concentrations: mean 1 assumed one-half the detection limits; mean 2 assumed zero ppb; mean 3 assumed the detection limits. Although Station MY operated for only the last 6 months of 1984, data collected at Station MY between August through December 1984 show 153 days of vinyl chloride monitoring, for which the average concentration was 5.43 ppb. FIGURE 6 displays the average annual concentrations of vinyl chloride detected at Stations A, B, and MY between January 1983 and March 1990. FIGURE 7 displays on a monthly basis the frequency of vinyl chloride detected at or above 2 ppb at Stations A, B, and MY. Appendix D contains a statistical evaluation of SCAQMD's 1983-1990 ambient vinyl chloride monitoring data. R&S145448 DRAFT -29- DRAFT TABLE 6 (Ogden Environmental and Energy Services Co., Inc.) 1983-1990 AVERAGE ANNUAL VINYL CHLORIDE CONCENTRATIONS (PPB) NEAR BKK LANDFILL 1983 1984 1985 1986 1987 1988 1989 1990(a) Monitoring Station A Max. Value Mean 1 Mean 2 19.0 21.0 16.0 11.0 7.0 7.4 2.4 1.0* 2.84 4.17 3.45 1.92 1.67 1.30 0.79 1.00* 2.32 3.76 3.02 1.26 0.94 0.77 0.03 0.00 Mean 3 3.37 4.57 3.87 2.58 2.40 1.83 1.56 2.00 Max. Value Monitoring Station B Mean 1 Mean 2 16.0 23.0 15.0 8.0 9.0 9.4 2.4 1.0* 2.98 3.93 2.29 1.33 1.16 0.76 0.78 1,00* 2.42 3.56 1.74 0.49 0.25 0.08 0.01 0.00 Mean 3 3.54 4.30 2.84 2.18 2.07 1.44 1.56 2.00 Max. Value Monitoring Station MY Mean 1 Mean 2 _. 20.0 14.0 15.0 15.0 3.6 2.2 5.36 3.02 2.60 2.48 0.92 1.04 - 5.07 2.57 2.04 2.10 0.21 0.07 Means 1, 2, and 3 calculated with the following assumptions regarding below detectable Vinyl Chloride measurements: Mean 1 - assume one-half detection limit. Mean 2 - assume zero ppb. Mean 3 - assume detection limit. For monitoring periods 1983-1987 and 1990, reported instrument detection limit was 2.0 ppb. For January 1988 through September 1989, detection limit was 1.4 ppb. (a) Data collected only in January. February, and March during 1990. * Ail nondetects (asterisks not in original report). Mean 3 . - 5.66 3.46 3.15 2.87 1.62 2.01 Source: "Table 4-3, Air Quality Modeling for the BKK Landfill Air Toxic Exposure Study," Ogden Environmental and Energy Services Co., Inc., November 1992, San Diego, California , pg. 32. Derived from South Coast Air Quality Management District's daily ambient vinyl chloride monitoring data, January 1983 through March 1990. Although Station MY operated for only the last 6 months of 1984, data collected at Station MY between August and December 1984 show 153 days of vinyl chloride monitoring, with an average concentration of 5.43 ppb. DRAFT 6trVSHSVb -30- DRA FIGURE 6 1983 -1990 AVERAGE ANNUAL VINYL CHLORIDE CONCENTRATIONS (PPB) NEAR BKK LANDFILL, WEST COVINA, CALIFORNIA _6 Year Source: Figure derived from Table 6 of this draft addendum report "1983-1990 Average Annual Vinyl Chloride Concentrations (ppb) Near BKK Landfill." The source for Table 6 was "Air Quality Modeling for the BKK Landfill Air Toxic Exposure Study," Ogden Environmental and Energy Service Co., Inc., November 1992, San Diego, California. The slight increase in 1990 reflects the fact that 1 ppb was substituted for nondetects in the data, and data was only collected in January, February, and March of 1990. gj Nondetected concentrations were given the value of half the detection limit. Detection limit: 1983-1987, 2 ppb; January 1988-September 1989, 1.4 ppb; October 1989-March 1990, 2 ppb. Si g DRAFT -31- DRAFT Frequency (%) FIGURE 7 FREQUENCY OF VINYL CHLORIDE DETECTED AT OR ABOVE 2 PPB, 1983-1990 BKK LANDFILL, WEST COVINA, CALIFORNIA Source: Figure derived from South Coast Air Quality Management District's ambient vinyl chloride monitoring data, January 1983 through March 1990. DRAFT -32- DRAFT R&S145451 Combined 1981-1990 Data TABLE 7 shows the number of samples with nondetectable concentrations per number of days sampled at Stations A, B, and MY for SCAQMD's combined 1981-1990 ambient vinyl chloride monitoring data. FIGURE 8 displays the frequency of vinyl chloride detected at or above the ambient air quality standard of 10 ppb at Stations A and B between 1981 through 1989. FIGURE 9 shows on a monthly basis the maximum measured vinyl chloride concentrations detected at Stations A, B, and MY between 1983 and 1990. The last year in which detections of vinyl chloride at or above 10 ppb occurred at each station are as follows: - at Station A, in 1986, once in January (10 ppb) and once in February (11 ppb); - at Station B, once in May 1985 (15 ppb); - at Station MY, nine days in 1988. (See also next data group for one detection above 10 ppb in June 1991.) Control measures at the landfill were effective in reducing vinyl chloride emissions over time. By 1989, vinyl chloride was detected at or above the detection limit of 2 ppb only 31 times at Station MY, 4 times at Station A, and once at Station B. During the first three months of 1990, vinyl chloride was only detected three times at or above 2 ppb; all three detections occurred at Station MY and in January. R&S145452 DRAFT -33- D R AFT TABLE 7 NUMBER OF SAMPLES WITH NONDETECTABLE VINYL CHLORIDE CONCENTRATIONS PER TOTAL NUMBER OF DAYS SAMPLED 1981-1990 SCAQMD AMBIENT VINYL CHLORIDE MONITORING DATA BKK LANDFILL, WEST COVINA, CALIFORNIA 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 # Non-. detects 116 181 134 123 137 222 246 240 345 88 Station A # Days Sampled 191 225 254 303 321 337 338 317 349 88 Percent % 60 80 53 41 43 66 73 76 99 100 # Nondetects 125 185 142 113 160 284 305 316 325 81 Station B #Days Sampled 191 224 252 304 289 338 335 327 326 81 Percent % 65 83 56 37 55 84 91 96 99 100 # Nondetects Station MY # Days Sampled Percent % - -- - -- - -- 90 307 29 152 344 44 191 345 55 180 329 55 312 344 91 85 88 97 SCAQMD = South Coast Air Quality Management District Detection Limits = 6/81-9/82, 10 ppb; 10/82-12/87, 2 ppb; 1/88 - 9/89,1.4 ppb; 10/89 - 3/90, 2 ppb. DRAFT FCbQf V SW -34- DRAFT FIGURE 8 FREQUENCY OF VINYL CHLORIDE DETECTED AT OR ABOVE 10 PPB, 1981-1989 BKK LANDFILL, WEST COVINA, CALIFORNIA Frequency Mar-90 Source: Figure derived from South Coast Air Quality Management District's ambient vinyl chloride monitoring data, January 1983 through March 1990. DRAFT frSt'SHS'SH -35- DRAFT FIGURES MAXIMUM MEASURED VINYL CHLORIDE LEVEL EACH MONTH, 1983-1990 BKK LANDFILL, WEST COVINA, CALIFORNIA Vinyl Chloride (ppb) Source: Figure derived from South Coast Air Quality Management District's ambient vinyl chloride monitoring data, January 1983 through March 1990. DRAFT -36- DRAFT 1993-1994 Data Between 1990, when SCAQMD discontinued the almost daily ambient monitoring for vinyl chloride at residential locations, and 1993, when the B.K.K. Corporation began the Proposition 65 ambi nt vinyl chloride monitoring every 12 to 14 days, data was collected under 2 regulatory programs: USEPA's Site Assessment and Mitigation (SAM) Workplan (Stirrat, 1991) and SCAQMD's Rule 1150.1. - Under an order issued by USEPA in 1986, the SAM workplan required the B.K.K. Corporation to determine the extent of contamination on and off the landfill. In the ambient air monitoring component of the workplan, samples were collected for a total of 33 days between December 1989 and August 1990, and analyzed for 20 volatile organic compounds. The detection limit for vinyl chloride was reported to be 0.1 ppb. Data for the station located at Myra Court showed that of the total 33 samples, vinyl chloride was detected in 21 samples as follows: above 0.1 ppb, 14 times; above 1 ppb, 5 times; above 2 ppb, twice, with a maximum detection of 2.73 ppb in June 1990 (Stirrat, 1990). USEPA's validation of the data concluded that the detected results and quantitation limits for vinyl chloride were estimates "and usable for limited purposes only"; additionally, "the detected results and quantitation limits for many of the target analytes in all samples were qualified as the laboratory did not run initial calibration curves" (ICF Technology Incorporated, 1992). - Ambient air monitoring required by SCAQMD's Rule 1150.1 found vinyl chloride at the southern perimeter of the landfill ("Nogales Street" station) at 10.2 ppb in June 1991; 1.38 ppb in January and 1.40 ppb in June, 1992; and 0.12 ppb in February 1993. Based on the ambient air data collected at the perimeter of the landfill under SCAQMD's Rule 1150.1, the B.K.K. Corporation published a warning in the San Gabriel Valley Tribune on August 29,1993, for detections of vinyl chloride above the Proposition 65 NSRL (B.K.K. Corporation, 1993b). During 1993-1994, the B.K.K. Corporation added several offsite stations to monitor concentrations, collected 24-hour ambient air samples every 12 to 14 days, and updated its Proposition 65 vinyl chloride monitoring data quarterly. TABLE 8 is B.K.K. Corporation's monitoring data for the peri d September 1993 through September 1994 (BKK Corporation, 1994). USEPA has stated that the analytical procedure appears to be acceptable to USEPA and SCAQMD, although not all of the data have been validated by a regulatory agency (USEPA, 1994e). FIGURE 10 shows the locations of the B.K.K. Corporation's Proposition 65 monitoring stations. Stations #3 ("Nogales End").and #6 ("Lynn Court") are perimeter monitoring stations located on the landfill. They are used to represent the locations of SCAQMD's residential monitoring Stations MY and B, respectively. This may overestimate exposures since some dilution in the ambient air concentration would be expected between the perimeter and the residential locations. Station #10 ("Amar-at-Nogales") is used to represent the location of SCAQMD's residential monitoring Station A. This may underestimate the exposure since Amar is south of Mariena on Nogales, where Station A had been located. The detection limit for B.K.K. Corporation's data varies from 0.005 to 0.010 ppb. In TABLE 8, only values above 0.005 ppb are detected concentrations. Samples with nondetectable concentrations are given a value of half the detection limit by the B.K.K. Corporation for each day and station. The number of samples with nondetectable concentrations per total number of days sampled at each of the three stations is as follows: #10, "Amar-at-Nogales" (Station A), 4 nondetects in 17 days sampled (18 percent); #6, "Lynn Court" (Station B), 13 nondetects in 28 days sampled (46 percent); and #3, "Nogales End" (Station MY), 12 nondetects in 35 days sampled (31 percent). R&S145456 DRAFT -37- DRAFT TABLE 8 (BKK Corporation) BKK LANDFILL PROPOSITION 65 VINYL CHLORIDE MONITORING PROGRAM Cumulative Average Last 12 Months (Parts per billion volume/volume) Sample Station & Location Sample Date 14-Sep-93 15-Sep-93 16-Sep-93 20-Sep-93 22-Sep-93 28-Sep-93 12-00-93 21-Oct-93 OS-Nov-93 IS-Nov-93 07-Dec-S3 16-Dec-93 29-Dec-93 11-Jan-94 25-Jan-94 03-Feb-94 11-Feb-94 16-Feb-94 OI-Mar-94 15-Mar-94 29-Mar-94 12-Apr-94 26-Apr-94 10-May-94 24-May-94 07-Jun-94 21-Jun-94 28-Jun-94 05-JUI-94 19-Jul-94 03-Aug-94 16-Aug-94 30-Aug-94 13-Sep-94 27-Sep-94 1 23 Microwave Azusa Nogales Tower Spillway End 4 NW Gate 5 West Borrow 6 L*fin Court 10 Amarat Nogales 11 Marlena 12 Melissa at Marcella 13 Miranda Fence 14 Loralne Street 0.0025 . 0.0560 0.0025 0.0030 0.0025 0.0025 0.0025 0.0025 0.0025 0.0140 0.0045 0.0035 0.0045 0.0030 0.0035 0.0045 0.0040 0.0035 0.0040 0.0040 0.0045 0.0050 0.0025 0.0025 0.0025 0.0025 0.0900 0.0025 0.0025 0.0030 0.0025 0.0025 0.0025 0.0025 0.0260 0.0250 0.0190 0.0040 0.0040 0.0260 0.0040 0.0130 0.0040 0.0030 0.0040 0.0760 0.0045 0.0025 0.0240 0.0025 0.0040 0.0035 1.4000 0.0025 0.0035 0.0025 0.0030 0.0025 0.0025 0.5100 0.7100 0.5800 0.0380 0.3200 0.1400 . 0.3400 0.2700 0.3300 0.3100 0.0250 0.0170 0.0050 0.5800 1.0000 0.3800 0.0050 0.0045 0.0045 0.0040 0.0073 0.0040 0.0150 0.0040 0.0290 0.0055 0.0035 0.0500 0.0660 0.0380 0.1800 0.4400 0.1900 0.0045 0.4100 0.5700 0.0025 0.0050 0.0025 0.0025 0.0030 0.0025 0.0025 0.0035 0.0045 0.0030 0.0040 0.0045 0.0140 0.0040 0.0090 0.0025 0.0025 0.0025 0.0025 0.0025 0.0150 0.0150 0.0140 0.0130 0.0025 0.0025 0.0035 0.0025 0.0030 0.0025 0.0025 0.0025 0.0025 0.1000 0.0470 0.0660 0.0700 0.0720 0.0660 0.0540 0.0060 0.0240 0.0370 0.0040 0.0040 0.0390 0.0040 0.0025 0.0260 0.0125 0.003S 0.0470 0.0610 0.0520 0.1600 0.0250 0.0620 0.0790 0.0035 0.0040 0.0045 OL0160 0.1600 0.0690 0.0590 0.0460 0.0520 0.0030 0.0040 0.0050 0.0770 0.1500 0.0050 0.0240 0.0580 0.0370 0.0035 0.0840 0.1100 0.0050 0.0650 0.0480 0.0560 -0.0035 0.0320 0.0690 0.0580 0.0490 0.0390 0.0210 0.0040 0.0035 0.0030 0.0940 0.0040 0.0035 0.0340 0.0380 0.0290 0.0035 0.0320 0.0260 0.0600 0.0120 0.0180 0.0180 0.0260 0.0150 0.0040 0.0860 0.0045 0.0640 0.0760 0.0040 0.0050 6.0055 0.0820 0.0035 0.0330 0.0310 0.0340 0.0050 0.0110 0.1000 0.0880 0.0050 0.0240 0.0450 0.0300 0.0590 0.0920 Walnut Village 0.0025 0.0035 0.0025 0.0025 0.0025 0.0030 0.0025 0.0025 0.0025 0.0035 0.0045 .0.0030 0.0040 0.0030 0.0040 0.0040 0.0045 0.0030 0.0045 0.0035 0.0045 0.0045 0.003O 0.0030 0.0030 0.0093 Avg. 24-hr Avg. ug/day No. Samples Risk 0.0063 0.33 29 1.3E-06 0.0158 0.82 31 3.2E-06 0.2S26 13.13 35 5.1E-05 0.0033 0.17 12 6.7E-07 0.0076 0.40 13 1.5E-06 0.0285 1.48 28 5.7E-06 0.0522 2.71 17 1.0E-05 0.0465 242 16 9.3E-06 0.0276 1.43 16 5.5E-06 0.0341 1.77 16 6.8E-06 0.0381 1.98 13 7.6E-06 ND ND 26 Source: 'BKK Landfill 3008(h) Consent Order, EPA Docket No. RCRA-09-89-0019, Monthly Progress Report for September 1994, Attachment: BKK Landfill Proposition 65 Vinyl Chloride Monitoring Program.* Letter dated October 7,1994, from Julia M. Bussey, Corporate Manager, Regulatory Affairs, BKK Corporation. Torrance, California to Ms. Carmen Santos, United States Environmental Protection Agency-Region IX, San Francisco, California. The detection limit varies from 0.005 to'O.QIOppb. Only values above 0.005 ppb are detected concentrations. Samples with nondetectable concentrations are given a value of half the detection limit by the B.K.K. Corporation for each day and station. The number of samples with nondetectable concentrations per total number of days sampled at the three stations is as follows: #10, "Amar-at-Nogales" (Station A), 4 nondetects in 17 days sampled (18%); #6, "Lynn Court* (Station B), 13 nondetects in 28 days sampled (46%); and #3, 'Nogales End" (Station MY), 12 nondetects in 35 days sampled (31%). DRAFT -38- DRAFT ^ ^ ~'J FIGURE 10 (B.K.K. Corporation-ENVIRON Corporation) Sgt'SHS'StJ CNV1RON " insel in HeoHh and Cnwonmenlai Science Proposition 65 Ambient Monitoring Station Locations Vinyl Chloride Study BKK Landfill West Covina, California _(>ConlroelJNumben>03^2747A_ JjT0ve* Hqur* Revised' Source: Memorandum dated December 21,19M, from ENVIRON Corporation M Ihe requeat of Julia M. Buttay, Corporate Manager, Regulatory Affaire, B.K.K. Corporation, Torrance, CaliTomla, to the Office of Environmental Health Haiard Assessment, Sacramento, California. O'! Site Activities Approximately 72 percent of the total 3.4 million tons of hazardous waste disposed of at the landfill between 1975 and 1984 was liquid hazardous waste (CH2M Hill, 1988). Four disposal methods were practiced between 1972 and 1984 (CH2M Hill, 1988): - Commingling: approximately 85 percent of accepted fluids were disposed of by this method between 1972 to May 1984 (The Janes Network, 1994); bulk liquid hazardous wastes were discharged into a cavity prepared in the daily working face and commingled with solid nonhazardous wastes at a ratio of approximately onepart liquid to two-parts refuse; - Solidification: from May 1984 through November 1984, hazardous and nonhazardous liquid wastes were mixed with soil on approximately 15 acres of th top of the Class I Unit prior to burial; gas condense generated onsite and contaminated groundwater from extraction wells were air stripped and then disposed of by this method until November 1987, at which time the leachate treatment plant began operating. - Drum disposal: from 1972 through 1984, closed drums were stacked on pallets then covered with soil to a total height of five feet; drums containing acid, alkaline, or solvent waste were separated from each other by unspecified distances; Injection wells: from 1975 through 1980, waste acids, cyanide solutions, and organic fluids were injected into 96 boreholes ("injection wells") drilled into the buried waste; these wells were 10 feet wide holes, 120 feet deep; approximately 10 percent of accepted fluids were disposed of by this method. In 1985.USEPA prepared an aerial photographic analysis of the B.K.K. Landfill (USEPA, 1985). Twelve photographs dating from 1964 through 1984 show the expansion of the landfill, and of the residential community to the south of the landfill. The focus of USEPA's analysis was the identification of surface drainage, seepage, leachate, disposal practices, point discharges, and vegetation damage at the landfill. Of the four disposal methods practiced at the landfill between 1972 and 1984, all but the injection well method can be seen in the photographs. Onsite disposal operations seen in the photographs include the working face/active disposal area, standing liquid, and the liquid waste disposal (solidification) area. The following figures are selected from USEPA's aerial analysis: FIGURE 11, October 20, 1980; FIGURE 12, September 2,1983; and FIGURE 13, June 15,1984. R&S145459 DRAFT -40- DRAFT FIGURE 11 (United States Environmental Protection Agency) BKK SANITARY LANDFILL, OCTOBER 20,1980 R&S145460 Source: "Aerial Photographic Analysis of the BKK Sanitary Landfill, West Covina, California," January 1985, United States Environmental Protection Agency, EPA Region 9, Environmental Monitoring Systems Laboratory, Las Vegas, Nevada, pg. 21. IS-AMD-8307a/3600. DRAFT -41- DRAFT J FIGURE 12 (United States Environmental Protection Agency) BKK SANITARY LANDFILL, SEPTEMBER 2,1983 R & S 145461 Source: "Aerial Photographic Analysis of the BKK Sanitary Landfill, West Covina, California," January 1985, United States Environmental Protection Agency, EPA Region 9. Environmental Monitoring Systems Laboratory, Las Vegas. Nevada, pg. 23. TS-AMD-8307a/3600. Note: Incinerator * Flare Station DRAFT -42- DRAFT FIGURE 13 (United States Environmental Protection Agency) BKK SANITARY LANDFILL, JUNE IS, 1984 R&S145462 Source: "Aerial Photographic Analysis of the BKK Sanitary landfill. West Covina, 'California," January 1985, United States Environmental Protection Agency, EPA Region 9, Environmental Monitoring Systems Laboratory, Las Vegas, Nevada, pg. 35. TS-AMD-8307a/3600. Note: Incinerator = Flare Station DRAFT -43- DRAFT Odor Complaints Data Complaints of odors emanating from the B.K.K. Landfill were lodged by residents to both SCAQMD and the City of West Covina as early as 1969 (CH2M Hill, 1988). While odors perse may not necessarily be hazardous, they indicate downwind receptors and suggest the potential for exposure when hazardous chemical contaminants are also present (Ziem and Davidoff, 1992). The first odor complaint recorded was in March 1969 to SCAQMD (SCAQMD, 1981). Odor complaints increased from 48 in 1971 to 57 in 1974. In 1974, the B.K.K. Corporation acknowledged complaints from residents situated to the north and northeast of the working face of the landfill (BKK Corporation, 1974). In 1979, B.K.K. Corporation contracted with the University of Southern California (USC) Environmental Engineering Program to investigate odors from the landfill. The study analyzed complaints received by the City during January 1,1978 through May 16,1979. The objectives of the study were to determine which areas were subject to odors, what climatological factors elicited an increase in complaints, identify sources of odor based on wind data, and select appropriate monitoring and sampling conditions for the next phase of the study. Results of USC's first interim report (USC, 1979) included the finding that of the 521 complaints received during the study period, a larger number were lodged during the initial four months of 1979 as compared to the same period in 1978. The majority of complaints were from residents of the "M" named streets, possibly because those residents were "closer to the working face of the B.K.K. Landfill" and at a "higher elevation consistent with the landfill" (USC, 1979). (It is assumed that the "M" named streets in the USC study included Miranda, Maria, Maureen, and Marlena Streets, developed in 1977. Marlena at Nogales Streets, location of future monitoring Station A, was developed by 1977; Lynn Court and Myra Court, locations of future monitoring Stations B and MY respectively, were developed in 1979 [City of West Covina, 1994].) USC's fmai report was released in February 1981 and concluded that odor problems were associated with the downslope air drainage into residential areas under nighttime meteorological conditions (USC, 1981). In 1980, the City Council directed city staff to scientifically measure odor emissions from the landfill, so the city contracted with Eutek Inc. Eutek's study included an analysis of odor complaints by month, day of week, and hour of the day. Complaints recorded on Sundays and after-hours suggested a mechanism for odor transport other than the working face. "M" and "L" named streets were more frequently affected by odors from the landfill (Eutek, 1981). DHS-DEODC analyzed odor complaints data in conjunction with its pending reproductive outcomes study. The frequency and distribution of over 4,000 odor complaints made between 1980 and 1985 indicate that topography and meteorology contributed to odor complaints (Kharrazi et al., 1993). FIGURE 14 is a three-dimensional map of the closed Class I Unit and the residential neighborhood one-mile south of the landfill. FIGURE 15 and FIGURE 16 show the location of odor complaints per housing unit for the periods 1980-1982 and 1984-1985, respectively. The 1983 tri-agency study, which monitored ambient vinyl chloride concentrations in the southeastern, southern, western, northern and eastern areas around the landfill, indicated that odors did predict the areas where highest detections of vinyl chloride occurred (DHS-ARB-SCAQMD, 1983). Updated census data for the residential community around the B.K.K. Landfill is presented in Appendix E of this report. R&S145463 DRAFT -44- D RAFT FIGURE 14 (Department of Health Services Division of Environmental and Occupational Disease Control) t'9i7SHS'8tl Courtesy of: Marlin Kharrazl, Ph.D., Tim Lomas, and Rachel Broadwln, California Department of Health Sendees, Division of Environmental and Occupational Disease Control, Environmental Heatlh Investloalions Branch Emeryville, California, April 1S94. DRAFT -45- DRAFT FIGURE 15 (Department of Health Services Division of Environmental and Occupational Disease Control) R&S145466 Courtesy of: Martin Kharrazi, Ph D , Tim Lomas, and Rachel Broadwin, California Department of Health Services, Division of Environmental and Occupational Disease Control, Environmental Health Investigations Branch, Emeryville, California, April 1994 DRAFT -46- D RA FT FIGURE 16 (Department of Health Services Division of Environmental and Occupational Disease Control) R&S145468 Courtesy of: Martin Kharrazi, Ph.D., Tim Lomas, and Rachel Broadwin, California Department of Health Services, Division of Environmental and Occupational Disease Control, Environmental Health Investigations Branch, Emeryville, California, April 1994 DRAFT -47- DRAFT Other Hazardous Ch micals Detected in Ambient Air As discussed in the Hazard Identification section of this report, the 1982 90-day ambient air monitoring program conducted by DHS-ARB-SCAQMD detected five other chemicals that are known or suspected to be human carcinogens: benzene (known), trichloroethylene, perchloroethylene, chloroform, and 1,2-dichloroethane (DHS-ARB-SCAQMD, 1983). Beginning in 1985, these chemicals were also monitored by ARB and/or SCAQMD as part of the air toxics monitoring program in the Los Angeles basin (SCAQMD, 1987). These data are not directly comparable because the data from the two sites were collected during two different years: Station A, in 1982 and Azusa Station, in 1985. Whether concentrations at Azusa Station were higher, lower, or the same in 1982 is not known. Consequently, there is insufficient information to estimate, in a manner similar to analysis of the ambient vinyl chloride monitoring data, risks associated with exposures to the other hazardous chemicals emitted from the Class I Unit of the B.K.K. Landfill. Use of flare data to project concentrations of the five other hazardous chemicals would involve additional assumptions, including extrapolation from the landfill to residential locations, and would not be consistent with USEPA's recommended guidance that past scenarios be based on actual exposure conditions (USEPA, 1989b). In 1995 OEHHA reviewed limited 1994-1995 ambient air monitoring data regarding potential exposures to future inhabitants of Walnut Village, a residential neighborhood proposed for development east of the B.K.K. Landfill in the City of Walnut. Ambient air levels of benzene, perchloroethylene, chloroform, and carbon tetrachloride monitored at the B.K.K. Corporation's Proposition 65 monitoring stations #1, located at the northeast comer of the facility, and #7, located offsite to the northeast (see FIGURE 10) were compared to levels of the same chemicals found at four of SCAQMD's air toxics monitoring stations (Burbank, Hawthorne, Anaheim, and Azusa). From the available data OEHHA concluded that potential health risks to future inhabitants of Walnut Village would not differ significantly from the potential health risks experienced by inhabitants of other similar areas of the Los Angeles basin exposed to ambient air contaminants (OEHHA, 1995). R&S145470 DRAFT -48- DRAFT BLANK PAGE R&S 145471 DRAFT -49- DRAFT RISK CHARACTERIZATION This section presents the assumptions used in the risk calculation, the individual excess lifetime cancer risk estimates, the exposed population, estimated excess lifetime cancer risks using different assumptions and methodology, limitations and uncertainties, and the findings of the 1995 addendum health risk assessment. The interim report included risk estimates based on exposure concentrations generated from ARB's modeling of 1987 vinyl chloride concentrations at Stations A, B, and MY (ARB Part A, 1990). In 1991, OEHHA and DHS attempted to refine the air dispersion model used in the interim report. However, the work showed that the B.K.K. Landfill was more complex than could be accounted for in air dispersion models approved for regulatory use in 1991. Appendix F contains information about the air dispersion model developed for this project, and the limitations and uncertainties.which precluded its use in this addendum report. This addendum report focuses on monitored data. Assumptions Regarding the Beginning of Exposures at Stations A, B, and MY There are no monitoring data to quantify exposures at Stations A, B, and MY prior to June 1981. Odor complaints data indicate residents were reporting odors from the landfill as early as 1969, and specifically, at HMB and "L" named streets southeast and south of the Class I Unit beginning in 1978. These odor complaints indicate areas of downwind impact and suggest emissions from the Class I Unit were reaching nearby residents. Homes near Station A were built by 1977, and near Stations B and MY, by 1979. Onsite disposal practices at the time included commingling (open-face disposal) of liquid hazardous wastes. It is assumed in this addendum report that exposures at Stations A. B. and MY began in 1980. Ascribing a value to exposures in 1980 at Stations A, B, and MY is done by looking at FIGURE 17. FIGURE 17 juxtaposes FIGURE 3 (tons of hazardous waste deposited in the landfill) with FIGURE 6 (average annual vinyl chloride concentrations in ppb detected between 1983 through 1990). The period of overlap is not long enough to determine if such a lag truly existed. By 1983, the landfill had been receiving wastes for 20 years. FIGURE 17 shows that: - No emissions of vinyl chloride could have occurred before 1963, the year the landfill opened; exactly when emissions of vinyl chloride began is not known; - The dip in the graph of hazardous waste deposited in 1981 is attributed to the prohibition of waste containing vinyl chloride after vinyl chloride was first detected above the ambient air quality standard of 10 ppb at the landfill perimeter; - The shapes of the curves of average annual concentrations of vinyl chloride at Stations A, B, and MY in FIGURE 17 and the estimated average annual concentrations at Stations A and B in 1981-1982 from TABLE 5 suggest exposures prior to 1981. R&S145472 DRAFT -50- DRAFT FIGURE 17 TONS OF HAZARDOUS WASTE DEPOSITED, AVERAGE ANNUAL VINYL CHLORIDE CONCENTRATIONS (PPB) B.K.K. LANDFILL, WEST COVINA, CALIFORNIA 800000 ^ 700000 .. 600000 | 500000 .. | 400000 .. 1 | 300000 - 200000 4-/ X 100000 .. 1 "1975 - 1976 . 1977 - Parts Per Billion 1963 1971 1972 130 acre BKK Landfill opened, approved by the City of West Covina and RWQCB BKK Landfill expanded to 583 acres State Hazardous Waste (HW) Control Act passed 40 acre Class 1 (HW) Landfill opened, permitted by DHS 1. Records of HW disposal at BKK begin Class I Landfill expands to 140 acres CO o h- r07 07 O^ CO CO CcMo o CD CD in 00 07 07 07 a> at o) |1 W astes containing vinyl chloride banned by DHS il Class I Landfill stopped accepting HW <D r- cd GO QO 00 07 07 07 1- ^ ^ l 1 Class 1 Landfill stopped accepting all waste 07 O 00 07 07 07 I 1 Class I Landfill capped and closed Juxtaposition of Figures 3, and 6 of this addendum report. This Figure is used to show that the shapes of the curves of average annual concentrations of vinyl chloride at Stations A, B, and MY and the estimated average annual concentrations at Stations A and B in 1981-1982 suggest exposures prior to 1981. Note: The increase in 1990 reflects the fact that 1 ppb was substituted for nondetects in the data, and that data were only collected for January, February, and March of 1990. DRAFT -51- D R AFT This information suggests that average annual concentrations of vinyl chloride in 1980 at Stations A, B, and MY were not likely zero. This addendum report assumes that average annual concentrations in 1980 at Stations A. B. and MY were 2 oob. This may underestimate exposures. Assumptions Regarding Ambient Vinyl Chloride Monitoring Data Estimates of the individual excess lifetime cancer risk are based on the assumption that ambient air concentrations of vinvl chloride represent indoor air exposures (USEPA. 1989a). The data used in the risk calculations are: SCAQMD's ambient vinyl chloride monitoring data from Stations A, B, and MY for the period June 1981 through March 1990; and the B.K.K. Corporation's Proposition 65 monitoring data from Stations "Amar-at Nogales," "Lynn Court," and "Nogales End" for the period September 1993-1994. The following assumptions are made regarding the data: 1981-1982 Data 1981-1982 average annual concentrations at Stations A and B are based on data collected for 7 of the 12 months in 1981, and 9 of the 12 months in 1982. The average concentrations for each set are assumed to be representative of a 12-month exposure (see TABLE 5); - Station MY, located 150 feet southeast of the landfill property line, was establish d in June 1984. Values for the period 1980-1982 are assumed to be at least equal to the average annual concentrations at Station A, located 450 feet southeast of the landfill property line (see FIGURE 4); - A value of 1 ppb is substituted for samples with nondetectable concentrations. (The detection limit between June 1981 through September 1982 was 10 ppb, and between October through December 1982,2 ppb.) 1983-1990 Data - The 1983 average annual concentration at Station MY is assumed to be 2.8 ppb, that is, at least equal to Station A's 1983 average annual concentration (see TABLE 6); - . The 1984 average annual concentration at Station MY is assumed to be 5.4 ppb, that is, the average concentration detected by SCAQMD between August through December at Station MY. The average concentration of the 5-month period is assumed to be representative of the 12-month exposure; - The detection limit between January 1983 through December 1987 was 2 ppb; between January 1988 through September 1989, 1.4 ppb; and between October 1989 through March 1990, 2 ppb. A value of one-half the detection limit is substituted for samples with nondetectable concentrations. DRAFT -52- DRAFT t 1993-1994 Data - It is assumed that the B.K.K. Corporation's Proposition 65 vinyl chloride monitoring data are acceptable for quantitative assessment; USEPA has stated that the analytical procedure appears to be acceptable to USEPA and SCAQMD, although not all of the data have been validated by a regulatory agency (USEPA, 1994e). The detection limit varied from 0.005 to 0.010 ppb (see TABLE 8); It is assumed that the B.K.K. Corporation's Proposition 65 monitoring stations "Amar-at-Nogales" (residential station), "Lynn Court" (perimeter station), and "Nogales End" (perimeter station) represent SCAQMD's Stations A, B, and MY respectively. Because of the difference in locations, this assumption may lead to an overestimation for Stations B and MY, and may lead to an underestimation for Station A; - Average annual concentrations for the 5-year period 1990-1994 are assumed to be equal to the average annual concentrations detected in the September 1993-1994 Proposition 65 monitoring; 1995-2009 Data - Average annual concentrations for the period 1995-2009 are assumed to remain the same as the September 1993-1994 average concentrations. Changes in site activities, corrective actions, and technological advancements over the 15-year period may invalidate this assumption. Individual Excess Lifetime Cancer Risk Estimates The "individual excess lifetime cancer risk" is an estimate of the risk for an individual above the background risk of developing cancer during a 70-year lifetime. In the United States, a new estimate of the normal background risk of developing cancer has been made since 1990 and it is greater than the value reported in the interim report (from approximately 1 in 3 individuals (DHS-HWTS, 1990) to 4 in 10 individuals (Miller et al., 1993); that is, approximately 40,000 in 100,000 individuals will develop cancer during their lifetime. Exposure Scenario The interim report estimated risk based on a "worst-case" exposure scenario. "Worst-case" represents a hypothetical individual and an extreme set of conditions, which will usually not be observed in an actual population. This addendum report estimates risks assuming a "reasonable maximum" exposure scenario and an "average" exposure scenario. USEPA defines the reasonable maximum exposure scenario as "the maximum exposure that is reasonably expected to occur at a site", and is intended to be a conservative estimate, well above the average yet within the range of possible exposures (USEPA, 1989a). R&S145475 DRAFT -53- DRAFT Only average concentrations and not upperbound (that is, the 95 percent upper confidence limit on the arithmetic average) concentrations are used in the risk equation. Because the monitoring stations were at th point of exposure, and samples with nondetectable concentrations were assigned the value of half the detection limits, it is assumed that these average concentrations can also be used in estimates of the reasonable maximum exposure. USEPA cites national statistics on the number of years an individual resides at one location, and indicates an upperbound (90th percentile) of 30 years and an average (50th percentile) of 9 years. USEPA recommends a 30-year exposure duration when calculating the reasonable maximum exposure and a 9-year exposure duration when calculating the average exposure. (USEPA, 1989a) Risk Equation The equation for the risk estimate is as follows: ECR where ECR Cvc YR EF UR LT = = = = = = Cvc x YR x EF x UR x 1/LT Excess lifetime cancer risk Concentration of vinyl chloride in.air (ppb) Years of residence associated with exposure Exposure factor, i.e., percent of time at home (80%) Unit risk value for vinyl chloride (20 x 10*5 per ppb) Human individual lifetime in years (70-years) The interim report estimated an individual excess lifetime cancer risk of 1 to 2 x 10*5, based on concentrations of vinyl chloride detected in SCAQMD ambient vinyl chloride monitoring data collected between 1982 through 1987, a worst-case exposure scenario (70 years residence), 80 percent time at home, and a unit risk value of 0.69 x 10*5 per ppb. TABLE 9 is the estimates of individual upperbound excess lifetime cancer risks of this add ndum report, assuming a reasonable maximum exposure scenario (30 years. 1980-2009). The estimates are based on concentrations of vinyl chloride detected at Stations A, B, and MY in SCAQMD data (June 1981 through March 1990) and the B.K.K. Corporation data (September 1993-1994), 80 percent time at.home, and the unit risk value of 20 x 10'5 per ppb. Exposure values have been rounded to two significant figures, and risk estimates to one significant figure. The individual excess lifetime cancer risk is estimated per a specified period in order to delineate the risk per exposure year(s). Years with higher exposure concentrations are associated with a greater portion of the lifetime risk. The cumulative risk is an estimate of the past risk incorporated into the current and future risk estimate. Using the assumptions and methodology of this risk characterization, the estimated excess cancer risks are: - at Station A, approximately 7 x 10*5; - at Station B, approximately 6 x 10'5; and - at Station MY approximately 9 x 10'5. These excess cancer risks mean that for an individual living from 1980 to 2009 near Station A, for example, the theoretical upperbound risk of developing cancer is increased from 0.4 (the background cancer risk in the United States) to 0.40007 as a result of exposure to emissions of vinyl chloride from the closed Class I Unit of the B.K.K. Landfill. R&S145476 DRAFT -54- DRAFT TABLE 9 INDIVIDUAL EXCESS LIFETIME CANCER RISKS FROM EXPOSURE TO AMBIENT FUGITIVE VINYL CHLORIDE EMISSIONS FROM THE CLASS I UNIT OF THE BKK LANDFILL, WEST COVINA, CALIFORNIA REASONABLE MAXIMUM EXPOSURE SCENARIO (30 YEARS) STATION EXPOSURE PERIOD CONCENTRATION (PPb) DURATION (yre) EXCESS RISK PER EXPOSURE PERIOD . CUMULATIVE EXCESS RISK A 1980* 2.0 1 5x10- 5x10- 1981 7.2 1 2x10' 2x10`5 1982 3.4 1 8x10- 3x10- 1983 2.8 1 6x10- 4x1 O' 1984 4.2 1 1x10`f 5x10' 1985 3.5 1 8x10" 5x10' 1986 1.9 1 4x10- 6x10* 1987 1.7 1 4x10-. 6x10' 1988 1.3 1 3x10" 6xio-5 1989 1990-1994 0.8 0.05 1 2x10* 5 6x10-7 7x10*5 7xio-5 1995-2009 0.05 15 2x10* 7x10* B 1980* 2.0 1 5x10- 5x10- 1981 6.0 1 1x1 O' 2x10* 1982 2.8 1 6x10-6 3x10" 1983 3.0 1 7x10" 3x10`5 1984 3.9 1 9x10`f 4x10* 1985 2.3 1 5x10- 5X10* 1986 1.3 1 3X10* 5x10*5 1987 1.2 1 3x10"f 5x10- 1988 0.8 1 2x10"f 5x10* 1989 0.8 1 2x10* 6x10* 1990-1994 0.03 5 3x10-7 6x10' 1995-2009 0.03 15 1x10" 6x10' MY 1960* 2.0 1981 7.2 1982 3.4 1983 2.8 1984 5.4 1985 5.4 1986 3.0 1987 2.6 1988 2.5 1989 0.9 1990-1994 0.25 1995-2009 0.25 1 5x10-f 1 2x10" 1 8x10-f 1 6x10" 1 1x1O' 1 ixio- 1 7x10-f 1 6x10- 1 6x10* 1 2x10-6 5 3x10-f 15 9x10* 5x10- 2x10* 3x10- 4x10- 5x10' 6x10* 7x10' 7x10' 8x10* 8x10' 8x10- 9x10' Calculated by ECR = Cve x YR x EF x UR x 1/LT where: ECR = Excess lifetime cancer risk Cvc = Concentration of vinyl chloride in air (ppb) YR = Years of residence associated with exposure EF = Exposure frequency, i.e., percent of time at home (80%) UR = Unit risk value for vinyl chloride (20x10-5[ppb]-1) 1/LT = Human lifetime (70 years) Exposure values have been rounded to two significant figures, and risk values, to one significant digit *1980 concentration = 2 ppb, assumed; no data available. 1981-1982 concentrations = SCAQMD ambient vinyl chloride monitoring data. Nondetected concentrations given the value of 1 ppb. 1983-1989 concentrations = SCAQMD ambient vinyl chloride monitoring data. Nondetected concentrations set at 1/2 the detection limit (detection limit 1983-1987, 2.0 ppb; detection limit 1988-9/89,1.4 ppb; detection limit 10/89-3/90, 2.0 ppb). 1990-1994 concentrations = B.K.K. Corporation's Proposition 65 Vinyl Chloride Monitoring Program, 9/93-9/94. Nondetected values set at 1/2 the detection limit The detection limit varied from 0.005 to 0.010 ppb. R&S145477 DRAFT -55- DRAFT Another way of expressing this excess cancer risk is: an individual living in the United States has a 40 percent (0.4) chance of developing cancer throughout a 70-year lifetime. For an individual living from 1980 to 2009 near Station A, there is an added 0.007 percent chance of developing cancer as a result of exposure to emissions of vinyl chloride from the closed Class I Unit of the B.K.K. Landfill. Assuming an average exposure scenario (9 years) and the average annual concentrations for the years 1981-1989 (the years of highest average annual concentrations), the estimated excess cancer risks are: - at Station A, 7x 10*5; - at Station B, 5 x lO"5; and - at Station MY, 8 x lO"5. The assumptions and methodology of this risk characterization suggest that: - The year 1981 was the year of highest risk, based on available monitoring data; - The majority of the excess lifetime cancer risk was incurred by 1983-1984; - Current and future estimates of risk associated with the B.K.K. Landfill which do not incorporate past exposures at Stations A, B, and MY would not fully characterize the risks potentially incurred by individuals who lived near those stations since 1980 (30 year exposure scenario), or during the decade of the 1980s (9-year exposure scenario). Exposed Population In addition to the individual excess lifetime cancer risk, health risk assessments may estimate the population excess cancer burden. The population excess cancer burden is an estimate of the excess number of cases of cancer that may occur in a defined population who ail have th same individual excess lifetime cancer risk. This addendum report does not estimate a population excess cancer burden because not all the population around the landfill were or are exposed to the concentrations of vinyl chloride detected at Stations A. B. and MY. and it is not possible to obtain a reliable estimate of exposure to other residents. The number of potentially exposed individuals near Stations A, B, and MY since 1980 or during the decade of the 1980s is unknown, but considered to be too small for the probability that even one excess case of cancer will develop as a result of exposure to emissions of vinyl chloride from the closed Class I Unit of the B.K.K. Landfill. As an example, there would need to be approximately 14,000 exposed individuals living near Station A between 1980 and 2009 for one excess case of cancer to develop, based on the individual excess lifetime cancer risk as estimated in this addendum report. Because the number of individuals near Station A is much smaller than 14,000, it is unlikely that excess cases of cancer will occur. However, each exposed individual may have an increased risk of developing cancer. Recently, DHS-Cancer Surveillance Section (DHS-CCS) reviewed the 1988-93 tumor incidence data for a one mile area around the landfill. DHS's review found no indication of increased cancer incidence (DHS-CSS, 1995; see Appendix H). Consequently, there is a need for a different way of evaluating the effect of the exposures at Stations A, B, and MY. Stratification of risks by year of exposure, as done in this addendum DRAFT -56- DRAFT R&S145478 report (see TABLE 9), accomplishes this by highlighting the different risks associated with exposures in and over time, namely: - Risks for individuals who have been living near Station A, B, or MY since 1980; - Risks for individuals who lived near Station A, B, or MY during the decade of the 1980s; and - Risks for individuals near Station A, B, or MY between 1990 and 2009. These different risks would not be evident in risk assessments which address only current and future risks. The stratification of risks by year of exposure is consistent with USEPA's position that past exposures may be important for selected sites (USEPA, 1989b). Estimated Excess Lifetime Cancer Risks Using Different Assumptions and Methodology TABLE tO shows the excess cancer risk at Station A, as an example, using different assumptions for time spent at home, the average annual concentration of vinyl chloride in 1980, the substituted value for samples with nondetectable concentrations in the 1981-1982 data, and the unit risk value. Time Spent At Home The interim report and this addendum report assumed individuals spend 80 percent of their time at home. USEPA assumes individuals spend 350 days per year at home, or 96 percent time at home (USEPA, 1991b). Using USEPA's percent time spent at home in the risk equation suggests slightly higher estimates of excess cancer risk: at Station A, for example, 8 x 10"5. There are also California-specific values. ARB funded a statewide survey of activity patterns for the purpose of obtaining representative data for modeling population exposures and designing appropriate monitoring strategies. Activity patterns of residents over 11 years of age were surveyed during 1987-1988 (ARB, 1991; Jenkins etal., 1992), and children 11 years and younger, during 1989-1990 (Phillips etal., 1991). Average data rather than frequency distributions were presented. Results showed that, on the average, Californians spend 87 percent of their time indoors, 7 percent in enclosed transit, and 6 percent outdoors. Of th 87 percent time indoors, 62 percent is spent as indoors at home for individuals over 11 years of age, and 76 percent, as indoors at home for children 11 years and younger. Using ARB's percent time spent at home suggests slightly lower estimates of excess cancer risk: at Station A, 5 x 10'5 using 62 % and 6 x 10`5 using 76%. These different assumptions regarding percent time spent at home suggest estimates of excess cancer risk which, at Station A, are approximately 29 percent below or 14 percent above the estimate obtained using the primary assumption in this addendum report for percent time spent at home (see TABLE 10). Average Annual Concentration in 1980 and Substituted Value for Samples With Nondetectable Concentrations in the 1981-1982 Data There is uncertainty associated with the average annual concentration assumed for exposures in 1980, and with the substituted value for samples with nondetectable concentrations. Nondetected concentrations could range from zero to just below the detection limit. 6 DRAFT -57- D RAFT TABLE 10 ESTIMATED EXCESS CANCER RISK AT STATION A USING DIFFERENT ASSUMPTIONS Different Time11 Assumptions Different Substituted11 Value Assumptions Different Unit Risk0 Assumptions Time Spent at Home Station A Average Annual Concentration 1980 Substituted Value for Samples with Non-Detectable Concentrations 1981-1982 Data Vinyl Chloride Unit Risk Cumulative Excess Cancer Risk* 1 ppb 1 ppb 1 ppb 1 ppb 20X10'* 20X10-* 20X10-* 20X10-* 5 XI O'* 6X10'* 7X10'* 8X10** 80% 2 ppb 80% 2 ppb 1 ppb 1 ppb 20X10-* 20 X Iff* 6X10** 8X1Q-* 0.9 XI O'* 1X10** * Note - Cumulative Excess Cancer Risk after replacement of shaded assumptions in column 1,2 or 3, but retaining ad other assumptions for 1983 to 2009 average annual concentrations as shown in TABLE 9. a 62% = for individuals over 11 years of age, taken from the Air Resources Board, "Activity Patterns of California Residents," Final Report, 1991, Research Division, Sacramento California; 76% = for children 11 years and younger, taken from Phillips, T.J., Jenkins, P.L., and Mulberg, E.J., "Children in California: Activity Patterns,and Presence of Pollutant Sources," 1991, Air Resources Board, Sacramento, California; 80% Office of Environmental Health Hazard Assessment (OEHHA) value; also assumed in "Health Risk Assessment of the B.K.K. Landfill, West Covina, California, Interim Report November 1990,* Department of Health Services-Hazardous Waste Toxicology Section, Emeryville, California; 96% United States Environmental Protection Agency value, taken from "Risk Assessment Guidance for Superfund; Volume I - Human Health Evaluation Manual, Supplemental Guidance, 'Standard Default Exposure Factors' Interim Final 1991, OSWER Directive: 9285. 6-03. Office of Emergency and Remedial Response, Toxics Integration Branch, Washington, D.C. b 0 ppb 1 ppb 2 ppb 5 ppb lowest possible value OEHHA's assumed value for samples with nondetectable concentrations of vinyl chloride in the 1981- 1982 data OEHHA's assumed average annual concentration of vinyl chloride at Station A in 1980, as described in the addendum report value based on half the detection limit for vinyl chloride in 1980 c 2.5 x 10'5 per ppb 4.5 x 10"* per ppb 20 x 10'5 per ppb value derived by OEHHA from a study of vinyl chloride workers who developed liver cancer value derived by OEHHA from combined studies of vinyl chloride workers who developed liver, brain, or lung cancers current unit risk value derived by OEHHA from a study in mice that developed lung cancer DRAFT -58- D R A FT R&S145480 Th "true" level cannot be known. The reasonable maximum exposure scenario as estimated in TABLE 9 assum s an average annual concentration in 1980 of 2 ppb, and the substituted value of 1 ppb for samples with nondetectable concentrations in the 1981-1982 data. If a value of 5 ppb (half the detection limit achievable in 1980-1982) were substituted for the average annual concentration in 1980 and for samples with nondetectable. concentrations in the 1981-1982 data, estimates of excess cancer risks are increased: at Station A, 8 x 10'5. If a value of zero were substituted for the average annual concentration in 1980 and for samples with nondetectable concentrations in the 1981-1982 data, estimates of excess cancer risks are decreased: at Station A, 6 x 10". These different assumptions regarding the average annual concentration in 1980 and the substituted value in the 1981-1982 data give estimates of excess cancer risk approximately 14 percent above or below estimates obtained using the primary assumption for the average annual concentration in 1980 and for samples with nondetectable concentrations in the 1981-1982 data (see TABLE 10). Unit Risk Values The Cal/EPA unit risk value of 20 x lO-5 per ppb is an upperbound estimate of the carcinogenic activity of vinyl chloride in humans, derived from studies in female mice that developed lung carcinoma. TABLE 2 also shows two unit risk values based only on human studies. The unit risk values derived from human data have the advantage that they do not have to incorporate an adjustment for interspecies variation. However, they have limitations which include use of studies of only male workers and use of estimates of exposure based on iob descriptions rather than actual exposure monitoring data. The unit risk value 2.5 x Itr5 per ppb is derived from studies of vinyl chloride workers who developed angiosarcoma of the liver; the unit risk I value derived from combined studies of vinyl chloride workers who developed liver, lung, or brain cancers is 4.5 x 10" per ppb. Assuming the unit risk value 2.5 x 10" per ppb, the excess cancer risks (calculated for the period 1980 to 2009, using the average annual concentrations shown in TABLE 9) decrease: at Station A, 0.9 x 10-. Assuming the unit risk value 4.5 x 10" per ppb, the excess cancer risk at Station A is 1 x lO-5. These different assumptions regarding the unit risk value suggest estimates of excess cancer risk approximately 87 percent lower than estimates assuming the current Cal/EPA unit risk value (see TABLE 10). Youno-Aae Susceptibility The methodology suggested by USEPA to estimate young-age susceptibility to vinyl chloride assumes that an individual exposed during the first six years of life (ages 0-5) incurs the full conventional (70-year) lifetime risk, and that an individual exposed from birth for 70 years incurs double the conventional lifetime risk. Young-age susceptibility does not mean that a child will develop cancer but that when the exposed child becomes an adult, her or his risk of developing cancer is increased. Although referred to in USEPA's guidance documents, the methodology for assessing young-age susceptibility is still pending final adoption by USEPA. Summary of Health Risk Assessments Conducted To-Date Regarding the B.K.K. Landfill TABLE 11 summarizes results of the health risk assessments conducted to-date regarding the B.K.K. Landfill. Different assumptions, methodologies, and data bases were used. Estimated risks associated with exposures to vinyl chloride range from 0.04 x 10`5 to 9 x 10`. DRAFT -59- DRAFT R&S145481 t TABLE 11 SUMMARY OF HEALTH RISK ASSESSMENTS OF THE BKK LANDFILL, WEST COVINA, CALIFORNIA Report Assumptions 1. "Ambient Air Monitoring and Health Risk Assessment for Suspect Human Carcinogens Around the BKK Landfill in West Covina" Department of Health Services(DHS)/Air Resources Board(ARB)/South Coast Air Quality Management District(SCAQMD), 1983 No dilution in measured concentrations at stations A, B, C, D, E, F Exposure for 24 hrs/day, 365 days/year, for the 7 years (1976-1982) 100% absorption in the lungs Exposure to 7 chemicals: vinyl chloride, benzene, trichloroethylene, perchloroethylene, 1,1-dlchloroethyiene, 1,2-diehloroelhane, and chloroform Unit risk for vinyl chloride 1.3 x 10f* per ppb 2. "Estimates of Carcinogenic Risk in the Vicinity of the BKK Landfill" K.S. Crump Co., 1986 Average air concentrations from 12 SCAQMD stations and 4 University of Southern California stations Exposure for 24 hrs/day, 365 days/year, for the 8 year period 1978-1985 Exposure to 7 chemicals (see above list) Unit risk value for vinyl chloride: 1 x 10*per ppb 3. 'Risk Assessment for Exposure to Ambient Air In the Vicinity of the BKK Landfill in West Covina, 1978-1985' Bogen and Smith, 1986 50% dilution In measured concentrations at stations A, 8, D, F Exposure for 15 hrs/day, 365 days/year, for the 7 years (1978-1985) 50% absorption In the lungs Exposure to 7 chemicals (see above list) Unit risk value for vinyl chloride: 1 x 10'*per ppb 4, "Health Risk Assessment of the BKK Landfill, West Covina, California, Interim Report" DHS-Hazardous Waste Toxicology Section (DHS-HWTS), 1990 No dilution in monitored concentrations at stations A, B, and MY; 1982-1987 SCAQMD data Exposure for 24 hrs/day, 292 days/year for 70 years 100% absorption in the lungs Exposure to vinyl chloride primarily Unit risk value for vinyl chloride: 0.69 x Iff9 per ppb 5. "Risk Assessment in Fulfillment of AB2588 Requirements for SCAQMD Facility No. 55449" ENVIRON, 1991 - Under review by SCAQMD - 6. "Draft Addendum Health Risk Assessment of Ambient Fugitive Vinyl Chloride Emissions from the Class 1 Unit of the BKK Landfill, West Covfna, California" Office of Environmental Health Hazard Assessment-HWTS, 1995 No dilution in monitored vinyl chloride concentrations at stations A, B, and MY: data sets: 1961-1982 SCAQMD; 1983-1990, SCAQMD; 1993-1994, BKK Corporation Exposure for 24 hrs/day, 292 days/year, for 30 years (1980 to 2009) Exposure to vinyl chloride primarily Unit risk for vinyl chloride: 20 x 10f5 per ppb Methods Individual excess lifetime cancer risk andpopulation excess cancer burden ' Maximum likelihood estimate (MLE) and upper 95% confidence limit estimate (UCL) Monte Carlo potency analysis method and Monte Carlo procedure; best estimate Worst case scenario; Individual excess lifetime cancer risk and population excess cancer burden Reasonable maximum exposure scenario; individual excess lifetime cancer risk Excess Cancer Risk 5x10* (all 7 chemicals) 0.25 x Iff5(MLE) 1.1 x10"*(UCL) (all 7 chemicals) 0.1 -0.2 x10 s (vinyl chloride) 1.7 x10 s (all 7 chemicals) 0.04 x10 s (vinyl chloride) 1 -2x10 s - Station A: 7x10'* Station B: 6 x 10"* Station MY: 9x Iff* DRAFT S8frSHS'8y -60- DRAFT Limitations and Uncertainti s The estimated risks calculated in this addendum report are upperbound estimates based on the assumptions, methodology, limitations, and uncertainties specified. Other methods (maximum likelihood estimates, best estimates, Monte Carlo estimates) may yield different risk estimates. Most of the assumptions used in this report tend to overestimate the risk. Normally, the actual risks from a site would be no more than, and likely less than (if not zero), the estimates given in this type of assessment. Limitations and uncertainties associated with the data and methodology of this addendum report are the following: Hazard Identification - Other hazardous chemicals known to be emitted from the B.K.K. Landfill include benzene (also a known human carcinogen), trichloroethylene, perchloroethylene, chloroform, and 1,2-dichloroethane. These chemicals were not quantitated to the same extent as vinyl chloride, and have also been detected in background air in the South Coast air basin. It is not possible with the available data to distinguish between the amount of those chemicals emitted from the Class I Unit of the B.K.K. Landfill and the amount found in ambient air from other sources. Toxicity Assessment - The unit risk value for vinyl chloride (20 x 10'5 per ppb) was estimated using the linear multistage model. This model extrapolates the incidence of the carcinogenic effect observed at high exposure levels, in this case, in the ppm range, to what may be expected at much lower exposure levels, in this case, more than 1,000 times lower (ppb). The unit risk value is the upperbound 95 percent confidence limit of the maximum likelihood estimate. This model may underestimate the unit risk value but is more likely to overestimate it. There is the possibility that the unit risk value is zero at low ppb levels; - The unit risk value is based on an animal study. Other values calculated from data obtained in occupational studies were lower. However, the occupational studies were only of male workers and the exposure levels were not actually measured; - There is evidence that very young animals are more susceptible to the carcinogenic effects of vinyl chloride. USEPA recommends age-attributable risk estimations for exposures to vinyl chloride. The unit risk value developed by OEHHA accounts for age specific susceptibility. Exposure Assessment - There are no ambient vinyl chloride monitoring data for the year 1980. It is an assumption of this addendum report that exposures at Stations A, B and MY began in 1980. Residential development near the monitoring stations was completed in 1979, and odor complaints data from 1978 to 1981 suggest that residents on the "M" and "L" named streets were subject to downwind exposures before the residential monitoring program began; R&S145483 DRAFT -61- D R AFT - The 1981-1982 ambient vinyl chloride monitoring data were collected for 16 of the 24 months, and the average concentrations of the available data for each year were assumed to be representative of a 12-month period. This may overestimate exposure; Results of the data collected between October 16 and December 31,1982 are available in terms of the ambient air quality standard (10 ppb) rather than the detection limit (2 ppb). Consequently, the number of samples with nondetectable concentrations in this portion of th'e data are likely over-reported. A value of 1 ppb was substituted for samples with nondetectable concentrations in the 1981-1982 data; this may underestimate exposure; - During the period 1983-1990, ambient air monitoring was conducted only in residential areas to the southeast and south of the landfill. These data may have identified the highest detectable ambient levels of vinyl chloride but they do not provide information for other residential areas around the landfill; - Monitoring at Station MY began in June 1984. Average annual concentrations at Station A for the years 1981 through 1983 are used to represent exposures at Station MY for those three years. This may underestimate exposures at Station MY because it is closer to the landfill than Station A and higher levels were consistently reported for Station MY when both stations were in service; - The majority of samples in SCAQMD's 1981-1989 ambient vinyl chloride monitoring data were samples with nondetectable concentrations (21 of 26 data sets, see TABLE 7). The substitution of 1 ppb for samples with nondetectable concentrations is likely to underestimate exposures in the 1981-1982 data since some of the samples may have had concentrations of vinyl chloride below 10 ppb but above 2 ppb. The substitution of 1 ppb for samples with nondetectable concentrations in the 1983-1989 data is likely to overestimate exposures; - The B.K.K. Corporation's 1993-1994 Proposition 65 monitoring data have not been fully validated by a regulatory agency, although the analytical procedure appears to be acceptable. Risk Characterization Using a substituted value greater than zero for samples with nondetectable concentrations yields an risk estimate that will always be above zero, whether there were actual exposures or not; - The assumption that 2 ppb is a reasonable estimate for an average annual concentration in 1980 may underestimate exposure because of the average annual concentrations of vinyl chloride at Stations A and B in 1983, and the estimated average annual concentrations of vinyl chloride at Stations A and B in 1981-1982; R&S145484 DRAFT -62- DRAFT Actual indoor air levels of vinyl chloride are not known. Indoor air monitoring was conducted only in October 1984 and only in ten homes along the southern border of the landfill. The assumption that ambient air and indoor air concentrations are equal may either underestimate or overestimate exposure; The length of residency and percent time at home are general assumptions which tend to overestimate exposures. They are not based on actual information from residents living near the monitoring stations. Findings ofthe Draft Addendum Health Risk Assessment This addendum health risk assessment provides an assessment of past, present, and future risks for individuals living near Stations A, B, and MY from exposures to ambient fugitive emissions of vinyl chloride associated with the closed Class I Unit of the B.K.K Landfill. There are four findings of this report: 1. From the available monitoring data, the single year of highest exposure to vinyl chloride was 1981. The maximum detected concentration of vinyl chloride at Station A in 1981 was 50 ppb, compared to 0.16 ppb in 1994. The average annual concentration at Station A in 1981 is estimated to have been 7.2 ppb, compared to an estimate of 0.05 ppb in 1994. For individuals who lived near Stations A, B, and MY during the 1980's, past exposures to vinyl chloride were higher than current exposures. The cumulative individual excess lifetime cancer risk suggests that for exposures beginning in 1980, the majority of the cancer risk was incurred by 1983-1984, and that there is little change (on the order of 15 to 22 percent) in the cumulative risk after 1986. f 2. The landfill gas collection system, which was expanded over time, and the cap covering the closed Class I Unit have been successful in lowering the frequency and level of vinyl chloride emissions to levels that pose little, if any, risk to nearby residents. 3. Regulatory agencies with responsibility for remediation or control of the B.K.K. Landfill may want to include past exposures of vinyl chloride near Stations A, B, and MY in subsequent health assessments of emissions from the landfill to ensure future risks do not add significantly to the past cumulative risk. 4. In spite of using best available scientific knowledge, there is considerable uncertainty associated with the estimated exposures, the carcinogenic potency value of vinyl chloride, and young-age susceptibility methodology. The estimated excess cancer risks calculated in this addendum report are upperbound estimates, based on the assumptions, methodology, limitations and uncertainties specified. The actual excess cancer risk is likely to be lower than these estimates and may be zero. Because the number of people who actually lived or are living near Stations A, B, and MY is small, it is unlikely that excess cases of cancer will occur. Each exposed individual may have an increased risk of developing cancer, however the added risk is small. R&S145485 DRAFT -63- DRAFT REFERENCES Agency for Toxic Substances and Disease Registry. (ATSDR, 1984).'Report of Site Visit to BKK Landfill, West Covina, California." Memorandum dated Septembers, 1984 from Vernon N. Houk, M.D., Assistant Administrator, ATSDR, to The Record, United States Department of Health and Human Services, Public Health Service, Atlanta, Georgia. Agency for Toxic Substances and Disease Registry. (ATSDR, 1990). "Case studies in environmental medicine: vinyl chloride toxicity." Clin. Toxicol.. 28(3):267-286. Agency for Toxic Substances and Disease Registry. (ATSDR, 1993). Toxicological Profile for Vinyl Chloride." United States Department of Health and Human Services, Public Health Service, Division of Toxicology/Toxicology Information Branch, Atlanta, Georgia. Agency for Toxic Substances and Disease Registry. (ATSDR, 1994). `FY1994 Agency Profile and Annual Report, October 1, 1993 to September 30, 1994."United States Department of Health and Human Services, Public Health Service, Atlanta, Georgia. Air Resources Board. (ARB, 1982a). South Coast Air Quality Management District Actions Toward Achievement of the Vinyl Chloride Ambient Air Quality Standard." Unpublished report. Enforcement Division, Sacramento, California. Air Resources Board. (ARB, 1982b). Portion of ARB's BKK Files, Stationary Source Division,. Sacramento, California. Air Resources Board. (ARB, 1983). "Developments in the BKK Landfill Situation." Memorandum dated January 12, 1983 from James J. Morgester, Chief, Enforcement Division, to James Boyd, Executive Officer, Sacramento, California. Air Resources Board. (ARB, 1990). Technical Support Document, Proposed Identification of Vinyl Chloride as a Toxic Air Contaminant," Parts A, B, C, and Executive Summary, October 1990. Stationary Source Division, Sacramento, California. Air Resources Board. (ARB, 1991). "Activity Patterns of California Residents." California Environmental Protection Agency, Research Division, Sacramento, California. Contract No. A6-177-33, Final Report. Baker, L.W. and MacKay, K.P. (1985). "Screening models for estimating toxic air pollution near a hazardous waste landfill." J. AirPollut. Control Assoc.. 35(11):1190-1195. Referenced in Acknowledgments, Barnes, A.W. (1976). "Vinyl chloride and the production of PVC." Proc. Rov. Soc. Med.. 69:277-281. Baxter, P.J., Anthony, P.P., MacSween, R.N.M., and Scheuer, P.J. (1977). "Angiosarcoma of the liver in Great Britain, 1963-73." Br. Med. J.. 2:919-921. Bi, W,, Wang, Y., Huang, M., and Meng, D. (1985). `Effect of vinyl chloride on testis in rats." Ecotoxico! and Environ. Safety. 10:281-289. B.K.K. Corporation (The B.K.K. Co.). (BKK, 1974). `Resident Complaints re Odors." Letter dated March 26,1974 from E.T. Winter, General Manager, to City of West Covina, Attention Hon. Nevin Browne, Councilman and City Engineer, Mr. George Zimmerman, West Covina, California. R&S145486 DRAFT -64- D R AFT B.K.K. Corporation. (1993a). `BKK Landfill 3008(h) Consent Order, EPA Docket No. RCRA-09-89-0019, Monthly Progress Report for March 1993, Attachment 1: Method Detection Limit Study for Vinyl Chloride in Air Using EPA Method TO-14 (GC/MS/SIM)." Letter dated April 8,1993 from Julia M. Bussey, Corporate Manager, Regulatory Affairs, Torrance, California to Ms. Carmen Santos, United States Environmental Protection Agency, Region IX, San Francisco, California. B.K.K. Corporation. (1993b). `Proposition 65 Warning.' San Gabriel Valiev Tribune. August 29,1993. B.K.K. Corporation. (1993c). `BKK Landfill 3008(h) Consent Order, EPA Docket No. RCRA-09-89-0019, Monthly Progress Report for September 1993." Letter dated October 8,1993 from Julia M. Bussey, Corporate Manager, Regulatory Affairs, Torrance, California to Ms. Carmen Santos, United States Environmental Protection Agency, Region IX, San Francisco, California. B.K.K. Corporation. (1994). `BKK Landfill 3008(h) Consent Order, EPA Docket No. RCRA-09-89-0019, Monthly Progress Report for September 1994, Attachment: BKK Landfill Proposition 65 Vinyl Chloride Monitoring Program." Letter Dated October 7,1994 from Julia M. Bussey, Corporate Manager, Regulatory Affairs, Torrance, California, to Ms. Carmen Santos, United States Environmental Protection Agency-Region IX, San Francisco, California. B.K.K. Corporation, RES Environmental Inc., and ENVIRON Corporation. (1994). `Ambient Air Sampling Plan, BKK Landfill, West Covina, California, Final Approved Version, October 7, 1994."Torrance, California. Bogen, K.T. and Smith, M.T. (1986). "Risk Assessment for Exposure to Ambient Air in the Vicinity of the B.K.K. Landfill in West Covina, 1978-1985. "Unpublished paper. Health Risk Associates, Berkeley, California. Brady, J., Liberatore, F., Harper, P., Greenwald, P., Burnett, W., Davies, J.N.P., Bishop, M., Polan, A., and Vianna, N. (1977). "Angiosarcoma of the liver an epidemiologic survey." J. Natl, Cancer Inst. 59(5):1383-1385. Brown, K.G. and Hoel, D.G. (1986). "Statistical modeling of animal bioassay data with variable dosing regimes: example - vinyl chloride." Risk Anal.. 6(2):155-166. California Air Pollution Control Officers Association. (CAPCOA, 1991). `Air Toxics `Hot Spots" Program: Risk Assessment Guidelines. ' California Air Pollution Control Officers Association, January. California Environmental Protection Agency. (Cal/EPA, 1992)."Cal/EPA Report, Vol. 1/No. 6, AugustSeptember 1992."Sacramento, California. Chen, C.W. and Blancato, J.N. (1989). "Incorporation of biological information in cancer risk assessment: example - vinyl chloride." Cell Biol, and Toxicol.. 5(4):417*444. City of West Covina. (1994). "Permit and Final Date of Construction." Memorandum dated March 10, 1994 from Dina Aman to Steven Samaniego, Waste Management Enforcement Manager, West Covina, California. CH2M Hill. (1988). "BKK Landfill Environmental Exposure Characterization Report, West Covina, California, Volume /."Santa Ana, California. Cogliano, V.J. and Parker, J.C. (1992). "Some implications of toxicology and pharmacokinetics for exposure assessment." J. Expo. Anal. Environ. Epidemiol.. Suppl. 1:189-207. Creech, J.L. and Johnson, M.N. (1974). "Angiosarcoma of liver in the manufacture of polyvinyl chloride." J. Occud. Med.. 16(3): 150-151. Crump, K.S. and Co. (1986). "Estimates of Carcinogenic Risk in the Vicinity of BKK Landfill." Unpublished paper. Ruston, Louisiana. R&S145487 DRAFT -65- DRAFT Danziger, H. (1960). "Accidental poisoning by vinyl chloride: report of two cases." Can. Med. A. J.. 82:828-830. Department of Health Services-Air Resources Board-South Coast Air Quality Management District. (DHS-ARB-SCAQMD, 1983>. 1Ambient Air Monitoring and Health Risk Assessment for Suspect Human Carcinogens Around the BKK Landfill in West Covina." Sacramento, California. Department of Health Services-Cancer Surveillance Section. (DHS-CSS, 1995). Letter dated Novembers, 1995 from Eva R. Glazer, M.D., M.P.H., Cancer Surveillance Section, Berkeley, California, to Robert L. Holtzer, M.D., Hazardous Waste Toxicology Section, Office of Environmental Health Hazard Assessment, Sacramento, California. Department of Health Services-Environmental Epidemiology and Toxicology Branch. (DHS-EETB, 1990). "December, 1990 Fact Sheet. BKK Landfill, West Covina, California." Emeryville, California. Department of Health Services-Hazardous Waste Toxicology Section. (DHS-HWTS, 1990). "Health Risk Assessment of the B.K.K. Landfill, West Covina, California, Interim Report, November 1990." Environmental Epidemiology and Toxicology Branch, Sacramento, California. Doll, R. (1988). "Effects of exposure to vinyl chloride, an assessment of the evidence." Scand. J. Work Environ. Health. 14:61-78. Drew, R.T., Boorman, G.A., Haseman, J.K., McConnell, E.E., Busey, W.M., and Moore, J.A. (1983). The effect of age and exposure duration on cancer induction by a known carcinogen in rats, mice, and hamsters." Toxicol. Aool. Pharmacol.. 68:120-130. Eutek Inc. (1981). "BKK Landfill Odor Study, Final Report." February 28,1981. Prepared for the City of West Covina by Eutek Inc. Sacramento, California. ENVIRON Corporation. (1991). "Risk Assessment in Fulfillment ofAS 2588 Requirements for SCAQMD Facility No. 55449. "Prepared for the B.K.K. Corporation, Torrance, California for submittal to South Coast Air Quality Management District, Engineering Division-Toxics Unit, Diamond Bar, California, by ENVIRON Corporation, Emeryville, California. Falk, H., Creech, J.L., Heath, C.W., Johnson, M.N., and Key, M.M. (1974). "Hepatic disease among workers at a vinyl chloride polymerization plant." J.A.M.A.. 230(1):59-63. Forman, D., Bennett, B-, Stafford, J., and Doll, R. (1985). "Exposure to vinyl chloride and angiosarcoma of the liver, a report of the registry of cases." Br. J. Ind. Med.. 42:750-753. Helsel, D.R. (1990). "Less than obvious, statistical treatment of data below the detection limit." Environ. Sci. Techno!.. 24(12):1767-1774. Hiatt, G.F.S., Cogliano, V.J., Becker, R.A., Siegel, D.M., and Den, A. (1993). "Children as a Sensitive Subpopulation, Vinyl Chloride Action Levels - Indoor Air Exposures at a Superfund Site." United States Environmental Protection Agency, San Francisco, and California Environmental Protection Agency, Sacramento, California. In: Hazardous Waste and Public Health: International Congress on the Hearth Effects of Hazardous Waste. John S. Andrews, Jr., Howard Frumkin, Barry L. Johnson, Myron A, Mehlman, Charles Xintaras, and Jeanne A. Bucsela (ed.'s). Princeton Scientific Publishing Co., Inc., Princeton, New Jersey, 1994, pgs. 525-529. Homung, R.W. and Reed. L.D. (1990). "Estimation of average concentration in the presence of nondetectable values." AddI. Occud. Environ. Hva.. 5(1):46-51. ICF Technology Incorporated. (1992). `Revision of Data Validation Report for BKK Landfill." Memorandum dated November 6,1992 from Lisa Hanusiak, Organic Data Reviewer, Environmental Services Assistance Team, to Carmen Santos, Project Manager, Corrective Action Section (H-4-4), United States Environmental Protection Agency-Region IX, San Francisco, California. R&S145488 DRAFT -66- D RAFT Jenkins, P.L., Phillips, T.J., Mulberg, E.J., and Hui, S.P. (1992). `Activity patterns of Californians: use of and proximity to indoor pollutants sources.' Atmospheric Environment. 26(12): 2141-2148. Kharrazi, M., Smith, M,, Lomas, T., Armstrong, M., Broadwin, R., Blake, E., Worstell, G., and Goldman, L. (1993). `Adverse Pregnancy Outcomes Near a Hazardous Waste Landfill." California Department of Health Services, Environmental Health Investigations Branch, Emeryville, California presented at the 121st Annual Meeting of the American Public Health Association, San Francisco, California. October 26, 1993. Laib, R.J., Klein, K.P., and Bolt, H.M. (1985a). The rat liver foci bioassay: I. age-dependence of induction by vinyl chloride of ATPase-deficient foci.* Carcinogenesis. 6(1): 65-68. Laib, R.J., Pellio, T., Wunschel, U.M., Zimmermann, N., and Bolt, H.M. (1985b). The rat liver foci bioassay: II. investigation on the dose-dependent induction of ATPase-deficient foci by vinyl chloride at very low doses." Carcinogenesis. 6(1): 69-72. Mack, T.M. and Thomas, D. (1985). `Methodology for Evaluating Cancer Risk in Small Communities, Evaluation of Cancer Risk in the Residential Neighborhood Near BKK Landfill. ' University of Southern California, Department of Preventive Medicine, Cancer Surveillance Program. Report to State of California, Department of Health Services. Mack, T.M. and Pinder, R.L. (1988). `Assessment of Cancer Risk to Persons Residing Near BKK West Covina Landfill (Airborne Exposure)." University of Southern California School of Medicine, Department of Preventive Medicine. A report to California State Department of Health Services, Office of Environmental Health Hazard Assessment and Los Angeles County Department of Health Services, Toxics Epidemiology Program. Maltoni, C., Lefemine, G., Ciliberti, A., Cotti, G., and Carretti, D. (1981). "Carcinogenicity bioassays of vinyl chloride monomer a model of risk assessment on an experimental basis." Environ. Health Persoect.. 41:3-30. Miller, B.A., Ries, L.A.G., Hankey, B.F., Kosary, C.L, Harras, A., Devesa, S.S., Edwards, B.K., (eds). (1993). "SEER Cancer Statistics Review: 1973-1990." National Cancer Institute, Bethesda, Maryland. NIH Pub. No. 93-2789. Office of Environmental Health Hazard Assessment. (OEHHA, 1993). `Review ofthe risk assessment for the B.K.K. Landfill (SC-SS449)."Letterdated July 16,1993 from George V. Alexeeff, Ph.D., Chief, Air Toxicology and Epidemiology Section, Berkeley, California to Mr. Mohsen Nazemi, South Coast Air Quality Management District, Diamond Bar, California. Office of Environmental Health Hazard Assessment. (OEHHA, 1995). Letter dated March 14, 1995 from Richard A. Becker, Ph.D., Deputy Director for Scientific Affairs, to Mr. Roger Friesen, Planning Director, City of Walnut, California, to further clarify 1993 comments on the Draft Environmental Impact Report for Walnut Village. Ogden Environmental and Energy Services Co., Inc. (1992). `Air Quality Modeling for the BKK Landfill Air Toxic Exposure Study, November 1992."San Diego, California. Patty, F. (1987). `UnsaturatedHalogehatedHydrocarbons." In: Patty's Industrial Hvoiene and Toxicology. Volume 2B. Toxicology. Clayton, G. and Clayton,F. (eds). John Wiley & Sons, New York, pp. 3537-3543. Phillips, T.J., Jenkins, P.L., and Mulberg, E.J. (1991). `Children in California: Activity Patterns and Presence of Pollutant Sources. "California Air Resources Board, Sacramento, California, Presentation at the Air & Waste Management Association 84th Annual Meeting & Exhibition, Vancouver, British Columbia. R&S145489 DRAFT -67- DRAFT Pirastu, R., Comba, P., Reggiani, A.,Foa, V,, Masina, A.t and Maltoni, C. (1990). "Mortality from liver disease among Italian vinyl chloride monomer/polyvinyi chloride manufacturers." Am. J. Ind. Med.. 17:155-161. Rust, K.J., Rust, F.P., and Williams, R.L. (1988). "Pregnancy Outcomes for Residents Living Near the B.K.K. Landfill: A Study ofthe 1978-1984 Birth Cohorts. "Health Data Research Facility, Community and Organization Research Institute, University of California, Santa Barbara, prepared for the Department of Health Services, Epidemiological Studies and Surveillance Section, Emeryville, California. South Coast Air Quality Management District. (SCAQMD, 1981). *BKK Sanitary Landfill Report." Prepared by Melvin A. Schreckengost, Industrial Section, Enforcement Division, El Monte, California. South Coast Air Quality Management District. (SCAQMD, 1982a). Letter regarding South Coast Air Quality Management District's continuous sampling and analysis project for vinyl chloride monomer. Letter dated April 9,1982 from Edward Camarena, Director of Enforcement, Headquarters, El Monte, California to Mr. Joseph Pantalone, California Air Resources Board, Research Division, Sacramento, California. South Coast Air Quality Management District. (SCAQMD, 1982b). "Vinyl Chloride in the South Coast Air Basin."El Monte, California. South Coast Air Quality Management District. (SCAQMD, 1983). "Emissions of Potentially Toxic/Hazardous Contaminants in the South Coast Air Basin." Engineering Division, El Monte, California. South Coast Air Quality Management District. (SCAQMD, 1985). "Rule 1150.1, Control of Gaseous Emissions form Active Landfills." Diamond Bar, California. South Coast Air Quality Management District. (SCAQMD, 1987). "The Magnitude ofAmbient Air Toxics Impacts From Existing Sources in the South Coast Air Basin. "Air Quality Management Plan Revision Working Paper No. 3, Planning Division, El Monte, California. South Coast Air Quality Management District. (SCAQMD, 1994). `Report of Surface and Integrated Ambient Air Quality Monitoring Conducted in West Covina in Conjunction with a Joint Agency Inspection of BKK Landfill." Applied Science and Technology-Atmospheric Measurements Division, Diamond Bar, California. Standards and Criteria Work Group. (SCWG, 1994). "California Cancer Potency Factors: Update." California Environmental Protection Agency, Office of Environmental Health Hazard Assessment, Sacramento, California. Stirrat, B.A. & Associates. (1990). `BKK Landfill Ambient Air (Gas) Sampling Program Draft Final Report Volume II, October 30, 1990."Submitted to United States Environmental Protection Agency-Region IX, San Francisco, California. Stirrat, B.A. & Associates. (1991). `BKK Landfill 3013 SAM Workplan Book III Draft, Final Report, January 7, 1991." Submitted to United States Environmental Protection Agency-Region IX, San Francisco, California. The Janes Network. (1994). `Final Interim Remedial Measures Study Scope of Work, BKK Class l Landfill, West Covina, California, May 1994." Prepared for the BKK Corporation by The Janes Network, Santa Cruz, California. R&.S145490 DRAFT -68- D R AFT United States Department of Commerce. (1993). "1990 Census of Population and Housing, Population and Housing Characteristics for Census Tracts and Block Numbering Areas, Los Angeles-Long Beach, CA PMSA, Section 1 of 7." Economic and Statistics Administration, Bureau of the Census, Washington D.C. 1990 CPH-3-215B. United States Department of Labor. (USDOL, 1974). "Title 29-Labor, Chapter XVII, Occupational Safety and Health Administration, Department of Labor, Part 1910, Occupational Safety and Health Standards, Standard for Exposure to Vinyl Chloride." Fed. Regist.. 1974, 39(194):35890-35898. United States Environmental Protection Agency. (USEPA, 1985). "Aerial Photographic Analysis of the BKK Sanitary Landfill, West Covina, California, EPA Region IX." Office of Research and Development, Environmental Monitoring Systems Laboratory, Las Vegas, Nevada. TS-AMD-83073a/3600. United States Environmental Protection Agency. (USEPA, 1989a). "Risk Assessment Guidance for Superfund: Volume I - Human Health Evaluation Manual (Part A), Interim Final." Office of Emergency and Remedial Response, Washington D.C. EPA/540/J -89/002. United States Environmental Protection Agency. (USEPA, 1989b)."Region IX Recommendations: Risk Assessment Guidance for Superfund Human Health Risk Assessment, Interim Final."San Francisco, California. United States Environmental Protection Agency. (USEPA, 1991a;. "Risk Assessment Guidance for Superfund: Volume I - Human Health Evaluation Manual (Part C, Risk Evaluation of Remedial Alternatives), Interim."Office of Emergency and Remedial Response, Washington D.C. Publication 9285.7-01 C United States Environmental Protection Agency. (USEPA, 1991b;. `Risk Assessment Guidance for Superfund: Volume I - Human Health Evaluation Manual, Supplemental Guidance. 'Standard Default Exposure Factors' Interim Final." OSWER Directive: 9285.6-03. Office of Emergency and Remedial Response, Toxics Integration Branch, Washington, D.C. United States Environmental Protection Agency. (USEPA, 1992a). "Supplemental Guidance to RAGS: Calculating the Concentration Term."Office of Solid Waste and Emergency Response, Washington, D.C. Publication 9285.7-081. United States Environmental Protection Agency. (USEPA, 1992b). "Cancer Risk Estimates for Vinyl Chloride." Memorandum dated September 28,1992 from Jim Cogliano, Chief, Carcinogen Assessment Statistics and Epidemiology Branch, Office of Health and Environmental Assessment (RD-689) Washington D.C. to Arnold Den, Science Advisor, Region IX, San Francisco, California with September 26,1989 memorandum attached. United States Environmental Protection Agency. (USEPA, 1994a). "June 1994 Interagency Steering Committee (ISC) Inspection. " Letter dated August 29,1994 from Carmen D. Santos, Project Manager, Region IX, San Francisco, California to Mr. Paul Neff, Director, Regulatory and Environmental Compliance, BKK Landfill, West Covina, California. United States Environmental Protection Agency. (USEPA, 1994b;. "Health Effects Assessment Summary Tables FY- 1994 Annual."Office of Solid Waste and Emergency Response, Washington, D.C. 9200.6303(94-1), EPA 540-R-94-020, PB94-921199. United States Environmental Protection Agency. (USEPA, 1994c). "Health Effects Assessment Summary Tables FY 1994 Supplement Number 2." Office of Solid Waste and Emergency Response, Washington, D.C. 9200.6-303(94-3), EPA 540/R-94/114, PB94-921102, November 1994. United States Environmental Protection Agency. (USEPA, 1994d). `Integrated Risk Information System (IRIS)."Database access November 1994, and August 1995. R&S145491 DRAFT -69- DRAFT United States Environmental Protection Agency. (USEPA, 1994e). 'Clarification ofEPA's October 21, 1994 Letter Regarding Ambient-Air Data Validation Reports." Letter dated October 31,1994 from Carmen D. Santos-Prior, Project Manager, Region IX, San Francisco, California to Ms. Julia M. Bussey, Corporate Manager, Regulatory Affairs, B.K.K. Corporation, Torrance, California. University of Southern California. (USC, 1979). "Interim Report, Odor Investigation and Control for Class I Landfills. * Prepared for the B.K.K. Corporation by the Environmental Engineering Program, Los Angeles, California. University of Southern California. (USC, 1980). 'Second Interim Report, Investigation of Odorous and Volatile Compounds for BKK Class I Landfill Site in the City of West Covina. " Prepared for the B.K.K. Corporation by the Environmental Engineering Program, Los Angeles, California. University of Southern California. (USC, 1981)."Final Report, Investigation of Odorous and Volatile Compounds for BKK Class I Landfill Site in the City of West Covina. " Prepared for the B.K.K. Corporation by the Environmental Engineering Program, Los Angeles, California. Viola, P.L., Bigotti, A., and Caputo, A. (1971). "Oncogenic response of rat skin, lungs, and bones to vinyl chloride." Cancer Res. 31:516-522. Vogel, T.M., Criddle, C.S., and McCarty, P.L. (1987). "Transformations of halogenated aliphatic compounds." Environ. Sci. Techno!.. 21 (8):722-736. Wong, O., Whorton, M.D., Foliart, D.E. and Ragland, D. (1991). "An Industry-Wide Epidemiologic Study of Vinyl Chloride Workers, 1942-1982." Am. J. of Indust. Med. 20: 317-334. Wu, W., Steenland, K., Brown, D., Wells, V., Jones, J., Schulte, P., and Halperin, W. (1989). "Cohort and case-control analyses of workers exposed to vinyl chloride: an update.' J. Occup Med.. 31(6):518523. Ziem, G.E. and Davidoff, L.L. (1992). "Illness from chemical "odors": is the health significance understood?" Arch. Environ. Health. 47(1): 88-91. R&S145492 DRAFT -70- D RAFT BLANK PAGE R&S145493 DRAFT -71- DRAFT APPENDIX A ERRATA 145494 DRAFT -72- D RAFT ERRATA The following errors were contained in the interim report, "Health Risk Assessment of the B.K.K. Landfill, West Covina, California, November 1990", prepared by the Hazardous Waste Toxicology Section, Environmental Epidemiology and Toxicology Branch (EETB), Health Hazard Assessment Division, California Department of Health Services (DHS): Page 8, third paragraph: The B.K.K. Landfill, operated by B.K.K. (Kenneth B. Kazarian) Corporation, is located within the corporate boundary of the City of West Covina, California, 18 miles east of downtown Los Angeles in Los Angeles County (Figure 1)." The reference to Kenneth B. Kazarian as the BKK Corporation is not correct. The text should read: The B.K.K. Landfill, operated by the B.K.K. Corporation, is located within the corporate boundary of the City of West Covina, 18 miles east of downtown Los Angeles in Los Angeles County (Figure 1). Page 80, third paragraph: In 1985, EPA estimated the population within a one-mile radius of the center of the B.K.K. Landfill to be approximately 40,000 persons (LPA, 1985). The reference (LPA, 1985) should read (EPA. 1985). R&S145495 DRAFT -73- D RAFT APPENDIX B "B.K.K. LANDFILL, WEST COVINA, CALIFORNIA FACT SHEET, DECEMBER 1990," CALIFORNIA DEPARTMENT OF HEALTH SERVICES ENVIRONMENTAL EPIDEMIOLOGY AND TOXICOLOGY BRANCH EMERYVILLE, CALIFORNIA R&S 145496 DRAFT -74- D R AFT %^LjFOfiJ FACT SHEET California Department of Health Services Environmental Epidemiology and Toxicology Branch BKK LANDFILL West Covina, California DECEMBER 1990 In-Depth Summaries Of Health Studies Near BKK Landfill This fact sheet contains summaries of two can cer studies and a health risk assessment con cerning the BKK landfill, a hazardous waste site in West Covina, California. These studies were undertaken by the California Department of Health Services (DHS) in response to the con cerns of residents near the landfill. about possible health effects due to hazardous waste releases in air, surface water runoff, spills and dust from the landfill. Drinking water sup plies are not contaminated. 1. The Cancer Studies Background What Were The Studies Looking For? Under contract by the California Department of In 1963, the BKK landfill, operated by the Ben Health Services (DHS), Dr. Thomas Mack, Dr. Kenneth Kazarian Corporation, opened on 130 Duncan Thomas and Richard Pinder from the acres in the San Jose Hills in the Gty of West University of Southern California, Cancer Sur Covina in Los Angeles County. Initially, the veillance Program, conducted two studies that landfill accepted only municipal waste such as investigated the distribution of cancer cases in household and commercial refuse and construc residents living near the BKK landfill between tion debris. In 1971, the City of West Covina 1972 and 1982. approved an expansion of the facility to its present size of 583 acres. In 1972, a 40- acre haz ardous waste management unit (a state-desig nated Class I landfill) opened on the existing site and began receiving hazardous wastes. This unit was expanded by an additional 100 acres in 1975. In November, 1984, the landfill stopped accept ing hazardous waste. In March, 1989, the unit was formally closed. The closing process in cluded building a low-permeability soil cap over 180 acres, that is, over the regulated hazardous waste area and some surrounding municipal waste. The aim of the first study, completed in 1985, was to determine whether residents living south and west (mostly downslope) of the BKK land fill had a greater chance of getting cancer than the average resident of Los Angeles County. The second study, completed in 1988, focused on the area to the north and east (mostly downwind during the day) of the landfill. Both studies re lied on data collected by the Los Angeles County Cancer Surveillance Program, and examined cancer incidence from 1972 to 1982. Bach study analyzed cancer rates for all childhood cancers, for each of 89 different types of cancers, and for In 1969, area residents filed their first odor com all cancers taken together. In both studies, the plaint against the BKK landfill with the South distribution of those cancers found to have oc Coast Air Quality Management District. In 1979, curred at a higher than expected rate was exam 278 odor complaints were reported. Studies have ined to determine if the landfill might be a pos shown that hazardous waste migrated from the ; sible cause of the increase. landfill into air and water around the site. People I living near the landfill have been concerned I (continued on Page 2) R&S 145497 -75- CENSUS TRACTS IN STUDY AREA BKK LANDFILL, WEST COVINA, CA California Department Of Health Services i inch - 7.500 <oet 4*9 Census Tract -------- Highway The Cancer Surveillance Program collects infor mation on each Los Angeles County resident who has received a microscopically verified can cer diagnosis or for whom cancer is recorded on a death certificate. These two studies focused on persons who were diagnosed with cancer dur ing the 11-year period between January 1,1972, and December 31, 1982. Residents of 11 census tracts (1960 definitions) comprised the popula tion living near the BKK landfill (see map above). In total, about 100,000 people lived in the BKK study area in 1977 (midway thrqugh the 19721982 study period), and about 2,000 cancer cases were identified during the 11-year study period. Table 1 shows for each tract the estimated 1977 population (based on 1970 and 1980 census data) and the number of residents diagnosed with cancer between 1972 and 1982. What Did The Studies Find? Among residents of the 11 census tracts, the overall rate of cancer for both adults and chil dren was similar to that for Los Angeles County -76- as a whole. The rate of cancer was not higher for residents living closer to the landfill, nor did the average rate of cancer increase between the ear lier and later study time periods (from 1972-:1976 to 1978-1982). Overall sex-specific cancer rates are shown in Table 2 for each census tract, along with a comparison to total Los Angeles County rates. Even though the overall cancer rate in the BKK study area was not higher than the Los Angeles county rate, researchers studied 89 individual types of cancer to determine whether unexpect edly high levels of any one of them appeared in any census tract. A type of cancer was consid ered- in excess if: 1) there were more extra cases than could be accounted for by chance alone, 2) cases occurred at least twice as often as usual in Los Angeles County, and 3) that type of cancer met at least one of four other requirements (more than four excess cases; elevated in at least two census tracts; elevated in both sexes; or the rate of that cancer at least doubled over the study (continued on Page 4) R&SI45498 Table 1 Total number of cancer cases in 1972-1982 and estimated 1977 population in 11 census tracts around the BKK landfill, West Covina, California. Census Tract Direction of Census Tract from BKK Landfill EsL 1977 Population Total 1972-82 Cancer Cases 4080 Tract in Both Study One and Two Contains BKK landfill 8.565 142 4077 4078 4079 4081 4082 Southwest Southwest West South South and West Other Tracts in Study One 8,652 7,370 4.577 27.280 9.807 209 159 78 380 218 4034 4063 4064 4065 4066 East North and East North North Northwest Other Tracts in Study Two 10.533 3,470 6,720 -5,626 8,955 166 111 236 199 277 Total Tract Aggregate 101.555 2.175 Table 2 1972-1982 average annual cancer incidence rates by sex in Los Angeles County and in 11 census tracts around the BKK landfill. West Covina, California. Census Tract Sex 1972-1982 Cancer Cases Average Incidence Rate' Rate Relative To LA CO Rate1 Los Angeles County Male Female 127,003 148.563 375.6 328.5 -- - 4080 Male Female 83 59 368.1 187.9 1.0 0.6 4077 Male Female 87 122 364.7 362.7 1.0 1.1 4078 Male Female 76 83 466.1 364.3 1.2 1.1 4079 Male Female 35 43 297.5 263.5 0.8 0.8 4081 Male Female 176 204 290.7 245.7 0.8 0.7 40B2 4034 Male Female Male Female 95 123 77 89 262.5 255.9 343.7 284.2 0.7 0.8 0.9 0.9 4063 Male Female 56 55 354.2 290.4 0.9 0.9 4064 4065 Male Female Male Female 101 135 99 100 367.7 384.7 477.8 327.8 1.0 1.2 1.3 1.0 4066 Male Female 118 159 336.9 345.9 0.9 1.1 ' Average number of cancer cases per 100,000 population per year. * 1 A value of 1.0 means that the cancer rate in the census tract is equal to the rate in L.A. County. A value greater than 1.0 (e.g.. 1.2) means that the rate in census tract is greater than rate in L.A. County (e.g., by 1.2 times). A value less than 1.0 (e.g., 0.8) means the rate in the census tract is less than the rate in L.A. County (e.g.. by 0.8 times). 3 R&S 145499 -77- period). Ten such types of cancer were identi fied: hepatoma, meningioma, tongue, nasophar ynx, larynx, upper colon, pancreas, bladder, melanoma of trunk or scalp, and endometrium (Table 3). Whenever small geographic areas are closely studied as was done here, too many -- and too few -- cases of a few types of cancer are ex pected to appear in some areas by chance alone. Each cancer type listed in Table 3 was scrutinized to determine if any other evidence of a public health risk existed, for example, whether any cancer showed a consistent pattern of increased risk as might be expected from exposure to the landfill. Researchers concluded that excess cases of each of these 10 types of cancer were most likely not due to the landfill, but to other char acteristics of the affected population. First, some types of cancer are known to be related to high income and education. One is endometrial can cer. Risk of endometrial cancer is greater among high-income populations who use estrogen re placement hormones and delay childbearing. When the rates of this cancer in the BKK study area were compared with rates in census tracts of similar socioeconomic status in Los Angeles County, the rates were nearly the same. Second, the increase in some identified cancers disappeared after 1982. In the case of melanoma, its relatively higher rate in one census tract be tween 1972 and 1982 has not continued, and no additional cases appeared between 1983 and 1985. This drop in the rate led the authors to conclude that the 1972-82 rate was not due to the site. Third, and more significantly, no excess cancer cases were identified in the census tract contain ing the landfill (4080), which covered an area extending approximately one mile from the site. Residents with these 10 types of cancer were more likely to live farther away from the landfill than residents with other types of cancer. If ex posures from the site were causing the cancers, there would be a pattern of more cases near the site, not farther from it. (continued on Page S) Table 3 Selected characteristics of 10 specific types of cancers identified for in-depth analysis in two cancer studies of 11 census tracts around the BKK landfill. West Covina, California. Type of Cancer Hepatoma Meningioma Tongue Nasopharynx Larynx Upper Colon Pancreas Bladder Melanoma. Trunk/Scalp Endometrium Total Annual Rate Relative Number Rato In Sex Census Tract Cancer Cases To LA CO Rate' Excess Csses 1978-82/1972-76* F 4082 3 4.9 2.4 2.0 M 4079 M 4081 M 4082 1 5 2 3.7 0.7 0.0 3.5 3.6 0.7 2.7 1.3 1.0 F 4078 3 10.1 2.7 0.5 F 4082 3 4.6 2.3 0.5 F 4077 2 13.8 1.9 InP M 4078 2 9.1 1.8 InP M 4082 6 2.0 3.0 1.0 M 4077 F 4082 7 9 3.0 4.7 1.3 1.8 4.1 2.0 F 4077 6 2.8 3.8 0.5 M 4078 9 2.4 5.3 1.3 M . 4034 F 4064 F 4066 6 23 24 2.8 3.9 InP 2.0 11.7 0.8 1.7 9.4 0.8 1 Value greater man 1.0 (e.g.. 1.7) means rate m census tract ts greater man rate in L.A. County (e.g.. by 1.7 times). 1 This column is me rate of cancer occurrence in 1978-82 divided by the rate dunng 1972-76. For hepatoma, for example, the rate in 1978-82 was 2 times the rate in 1972-78. i inf means infinity, and indicates that there were no cases diagnosed in 1972-1976. 4 R&S 145500 -78- What May The Studi s Have Missed? Although a thorough study has been conducted, all studies have limitations. If there was a rela tionship between the BKK landfill and cancer, there are a few reasons why the study may have failed to find it. First, too small a proportion of the population in the nearby census tracts may actually have been exposed to the landfill. If, for example, only people on the blocks close to the landfill had exposures from the site, then ana lyzing cancer rates for the whole census tract may have been too crude. Census tracts, how ever, were the smallest unit from which the Cancer Surveillance Program could analyze its records. Second, because people moved in and out of the community often; exposed individu als who developed cancer may well have left the area by the time the disease appeared and so were not in the Cancer Surveillance Program's data base. A third reason may be that not enough time has elapsed for cancer to occur the consen sus among scientists is that there is often a 20- to 30-year period between exposure to a cancercausing chemical and the onset of disease. Conclusion These studies compared the rate of cancer occur rence in residents of 11 census tracts adjacent to the BKK landfill to rates in Los Angeles County as a whole. There was no overall increase in the cancer rate among residents living near the BKK landfill. There was no consistent pattern of oc currence to suggest that the BKK landfill is linked to individual types of cancer. The results do not substantiate concerns that there were excess cancers around the BKK landfill between 1972 and 1982. 2. The Health Risk Assessment Introduction In response to residents' requests, DHS con ducted a health risk assessment of the BKK land fill based on environmental monitoring from 1982 through 1987. It provides an estimate of the health risks to individuals living near the BKK landfill from exposure to Chemicals found in the air, groundwater and surface water. The assessment is primarily concerned with estimating the risk of developing cancer from exposure to chemi cals found in the air because: 1) monitoring ac tivities indicated that air was the main route of exposure, and 2) it is assumed that no amount of exposure to a cancer-causing chemical is without some risk. A risk assessment is an ongoing process that requires revision as science and technology pro vide new information. The 1990 health risk as sessment of the BKK landfill updates a 1982 risk assessment and will be revised when informa tion about vinyl chloride, one of the cancercausing chemicals found in the air around the BKK landfill, is updated. There were three previous health risk assess ments of the BKK landfill: one by public agen cies and two by private consultants to the BKK Corporation. Previous Cancer Risk Assessments In 1982, the Department of Health Services (DHS), the 5outh Coast Air Quality Management District (SCAQMD), and the California Air Re sources Board (CARB) monitored the air in resi dential neighborhoods around the BKK landfill. The following seven chemicals known or sus pected to cause cancer were identified: vinyl chloride, benzene, perchloroethylene, trichloroethene, 1,1-dichloroethylene, 1,2dichloroethane, and trichloromethane (chloro form). Public health data show that each person has a one-in-three risk of developing cancer during a 70-year lifetime. This means that 33,000 people in 100,000 will develop cancer sometime during their lifetime. This "one-in-three" risk is referred to as a "background" risk. The 1982 study estimated that for people living near the landfill, and exposed to all seven chemicals, the risk of developing cancer increased to 33,005 in 100,000. In 1986, consultants to attorneys for the BKK landfill performed two separate risk assessments. In the first, the increased cancer risk from the same seven chemicals found in 1982 was esti mated to be much less: between two and 11 in 1 million people. Results in the second assessment were similar an estimated increased cancer risk (continued on Page 6) i.ossns'su -79- from the seven chemicals of two additional cases in 1 million people. parts of vinyl chloride per billion parts of air (10 ppb). The estimates vary due to differences in the Other chemicals found in the air around the methods and assumptions used by the risk as landfill' are also commonly found in the Los sessors. DHS has used more health-protective Angeles air basin at detectable levels. However, methods and assumptions when estimating risk. ; vinyl chloride is rarely detected in the Los An For example, DHS assumes that 100% of a ' geles air basin. Therefore, vinyl chloride most chemical detected in the environment is absorbed j clearly represents the increased risk of develop by an individual and that individuals are at home ing cancer associated with the landfill. Liquid 80% of the time. One consultant to BKK used a , wastes containing vinyl chloride were buried at method that assumed that 50% of a chemical j the landfill until June 1981. found in the environment is absorbed by an in- | Vinyl chloride causes cancer in humans. Health dividual and that individuals are at home less > effects other than cancer are seen at levels above than 80% of the time. 10,000 parts per billion, which is much higher What Did The 1990 Health Risk Assessment Find? than any levels found near the BKK landfill. It is assumed that no amount of exposure to a cancer-causing chemical is without some risk. In 1985, the United States Environmental Protec- ' Therefore, the 1990 health risk assessment fo tion Agency (EPA) hired an engineering firm cuses on the risk of developing cancer from (CH2MHU1) to evaluate chemical exposure to j breathing the amount of vinyl chloride detected people living close to the BKK landfill. The re by air monitoring around the landfill from 1982 port, completed in 1988, evaluated chemical through 1987. The information used to estimate contaminants in the air, groundwater and sur the risk included the amount of vinyl chloride face water. Chemical analysis of the soil at the detected in the air and the unit risk value for landfill was not done. vinyl chloride. The unit risk value is a measure DHS based the 1990 health risk assessment pri marily on environmental measurements re viewed in the 1988 report. The measurements showed contaminants in groundwater (water found beneath the surface), surface water (water from steams, storm drains or run-offs) and air around the BKK landfill. of the cancer-causing potential of a chemical. It is the estimated excess risk of developing cancer as a result of constant exposure over 70 years to one microgram of a-chemical in one cubic meter of air. Unit risk values are determined by EPA and DHS toxicologists based on experimental animal and human epidemiological information. Groundwaten People living near the BKK land fill are not exposed to the contaminated groundwater because it is not used for drinking water or irrigation. i Among people who were exposed to vinyl chloride around the landfill between 1982-1987, the health risk assessment estimates that an ad ditional two people in 100,000 may develop can cer. This means that in every 100,000 people, Surface water People may have been exposed 33,002 of them (rather than 33,000 as in the U.S. to contaminated surface water. However, the average) may get cancer. For the BKK study area, health risk assessment determined that any ex few if any additional cases are expected, too few posure would have involved small quantities, to detect by a health study. Thus the cancer study occurred only once in a while, and lasted only a and risk assessment produced similar results. short period of time. Consequently, the risk to people who may have been exposed to contami nated surface water is considered to be extremely small. What The Health Risk Assessment May Not Show Ain People living near the BKK landfill may have been exposed to contaminants in the air. in As the health risk assessment was being com pleted, DHS also completed a re-evaluation of 1981, vinyl chloride was found in the air at the the ability of vinyl chloride to cause cancer. The landfill border. From 1982-1987 the amount of j re-evaluation suggests that vinyl chloride is more vinyl chloride found in residential air monitor- I potent than was previously thought. This re- ing stations around the BKK landfill was at times ! evaluation was not available for use in the health above the California air quality standard of 10 | risk assessment. (continued on Page 7) 145502 .HIV The health risk assessment used the amount of vinyl chloride that was measured near the landfill between 1982 and 1987. Since 1987, vinyl chloride has rarely been detected near the landfill, so residents' exposure has been reduced. The lower exposure would reduce the risk and the estimated number of additional cancers. Next Steps DHS plans to conduct a new health risk assess ment in 1991-92 based on both the new potency information and recent air measurements. DHS also will continue to watch the rate of cancer around the BKK landfill to see whether it in creases. This is because cancer may take a number of years to develop. Residents will be kept up to date as new information becomes available. DHS is conducting a third study at the request of people living near the landfill. This study is ex amining births in the area to see whether there has been any increase in such problems as infant deaths and low weight at birth. Residents will receive a summary of that study when it is com pleted in the first half of 1991. If you have any questions or comments about the studies described in this newsletter, please contact: Elinor Blake Community Relations Coordinator California Department of Health Services Environmental Epidemiology and Toxicology Branch 5900 Hollis Street, Suite E Emeryville, CA 94608 (415) 540-3657 For information about BKK landfill cleanup ac tivities, please contact: Tom Mays Public Participation Specialist California Department of Health Services Toxic Substances Control Program Region 3 1405 N. San Fernando Road, Suite 300 Burbank, CA 91504 (818) 567-3176 Regulation ofvinyl chloride by governmental agencies includes the following: The Deportment of Health Services (DHS/ limits the amount ofvinyl chloride in drinking water to 0-5 parts per billion (ppb). The California Occupational Safety and Health pro gram (Cal/OSHA) limits the level of vinyl thloride in the workplaceair to 100 ppb averaged over an eight -hour work period, never to exceed 100 ppb. The California Air Resources Board (CARS) limits the concentration of vinyl chloride in the ambient avr to 10 ppb, based on the technology available in 1978. CARB is also proposing to identify vinyl chloride as a toxic air contaminant. A toxic air contaminant is anair pollutant which may causean increase in serious illness. Identification of vinyl chloride as a toxic air contami nant allows CARB to develop control strategies that reduce vinyl chloride air levels far below 10 ppb. Copies of the full epidemiologic studies of can cer in people living near the BKK landfill, the health risk assessment and other relevant docu ments about the BKK landfill are available at the following libraries: La Puente Library 15920 East Central Avenue La Puente, CA 91744 (818) 968-4613 West Covina Library 1601 West Covina Parkway West Covina, CA 91790 (818) 962-3541 Walnut Library 21155 La Puente Avenue Walnut, CA 91789 (714) 595-0757 R&S 145503 -81 APPENDIX C UPDATED TOXICITY TABLES FROM THE 1990 INTERIM REPORT R&S 145504 DRAFT -82- DRAFT UPDATED TOXICITY TABLES FROM THE 1990 INTERIM REPORT In the 1990 interim report, OEHHA-HWTS provided a table showing the USEPA weight-of-evidence classification and site of cancer effect for the carcinogens detected in the environmental monitoring data. Since 1990, USEPA has added chemical abstract service (CAS) numbers to metals and updated the sites of carcinogenic effects associated with specific chemicals; "Lung" has been added to the site of carcinogenic effects associated with vinyl chloride (USEPA, 1994b). APPENDIX C-TABLE1 updates this information. APPENDIX C-TABLE 2 updates the unit risk values for carcinogens detected at the landfill. A side-byside comparison of the 1990 and 1994 values shows the changes (increases/decreases or no change) for each chemical. The 1994 values are taken from Cal/EPA's "Criteria For Carcinogens" (Standards and Criteria Work Group, 1994). OEHHA's slope factor for vinyl chloride is slightly more potent than USEPA's at this time: 0.27 (mg/kg-day)-1 versus 0.29 (mg/kg-day)-1, respectively. The weight-of- vidence classification for the carcinogens has not changed, although USEPA is in the process of reviewing the weight-of-evidence for trichloroethylene. R & S 145505 DRAFT -83- DRAFT APPENDIX C-TABLE 1a CARCINOGENS DETECTED IN GROUNDWATER, SURFACE WATER, AND AIR BKK LANDFILL WEST COVINA, CALIFORNIA Reported in the 1988 Exposure Characterization Report" Carcinogen Arsenic (inorganic) Cadmium Chromium(VI)f Lead Nickei(subsulfide) Benzene Bis-2-chloroethyl ether Carbon Tetrachloride Chloroform 1,2-Dichloroethane 1,1-Dichloroethylene Methylene chloride (dichloromethane) N-nitrosodimethylamine Perchloroethylene 1,1,2,2-Tetrachloroethane 1,1,2-Trichloroethane Trichloroethylene Vinyl chloride CAS#0 7440-38-2 7440-43-9 16540-29-2 7439-92-1 12035-72-2 71-43-2 111-44-4 56*23-5 67-66-3 107-06-2 75-35-4 75*09-2 62-75-9 127-18-4 79-34-5 79-00-5 79-01-6 75-01-4 USEPA0 Class A B1 A B2 A A B2 B2 B2 B2 C B2 B2 C C C B2 A Cancer Site lung, skin lung, prostate, breast lung kidnev. luna. stomach lung, nasal hematopoietic system (leukemia) liver liver kidnev. liver, rectum, colon, bladder forestomach, breast, uterus circulatory system, lung, liver kidney, breast, lung liver, breast, lung, leukemia multiple $(tes. liver liver liver liver. Dheochromocvtomas lymph, liver liver, lung a: Update of Table 3, "Health Risk Assessment of the BKK Landfill, West Covina, California," Interim Report, November 1990, page 24, Hazardous Waste Toxicology Section, California Department of Health Services, Sacramento, California. Additions are italicized and underlined (i.e., stomach). b: "BKK Landfill Environmental Exposure Characterization Report, West Covina, California," Volume I, August 15,1988, CH2M Hill, Santa Ana, California, c: Chemical Abstract Service number. d: USEPA weight of evidence classification: A, sufficient evidence in humans; B1, sufficient evidence in animals, limited in humans; B2, sufficient evidence in animals, inadequate in humans; C, limited evidence in animals, inadequate in humans. Taken from USEPA's Integrated Risk Information System (IRIS), November 1994, and August 1995. Database access August 1995 shows vinyl chloride, perchloroethylene, and trichloroethylene under review. With the exception of 1,1-dichloroethylene, the above carcinogens are listed as known to the State of California to cause cancer for purposes of the Health and Safety Code Section 25249.5 et seq. e: Additional sites of carcinogenic effects taken from IRIS November 1994 and August 1995, with the exception of vinyl chloride. Lung site for vinyl chloride listed in "Health Effects Assessment Summary Tables: FY - 1994 Annual," March 1994, Environmental Criteria and Assessment Office, U. S. Environmental Protection Agency. 9200.6-303 (94-1) EPA 540/R-94/020; PB94-921199. f: Inadequate evidence to quantitatively evaluate the carcinogenicity of this compound by the oral route. R&S 145506 DRAFT -84- D RAFT APPENDIX C-TABLE 2a INHALATION UNIT RISK (UR) VALUES FOR CARCINOGENS DETECTED AT BKK LANDFILL, WEST COVINA, CALIFORNIA Carcinogen Arsenic (inorganic) Cadmium Chromium(VI) Lead Nickel Benzene . Bis-2-chloroethylether Carbon Tetrachloride Chloroform 1,2-Dichloroethane 1,1-Dichloroethylene Methylene Chloride N-Nitrpsodimethylamine Perchloroethylene 1,1,2,2-Tetrachloroethane 1,1,2-Trichloroethane Trichloroethylene Vinyl Chloride Molecular Weight 74.92 112.40 52 207.2 58.71 78.11 143.02 153.81 119.39 98.96 96.95 84.93 74.10 165.85 167.84 133.40 131.4 62.5 1990 URb .(pg/m3)-1 4.3E-3 1.2E-2 1.5E-1 - 4.8E-4 5.3E-5 3.3E-4 4.2E-5 2.3E-5 2.2E-5 5.0E-5 1.0E-6 1.4E-2 5.8E-7 5.8E-5 1.6E-5 1.3E-6 2.7E-6 1994 Cal/EPA URC (pq/m3)-1 3.3E-3 4.2E-3 1.5E-1 8.0E-5 2.6E-4 2.9E-5 7. IE-4 NCf 5.3E-6 NCf Nl9 NCf 4.6E-3 5.9E-6 NCf 2. IE-5 2.0E-6 7.8E-5 1994 Cal/EPA URd (PPb)-1 1.0E-2 1.9E-2 3.2E-1 6.8E-4 6.2E-4 9.3E-5 4.2E-3 2.6E-4 2.6E-5 8.9E-5 - 3.5E-6 1.4E-2 4.0E-5 4.0E-4 1.1E-4 1.1E-5 20E-5 USEPAe Class - A B1 A B2 A A B2 B2 B2 B2 C B2 B2 C C C B2 A a: Update of Table 10, "Health Risk Assessment of the BKK Landfill, West Covina, California," interim Report, November 1990, page 47, Hazardous Waste Toxicology Section, California Department of Health Services, Sacramento, California. b: Values listed were derived by the United States Environmental Protection Agency (USEPA) or the California Department of Health Services, Health Hazard Assessment Division, Air Toxics Section (DHS) and were taken from Table 3.15, "Air Toxics Assessment Manual," California Air Pollution Control Officers Association, October 1987 pgs. 3.5-24 to 3.5-28. c: Taken from Standards and Criteria Work Group. (1994). 'California Cancer Potency Factors: Update," California Environmental Protection Agency (Cal/EPA), Office of Environmental Health Hazard Assessment, Sacramento, California. NOTE: 1,1-Dichloroethene is no longer considered a carcinogen in California and has been deleted from the California Cancer Potency Factors. Changes in the unit risk values are due to increased knowledge about the inherent toxicity of the chemicals. d: (ppb)*1 = ([pg/m3 x molecular weight] / [24.45m3/pmole]). e: USEPA weight of evidence classification: A, sufficient evidence in humans; B1, sufficient evidence in animals, limited in humans; B2, sufficient evidence in animals, inadequate in humans; C, limited evidence in animals, inadequate in humans. Taken from USEPA's Integrated Risk Information System (IRIS), November 1994. Database access August 1995 shows vinyl chloride, perchloroethylene, and trichloroethylene under review. f: NC = No Change. g: NL - Not Listed by Cal/EPA; no change in unit risk value or classification by USEPA per IRIS, November 1994. H&S145507 DRAFT -85- D R AFT APPENDIX D STATISTICAL EVALUATION OF THE 1983-1990 AMBIENT VINYL CHLORIDE MONITORING DATA R&S 145508 DRAFT -86- DRAFT STATISTICAL EVALUATION OF THE 1983-1990 AMBIENT VINYL CHLORIDE MONITORING DATA When estimating the average concentration of an environmental contaminant over time, a certain proportion of the data is often reported to be below the detection limit. Comparing two groups of data, such as site data and background data, requires summary statistics including means and standard deviations. Calculating means for samples with nondetectable concentrations requires exchanging nondetects for a value. There are three methods of estimating summary statistics for data that include samples with nondetectable concentrations: distributional, robust, and substitution methods (Helsel, 1990). Use of these methods when more than half the data are samples with nondetectable concentrations may result in biased or imprecise estimates (Homung & Reed, 1990). Distributional methods use the characteristics of known distributions to estimate summary statistics. A critical assumption when using distributional methods is how well the data can be expected to fit the assumed distribution. Commonly used distributions include the normal, lognormal, and Weibull. Estimates of summary statistics are computed that best match the observed concentrations above the detection limit and the percentage of data below the limit. A frequently used method for fitting points to a distribution is the maximum likelihood estimation (MLE). Robust methods combine the observed data above the detection limit with below-limit valu s extrapolated in order to compute the mean and standard deviation. The robustness results primarily from the use of observed data rather than a fitted distribution above the detection limit. Substitution methods for nondetects include using the detection limit, half the detection limit, or zero. The substitution of zero produces estimates that are biased low, and the substitution of the detection limit results in estimates considered to be above the true mean. USEPA recommends substituting half the detection limit (USEPA, 1989b). In generating values for samples with nondetectable concentrations in the SCAQMD data, HWTS requested statistical evaluation of the data by DHS-DEODC. The fit of the air monitoring data to normal, lognormal, exponential, and Weibull distributions was evaluated using data from Stations A, B, and MY for the years 1983 through 1989. To evaluate each distribution, Gibbs technique was used to estimate the value of samples with nondetectable concentrations as follows: first, the value of half the detection limit was substituted for samples with nondetectable concentrations; then, the MLE was used to estimate the parameters for the entire distribution; then, a random number generator was used to generate new values for samples with nondetectable concentrations. The data were generated using the given distribution and the most recent parameter estimate. The process was then iterated until a convergence criterion was met. The Gibbs method differs from other algorithms in that it requires no numerical integration. The integration is replaced by the random number generation. 1 R & S 145509 DRAFT -87- D R AFT J The lognormal distribution showed the best fit. Arithmetic means of the lognormal distribution for vinyl chloride concentrations at Stations A, B, and MY for the years 1983 through 1989 are given in APPENDIX D - TABLE 1. Blanks in the table indicate insufficient data to compute the algorithm. These concentrations are similar to the concentrations reported in TABLE 6 of this addendum report. When substituted into the risk equation, average annual concentrations using the Gibbs technique result in risk estimates per year that are similar to the risk estimates using the simple substitution method for samples with nondetectable concentrations. Since the substitution method can be more easily reproduced and the results are comparable to a more sophisticated method, the substitution method was used for samples with nondetectable concentrations. R&S145510 DRAFT -88- DRAFT APPENDIX D- TABLE 1 ' AVERAGE ANNUAL CONCENTRATIONS OF VINYL CHLORIDE BASED ON GIBBS TECHNIQUE* FOR SAMPLES WITH NONDETECTABLE CONCENTRATIONS Station A Station B Station MY 1983 2.84 2.98 - 1984 4.08 3.88 5.38 1985 3.34 2.20 5.36 1986 1.77 1.24 2.97 1987 1.51 1.12 2.45 1988 1.25 1.87 2.32 1989 - 0.83 *The Gibbs technique was used to estimate the value of samples with nondetectable concentrations as follows: first, the value of half the detection limit was substituted for samples with nondetectable concentrations; then, the maximum likelihood estimate was used to estimate the parameters for the entire distribution; then, a random number generator was used to generate new values for samples with nondetectable concentrations. The data were generated using the given distribution and the most recent parameter estimate. The process was then iterated until a convergence criterion was met. The Gibbs method differs from other algorithms in that it requires no numerical integration. The integration is replaced by the random number generation. NOTE: Values computed by Joel Swartz, Ph.D., California Department of Health Services-Environmental Epidemiology and Toxicology Section, Emeryville, California, 1992, using South Coast Air Quality Management District's ambient vinyl chloride monitoring data, January 1983 through December 1989. R&S 145511 DRAFT -89- DRAFT J APPENDIX E 1990 POPULATION CENSUS TRACT DATA FOR THE VICINITY OF THE B.K.K. LANDFILL, WEST COVINA, CALIFORNIA R&S145512 D RAFT -90- DRAFT APPENDIX E-FIGURE 1 (Department of Health Services, Division of Environmental and Occupational Disease Control) 1990 CENSUS TRACTS NEAR BKK LANDFILL R&S145513 Courtesy of; Rachel Broadwin, California Department of Health Services, Division of Environmental and Occupational Disease Control, Environmental Health Investigations Branch, Emeryville, California, April 1994. DRAFT -91- D R AFT 1. All Grouos Tolal Children (0-4) Children (S-9) Children (10-14) Children (IS-19) Ad'ulls (20-64) Adults (65+) Median Age II. Females Total Females (0-14) Females (15-44) Females (45-64) Females (65+) APPENDIX E-TABLE 1a 1990 POPULATION CENSUS TRACT DATA FOR THE VICINITY OF THE BKK LANDFILL, WEST COVINA, CALIFORNIA6 Contains BKK 4060.01 4080.02 4079 4075 Census Tract to the North of the BKK Landfill 4074 4067 4055 4056 4065 4066.02 4066.01 4064.11 4064.12 4064.02 4063 6,871 582 546 484 545 4,281 433 29.9 7,051 643 610 524 520 4,353 401 29.4 5,455 458 465 506 502 3,217 307 28.7 6,851 706 68B 568 565 3,845 479 27.6 1.464 106 119 115 141 874 109 30.2 B.332 760 646 596 644 4,833 853 30.5 5,954 481 453 406 424 3,588 602 32.4 4,748 334 364 347 339 2,753 611 34.0 5,834 455 417 424 410 3,529 599 31.5 4,315 369 339 318 304 2,570 415 31.1 4,571 313 305 314 310 2,731 598 36.2 2,006 173 143 192 160 1,192 146 28.9 2,209 121 131 159 143 1,374 281 37.6 1,999 133 95 131 125 1,213 302 38.0 4,655 237 336 358 369 2,899 456 35.7 3,473 786 1,859 602 226 3,489 815 1,853 599 222 2,751 722 1,341 512 176 3,449 970 1,688 524 267 719 4,314 2,988 159 951 646 351 2,069 1,386 155 755 613 54 539 343 2,441 504 1,086 502 349 3,002 634 1,474 532 362 2,208 523 1,024 438 223 2,341 468 961 577 335 1,020 262 486 186 86 1,129 222 441 313 153 1,030 174 418 268 170 2,333 443 1,115 541 234 nssnsw DRAFT -92- DRAFT APPENDIX E-TABLE 1a(continued) 1990 POPULATION CENSUS TRACT DATA FOR THE VICINITY OF THE BKK LANDFILL, WEST COVINA, CALIFORNIA13 1. All Grouos Total Children (0-4) Children (5-9) Children (10-14) Children (15-19) Adults (20-64) Adults (65+) Median Age II. Females Tolal Females (0-14) Females (15-44) Females (45-64) Females (65+) 4034 4081.31 4081.32 4081.02 Census Tracts to the South of the BKK Landfill 4081.01 4082.11 4082.12 4078 4077 4082.02 4072 4073 28,792 2,471 2,660 2,766 2,464 17,327 1,104 31.3 13,346 1,258 1,073 1,062 1,178 8,213 542 28.1 9,281 952 931 873 992 5,087 446 24.4 8,082 786 737 711 891 4,525 432 25.4 7,792 627 609 614 677 4,921 344 29.2 5,519 428 481 368 455 3,225 562 30.5 4,032 262 26B 346 364 2,501 291 32.7 7,438 665 673 686 740 4,269 385 27.5 11,642 1,196 1,090 908 1,047 6,761 640 26.0 2,308 207 192 182 204 1,317 206 28.1 6,865 570 608 657 675 3,872 4B3 273 7,438 596 641 68B 724 4,353 436 2B.4 4076 7,441 724 671 655 6B7 4,251 453 26.6 14,501 3,907 7,627 2,336 631 6,809 1,723 3,747 1,011 328 4,628 1,387 2,243 741 257 3,992 1,096 . 2,009 624 263 3,970 908 2,134 729 199 2,751 591 1,355 464 339 2,057 438 974 457 188 3,780 1,019 1,903 649 209 5,681 1,534 2,864 8B3 400 1.068 283 506 153 126 3,384 839 1,852 639 254 3,715 945 1,761 770 239 3,634 1,030 1,796 576 232 a: Update of Table 4, "Heallh Risk Assessment (4 Ihe BKK Landrill, West Covina. California * Interim Report, November 1990, page 34, Hazardous Waste Toxicology Section, California Department ot Health Services, Sacramento, California. Taken from 'BKK Landfill Environmental Exposure Characterization Report, West Covina, California, Volume I, August IS, 1988, CH2M Hill, Santa Ana, California. b: 'United Stales Department of Commerce, 1990 Census of Population and Housing, population and Housing Characteristics Tor Census Tracts and Block Numbering Areas, Los Angeles-Long Beach, CA PMSA, Section 1 of 7." August 1993. Economic and Statistics Administration, Bureau of the Census, Washington D.C. 1990 CPH-3-215B. si sensed DRAFT -93- DRAFT APPENDIX F AIR DISPERSION MODELING OF THE 1983-1990 AMBIENT VINYL CHLORIDE MONITORING DATA R&S145516 DRAFT -94- DRAFT AIR DISPERSION MODELING OF THE 1983-1990 AMBIENT VINYL CHLORIDE MONITORING DATA Ogden Environmental and Energy Services Co., Inc. (Ogden) was contracted by DHS-DEODC and OEHHA-HWTS in February 1991 to select an air dispersion model and develop a data base which would be used to model estimates of historical vinyl chloride concentrations in ambient air around the landfill. The modeled estimates were to be used in the pending DHS-DEODC reproductive outcomes study and in the present addendum health risk assessment. ARB provided technical consultation for the project and assisted staff from DEODC in refining the emission rates. In November 1992, Ogden submitted its report, "Air Quality Modeling for the B.K.K. Landfill Air Toxic Exposure Study" (Ogden, 1992). The modelino was conducted using the Fugitive Dust Model (FDM), a Gaussian air dispersion model developed by USEPA and similar to USEPA's Industrial Source Complex (ISC) model. The ISC model is an approved model for regulatory purposes. The FDM model was selected over the ISC model because at the time the study was initiated, the FDM model was considered to estimate air concentrations close to large area sources, like the B.K.K. Landfill, better than the ISC model. The version of ISCST available at the .time of the project represented an area source by a single line source segment. Consequently, estimated concentrations for receptors close to a source ("near-field") could be under- or over-predicted. Near-field concentrations have been associated with highest detected values of vinyl chloride in monitoring around the landfill. The inability of ISCST to capture near-field concentrations was considered to be a serious limitation for this project. Although intended primarily for the calculation of particulate concentrations, FDM is equally suited for any pollutant from non-buoyant sources. FDM uses the standard Gaussian plume formulation for computing downwind concentrations from an emission point, line, or area source. The area source algorithm was used for the B.K.K. Landfill. The algorithm provides a uniform distribution of emissions from the area source, represented as a series of line sources (rectangles) oriented perpendicular to the wind. For the purposes of this project, the area source for the model was considered to be the 170-acre closed Class I unit. Neither ISCST nor FDM can account for terrain influences on the direction of plume travel. Studies conducted in the 1980s around the landfill document a nighttime wind flow from the landfill down the hill to the residential community adjacent to the landfill. All of the available Gaussian complex terrain models are designed to simulate impacts on terrain elevated above the source; none are intended to simulate impacts on nearby receptors below the emission point, as exists at the B.K.K. Landfill. Meteorological data required for the model were obtained from three sources. The primary source was SCAQMD's meteorological station located at Station A. Wind speed and wind direction data were collected hourly between 1983 and 1985 at Station A. Data missing from Station A were replaced with corresponding data from SCAQMD's meteorological station at Walnut. Additional meteorological data used in the modeling were obtained for the same time period using hourly data collected by the National Climatic Data Center at Ontario Airport in Ontario. All three years of meteorological data were combined to represent average annual meteorological conditions at the B.K.K. Landfill during the modeled time periods. To predict annual average concentrations for the years after 1985, the three years of hourly meteorological data were run through the stability array (STAR) program. STAR is a statistical meteorological program which produces a composite wind direction frequency distribution, stratified by wind speed and stability class. Wind speed and wind direction determine both the location of pollutant impacts and their magnitude. Station A wind data were considered to be the most representative available historical information on the transport of pollutants from the landfill because vinyl chloride was monitored almost daily at Station A from June 1981 through March 1990. Walnut Station is located R&S145517 DRAFT -95- DRAFT approximately three kilometers south-southeast of the landfill and is influenced by different terrain features. Walnut data were not deemed as representative as the primary data source but were considered acceptable to fill in gaps missing in Station A data. Stability class is a measure of the dispersive capacity of the atmosphere. It is not measured directly but derived from other measurements. USEPA developed a data processing package called RAMMET which uses concurrent sky cover measurements and wind speed to derive stability class. Hourly stability categories were developed using the RAMMET program and sky cover data from Ontario Airport. Mixing height determines the depth through which pollutants can disperse in the atmosphere. Modeling for ground-level sources such as the B.K.K. Landfill are mostly insensitive to mixing height. Hourly mixing heights were calculated using the RAMMET program and average, seasonal mixing heights interpolated from values published for the contiguous United States. Annual vinyl chloride emission rates were estimated from continuous 24-hour average vinyl chloride concentrations measured at SCAQMD's three residential monitoring stations south of the landfill, Stations A, B, and MY. Average annual concentrations were then determined for each monitoring station, with the nondetected samples set at one-half the detection limit (1983 through 1987,2 ppb; January 1988 through September 1989,1.4 ppb; October 1989 through March 1990,2 ppb). To calculate emission rates, the FDM model was run with a nominal emission rate for each year at each monitoring station when monitoring data were available. All of the vinyl chloride was assumed to have originated homogeneously from a rectangle approximating the Class I unit. The emission rates were then scaled so that the modeled concentrations equaled the measured concentrations. The highest average annual emission rate from the three stations for each year was selected as representative of vinyl chloride emissions for that year. For all years except 1988, the highest emission rate was obtained from Station A. For 1988, the highest emission rate was obtained from Station MY. ARB provided technical consultation to the project. ARB recommended running tests to estimate the difference that would be predicted using different meteorological data sets (SCAQMD's Station A and Walnut Station) and different models (USEPA's regulatory model, ISCST; FDM; and ARB's regulatory screening model, SCREEN). To test the effects of using Station A meteorological data versus Walnut data, FDM was run twice: first using hourly Station A data for the time period October through December 1984, then using the wind data from Walnut for the same time period. In both tests, the model was run with a unit emission rate, and the landfill emission rate was then back-calculated from the measured concentrations at Station A, B, and MY. The results showed that significant differences in emission rates were obtained, with smaller emission rates obtained using Station A data. The conclusion for this project was that the site-specific data from Station A would more accurately reflect the micrometeorology around the B.K.K. Landfill. Comparison of the FDM and ISCST models was made using the estimated emission rates for JanuaryMarch 1983. The results showed similar isopleth contours and a similar point of maximum impact, located on the landfill boundary. However, the maximum concentration predicted by FDM was almost three times higher than that predicted by ISCST. The conclusion for this project was that FDM would not underpredict near-field receptors, such as Stations A, B, and MY. All air dispersion models are designed to be health protective. SCREEN is a worst-case' model which, rather than using actual meteorological data, calculates hourly concentrations from all combinations of wind directions, wind speeds, and stability conditions and reports the maximum of all three. Comparison of the FDM and SCREEN models was made using emission rates for Station A for the time period January-March 1983. Results showed that SCREEN predicts concentrations three- to ten-fold greater than FDM. The conclusion for this project was that the order of health protective conservatism built into the three models is: SCREEN > FDM > ISCST, as desired. R&S145518 DRAFT -96- D R AFT APPENDIX F-FIGURE1 is an isopleth of vinyl chloride at 2,1, and 0.05 ppb modeled concentrations around the B.K.K. Landfill in 1989 generated by FDM. The purpose of the isopleth is to show the general direction of the plume. Confidence in the extent of contamination depicted in the isopleth is iow for the following reasons: All of the vinyl chloride was assumed to have originated homogeneously from a rectangle approximating the Class I unit. This assumption may overestimate concentrations at residential locations on the eastern side of the landfill and underestimate concentrations at residential locations on the western side of the landfill since vinyl chloride may have been released from other areas of the landfill. Similarly, the assumption does not estimate potential localized "hot spot" areas of vinyl chloride emissions; Vinyl chloride monitoring data and the meteorological data were solely from the southern boundary of the landfill. Less confidence-can thus be placed on modeled estimates at other areas around and away from the landfill; Emission rates were developed from average annual vinyl chloride concentrations calculated with nondetected measurements set at one-half the detection limit. Between 37 and 100 percent of the measurements in any given year were below the detection limit. This assumption may produce overly conservative concentration estimates. In 1989, 99 percent of the data from Station A was non-detects; The emission rate estimated for each year was the highest emission rate back-calculated from the data at the three stations. Emission rates calculated using Station A data were on the average 139 percent higher than emission rates calculated using Station B data. This assumption will overestimate concentrations near stations which were not used to estimate a given year's emission rate, and may result in higher concentration estimates in other areas as well. In addition to data and methodology limitations given above, there are uncertainties and limitations inherent to all Gaussian air dispersion modeling, the extent of which, regarding the B.K.K. Landfill, were not apparent until after working with the model: Gaussian models cannot calculate concentrations accurately when wind speeds fall below one meter per second (m/s). As recommended by USEPA, all wind speeds which fell below one m/s were adjusted to one m/s. At the B.K.K. Landfill, wind speeds below one m/s occurred 60 percent of the time. Setting a lower wind speed boundary at one m/s would tend to overestimate the back-calculated emission rates and may result in higher concentration estimates away from the monitoring stations. The effect is somewhat offset by the fact that emission rates were back-calculated from measured data near the landfill. Gaussian models cannot factor in complex, topographical terrain, as exists around the B.K.K. Landfill; that is, models cannot account for an emission source which is at a higher elevation than the receptors. This limitation may overestimate concentrations on hilltops and underestimate concentrations in valleys. R&S145519 DRAFT -97- DRAFT APPENDIX F-FIGURE 1 {Department of Health Services, Division of Environmental and Occupational Disease Control) Note: Confidence in the extent of modeled vinyl chloride concentrations is low because of the assumptions used in, and limitations and uncertainties of, the Fugitive Dust Model. In the figure, the 2 ppb vinyl chloride isopleth is on the landfill, the 1 ppb vinyl chloride isopleth extends to Amar Road, and the 0.05 ppb vinyl chloride isopleth extends to the three mile radius southwest and east of the landfill. The purpose of the isopleth is to show the general direction of the estimated modeled plume. np a ct OESSHS^U -9R- D R AFT BLANK RAGE DRAFT -99- D RAFT V Z S S H S 'St) APPENDIX G UPDATED RISK ESTIMATE OF THE 1984 INDOOR AIR MONITORING PROGRAM EVALUATED IN THE 1990 INTERIM REPORT R&S145522 DRAFT -100- D RAFT UPDATED RISK ESTIMATE OF THE 1984 INDOOR AIR MONITORING PROGRAM EVALUATED IN THE 1990 INTERIM REPORT This Appendix revises the risk estimate for the USEPA-DHS 1984 indoor air monitoring program using updated unit risk values. In July 1984,19 homes along the southern and southeastern perimeter of the landfill were evacuated when methane, from subsurface migration of landfill gas, was detected at concentrations above the lower explosive limit (50,000,000 ppb). Ten of the evacuated homes were designated "Priority I" based on concentrations of vinyl chloride detected in grab, 2-liter air samples collected inside the homes. In October 1984, the ten Priority I homes were resampled with a "control" home. Samples were collected in Tedlar bags over 24-hours. The purpose of the indoor air monitoring program was to determine the safety of reoccupying the homes. There was a discrepancy regarding the concentrations of benzene detected in the Priority I homes: CH2M Hill reported laboratory contamination; however, no documentation or explanation was provided, and benzene data was included in the appendices of the exposure characterization (CH2M Hill, 1988). The limited scope of the program (grab samples in July and 24-hour samples in October) precludes its usefulness in the long-term assessment of this addendum report. APPENDIX G-TABLE1 updates the risk estimate associated with the five carcinogens detected in the evacuated homes. The individual excess lifetime cancer risk associated with an assumed one-year exposure to the concentrations detected in the homes is estimated to be approximately 2 x 10`5. Vmylidene chloride (1,1-dichloroethene) is no longer considered a carcinogen in California and has been deleted from the list of California Cancer Potency Factors. Consequently, it is not included in the revised risk estimate. R&S 145523 DRAFT -101- DRAFT APPENDIX G-TABLE 1a INDIVIDUAL EXCESS LIFETIME CANCER RISKb USEPA-DHS 1984 EXTENDED MONITORING PROGRAM (INDOOR AIR, EVACUATED HOMES) BKK LANDFILL, WEST COVINA, CALIFORNIA Carcinogen Medianc ppb pg/m^ Unit Riskd 0ig/m3)-1 1990 4994 Vinyl Chloride Perchloroethyiene Trichloroethene 1,2-Dichloroethane Benzene 4 10.2 2.5 17.0 1.5 8.1 3 12.1 7 . 22.4 2.7 E-6 5.8 E-7 1.3 E-6 2.2 E-5 5.3 E-5 7.8 E-5 5.9 E-6 2.0 E-6 2.2 E-5 2.9 E-5 Total Excess Lifetime Cancer Risk Including Benzene Total Excess Lifetime Cancer Risk Excluding Benzene Cancer Risk 1990 1994 3.1 E-7 1.1 E-7 1.2 E-7 3.0 E-6 1.4 E-5 9.1 E-6 1.1 E-6 1.9 E-7 3.0 E-6 7.4 E-6 1.8 E-5 3.5 E-6 2.1 E-5 1.3 E-5 USEPAe Class A C B2 B2 A a: Update of Table 16, 'Health Risk Assessment of the BKK Landfill, West Covina, California, Interim Report, November 1990,' pg. 68, Hazardous Waste Toxicology Section, California Department of Health Services. Sacramento, California, b: Calculated by ECR = CxYRxEFxURx1/LTwhere ECR = Excess lifetime cancer risk C B Concentration in pg/m3 YR E Years of residence associated with exposure (1) EF = Exposure factor, i.e. percent of time at home (80%) UR = Unit risk value LT = Human individual lifetime in years (70) c: Median values taken from Table 6-13, 'BKK Landfill Environmental Exposure Characterization Report, West Covina, California," CH2M Hill, 1988, Volume I, p. 6-45. d: 1990 values were derived by the United States Environmental Protection Agency (USEPA) or the California Department of Health Services, Health Hazard Assessment Division, Air Toxics Section and were taken from Table 3.15, 'Air Toxics Assessment Manual,' California Air Pollution Control Officers Association, October 1987 pgs 3.5-24 to 3.5-28. 1994 values were taken from the Standards and Criteria Work Group, 'California Cancer Potency Factors: Update 1994", California Environmental Protection Agency (Cal/EPA, Office of Environmental Health Hazard Assessment), Sacramento, California. NOTE: 1,1-Dichloroethene is no longer considered a carcinogen in California and has been deleted from the California Cancer Potency Factors. Consequently, it is not included in the table update. Changes in the unit risk values are due to increased knowledge about the inherent toxicity of the chemicals. e: USEPA weight of evidence classification: A, sufficient evidence in humans; B1, sufficient evidence in animals, limited in humans; B2, sufficient evidence in animals, inadequate in humans; C, limited evidence in animals, inadequate in humans. Taken from USEPA's Integrated Risk Information System (IRIS), November 1994. R&S145524 DRAFT -102- D RAFT BLANK PAGE R&S145525 DRAFT -103- DRAFT APPENDIX H DEPARTMENT OF HEALTH SERVICES-CANCER SURVEILLANCE SECTION LETTER REGARDING REVIEW OF RECENT TUMOR INCIDENCE DATA r &S145526 DRAFT -104. DRAFT STATE OF CALIFORNIA--HEALTH AND WELFARE AGENCY . DEPARTMENT OF HEALTH SERVICES 714/744 P STREET P.O. BOX 942732 SACRAMENTO. CA 94234-7320 (510) 540-2711 November 16, 1995 PETE WILSON, Govwno- Robert L. Holtzer M.D. Hazardous Waste Toxicology Section Office of Environmental Health Hazards Assessment 601 North 7th Street/MS 241 P.O.Box 942732 Sacramento, CA 94234-7320 RECEIVED VlOV Z& Hazardous Waste Toxicology Section Dear Dr. Holtzer, In response to your request, the Cancer Surveillance Section of the Department of Health Services, in collaboration with the Cancer Surveillance Program of Los Angeles, has examined the incidence of invasive cancer in the six census tracts (see enclosed map) around the BKK landfill in West Covina. We have compared the observed cancer incidence in the area with the incidence expected on average if the residents had the same cancer rates as Los Angeles County as a whole. As you know, California has had a statewide cancer reporting system since 1988. The California Cancer Registry (CCR) has information on every cancer case diagnosed in a California resident after January 1, 1988, with the exception of squamous and basal cell carcinomas of the skin, which are very common and usually treated in doctors' offices. Th information gathered includes addresses at the time of diagnosis, which are allocated to the appropriate census tracts. Data for Los Angeles County are collected by the Cancer Surveillance Program of Los Angeles, University of Southern California. These data enabled us to obtain the observed number of cancers, that is the number of invasive cancers of all anatomical sites combined that were actually diagnosed among residents of the area of the six census tracts during the six-year period 1988-93. We estimated the expected number by applying the average annual incidence rates of invasive cancer for Los Angeles County, specific for five-year age group, race, and sex, to the corresponding 1990 population data for the census tracts. Assuming the population either to be stable or to have increased linearly between 1988 and 1993, multiplying the'expected numbers for 1990 by six, produces estimates of the cases expected during the six years, 1988-93. The table below shows the numbers. -105- R&S145527 THE INCIDENCE OF INVASIVE CANCER IN THE BKK LANDFILL AREA ALL RACES, ALL ANATOMICAL SITES COMBINED LOS ANGELES COUNTY, 1988-93 Census Tract Expected No. 1990 Expected No. 1988-93 Observed No. `Iggfe23 4034 4078 . 4079 4080.01 4080.02 4081.31 . 56.3 17.0 12.6 18.7 16.8 23.7 338 102 76 112 101 142 333 114 85 114 81 128 Total 145.1 871 855 As the the table shows, the observed number of cases in the entire area, 855, was actually lower than the number expected, on average, during this time period, 871. Neither this difference nor the differences between the observed and expected numbers for the individual census tracts are statistically significant; the differences are within the bounds of what can be expected to occur, in either direction, by chance alone. No cases of hemangiosarcoma of the liver were reported among residents of these six census tracts during the years 1988-93. Of the 27 hemangiosarcomas diagnosed in California during this time period, seven occurred in Los Angeles County, a proportion roughly equivalent to the population proportion in Los Angeles. Only one case occurred within five miles (neither downwind nor downwater) of the BKK landfill. This was in an elderly person who moved into the area in 1989, and was diagnosed a few years later. Thus there is no indication of an increase in hemangiosarcoma of the liver in the area around the BKK landfill durin this time period. In summary, for the six-year period, 1988-93, there is no indication that the incidenc of invasive cancer among residents of the area around the landfill has been different than cancer incidence among residents of the. entire Los Angeles region. -106- R & S 145528 If there are any questions, please call me at (510) 540-2711. Sincerely, Eva R. Glazer, M.D., M.P.H. Cancer Surveillance Section 2151 Berkeley Way, Annex 2 Berkeley, CA 94704 cc: John L. Young Jr., Dr.P.H., CTR Cancer Surveillance Section P.O. Box 942732 MS 592 Sacramento, CA 95814 Wendy Cozen D.O., M.P.H. USC Cancer Surveillance Program 1540 Alcazar St., CHP-204 Los Angeles, CA 90033 Phil Jacobs Toxics Epidemiology Program Los Angeles County Department of Health Services 510 S. Vermont, Room 215 Los Angeles, CA 90020 Richard Kreutzer, M.D. Environmental Health Investigations Branch 5900 Hollis Street, Suite E Emeryville, CA 94608 -107- ezssus'sy -108-