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Health Risk Assessment of the B.K.K. Landfill, West Covina, California Prepared by: David M. Siegel, Ph.D., D.A.B.T. Lillian J. Kelly, R.E.H.S., R.N., M.P.H. Katherine L. Goldsmith, Dr.P.H. Hazardous Waste Toxicology Section Environmental Epidemiology and Toxicology Branch Health Hazard Assessment Division California Department of Health Services 714 P Street, Room 499, Sacramento, CA 95814 November 1990 INTERIM REPORT R&S145922 ACKNOWLEDGEMENTS In June 1990, a draft copy of the "Health Risk Assessment of the B.K.K. Landfill, West Covina, California" was reviewed by members of the Air Quality Advisory Committee, a technical subcommittee of the Interagency Steering Committee of the B.K.K. Landfill. The Department of Health Services expresses appreciation to the committee members for their critique of the draft report. Comments and suggestions were incorporated into this interim report. Statistical evaluation of the data in the 1984 Extended Monitoring Program of the risk characterization was performed by Joel Swartz, Ph.D., Environmental Epidemiology and Toxicology Branch. Special recognition is given to Sharon Davis, Office Technician, and Shirley Williams, Word Processing Technician, for their patient and diligent word processing support. 33 C/3 tJl wtroo TABLE OF CONTENTS LIST OF FIGURES....................................................................................................................................it! LIST OF TABLES........................................................................................................................................ iv GLOSSARY OF TERMS................................................................................................................................. vi EXECUTIVE SUMMARY....................................................................................................................................1 INTRODUCTION............................................................................................................................................... 7 Nature of Health Risk Assessments..................................................................................... 7 Purpose and Scope of this Health Risk Assessment.................................................. 7 History of the BKK Landfill, West Covina, California.........................................8 HAZARD IDENTIFICATION........................................................................................................................ 18 Indicator Chemicals Detected at the BKK Landfill................................................18 Carcinogens Detected at the BKK Landfill.................................................................. 22 EXPOSURE ASSESSMENT.............................................................................................................................25 Population in The Vicinity of the BKK Landfill.................................................... 26 Pathways of Exposure to Neighboring Residents.......................................................32 Air Monitoring/Modeling Programs Used in the Quantitative...........................40 Risk Characterization DOSE-RESPONSE ASSESSMENT.................................................................................................................43 Chronic Reference Doses..........................................................................................................43 Inhalation Unit Risk Values................................................................................................ 45 RISK CHARACTERIZATION........................................................................................................................48 Risk Characterization of Exposure to Contaminants Detected........................ 48 in Offsite Surface Water Near the BKK Landfill Risk Characterization of Noncarcinogens Detected in ...................................... 50 Air Near the BKK Landfill Risk Characterization of Carcinogens............................................................................51 Numerical Estimations of Risk............................................................................................ 53 Limitations and Uncertainties............................................................................................ 81 Significance of the Risk....................................................................................................... 83 REFERENCES................................................................................................................................................. 85 APPENDICES Appendix A Summary of the Three Previous Health Risk Assessments of the BKK Landfill, West Covina, California. -i- R&S145924 Appendix B "Ambient Air Monitoring and Health Risk Assessment for Suspect Human Carcinogens Around the BKK Landfill in West Covina," March 1983. California Department of Health Services-Toxic Substances Control Division, California Air Resources Board, and South Coast Air Quality Management District. Appendix C "Estimates of Carcinogenic Risk in the Vicinity of the BKK Landfill," March 1986. K.S. Crump and Co., Inc., Ruston, LA. Appendix D "Risk Assessment for Exposure to Ambient Air in BKK Landfill in West Covina, 1978-1985," April 1986. Martyn T. Smith, Health Risk Associates, Berkeley, CA. the Vicinity of the Kenneth T. Bogen and Appendix E Analysis of Variance of the Data in EPA and DHS' 1984 Extended Monitoring Program. Note: Copies of the three previous health risk assessments of the B.K.K. Landfill are provided for the reader who wishes to review the methods and assumptions of those reports. R&S145925 -ii- LIST OF FIGURES FIGURE PAGE 1 LOCATION MAP, BKK LANDFILL, WEST COVINA, CA..........................................................9 (Environmental Solutions, Inc.) 2 WASTE LOCATION INDEX MAP, BKK LANDFILL, WEST COVINA, CA........................... 10 (Environmental Solutions, Inc.) 3 VICINITY MAP, BKK LANDFILL, WEST COVINA, CA....................................................... 14 (Environmental Solutions, Inc.) 4 POPULATION CENSUS TRACTS IN THE VICINITY OF THE BKK LANDFILL............... 28 (CH2MH111) 5 SENSITIVE POPULATIONS NEAR THE BKK LANDFILL (CH2MHill)..............................31 6 SCHEMATIC OF EXISTING AND POTENTIAL CONTAMINANT MIGRATION...................... 33 PATHWAYS, BKK LANDFILL (CH2MHU1) 7 AIR MONITORING PROGRAMS, BKK LANDFILL, WEST COVINA, CA (CH2MHill)..52 8 VINYL CHLORIDE IN AMBIENT AIR, 1983-1987 STATION A MONTHLY..................57 MONITORING DATA, BKK LANDFILL, WEST COVINA, CA 9 AMBIENT AIR TOXIC MONITORING SITES IN THE SOUTH COAST AIR.................... 69 BASIN (SCAQMD) NOTE: A parenthetical notation in the title credits the source of the Figure. A footnote on the Figure provides the full reference. R&S145926 -iii- LIST OF TABLES TABLE PAGE 1 HAZARDOUS WASTE TYPES DEPOSITED IN BKK LANDFILL, 1975-1984.................... 12 (Environmental Solutions, Inc.) 2 LISTINGS OF CHEMICALS DETECTED AND INDICATOR CHEMICALS..............................19 BKK LANDFILL, WEST COVINA, CA (CH2MHill) 3 CARCINOGENS DETECTED IN GROUNDWATER, SURFACE WATER, AND AIR..................24 BKK LANDFILL, WEST COVINA, CA 4 SUMMARY OF POPULATION CENSUS TRACT DATA FOR THE VICINITY.........................29 OF THE BKK LANDFILL (CH2MH111) 5 POTENTIALLY SENSITIVE POPULATION SUBGROUPS FROM CENSUS TRACTS............. 30 IN THE VICINITY OF THE BKK LANDFILL (CH2MH111) 6 INDICATOR CHEMICALS DETECTED IN OFFSITE SURFACE WATER,..............................35 1981-1985, BKK LANDFILL, WEST COVINA, CA 7 SUMMARY OF AIR QUALITY RELATED DATA COLLECTIONS FOR THE........................... 36 BKK LANDFILL AND VICINITY (CH2MHill) 8 AIR MONITORING/MODELING PROGRAMS USED IN THE QUANTITATIVE...................... 41 RISK CHARACTERIZATION OF THE BKK LANDFILL, WEST COVINA, CA 9 REFERENCE DOSES FOR INDICATOR CHEMICALS DETECTED IN.................................... 44 OFFSITE SURFACE WATER AND AIR, BKK LANDFILL, WEST COVINA, CA 10 INHALATION UNIT RISK (IUR) VALUES FOR CARCINOGENS DETECTED AT.............47 BKK LANDFILL, WEST COVINA, CA 11 COMPARISON OF INDICATOR CHEMICALS DETECTED IN OFFSITE................................49 SURFACE WATER, 1981-1985, TO ORAL CHRONIC REFERENCE DOSES, BKK LANDFILL, WEST COVINA, CA 12 VINYL CHLORIDE IN AMBIENT AIR (ppb), 1983-1987, MONTHLY AND ............... 56 ANNUAL GEOMETRIC MEANS, SCAQMD MONITORING STATIONS AROUND BKK LANDFILL, WEST COVINA, CA 13 INDIVIDUAL EXCESS LIFETIME CANCER RISK, SCAQMD AMBIENT VINYL............... 59 CHLORIDE MONITORING PROGRAM, BKK LANDFILL, WEST COVINA, CA 14 INDIVIDUAL EXCESS LIFETIME CANCER RISK, DHS-TSCP/CARB/SCAQMD............... 63 1982 EXPANDED MONITORING PROGRAM, BKK LANDFILL, WEST COVINA, CA 15 SUMMARY OF 1984 INDOOR MONITORING IN PRIORITY I HOMES................................65 AND A CONTROL HOME (CH2MHill) r &S 145927 -iv- TABLE PAGE 16 INDIVIDUAL EXCESS LIFETIME CANCER RISK, EPA AND DHS 1984.........................68 EXTENDED MONITORING PROGRAM, BKK LANDFILL, WEST COVINA, CA 17 1985 ANNUAL AVERAGE AMBIENT AIR CONCENTRATIONS OF VARIOUS...................... 71 TOXIC ORGANIC GASES IN THE SOUTH COAST AIR BASIN (SCAQMD) 18 INDIVIDUAL EXCESS LIFETIME CANCER RISK, CARCINOGENS.................................... 74 DETECTED AT EL MONTE STATION, 1985 LOS ANGELES BASIN AIR TOXICS MONITORING PROGRAM, AND ALSO DETECTED NEAR BKK LANDFILL, WEST COVINA, CA 19. SUMMARY STATISTICS FOR THE JANUARY 1987 THROUGH DECEMBER1987.................77 MONITORING DATA FOR VINYL CHLORIDE NEAR BKK LANDFILL (CARB) 20 RANGE OF CUMULATIVE POPULATION EXPOSED TO VINYL CHLORIDE........................ 78 NEAR BKK (CARB) 21 INDIVIDUAL EXCESS LIFETIME CANCER RISK, CARB MODELING OF........................ 79 1987 AMBIENT VINYL CHLORIDE CONCENTRATIONS NEAR BKK LANDFILL, WEST COVINA, CA 22 SUMMARY OF THE THREE PREVIOUS HEALTH RISK ASSESSMENTS OF THE BKK LANDFILL, WEST COVINA, CA..................................................................... Appendix NOTE: A parenthetical notation in the title credits the source of the Table. A footnote on the Table provides the full reference. R&S145928 -v GLOSSARY OF TERMS ANALYSIS OF VARIANCE - A statistical technique that isolates and assesses the contribution of one or more factors to the variation in an outcome of interest. In analysis of variance (ANOVA), independent categorical variables (factors) are investigated for their influence on the dependent continuous random variable (outcome). Assumptions underlying ANOVA are: independence of the values, normality of the errors in the values, and equal variance for all observations. AMBIENT AIR - Outdoor air. AMBIENT AIR QUALITY STANDARD - A standard adopted by CARB in consideration of public health, safety, and welfare, including, but not limited to, health, illness, irritation to the senses, aesthetic value, interference with visibility, and effects on the economy; standards may vary from one air basin to another; standards relating to health effects are based on the recommendations of DHS (California Health and Safety Code Section 39606). An ambient air quality standard applies at the boundary of a facility. In 1978, CARB adopted an ambient air quality standard for vinyl chloride of 10 parts per billion (ppb) for a 24-hour average. The standard represented the limit of detection for vinyl chloride at that time. CARB - California Air Resources Board CAPCOA - California Air Pollution Control Officers Association CERCLA - In 1980, Congress passed the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) which established broad federal authority to deal with releases or threats of releases of hazard us substances. CERCLA, also known as Federal Superfund, was amended in 1986. CH2MHILL - A consulting engineering firm contracted by EPA in October 1985 to conduct an exposure assessment of the B.K.K. Landfill. CHRONIC REFERENCE DOSE - An estimate of the daily exposure to humans, including sensitive populations, that is likely to be without an appreciable risk of adverse health effects during the lifetime (70-years). Developed by EPA, the chronic reference dose is specifically designed to be protective for long-term exposures; the subchronic reference dose is used with short-term exposures. CLASS I LANDFILL - A classification system for landfills in California developed by state agencies. All landfills require a permit to operate. Class I landfills may accept hazardous waste, subject to federal and state regulations for hazardous waste management units. CLASS III LANDFILL - A landfill that accepts only non-hazardous waste (municipal refuse and dewatered sludge). Class III landfills are regulated by state and local agencies. DHS - California Department of Health Services -vi e z e s w s 'sy DHS-EETB - California Department of Health Services, Environmental Epidemiology and Toxicology Branch DHS-TSCP - California Department of Health Services, Toxic Substances Control Program EPA - United States Environmental Protection Agency HEALTH RISK ASSESSMENT - An analysis of the potential adverse health effects associated with exposure to hazardous substances based upon four systematic components: hazard identification, exposure assessment, dose-response assessment, and risk characterization. INDIVIDUAL EXCESS LIFETIME CANCER RISK - An upper-bound estimate of the probability of an individual developing cancer due to a lifetime (70-year) exposure to the level in question of a carcinogen. LANDFILL GAS - Methane, carbon dioxide, and trace gases generated by the anaerobic decomposition of buried organic wastes (both municipal and hazardous wastes). These gases serve as a transport medium for volatile organic compounds deposited or generated onsite. Landfill gas that is not collected by a gas collection system is released to ambient air, or migrates laterally through the soil before being released to the air or groundwater. LEACHATE - Any liquid, including suspended components in the liquid, that p rcolates through or drains from buried wastes. LINEARIZED MULTISTAGE MODEL - A mathematical model used to estimate the probability of incidence of disease by extrapolating from high dose animal studies to low level human exposures. This model is commonly used in quantitative carcinogenic risk assessments where the chemical agent is assumed to be a complete carcinogen and the risk is assumed to be proportional to the dose in the low region. This model yields estimates of risk that are conservative, representing a plausible upper limit for the risk. MAXIMUM CONTAMINANT LEVEL - The enforceable drinking water standard, based on health and technical feasibility. MAXIMUM LIKELIHOOD ESTIMATE - The best fit dose-response line from a set of data. POPULATION EXCESS CANCER BURDEN - An upper-bound estimate of the increase in cancer cases in a population as a result of a defined exposure to a carcinogen. RCRA - In 1976, Congress passed the Resource Conservation and Recovery Act (RCRA) which controls the generation, treatment, storage, and disposal of solid and hazardous waste. The Act, referred to as "cradle-to-grave" regulation of solid and hazardous waste, was amended in 1980 and 1984. R&s 145930 -vil- RCRA PART B PERMIT APPLICATION - Requires owners and operators of hazardous waste facilities to submit detailed information about a facility, such as: a description of the procedures, structures or equipment used to prevent runoff and contamination of water supplies; a topographic map showing surface waters, surrounding land uses (residential, commercial, agricultural, recreational); a wind rose; and injection and withdrawal wells onsite and offsite. Contents of Part A and Part B of the Application are specified in the California Code of Regulations, Title 22, Division 4, Chapter 30, Sections 66390 and 66391. SAM WORK FLAN - The Site Assessment and Mitigation (SAM) Work Plan for the Class I Hazardous Waste Management Unit, developed by consultants to the B.K.K. Landfill in coordination with regulatory agencies. Provisions of the SAM Work Plan address ongoing monitoring requirements of the B.K.K. Landfill. SCAQMD South Coast Air Quality Management District SLOPE FACTOR - An upper-bound estimate of the probability of developing cancer per unit intake of a chemical over a lifetime (70-year). The slope factor is usually, but not always, the upper 95th percent confidence limit of the slope of the dose-response curve and is expressed as (mg/kg-day)_1. THRESHOLD - A dose level below which a response attributable to a particular substance will not occur. TOXIC AIR CONTAMINANT - An air pollutant which may cause or contribute to an increase in mortality or an increase in serious illness, or which may pose a present or potential hazard to human health. As established by legislation in 1983, and in consultation with DHS, CARB is implementing a program which first identifies and then controls toxic air contaminants (California Health and Safety Code Section 39650 eC seq, Food and Agriculture Code Section 14021 et seq). UNIT RISK - A measure of the carcinogenic potential of a substance, expressed in terms of risk per unit concentration of the substance in the medium where human contact occurs. The inhalation unit risk is an estimate of the probability of developing cancer as a result of constant exposure over 70 years to 1 ng/m3 of a substance in air, UPPER 95 PERCENT CONFIDENCE LIMIT - The statistical upper bound of the excess cancer risk derived from low dose extrapolation models. V0C - Volatile organic compound * *. R&S145931 EXECUTIVE SUMMARY In October 1985, the United States Environmental Protection Agency (EPA) contracted CH2MHill to conduct an exposure assessment of the B.K.K. Landfill, West Covina, California with the understanding that the California Department of Health Services (DHS) would perform a quantitative health risk assessment based on the data collected and evaluated. In August 1988, CH2MHI11 completed its seven-volume report, entitled "B.K.K. Landfill Environmental Exposure Characterization Report, West Covina, California." The report was reviewed by EPA, DHS, a technical peer review subcommittee, and a citizens advisory committee. This health risk assessment of the B.K.K. Landfill was prepared by the Hazardous Waste Toxicology Section of the California Department of Health Services, Health Hazard Assessment Division. The health risk assessment is concerned primarily with the risk of developing cancer from a 70-year exposure to the concentrations of carcinogens detected in air around the B.K.K. Landfill between 1982 through 1987. Air monitoring data from this period met retrospective quality assurance review for use in a quantitative risk characterization. The health risk assessment is divided into five parts: INTRODUCTION, which introduces the health risk assessment and summarizes the history of the B.K.K. Landfill; R&S145932 HAZARD IDENTIFICATION, which gives information about the indicator chemicals (carcinogens and noncarcinogens) detected in groundwater, surface water, and air in and around the B.K.K. Landfill; EXPOSURE ASSESSMENT, which describes the population in the vicinity of the B.K.K. Landfill, evaluates the pathways of exposure to neighboring residents, and describes the air monitoring programs used in the risk characterization; DOSE-RESPONSE ASSESSMENT, which identifies the chronic reference doses for noncarcinogens and the inhalation unit risk values for carcinogens used in the risk characterization; RISK CHARACTERIZATION, which estimates the individual excess lifetime cancer risk and the population excess cancer burden from a 70-year exposure to the concentrations of carcinogens detected In air around the B.K.K. Landfill between 1982 through 1987. A summary of the three previous health risk assessments of the B.K.K. Landfill is provided in the Appendix for informational purposes. The B.K.K. Landfill in West Covina, California, operated a Class I landfill (that is, a landfill permitted for disposal of hazardous waste) from approximately 1972 to December 1984. During that time, the B.K.K. Landfill was the largest Class I hazardous waste land disposal facility in California and the primary hazardous waste disposal facility for the Los Angeles area. The Class I landfill began as 40 acres in 1972, expanded to 140 acres in 1975, -2- R&S 145933 and by 1984 encompassed approximately 170 acres of the 583-acre facility. Acreage in excess of the 140 acres includes a buffer zone of the adjoining non-hazardous waste disposal area. Approximately 3.4 million tons of hazardous waste were deposited at the facility. Seventy-two percent of the waste was liquid hazardous waste such as acid solutions, alkaline solutions, solvents, and wastes containing vinyl chloride. Hazardous wastes were buried in drums, injected into wells, co-mingled with non-hazardous waste, or solidified (mixed) with onsite soil. The surrounding land was relatively undeveloped when the B.K.K. Landfill opened as a municipal waste disposal facility in 1963. Since that time, residential neighborhoods were developed to the north, west, south, and southeast. By 1985, EPA estimated the population within a one-mile radius from the center of the landfill to be approximately 40,000 persons (EPA, 1985). Beginning in 1969, neighboring residents complained about odors, surface water runoffs, spills, and dust releases from the facility. Since 1979, studies, investigations, and hearings have been conducted in response to complaints from residents and concerns of regulatory agencies. Environmental monitoring at the B.K.K. Landfill detected volatile . organic compounds in air, groundwater, and surface water in and around the facility. Vinyl chloride, a human carcinogen, was detected in ambient air at concentrations above California's ambient air quality standard of 10 parts per billion (ppb). EPA issued orders in 1984 and 1986 to the B.K.K. Corporation citing hazardous waste violations. On November 30, 1984, the B.K.K. Landfill stopped accepting hazardous waste. Under the direction of EPA and State -3- R&S145934 agencies, che B.K.K. Landfill completed closure of the Class I landfill in March 1989, and is conducting a Site Assessment and Mitigation (SAM) Work Plan. A Class III (non-hazardous waste) land disposal facility continues to operate on approximately 150 acres of the remaining 413 acres. EPA contracted the engineering firm of CH2MHill to conduct an exposure assessment to evaluate whether contaminants released from the B.K.K. Landfill presented a health risk to neighboring residents in comparison to background exposure concentrations. CH2MHill's report evaluated groundwater, surface water, and air monitoring data for 1975 to March 1986. The CH2MH111 report had several important conclusions about plausible past routes of exposure: 1) although groundwater below the B.K.K. Landfill is contaminated, groundwater is not used for drinking water or irrigation; 2) human exposure could have potentially occurred through ingestion or dermal contact with contaminated surface water released from the B.K.K. Landfill, but exposure would have been limited and infrequent; and 3) air monitoring data indicated an exposure pathway for neighboring residents. The hazard identification section and the exposure assessment section of this health risk assessment summarize information presented and evaluated by CH2MH111 in its 1988 report. The dose-response section identifies the toxicity values (reference doses and unit risk values current through June 1989) used in the quantitative risk characterization. The risk characterization section estimates the risk of adverse health effects associated with exposure to the concentrations of contaminants (carcinogens R&S 145935 -4- and noncarcinogens) detected in offsite surface water and air for residents living near the B.K.K. Landfill, Because it is assumed that no threshold exists for substances that induce cancer, the risk characterization is concerned primarily with the risk of developing cancer from a 70-year exposure to the concentrations of carcinogens detected in air around the B.K.K. Landfill between 1982 through 1987. Individual excess lifetime (70-year) cancer risks are estimated using data from three site-specific air monitoring programs and one Los Angeles basin air monitoring program evaluated by CH2MHill, and one air modeling program of site data used by the California Air Resources Board (CARB). The population excess cancer burden is estimated for residents within a one-mile radius of the landfill. Ambient vinyl chloride monitoring data represent the most appropriate data to assess the excess cancer risk associated with the B.K.K. Landfill because vinyl chloride is a human carcinogen and is not commonly detected in the Los Angeles air basin. Carcinogens such as benzene, perchloroethylene, and trichloroethylene are detected in ambient air both at the B.K.K. Landfill and in the Los Angeles basin (SCAQMD, 1987). These compounds may present an additional cancer risk to people living around the B.K.K. Landfill, but it is not possible with the present data to distinguish between exposure due to ambient levels and exposure due to the B.K.K. Landfill. Vinyl chloride is rarely detected in ambient air and therefore more clearly represents exposure associated with the B.K.K. Landfill. -5- R&S145936 Based on the 1987 ambient vinyl chi ride concentrations and the methods and assumptions used in this health risk assessment, the individual exc ss lifetime cancer risk associated with exposure to the carcinogen detected in air around the B.K.K. Landfill is estimated to be approximately 1 to 2 individuals in 100,000 persons. This assumes everyone is exposed to vinyl chloride at the 1987 concentrations for an entire 70-year lifetime. In the population of 40,000 persons living within a one-mile radius of the B.K.K. Landfill, less than one additional case of cancer would be expected to occur from this exposure. Currently, DHS and CARB are reevaluating the data on the carcinogenicity of vinyl chloride, in recent and past literature, for the purpose of identifying vinyl chloride as a toxic air contaminant. When this process is completed, a new unit risk value for vinyl chloride will be established. The new value is likely to be about 29 times greater than the value used in this health risk assessment. When this new value is adopted, DHS will prepare an addendum t this health risk assessment, reflecting the changed unit risk value for vinyl chloride, updating toxicity values, and adding air monitoring data collected since 1987. -6- 5 R&S145937 INTRODUCTION Nature of Health Risk Assessments Health risk assessments estimate potential adverse health effects associated with exposure to toxic and hazardous compounds based upon four systematic components: hazard identification, exposure assessment, dose-response assessment, and risk characterization. Each component refines the analysis and all four together are the assessment. Results of a health risk assessment are conditional on the methods and assumptions used, and the limitations and uncertainties identified. Health risk assessments are derived from the kn wledge and technology available at a particular time, and consequently need to be continually reviewed to ensure consistency with scientific advances. Purpose and Scope of this Health Risk Assessment The purpose of this health risk assessment is to estimate, for residents living near the B.K.K. Landfill, the risk associated with exposure to the concentrations of contaminants detected in environmental monitoring of the facility through 1987. This 1990 health risk assessment updates a 1982 joint agency assessment (DHS-TSCP/CARB/SCAQMD, 1983) and is expected to be updated when reevaluation of the cancer potency of vinyl chloride is completed. Information on the history of the B.K.K. Landfill, the choice of indicator chemicals, and the exposure assessment was taken primarily from Volume I of CH2MHill's seven-volume report to EPA. For a more detailed discussion of the -7- R&S145938 history, indicator chemicals, or exposure assessment, the reader is referred t that report (CH2MHill, Volume I, 1988). The CH2MH111 report was reviewed by EPA, DHS, a technical peer review subcommittee, and a citizens advisory subcommittee. Figures and tables taken from CH2MHill's report and other reports are individually referenced. History of the B.K.K. Landfill. West Covina. California 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). In 1963, the B.K.K. Landfill opened on 130 acres in the San Jose Hills as a municipal waste landfill for the disposal of household and commercial refuse and inert solids such as construction debris. A land use permit was obtained from the City of West Covina, and waste discharge requirements were prescribed by the Los Angeles Regional Water Quality Control Board. In 1971, the City of West Covina approved an expansion of the facility from 130 acres to the present 583 acres, and permitted the disposal of hazardous waste onsite. In 1972, the B.K.K. Landfill opened a 40-acre Hazardous Waste Management Unit (that is, a Class I landfill) and began accepting hazardous waste. In 1975, the Class I Hazardous Waste Management Unit expanded by an additional 100 acres (Figure 2). -8- R&S145939 The B.K.K. Landfill was the largest Class I hazardous waste land disposal facility in California and the primary commercial hazardous waste disposal facility for the Los Angeles area. Annual summaries of hazardous wastes deposited at the facility are available for the years 1975 through 1984. These summaries record that approximately 3.4 million tons of hazardous waste were deposited at the B.K.K. Landfill. Seventy-two percent of the waste was liquid hazardous waste. Wastes accepted in the greatest quantities were: acid solutions, alkaline solutions, contaminated soils, drilling muds, oil and oil sludges, tank bottom sediments, and other (unspecified) hazardous waste (Table 1). Hazardous wastes were deposited onsite by four methods: buried in drums, injected into wells, co-mingled with solid non-hazardous waste, and "solidified" (mixed) with onsite soil. In 1963, the B.K.K. Landfill was located in a relatively undeveloped area of the San Gabriel Valley. In 1971, a residential neighborhood was sited approximately 2,000 feet from the northern border. By 1975, residential zoning and land use permits in West Covina allowed the construction of hemes up to the property line on the southern and southeastern borders (Figure 3). Migration of hazardous waste constituents from the landfill occurred. Anaerobic decomposition of the waste generated landfill gas which served as a transport medium for volatile organic compounds (VOCs) deposited onsite to migrate to ambient air. Hydrogeologic investigations found contamination in groundwater under the facility. R& S 145940 -11- EN VIR O N M EN TAL SOLD TABLE 1 (Environmental Solutions, Inc.) TABLE 1.4 HAZARDOUS WASTE TYPES DEPOSITED IN BKK LANDFILL(*)(2) (1975-1984) (TONS) WASTE TYPE 1975 1976 1977 Acid Sludge Acid Solution Acid Solution w/Metals Acid Solution w/o Metals Acid Solution - Neutndized Adhesive Alkaline Sludge Alkaline Solution Alkaline Solution w/Metals Alkaline Solution w/o Metals Alkaline Solution Neutralized Alkali Sotirb Alum Sludge A. P. I. Generator Sludge Aqueous Solution w/Metals Aqueous Sotuiton w/>10% Organics Asbestos-Containing Wastes Ashes Baghouse Waste Bilge Wrier Bio. Waste Other Than Sewage Blasting Sand Brine Cannery Waste Catalyst Chemical Toilet Waste Chemicals, Unused Coninineis. Empty Contaminated Equipment Contaminated Soil and Sand Cyanide Waste Degreasing Sludge Detergent and Soap Distillation Bottoms Drilling Mud FCC Waste Filler Cake Filters, spent Flux Fly Ash Gasoline and Wrier Glare Sludge Glue Hair Puln I leavy Metal Solution Heavy Metal Sludge Ink and Solvent 19,300 33,497 41,756 49,598 62,761 70,747 6(5 9,046 220 172 22,998 45 329 17,380 34 708 289 585 17,2(8 12.316 13,773 (1) Source: BKK annual waste summaries, 1975 through 1914. (2) Blanks in the table result from change in waste classification. Dtposiled in the greatest quantity during this period. Reference: Modified from ClIjM Hill (March 6,19B6). 1978 1979 1980 71,615 83,440 112,755 69,782 69,396 79,487 1,121 3,895 34 648 1,641 31 673 367 213 1,421 3,978 4,488 41,650 27,319 19,153 fp6Sbl.S'8y 1981 299 66,526 5,395 210 1,361 45,899 281 269 919 721 5,393 69 91 185 4,256 2,645 564 25,388 59 206 2,084 It 55 2,263 240 716 1912 1,817 31,483 21,063 371 3.064 40,732 1983 22,649 13,942 2,984 481 18,219 18021 12,595 1,025 3,713 21,254 1,783 150 2,511 1,073 3,881 6,312 30,292 4,729 2,506 1,692 2,868 404 8,974 11 485 1.073 6,523 79,927 1,257 1,332 1,235 7,394 4,323 2.238 304 14 30 1.590 542 61 131 7,221 6,342 971 5,870 834 966 299,417 1,285 2,065 2,243 10,210 8,411 1984 312 24 146 406 6,177 9,149 3,176 7,090 19,863 6,664 2,659 286 1,890 278 3,623 894 i.m 76,929 1,157 1,733 237 1,392 5,678 TOTAL 2,116 4B3.333 13,966 3.130 26,458 1,475 4,425 512,798 27,170 15,771 281 1,025 17,384 22,173 50,155 11,393 6,948 2,128 7,269 1,794 682 3,881 3,628 55,327 23,860 657 2,304 3,150 6.523 458,540 15,400 2,442 7,775 4,279 175,883 18,471 2,444 304 t4 30 3,674 553 118 131 9,484 6,582 1,687 TABLE 1.4 HAZARDOUS WASTE TYPES DEPOSITED IN BKK LANDFILL (U(2> (1975-1984) (TONS) S ource: E n v iro n m e n ta l S o lu tio n s , In c ., Table 1 .4 , "BKK L a n d f ill S ite Assessm ent and M itig a tio n Work P lan, Book I , S ubsurface: S ite C h a ra c te ris a tio n ," March IS , 1986, p g s. 1*22 and 1~23. WASTE TYPE 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 TOTAL Ink Sludge Ink Wastewater Laboratory Chemicals Latex Waste Lime Sludge Machine Tool Coolant Meta) Sludge Meta) Dust aid Machining Waste Mud and Water Oil Chi Sludge Oil and Water Oil-Containing Waste, Unspecified Organic Liquids Organic Monomer Waste Organic Solids Paint Waste Paper SludgefPulp Pesticides Pesticide Containers Pesticide Rinsewater Pharmaceuticals Phenolic Waste Phosphate Sludge Photoproccssing Waste Plating Sludge Plating Solution, Acid Plating Solution, Alkaline Polychlorinated Biphenyls Resin Waste Scrubber Waste Solvent, Halogcnaied Solvent, Hydrocarbon Solvent, Oxygenated Solvent, Mixed Solvent, Unspecified Spill Cleanup Stretford Solution Sulfide Sludge Sump Sediment Tank Bottom Sediment Tanning Sludge Tetraethyl Lead Sludge Wastewater Treatment Sludge Other liquids Misc. Sludge Waste Other Hazardous Waste 714 17,754 24,630 3,377 904 3.447 24,205 88 6,769 3,107 31,416 11,229 3,401 334 6,424 32,742 91 3,803 446 6,482 5,433 1,586 29,259 65,816 44,437 38,426 9,467 27,403 22,276 14,137 6,372 130 7,414 189 6,952 290 5,092 358 9,211 16,649 17,139 27,340 37,661 100,434 124.448 146,152 33 25 60 3,250 13,863 24 290 2,302 1,501 4,890 8,966 76 423 186 3,053 3,528 1,376 1,177 1,204 2,568 35,201 3,628 353 263 33 82 823 1,870 5,848 879 1,158 350 1.046 813 188 19,418 856 1,583 211 12.734 13.088 155 6,344 989 541 1,215 253 10,304 3.582 529 471 9,516 35,611 17,604 238 24 26 578 32 1,445 5.949 3.583 2,4 BO 7 11,320 1,103 9,498 853 171 14,662 3,925 4,640 625 25,920 39,964 1,097 32 16,674 3,143 658 10,679 22,857 406 3,650 70,711 24,703 I.69Q 131 534 15,256 53 245 79 301 53 528 1,099 606 2,737 15,393 293 1,369 26,345 18,462 303 281 927 11,643 59 169 42 124 61 877 1,680 49 3,377 982 1,392 652 1,281 17,612 65 1,142 79 585 122 224 960 2,589 44,471 150 5,170 26,248 12,522 20,037 3,054 11,733 8 2,221 13,191 1,970 74,451 617 1,638 439 19,032 26,775 7,110 38,250 2,604 248,375 115,838 109,140 70,832 43,165 1,993 412 1,461 82,739 112 3,410 145 714 727 114 1,405 5,047 7,819 9,431 3,359 121 16,997 2,714 12,521 2,440 1,864 52,652 80,210 4,781 6,223 6,479 38,654 614,898 1,252 513 49.B09 43,571 14,492 124,721 mz TOTALS 178,733 268,897 259.487 418,683 428,261 459,507 287,813 493,539 759,660 342,050 3,896.630 >r (1 (Source: BKK annual waste summaries, 1975 through 1984. (2(Blanks in the table result from change in waste classification. (fl O Deposited in the greatest quantity during this period. Reference: Modified front Cl l^M Hill (March 6. 1986). z^esns'su  Source: Environmental Solutions, Inc.. Figure 1.2, "BKK Landfill Site Assessment and Mitigation Work Plan, Book I. Subsurface: Site Characterization," March 15, 1980, P- 1"3. -14- R&S145943 The first odor complaint against the B.K.K. Landfill was reported to the South Coast Air Quality Management District (SCAQMD) in 1969. The number of odor c mplaints reported to SCAQMD increased to 278 in 1979, 537 in 1980 and 936 in 1981. Neighboring residents have been concerned for many years about odors and hazardous waste releases in surface water runoff, spills, and dust from the B.K.K. Landfill, and have voiced general health concerns about living near a hazardous waste facility. Since 1979 various studies, investigations, and hearings have been conducted in response to complaints from residents and concerns of regulatory agencies. R&S 145944 In 1980, SCAQMD began monitoring ambient air in the vicinity of the B.K.K. Landfill for odorous organic compounds. In 1981 vinyl chloride, an odorless gas and a human carcinogen, was detected in concentrations above California's ambient air quality standard of 10 ppb. In June 1981, the California Department of Health Services-Toxic Substances Control Program (DHS-TSCP) banned further disposal of waste containing vinyl chloride from the B.K.K. Landfill, and SCAQMD established a program to monitor ambient air around the B.K.K. Landfill for vinyl chloride. I The following nine agencies formed an interagency task force in 1981 to coordinate activities associated with the B.K.K. Landfill: California Department of Health Services (the Control Program and Public Health) Los Angeles Regional Water Quality Control Board United States Environmental Protection Agency Toxic Substances -15- California Waste Management Board South Coast Air Quality Management District City of West Covina County of Los Angeles Department of Public Works County of Los Angeles Department of Health Services County of Los Angeles Sanitation Districts. In 1983, EPA requested a Resource Conservation and Recovery Act (RCRA) Part B Permit Application from the B.K.K. Landfill. During a facility inspection and permit application review later that year, EPA found several violations regarding groundwater monitoring, bulk liquid disposal, and ignitable/reactive waste disposal. In April 1984, EPA issued B.K.K. Corporation a RCRA Section 3013 Order of Consent, requiring a comprehensive investigation of onsite and offsite contamination. In July 1984, 19 homes along the southern perimeter were evacuated as a result of lateral subsurface migration of landfill gas. EPA issued B.K.K. Corporation a Comprehensive Environmental Respoi.se, Compensation, and Liability Act (CERCLA) Section 106 Order, requiring mitigation of landfill gas emissions and leachate migration. EPA and DHS monitored indoor air in homes, and reoccupancy criteria were developed by DHS Epidemiologic Studies and Surveillance Section (DHS, 1984). All evacuated homes were allowed to be reoccupied by December 1984. On November 30, 1984, the B.K.K. Landfill withdrew its RCRA permit application, stopped accepting hazardous waste, and began closure of the Hazardous Waste Management Unit. At that time, the size of the Class I unit was defined as 170 acres, which includes a buffer zone from the adjoining non-hazardous waste disposal area. -16- R&S145945 In 1986, EPA again issued orders to B.K.K. Corporation: a RCRA Section 7003 Order finding that an imminent and substantial endangerment to human health may have been present from handling and disposal practices at th B.K.K. Landfill; and a RCRA Section 3013 Order finding that a substantial hazard to human health or the environment may have been present from air and groundwater contamination and the proximity of drinking water sources in th area. The B.K.K. Corporation retained Environmental Solutions, Inc. to pr pare a SAM Work Plan in response to the EPA orders and in conjunction with federal, state, and local regulatory agencies. In March 1989, closure of the Class I Hazardous Waste Management Unit was completed with the placement of the final cover and collection systems as stipulated in federal and state regulations. As part of the post-closur permit, monitoring will continue at B.K.K. Landfill, and may continue for 30 years from the date of closure. A Class III (non-hazardous waste) land disposal facility continues in operation on approximately 150 acres of the remaining 413 acres. SAM Work Plan activities completed in 1989 included: a "phase I" sit hydrogeologic characterization, a landfill gas analysis, flare source testing, a soil and sediments sampling program, an ambient air gas and particulate monitoring program, and an air tracer test. An odor study, an elevated subsurface temperature and carbon monoxide sampling program, and a surface emissions program were in progress. Final SAM Work Plan reports are due in December 1990. -17- R&S145946 HAZARD IDENTIFICATION The hazard identification component of a health risk assessment determines whether or not chemicals present at a site may pose a hazard to human health, and whether the health hazard is carcinogenic or noncarcinogenic. Noncarcinogenic effects may result from acute or chronic exposures, and threshold levels are established below which no adverse health effect is expected. It is assumed that no threshold exists for carcinogens. This section identifies the indicator chemicals (carcinogens and noncarcinogens) detected in groundwater, surface water, and air in and around the B.K.K. Landfill. Indicator Chemicals Detected at the B.K.K. Landfill CH2MHill prepared a list of all chemicals detected in groundwater, surface water, and air around the B.K.K. Landfill (CH2MHI11, 1988). To focus on the contaminants of primary concern, CH2MHill applied the indicator chemical selection process, outlined by EPA in the "Superfund Public Health Evaluation Manual (1986)", and identified carcinogen and noncarcinogen indicator chemicals (Table 2) . The indicator chemical selection process directs attention to the contaminants of primary concern to human health and the environment, while not excluding any chemical that may cause harm to human health or the environment. Criteria used in the selection process are: the measured concentration of the -18- R&S145947 TABLE 2 (CHZMHill) listing of chemicals detected ano indicator CHEMICALS FOR GROUNDWATER, SURFACE WATER, AND AIR* BKK LANDFILL. WEST COVINA, CALIFORNIA A: GROUNDWATER CHEMICALS DETECTED INDICATOR CHEMICALS VOLATILE ORGANICS 1.1.1- Trichloroethene 1,1,2,2-T et raehloroetDane 1,1,2 T richloroethane 1.1- Dfchloroethane 1.1- Diehloroethylene 1,2Dichlorobenzene 1.2- Diehloroethene 1,2DichLoropropane 1,3Diehlorobenzene 1.4- 0ichlorobenzene 2-Butanone Acetone Benzene Brcmomethane Carbon tetrachloride Chlorobenzene Chloroethane Chloroform cis-1,2-Dlchloroethylene trans1,2-Dichloroethyt ene Ethylbenzene Methylene Chloride Xylenes o-Chlorotoluene Perchloroethylene Propylbenzene Styrene Toluene Trichloroethylene T riehloromonofluoromethane Vinyl Chloride SEMI-VOLATILES 1.2.4-Trichlorobenzene 1,3,STrimethylbenzene 2 Hexanone 2.4- Dimethylphenol bit(2-Chloroethyl)ether bia(2-Chloroi*opropyl)ether bis(2-Ethylhexyl)phthalate Dibutylphthalate Diethylphthalate Dimehiylm trosamine di-Octylphthalate tsophorone Naothalene n-Nitrosodimethylamine Phenol Phenols (total) Tetrahydrofuran INORGANICS Arsenic Barium Boron Cadaiun Chromum( total) Cobalt Copper Cyanide Fluoride Iron Lead Manganese Mercury Nickel Nitrates Seleniun Silver Zinc NON-CARCINOGENS VOLATILE ORGANICS 1,1,1T richloroethane 1.1- Dichloroethane 1.2- Diehlorooenzene 2-Butanone Chlorobenzene cis-1,2-Dichloroethylene trans-1,2-Diehloroethylene Ethylbenzene o,p-Xylene Toluene SEMI-VOLATILES Phenols, (total) Phenol INORGANICS Barium Cadmiun Copper Fluoride Lead Manganese Mercury Silver Zinc CARCINOGENS VOLATILE ORGANICS 1.1.2.2- Tetraehloroethane 1.1.2- Trichloroethane 1.1- Diehloroethylene 1.2- Dichloroethane Benzene Carbontetrachloride Chloroform Methylene Chloride Perchloroethylene Trichloroethylene Vinyl Chloride SEMI-VOLATILES bis(2-Chloroethyl)ether n-Nitrosodimethylamine INORGANICS Arsenic B & S 145948 Chemicals detected represent those found in the landfill gas; thc indicator chemicals represent those analyzed in the monitoring programs SYNONYMS 2-Butanone * Methylethylketone 2-Hexanone * Methylbutylketone n-Nitrosodimethylamine = Dimethylnitsosamine Methylene Chloride - Oichloromethane Perchloroethylene * Tetrechloroethylene TABLE 2 (Continued) LISTING OF CHEMICALS DETECTED AND INDICATOR CHEMICALS 8: SURFACE WATER CHEMICALS DETECTED INDICATOR CHEMICALS VOLATILE ORGANICS 1,2-Dichlorobeniene 1,1,1-Trichloroetnane 1,1,2-Triehloroetnene 1,1-Oichloroethane 1,1 -Diehloroethylene 1,2-Dichloroethane Acetone Benzene Bromodichloromethane Chlorobenzene Chlorodibromomethane Chloroform cis-1,2-Dichloroetnylene trans-1,2-Diehloroethylene Dichloromethane Ethylbenzene Xylenes o-Chlorototuene Perchloroethylene Styrene Propylbenzene Toluene Trichloroethylene Vinyl chloride SEMIVOLATILES 1,3,5-Trimethylbenzene 1,4-Diehlorobeniene Acenaphtnene bis(2-Ethylhexyl)phthalate Dibutyl phthalate oi-Octytphthalate Nitrosooipnenylamine Phenols (total) INORGANICS Arsenic Cackniun Chromium (total) Copoer Cyanide Lead Nickel Selentun Silver Zinc NON-CARCINOGENS VOLATILE ORGANICS 1,1,1-Trichloroethane 1,1-Dichloroetnane 1,2-DichloroDenzene Chlorooenzene Ethyl Benzene Xylenes Toluene SEMI-VOLATILES Phenol (total) INORCANICS Cadmiun Chremiun (total) Copoer Cyaniae Lead Nickel Seteniixn Zinc CARCINOGENS VOLATILE ORGANICS 1,1,2-Triehloroetnane 1,2-Dichloroethane Benzene Chloroform Methylene Chloride Perehloroethylene Trichloroethylene Vinyl Chloride INORGANICS Arsenic The indicator chemicals reDresent those analvied in the monitoring programs SYNONYMS 2-Butanone * Methylethylketone 2*Hexanone Methylbutylketone n-Nitrosodtmethylamme = Dimethylnitrosamine Methylene Chloride = Oichloroethane Perchloroethylene * letractuoroethvlene R & S 145949 -20- TABLE 2 (Continued) listing of chemicals detected and indicator chemicals C: AIR* CHEHICALS DETECTED VOLATILE ORGANICS 1.1-Dichloroethane 1.1-Dichloroethylene 1.2-Dichloroethane 1,3 - D i eh l oropropene 1,1,1 * Triehloroethane 1.1.2-Triehloroethane 2,3-Dimethylbutane Benzene Carbon Tetrachloride Chlorobenzene Chioroethane Chloroform Cyclohexane cis*1,2-Dichloroethylene trans-1,2-Dichloroethylene Hexane 1sopropylbenzene lso-octane Methane Methyleyelohexane Methycyclopentane Methylene Chloride Nonane n*Propylbenzene Perchloroethylene Toluene T riehloroethylene Vinyl Chloride Xylene (total) INDICATOR CHEMICALS NON-CARCINOGENS VOLATILE ORGANICS 1,1,1-Trichloroethane Chlorobenzene trans-1,2-Dichloroethylene CARCINOGENS VOLATILE ORGANICS 1.1-Dichloroethylene 1.2-Dichloroethane Benzene Carbon Tetrachloride Chloroform Perchloroethylene Trichloroethylene Vinyl Chloride BASE/NEUTRALS 1,4-Dichlorobenzene Dichlorobenzene ACID EXTRACTABLES 2-Butanol Chemicals detected represent those found in the landfill gas; the indicator chemicals represent those analyzed in the monitoring programs SYNONYMS 2-Butanone = Methylethylketone 2-Hexanone = Methylbutyl ketone n-Nitrosodimethylamine * Dimethylintrosamine Methylene Chloride Dichloromethane Perchioroethyiene = Tetrachloroethylene R&S 145950 Source: CH2MHH1. Table 5-4, "EKK Landfill Environmental Exposure Characterization Report, Halt Covina, California,'' August 15, 1988, Voltssa 1, p. 5-22. -21- chemical; the toxicity of the chemical; and the physical/chemical properties of the chemical, which determine fate and transport in environmental media. Consequently, indicator chemicals represent the most toxic, mobile, and persistent chemicals at a site as well as those in the greatest concentrations. Carcinogens Detected at the B.K.K. Landfill EPA evaluates available data on the carcinogenic effects of chemicals from two sources: human epidemiologic investigations and long-term animal tests. EPA applies to the data a "weight of evidence" judgment on the likelihood that the chemical is a human carcinogen (EPA, 1986; EPA, 1989). The evidence is characterized separately for human studies and animal studies as sufficient, limited, inadequate, no data or no evidence. For example, the weight-of-evidence for human studies is as follows: sufficient evidence of carcinogenicity, which indicates that there is a causal relationship between the chemical and human cancer; limited evidence of carcinogenicity, which indicates that a causal interpretation is credible, but that alternative explanations, such as chance, bias, or confounding, could not adequately be excluded; inadequate evidence. which indicates that either there were few pertinent data, or that available studies, while showing evidence of association, did not exclude chance, bias, or confounding and therefore a causal interpretation is not credible; R&S 145951 -22- no data, which indicates that data are not available; no evidence. which indicates that no association between an exposure and an increased risk of cancer was found in well-designed and well-documented epidemiologic studies. Based on the "weight of evidence", EPA classifies carcinogens as follows: - A: Human carcinogen, i.e., sufficient evidence of carcinogenicity in humans; - II: Probable human carcinogen, i.e., sufficient evidence of carcinogenicity in animals with limited evidence in humans; - BZ: Probable human carcinogen, i.e., sufficient evidence of carcinogenicity in animals with inadequate evidence in humans; - C: Possible human carcinogen, i.e., limited evidence of carcinogenicity in animals with inadequate evidence in humans; - D: Not classifiable as to human carcinogenicity, i.e., inadequate evidence of carcinogenicity in animals with no evidence in humans; - : Evidence of noncarcinogenicity for humans. The "weight of evidence" classifications for the carcinogens detected in groundwater, surface water, and air around the B.K.K. Landfill are A, B2, and C. The sites of carcinogenic effects for these chemicals include the liver, lung, skin, kidney, breast, and stomach. Table 3 presents this information for the carcinogens detected around the B.K.K. Landfill, based on toxicological data current through June 1989. -23- R&S 145952 table 3 CARCINOGENS DETECTED IN GROUNDWATER, SURFACE WATER, AMD AIR EKX LANDFILL WEST COVINA. CALIFORNIA Carcinogen CAS#* EPAb Class Cancer Site Arsenic (inorganic) Cadmium ChromiumCVI) Laad Nickel Benzene Bis-2-chloroethyl ether Carbon Tetrachloride Chloroform 1,2-Dichloroethane 1,1-Dichloroethylane Methylene chloride N-nitrosodimathylamine .. Ferchloroethylene 1.1.2.2-Tetrachloroethane 1.1.2- Trichloroethane Trichloroethylene Vinyl chloride 71-43-2 111-44-4 36-23-5 67-66-3 107-06-2 73-35-4 75-00-26 62-73-9 127-16-4 70-34-5 70-00-5 79-01-6 73-01-4 A B1 A B2 A A B2 B2 B2 B2 C B2 B2 C C C B2 A lung, skin lung, prostate, msmeary lung kidney, lung, nervous system lung, nasal hematopoietic system (leukemia) liver liver kidney, liver stomach, breast, uterus circulatory system, lung, liver kidney, bresst, lung liver, breest lung, hematopoietic system (leukemia) liver, lung, kidney, circulatory system liver liver liver, kidney, adrenal, spelen, circulatory system lymph, liver liver a~ Chemicsl abstract service number b" EFA weight of evidence classification: A, sufficient evidence in humans; Bl, sufficient evidence in animals, limited in humans; B2, sufficient evidence in snimals, inadequate in humans; C, limited evidence in animels, inadequate in humans. Taken from EFA'a Integrated Risk Information System (IRIS). June 1989. With the exception of 1,1-dichloroethylene and certain lead compounds, the above carcinogens sre listed as known to the State of California to cause cancer for purposes of the Health and Safety Code Section 25249.5 at seq. -24- EXPOSURE ASSESSMENT The exposure assessment component of a health risk assessment identifies and describes the population at risk, and the types, frequency, magnitude, and duration of exposures. This section describes the population in the vicinity of the B.K.K. Landfill, evaluates the pathways of exposure to neighboring residents, and tabulates the air monitoring programs which will be used in the risk characterization. For a more detailed analysis of the exposure assessment, the reader is. referred to Volume I of CH2MHill's report (CH2MH111, 1988). In October 1985, EPA contracted CH2MHill to conduct an exposure assessment as a technical enforcement support activity. The regulatory basis for the assessment was RCRA Section 3019, Subsection (b) and the procedural basis was the Superfund Public Health Evaluation Manual (EPA, 1986). The report, completed in 1988, included data available through March 1986 and consisted of the following volumes: Volume I - Text; Volume II - Plates; Appendices Volume 1 (groundwater data), Volume 2 (groundwater data), Volume 3 (groundwater data), Volume 4 (groundwater and surface water data), Voluma 5 (surface water, air, and soils data). Limited environmental monitoring data for the B.K.K. Landfill and the surrounding area have been collected since 1975, specifically: groundwater data are available from 1975 to the present; surface waters have been sampled since 1980; landfill gas, ambient air, and odor studies have been conducted -25- R&S 145954 onsite and offsite since 1979, In 1984, ten onsite soil samples were analyzed for particle size only; one offsite residential soil sample was analyzed for volatile organic compounds and none were detected. CH2MHill's objectives for the exposure characterization were: 1. to compile and evaluate existing environmental monitoring data collected onsite and near the B.K.K. Landfill; 2. to provide detailed analyses of the data to assess whether exposure to contaminants released from the B.K.K. Landfill posed either an immediate or a long-term risk to human health or the environment, in comparison to background exposure concentrations. Data analyses included both: retrospective quality assurance review of the environmental monitoring data, and fate and transport evaluation of the contaminants in groundwater, surface water, and air. Population in the Vicinity of the B.K.K. Landfill In 1963, when the B.K.K. Corporation received its permit, the landfill was located in a relatively undeveloped area of the San Gabriel Valley. In 1967, the California Department of Finance estimated a population of approximately -26- b8lS 145955 67,000 in West Covina to the north and west of the facility, and a population of approximately 4,500 in Walnut to the east. In 1988, the Department of Finance estimated a population of 94,000 in West Covina and 25,000 in Walnut. CH2MHill identified the age and sex distribution of the population in whole census tracts around the B.K.K. Landfill (Figure 4, Tables 4 and 5). Ethnicity, occupation, and socioeconomic status were not characteriz d. Demographics, prepared by CH2MH111 from the 1980 U. S. population census, Indicated that the residential communities in and around the B.K.K. Landfill consisted primarily of young adults, families with children, and women of childbearing age. CH2MHill examined sensitive population groups within a one-mile radius of the landfill boundary and identified 12 elementary schools, 2 child care centers, and 1 nursing home (Figure 5). The population within a one-mile radius around the landfill was estimated for use in previous risk assessments and in the exposure assessment. In 1982, three agencies jointly conducted the first health risk assessment (DHS-TSCF/CARB/SCAQMD, 1983) and identified a population of 7,700 people at a distance of one mile from the B.K.K. Landfill property line. This population was derived by dividing the assessor's plot maps into quadrants corresponding to four monitoring stations (A, B, D, and F) , and estimating the population within each quadrant using 1980 census data. In 1985, EPA identified a population of 40,000 people within a one-mile radius from the center of the landfill (EPA 1985). The difference in population numbers reflect different estimation methods rather than real population increase. This 1990 health -27- R&S145956 S ource: CH2MH111, F ig u re 6 -3 , "BK3C L a n d f i l l E n v iro n m e n ta l Exposure C h a r a c te r ir a tio n K e p o rt, W est C o v in a , C a lifo r n ia ," August 15, 1988, Volume I , p . 6-Z2. FIGURE 4 (CH2MH111) igesKSW a o.s i.o SC*lf: i ti- = I "U-t FIGURE 8-3 POPULATION CENSUS TRACTS IN THE VICINITY OP THE BKK LANDFILL Kft lAHDMtl EHVIBOHHENT4L EMPOSUBE CH4AAC TCflllAllOM S o u rce : CH2MB111, T able 6 -4 , "BKK L a n d fiL l E n v iro n m e n ta l Exposure C h a r a c te r iz a tio n R e p o rt, Meat C ovina, C a lifo r n ia ," August 15, 1988, Volume 1, p . 6-21, TABLE 4 (CH2MHill> Table 8-1 SUMURY OP POPULATION CZMSU3 TRACT DATA ro* Hit VICINITY OP THE BKK LAHDPILL Contains BKK "icai'.ir Locatleo Bclallve to BKK Land!Ill (Census Traci Wo. Beloul South tast-Soutbeast Nest-Soettmest Northwest 40dl.ll (081781 TBJl 1881.01 "IBlB 4079 4000.03 4066.til 4066.01 (065 I. All Groups Total Children tO-tl Children IS-9) Children (10-141 Children (15-19) Adults 110-11) Adults (15-64) Adults (50 Median Age 5,311 564 ill 300 389 71 1, STS HI 1T.J* 10,535 1,154 1,057 756 611 1,041 5,511 11( 17.1 8,101 B44 940 1,061 1,057 666 1,111 110 31*0 7,101 ns ait 97 840 661 1,966 171 11.1* 11,47i 1,161 1,161 1,481 1,115 111 6,195 171 16.6 6,01$ 314 566 671 611 501 1,949 III 19.1* 7,107 519 111 871 961 915 1,160 197 71. 1* 5,015 459 469 515 547 175 1,111 111 16.1* 4,885 519 165 IDS SOS 596 1,419 159 16.0* 1,759 135 191 191 571 199 1,551 101 11.1* 3,996 514 160 111 460 166 1,969 156 19.9* 5,411 361 167 ISO 509 601 1,911 197 19.1 tunNorth Northeast 4061.01 1064.02 4,411 177 111 111 539 110 1,131 167 10.9 1,998 91 91 179 115 108 1,091 111 16.9 1.B16 110 188 101 50) 506 1,911 11$ 11.1* II. Fesales Total resales (0-191 Feuslea 110-141 Peeales IJS-641 Pnalcs (65*1 1,693 dll 1,00) 791 76 5,167 1,661 1,131 1,145 130 1,097 1,917 691 1,111 171 1,619 1,595 960 911 151 6,116 l,5tl 1,691 1,916 155 1,991 1,179 967 690 91 5,579 1,517 95 1,079 106 1,517 1,011 Cfil 75) too 1,199 11 60 75? 100 1,409 711 501 1,001 165 1,000 999 164 114 154 1,913 799 79 951 738 1,116 111 150 991 140 970 1,491 117 561 149 111 457 175 67 136 "Represents the arerlfe aedlan age for the census tract, because eedlaas are calculated separately (or populations althln each city boundary vltbto each census tract. Source: Based on 1980 Census (U.S. Dept, of Coeeerce, 19811. LASUPEM/036 8969HS'3H S ource; CH2MH11L, T a b le 6 -5 , "BKK L a n d f i l l E n v iro n m e n ta l Exposure C h a r a c te r iz a tio n R e p o rt, West C ovina, C a lifo r n ia ," A ugust 15, 1988, Volume I , p, 6 -2 9 . TABLE 5 (CH2Hlli.il) Table 6-5 potentim.lv sensitive population subgroups from census tracts IN THE VICINITY OF THE BKK LANDFILL Regions (Located Relative to BKK) Contains BKK South East-Southeast Northeast North Northwest West Southwest Census Tract No. 4080.01 4081.31 4081.32 4081.02 4001.01 4034 4063 4064.01 4064.02 4065 4066.01 4066.02 4080.02 4079 4078 Percent of Census Tract Populations by Subgroups Females of Child- Senior Infants (0-4 yrs) Children (5-14 yrs) Bearing Age (15-44 yrs) Adults (65+ yrs) 10.6 12.7 28.4 2.8 11.9 10.4 10.0 17.2 24.7 23.8 29.5 24.0 24.7 2.2 3.8 3.8 8.9 20.6 23.9 9.3 22.0 27.8 2.8 2.2 2.9 12.8 24.8 6.4 6.3 16.4 23.3 4.8 14.2 20.6 6.0 6.5 6.7 13.7 25.5 5.4 14.4 23.6 8.1 15.6 22.3 7.1 6.4 6.4 7.9 15.7 29.2 9.7 20.0 25.7 3.2 3.6 8.3 22.3 25.4 2.0 Total No. of Females of ChildBearing Age (15-44 yrs) 1,511 3,109 1,943 1,781 1,443 3,465 950 1,031 391 1,391 1,124 891 1,418 1,287 1,804 Census Tract Total No. 5,324 10,535 8,101 7,201 6,025 12,478 3,826 4,424 1,898 5,444 4,759 3,998 4,855 5,015 7,107 Region Total No. 5,324 25,837 18,503 3,826 6,322 14,201 9,900 7.107 Source of Data: 1980 Census (U.5. Dept. of Commerce, 1983) LASUPER8/031 esesnssH FIGURE 5 (CH2MH1II) 096SWSSU S ource: CH2MHilL, F ig u re 6 . A, "BKK L a n d f i l l E n v iro n m e n ta l Exposure C h a ra c te riz a tio n R e p o rt, Weat C ovina, C a lif o r n ia , " August 15, 1368, Volume I , p. 6-27. risk assessment uses EPA's population estimate of 40,000 people within a one-mile radius of the landfill. Pathways of Exposure to Neighboring Residents Pathways of exposure to humans include environmental media (air, water, soil, and food) and routes of exposure (ingestion, dermal contact, and inhalation). CH2MHill prepared a schematic (Figure 6) to illustrate existing and potential pathways of exposure to contaminants from the B.K.K. Landfill. All the pathways together represent the total exposure from the site. Analysis of each individual pathway represents the exposure to different populations, such as onsite workers or neighboring residents. Groundwater Although groundwater below the B.K.K. Landfill has been contaminated, contaminants from the landfill have not been detected in the municipal drinking water supply wells, located one to three miles from the facility. Mitigation measures and monitoring schedules stipulated in the SAM Work Plan are designed to detect if contaminants migrate to municipal drinking water supply wells, at which time EPA and/or the State would issue a corrective action order. Groundwater in the vicinity is not used for irrigation. Seeps near the B.K.K. Landfill may have provided a potential source of exposure to contaminated groundwater in the past during rainy seasons. Seeps were dewatered by extraction wells, and have been dry since 1984. -32- FIGURE 6 (CH2MHi.II) ieesns^a S o u rce : CH2MH111, F ig u re 6 .1 , "BMC L a n d f ill E n v iro n m e n ta l Exposure C h a r a c te r iz a tio n R e p o rt, Weat C ovina, C a lifo r n ia ," August 15, 1988, Volune I , p, 6-3. Surface Water Three surface water drainage areas exist around the B.K.K. Landfill: Vine Creek Drainage to the north, Nogales Street Storm Drain/Giano Channel Drainage to the southeast, and Puente Creek Drainage to the southwest. Measured and estimated concentrations of contaminants in surface water originating from the landfill were less than the Clean Water Act criteria for acute toxicity in freshwater organisms; drainages are ephemeral and do not support permanent populations of aquatic organisms (CH2MHill, 1988). Human exposure could have potentially occurred through ingestion or dermal contact with contaminated surface water released from the B.K.K. Landfill. Unfortunately, no quantitative estimate of exposure can be made based on the available information. Median values of indicator chemicals detected in offsite surface water are given in Table 6. The volume of runoff discharge from the Nogales Street Storm Drain/Giano Channel Drainage was reduced 95 percent in November 1986, at which time drains and containment .measures were constructed on the landfill. Soil Soil from only one residential yard located on Miranda Street was analyzed in July, 1984 for VOC's and none were detected. Air Fifteen separate air sampling programs were conducted between 1979 to 1986. These programs included odor studies, landfill gas emissions monitoring, flare gas testing, periodic and continuous ambient air monitoring, and indoor air monitoring. CH2MHill tabulated the 15 programs, dates, and methods (Table 7) . Sampling stations located in residential neighborhcods R & S 145962 -34- TABLE 6 INDICATOR CHEMICALS DETECTED IN OFFSITE SURFACE WATER, 1981-1985 BKX LANDFILL, WEST COVINA. CALIFORNIA Indicator Chemical Non-Carcinogens Trans-1,2-Dichloroethylene 1,1,1-Trichloroethane 1,1-Dichloroethane 1,2-Dichlorobenzene Chlorobenzene Ethyl benzene Xylenes Toluene Phenol Copper Cyanide Selenium Zinc Median Value (nob) 2.4 3.4 56 M* 1.08 ND1* 0.2 0.2 3,900 40 3 41 17,000 Location storm drain, Azusa Avenue storm drain, Azusa Avanue runoff discharge, Nogales Street Galster Park Spring storm drain, Azusa Avanue Galster Park Spring storm drain, north of entrance gate storm drain, north of entrance gate Hidden Valley Spring south fork, Puente Creek GTE manhole, Amar and Woodgate Galster Park spring Carman's Fond discharge Carcinogens Arsenic Cadmium Chromium Lead Nickel 1,1,2-Trichloroethane 1,2-Dichloroethane 1,1-Dichloroethylene Benzene Chloroform Methylene Chloride Perchloroethylene Trichloroethylene Vinyl Chloride 88" 2 5 12 100 14 230 3.2 ND** 1.7 71 3.3 2.1 40 runoff discharge, Nogales Street Hidden Valley Spring storm drsin, Azusa Avenue storm drain, Nogales and Shakespeare seep above Miranda Street runoff discharge, Nogales Street runoff discharge, Nogales Street seep above Miranda Street Galster Park Spring storm drain, north of entrance gate runoff discharge, Nogales Street runoff discharge, Nogales Street runoff discharge, Nogales Street satp abova Miranda Straat a: Median valuaa taken from Table 3-18 BKK Landfill Comparison of Contaminants Detected In Offsite Surface Water With State And Federal Standards, "BHC Landfill Environmental Exposure Characterization Report West Covina, California," CH2MH111, 1988, Volume I, pgs. 3-90 to 3-91, b: Taken from Table 5-21 Maximum Values of Indicator Chemicals In Surface Water Samples Collected From the Vineinity of the BKK Landfill, CH2MH111, 1988, Volume I. pgs. 5-125 to 5-127. ND " Not Detected. R&S 145963 -35- -36* Sampling Program Investigation of Odorous and Volatile Compounds for BKK Landfill BKK Odor Study BKK Flare Station No. 1 Source Testing Ambient Air Honitoring Program Sampling Period Nov. 1979 dune 1980 Dec. 1980 April, May, and June 1980 June 1981 present TABLE 7 (CH2MH111) Table 3-19 SUKKARY OF AIR QUALITY RELATED DATA COLLECTIONS FOR THE BKK LANDFILL AND VICINITY Sampled By Univ. of So. Calt Environ. Engineering Dept. Sampling Activities Onsitei o Suction pump sampling using a Tenax-QC trap for Volatile Organics o Suction pump sampling for H^S Euteck Inc. Oneitsi o Landfill gas sampling SCAQHD Onsitei o 2 liter bulb sampling of gas collection system inlet and gas outlet (at the flare)i and ambient samples onsite end offsite SCAQHD Offsltei o 24-hour Tedlsr bag samplings at various locations around the site o Two long-term stations and 12 mid- or short-term stations used to evaluate station sitings Page 1 of 4 Sample Analyses o GC/HS speciatlon of organics (limited) o GC analysis of gas samples o GC/HS analysis for Vinyl Chloride o GC analysis for Vinyl Chloride only o ID ppm detection limit for 6/81 through 12/82 o 2 ppm detection limit for 1/83 through present Sampling Program BKK Expanded Monitoring program Directional Ambient Air Sampling and Micrometeorological Survey BKK Flare Station Ho. 1 Source Testing BKK Flare Station No. 1 Source Testing Ambient Air Monitoring During Drilling at Barrier 2 S96SHS'8U Sampling Period July 19, Oct. 15, 1982 Sampled __ SCAQMD, ARB, and DOKS-TSCD July-Aug. 1982 SCAQHO Oct. 1982 ARB Oct. 1983 Science Applications Inc. for BKK Hay and June 1984 BKK Table 3-19 (Continued) Sampling Activities Offsltei o 24-hour Tedlar bag samplings at S stations near the site and one control site Onsitet o Nine directionally controlled portable bag samplers, and eight portable wind recorders Onaltei o Grab saeples In Tedlar bags froe the Inlet line and iron four burners o Four composite samples of ambient air (2-to 3-hour composites) upwind and downwind of disposal areas Onsite o Saeples collected at the maIn header to the flare station (lnlet)i sample collection ethod unknown (to be deter mined Onsite: o Eight-hour composite and grab samples in Tedlar bags; from one upwind and two downwind stations to the drill site Page 2 of 4 Sample Analyses o GC/HS analysis for eight vola tile organic compounds o GC analysis for Vinyl Chloride only o GC/HS analysis for six volatile organic compounds o GC/HS analysis, 23 volatile organic compounds detected o GC analysis for Vinyl Chloride only -38- Sampling Program Emergency Response Sampling Indoor Air Sampling Extended Monitoring Program 996St-LS^y Sampling Period July 17-24, 1984 Sampled 8? SCAQKD July, Aug., and Sept. 19B4 DOHS-TSCD Aug. Sept., Oct. 19B4 SCS Eng. for DOHS and EPA Table 3-19 (Continued) Sampling Activities Page 3 o'f 4 Sample Analyses Offsitei o HHO/OVA and flask samples Indoor and at subsurface areas around selected evacuated homes o flask samples analyzed for Vinyl Chloride and Methane Oftaltei o Bulb and flask samples from under the sinks of 21 hones taken periodically Offsitei 1- Collected 24-hour composite air samples (Tedlar baga) from indoors at 10 Priority I homes and 1 control 2- Collected 24-hour charcoal tuba samples from indoors at 51 Prior ity II homes and 10 control 3- Continuous OVA monitoring in homes to parallel the composite sample collections 4- Periodic flask samples collected when OVA readings exceeded 100 ppm indoors 5- Subsurface probes (deep and shallow) monitoring with OVA meter, and flask collections when readings exceeded 1000 ppm o Bulb and flask samples analyzed for 14 volatile organlca, 3 In ert gaaea, and CO. (Analyses by ARB and SCAQMD) o Analysis for 10 volatile organic compounds using GC/MS o Analysis for Vinyl Chloride o For total hydrocarbons o Analysis for 10 volatile organics o Flask samples analyzed for 10 volatile compounds S o u rc *: CH2MB11.1., T a b l. 3 -1 9 , "BKX L a n d f i l l E n v iro n m e n ta l Exposure C h a ra c te riz a tio n R a p o rt. Waat C ovina, C a lifo r n ia ," August I f . 1988, Volune I , pgs. 3-97 to 3-100. Sampling Progran Ambient Air Collections During Excavation of the Ephemeral Pond Sanpling Period March 1985 Sampled ___er___ BKK Surface Emissions Monitoring Program April 198S (1st Sampling) BKK Oct.-Nov. 1985 BKK BKK flare Station No. 1 * Oct. 1985 Certified Testing Laboratories for BKK Table 3-19 (Continued) Sampling Activities________________ Onsitei o Tedlsr bag samples collected both during days of excavation and daye without excavation Onsite: o Integrated gas samples, each collected over a 100'x500' area using a flow metering pump Into a Tedlar bagj with a total of approximately 150 acreB sampled onsite Page 4 of 4 Sample __________________Analyses o GC analysis for Vinyl Chloride and Methane (analysis by Trueedall Labe) o Analysis for methane by BKKi and quantitative speciatlon of approximately 10 percent of samples by Truesdail Labs for 30 volatile organic (14 detec ted) o Repeat of the 1st sampling, with approximately 150 acres sampled onsite Onsite o Grab samples (3) into Tedlar bags from the Inlet line and from one outlet (burner) o Analysis for methane by BKK) and quantitative speciatlon of approximately 10 percent f samples by Nest Coast Analytical Lab for 49 compounds (21 detec ted) o GM/MS analysis for 13 volatile organic compounds and polychlori nated blphenyla and related dioxin derivatives (data under review at this tine LASUPER4/049 Z969HS2H detected VOC's and indicated air as an exposure pathway for neighboring residents. Air Monitoring/Modeling Characterization Programs Psed in the Quantitative ' lsk CH2MHill's retrospective quality assurance review identified 4 of the 15 air monitoring programs as relevant to quantitative analysis. Three of the four programs monitored ambient air around the B.K.K. Landfill; the fourth program monitored ambient air in the Los Angeles basin, in which the B.K.K. Landfill is located. Data from these four programs are used in the risk characterization and described in that section. CARB used the 1987 ambient vinyl chloride monitoring data from the landfill in an air dispersion model to estimate population exposure to vinyl chloride for the purpose of proposing to identify vinyl chloride as a toxic air contaminant. The risk characterization uses CARB's modeled data and describes the program in that section. Table 8 summarizes the programs and data used in the quantitative risk characterization. R&S145968 -40- Program SCAQMD 1983-1987 Ambient Vinyl ChlorLde Monitoring Program DHSTSCP/CARB/SCAQMD 1982 Expanded Monitoring Program EPA-DHS 1964 Extended Monitoring Program SCAQMD - CARE 198J Los Angeles Basin Air Ioxlci Monitoring Program CARB Modeling of 1987 Ambient Vinyl Chloride Monitoring Data 696SH S'Sb AIR MONITORING/MODELING PROGRAMS USED IN THE QUANTITATIVE RISK CHARACTERIZATION OP THE B.K.K. LANDFILL, WEST COVINA, CA Data Statlon(s) Chemical!si Monitored Methods A, B, MY: Located In residential neighborhoods south, southeast of the landfill Vinyl chloride (detection limit 2 ppb) 24-hour continuous: Tedlar bags: CC analysis: dally 6/81-1990 At considered in 1982 as the location for ''worst-case' meteorologic conditions Indoor air 10 Priority I evacuated homes El Monte, CARB A, B. MY 9: vinyl chloride, perchloroathylene, trichloroethylene, 1,2-dlchioroethane, chloroform, benxene, chlorobenzene, trans-1,2-dlchloroethene, 1.1-dichloroethene 9: vinyl chloride, perchloroathylene, trichloroethylene, 1.1-dlchloroathene, 1.2-dlchloroethane, chloroform, benxene, carbon tetrachloride, 1,1,1-trlchloroethane 11: benxene, carbon tetrachloride, chloroform, ethylene dlbromlda, ethylene dlchlorlde, methylene chloride, perchloroathylene, toluene, 1,1,1t r1chioroethane, trichloroethylene, vinyl Chloride vinyl chloride (detection limit 2 ppb) 24-hour continuous! Tedlar bags: Sunday through Thursday, July 19-0ctober IS: CC analysis, split samples analyzed by CARB lab and SCAQMD lab 24-hour coaqjosite: Tedlar bags: GC-MS analysis not described in SCAQMD 19B7 report SCAQMD's data: 24-hour continuous: Tedlar bags: CC analysis Summary Statistics) Monthly and annual geometric means, calculated by DHS from SCAQMD's dally measurements Arithmetic means, taken from Table II, DHSTSCP/CARB/SCAQMD 1983 report (a) Median values, taken from Table 6-13 and Volume 5 Appendix H-2 CH2MBU1 1988 report (b) Annual average taken from Table V-l SCAQMD 1987 report (c) Range of modeled concentrations, taken from Table II-S, CARB 1990 report (d) TABU B (continued) Abbreviations: SCAQMD DHS-TSCP CARB EPA CC GC-HS South Coast Air Quality Management District Department of Health Services-Toxic Substances Control Program California Air Resources Board U. S. Environmental Protection Agency gas chromatography gas chromatography-mass spectrometry a: DHS-TSCP/CARB/SCAQKD, "Ambient Air Monitoring and Health Risk Assessment for Suspect Human Carcinogens Around the BRK Landfill In West Covina," March 1983. b: CH2MH111, "BKK Landfill Environmental Exposure Characterisation Report Heat Covina, California," Volume I Text snd i Volume i Appendix H-2, August IS, 1968. to ex SCAQMD, "The Magnitude of Ambient Air Toxics Impacts Prom Existing Sources In the South Coast Air Basin," 1987 Air Quality Management Plan Revision, Working Paper Ho. 3, June 19B7. d; CARB, "Technical Support Document, Proposed Identification of Vinyl Chloride as a Toxic Air Contaminant, Draft Report Executive Summary and Part A, May 1990. ozesHs'sy DOSE-RESPONSE ASSESSMENT The dose-response assessment defines the relationship between the "dose" (intake) of a chemical and the probability of a response, such as induction of a carcinogenic effect. EPA uses the term intake instead of dose because the information required to estimate "dose" (that is, the amount of a chemical absorbed and subsequently distributed to target organs) is usually not known. Numerical expressions of a chemical's dose-response relationship are called toxicity values: reference doses are values for noncarcinogenic effects; slope factors and unit risks are values for carcinogenic effects. This section identifies the chronic reference doses and inhalation unit risk values, current through June 1989, used in the risk characterization. Chronic Reference Doses Information about the amount of a chemical that produces a toxic response and the type of toxic response produced at a given dose level is obtained quantitatively from studies in experimental animals or observations in human epidemiologic investigations. Noncarcinogenic effects may result from acute or chronic exposures, and threshold levels are established below which no adverse health effect is expected. EPA has derived reference doses for chemicals based on different routes of exposure. The chronic reference dose (RfDc) is an estimate of the daily exposure to humans, including sensitive p pulations, that is likely to be without appreciable risk of adverse effects during a lifetime. Reference doses for carcinogens refer to effects other than the risk of cancer. Table 9 lists the ref rence doses for indicator -43- R & S 145971 TABLE 9 REFERENCE DOSES* FOR INDICATOR CHEMICALS DETECTED IN OFFSITE SURFACE WATER AND AIR BKK LANDFILL. WEST COVINA, CA Indicator Chemical Non-Carcinogena Trans-1,2-Dichloroethylenec 1.1,1-Trichloroethane 1,1-Dichloroethane 1,2-Dichlorobanrena Chlorobenzene Ethyl Benzene Xylenes Toluana Phenol Copper Cyanide Selenium Zinc Carcinogens Arsenic Cadmium Chromium Lead Nickel Benzene Carbon Tetrachlorida Chloroform 1,2-Dichloroathane 1,1-Dlchloroethylene Methylene Chloride Perchloroethylene 1,1,2-Trichloroethane Trichloroethylene Vinyl Chloride RfDc-0 mg/kg-day 2E-2 9E-2 IE-1 9E-2 2E-2 IE-1 2E+0 3E-1 6E-1 1E-0 2E-2 2E-3 2E-1 IE-3 5E-4 2E-Z 7E-4 IE-2 9E-3 6E-2 IE-2 4E-3 - RfDc-0 ppb * 700 3,150 3,500 3,150 700 3,500 70,000 10,500 21,000 1,300 700 105 7,000 35 17.5 MCL-50b MCL-50b 700 MCL-lb 24.5 350 MCL-0.5b 315 2.100 350 140 MCL"5b MCL-0.5b RfDc-I mg/kg-day RfDc-I Mg/m3 3E-1 IE-1 4E-2 5E-3 3E-1 mg/m3 2E+0 mg/m3 IE-3 70 1,050 350 140 17.5 350 300 2,000 2,100 130 70 3.5 700 - 3.5 - 1.75 --- 70 -- - 2.45 - 35 -- 31.5 - 210 - 35 - 14 -*d a: Oral and Inhalation Chronic Reference Doses (RfDc-0, RfDe-I) in mg/kg-day are taken from Table A, "Health Effects Assessment Summary Tables, Third Quarter FY 1989," EPA July 1989, OERR 9200.6-303-(89-3). Chronic Reference Doses in ppb and lig/mr are calculated using conversion factors of 70 kg, 2 litars/day, and 20 nr/day. b: MCL - Maximum Contaminant Laval in Drinking Watar, California Coda of Regulations, Title 22, Division a, Chapter 16, Sections 64435 and 64444.5. c: Trans-1,2-Diehloroethylene was reportedly not detected in ambient air in the 1982 Expanded Monitoring Program (DHS-TSCP/CARB/SCAQMD, 1983); CH2MH111 included data for the chemical in its 1988 report (Volume 5, Appendix H-2, CH2MH111, 1988). d: Noncarcinogenic affacts of vinyl chloride occur at concentrations in air near or above 10,000 ppb which is muc greater than ambient levels detected near the BKK Landfill, West Covina ("Technical Support Document, Proposed Identification of Vinyl Chloride as a Toxic Air Contaminant, Draft Report Part B," CARB May 1990, pg. 1-2). R&S145972 -44- chemicals detected in offsite surface water and/or air around the B.K.K. Landfill. For those chemicals detected around the landfill that do not have a reference dose, the maximum contaminant level in drinking water is listed. Inhalation Unit Risk Values Cancer is considered a multistage process, and it is assumed that no threshold exists for substances that induce cancer. For carcinogens, risks are estimated as probabilities. Mathematical models used to derive estimates of risk associated with carcinogens are generally based on theories of carcinogenesis. EFA normally uses the linearized multistage model to extrapolate from observed high dose animal studies to expected low level environmental exposures. Values obtained from this extrapolation ar expressed as slope factors or unit risks for a lifetime (70 years) exposur . Generally, after the data are fit to the appropriate mathematical model, the upper 95 percent confidence limit of the slope of the resulting dose-response curve is calculated. This value is known as the slope factor and represents an upper 95 percent confidence limit on the probability of a response per unit intake of a chemical over a lifetime. In some cases, slope factors based on human dose-response data use a "best" estimate (that is, the best fit dose-response line from a set of data) instead of the upper 95 percent confidence limit. The slope factor, expressed as (mg/kg-day)'1, is used when calculating the risk from actual daily dose in mg/kg to an individual. R&S145973 The unit risk is the risk per unit concentration of a chemical in the medium where human contact occurs. The unit risk, expressed as ppm'1, ppb'1, or -45- (ug/m3)'1, is used when calculating the risk from ambient air concentrations to which an individual is exposed. EPA recommends that numerical estimations of risk be coupled with the "weight-of-evidence" classification of a carcinogen. Risk assessors may arrive at different values for a carcinogen because they select different data sets or different extrapolation models. This health risk assessment uses the unit risk values derived by either EPA's Carcinogen Assessment Group or DHS's Air Toxics Section, and contained in California's "Air Toxics Assessment Manual, Table 3.15" (CAPCOA, 1987). Table 10 presents the unit risk values and the corresponding "weight-of-evidence" classification for the carcinogens detected at the B.K.K. Landfill. -46- TABLE 10 INHALATION UNIT RISK (IUR) VALUES FOR CARCINOGENS DETECTED AT BKK LANDFILL, WEST COVINA, CALIFORNIA Carcinogen AGENCY* IUR* (Mg/m3)*1 EPAb Claai Arsenic (inorganic) Cadmium Chromium(VI) Lead Nickel Benzene Bis-2-chloroethylather Carbon Tetrachlorida Chloroform 1,2-Dichloroethane 1,1-Dichloroethylene Methylene Chloride N-Nitrosodimethylamina Perchloroethylene 1,1,2,2-Tetrachloroethana 1,1,2-Trichloroethana Trichloroethylene Vinyl Chloride EFA DHS DHS EFA DHS EFA DHS EFA DHS EPA DHS EPA EFA EPA EFA EFA EFA 4.3E-3 1.2E-2 1.5E-1 *.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 3.8E-5 1.6E-5 1.3E-6 Z.7E-6 A Bl A B2 A A B2 B2 B2 B2 C B2 B2 C C C 82 A a; Rafaranea documents far tha valuaa liitad ware darlvad by tha Environmental Protection Agency (EFA) or tha Department of HaaLth Services, Health Hazard Asaeaament Diviaion, Air Toxica Section (DHS), and are givan with Table 3.IS, "Air Toxica Assessment Manual," California Air Pollution Control Officers Association, October 1987 pgs. 3.5-2* to 3.5-28. Valuaa are currant through June 1989. b: EFA weight of avidenca classification: A, sufficient evidence in humans; Bl, 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 EFA*a Integrated Risk Information System (IRIS), June 1989. R&S145975 -47- RISK CHARACTERIZATION Risk characterization integrates the three previous components of a health risk assessment (hazard identification, exposure assessment, and dose-response assessment), to provide a numerical estimation of risk and a framework to relate the significance of the risk. This section estimates, for residents living near the B.K.K. Landfill, the risks associated with exposure to the concentrations of contaminants detected in offsite surface water and air. Individual excess lifetime cancer risks are calculated for carcinogens detected in three site-specific air monitoring programs, one Los Angeles basin air monitoring program, and one air modeling program. The population excess cancer burden is also estimated. Limitations and uncertainties of the estimated risk are discussed, and the significance of the risk estimate is explained. Risk Characterization of Exposure to Contaminants Detected in Offsite Surface Water Near the B.K.K. Landfill Most indicator chemicals detected in offsite surface water near the B.K.K. Landfill were detected in concentrations below their thresholds for noncarcinogenic effects (Table 11). Four indicator chemicals were detected in concentrations above their reference dose or maximum contaminant level: tine was detected at 17,000 ppb; arsenic, at 89 ppb; 1,2-dichloroethane, at 230 ppb; and vinyl chloride, at AO ppb. Surface waters near the B.K.K. Landfill are not used for drinking water. Any exposure to contaminated -48- R&S145976 TABLE 11 COMPARISON OF INDICATOR CHEMICALS DETECTED IN OFFSITE SURFACE WATER, 1981-1985 TO ORAL CHRONIC REFERENCE DOSES BKX LANDFILL, WEST COVINA, CA Indicator Chemical Madlan Value ppb RfDc-0ralb ppb Non-Carclnogans Trans-l,2-Dichloroethylana 1.1.1-TrlchLoroathana 1.1-Dlchloroathana Chlorobenzene Xylanas ToLuana Phanol Coppar Cyanide Lead Salanium Zinc Carcinogens Araanic Cadmium Chromium Laad Niekal 1.1.2-Trichloroathana 1.2-Dichloroathana 1,1-Dichloroathylana Chloroform Mathylena Chloride Perchloroathylena Trichloroethylene Vinyl Chloride 2.A 3.A 56 1.08 0,2 0.2 3,900 AO 3 12 A1 17,000 89* 2 5 12 100 1A 230 3.2 1.7 71 3,3 2.1 A0 700 3,150 3,500 700 70.000 10,500 21.000 1,300 700 MCL-50c 105 7,000 35 17.5 MCL-50 MCL-50c 700 1A0 MCL-0.5C 315 350 2,100 350 MCL-5c MCL-0.5c a: Median Valuaa are taken from Table 3-18, "BKK Landfill Environmental Exposure Characterization Report, Weet Covina, California," CH2MH111, 1988, Volume I, pgs. 3-90 to 3-9A. (Table 6 of this report). b: Chronic Rafarenca Doses (RfDc-Oral) were calculated from chronic reference doses listed in Table A, "Health Effects Assessment Stannary Tables Third Quarter FY 1989." EFA July 1989 (Table 9 of this report). c: MCL - Maximum Contaminant Level in Drinking Water, California Coda of Regulations, Title 22, Division A, Chapter 15, Sections 6AA35 and 6AAAA.5. d: Maximum value taken from Table 5-21, CH2MH1U, 1988, Volume I, pgs. 5-125 to 5-127. R&S 145977 -49- surface water would have been infrequent, much less than two liters a day, and of limited duration. The risk associated with exposure to the concentrations of these contaminants in offsite surface water near the B.K.K. Landfill is not considered significant. No numerical estimate of risk is made because no quantitative estimate of exposure can be made from the available information. Risk Characterization of Noncarcinogens Detected in Air Near the B.K.K. Landfill From the limited sampling in air monitoring programs around the B.K.K. Landfill, only two noncarcinogen indicator chemicals were detected in air, both below their reference dose. 1,1,1-Trichloroethane was detected in 10 Priority I homes during the 1984 Extended Monitoring Program at a median value of 4 ppb; the inhalation chronic reference dose is approximately 192 ppb. Trans-1,2-dichloroethylene, originally reported not detected in the 1982 Expanded Monitoring Program (DHS-TSCP/CARB/SCAQMD, 1983), was reported by CH2MHill (Volume 5, Appendix H-2, CH2MHill, 1988); the median value was 1 ppb and the inhalation chronic reference dose is approximately 18 ppb. Noncarcinogenic effects of vinyl chloride occur at concentrations in air near or above 10,000 ppb, which is much greater than ambient levels detected around the B.K.K. Landfill (CARB, Part B, 1990). Because the concentrations of contaminants detected in ambient air around the landfill do not exceed their thresholds for chronic reference doses, impacts from noncarcinogenic adverse health effects are not anticipated. -50- R&S 145978 Risk Characterization of Carcinogens No threshold is assumed for carcinogens, therefore, this risk characterization estimates the risk of developing cancer from exposure to the carcinogens detected in air around the B.K.K. Landfill between 1982 through 1987. Data is taken from the following programs, which are summarized in Table 8 of the exposure assessment section: Site-specific programs (see Figure 7) - SCAQMD's 1983-1987 Ambient Vinyl Chloride Monitoring Program DHS-TSCP/CARB/SCAQMD's 1982 Expanded Monitoring Program EPA and DHS's 1984 Extended Monitoring Program Los Aneeles air basin program CARB and SCAQMD's 1985 Los Angeles Basin Air Toxics Monitoring Program Modeling program - CARB's Modeling of 1987 Ambient Vinyl Chloride Concentrations Around the B.K.K. Landfill. Two measures are used to estimate the risk: the "individual excess lifetime cancer risk" and the "population excess cancer burden". These risk estimates are statistical concepts which represent plausible upper bound estimates of the probability of developing cancer due to lifetime (70-year) exposure. The individual excess lifetime cancer risk implies that an individual remains in the same location for an entire lifetime, and that the concentrations of carcinogens remain unchanged. The population excess cancer burden represents the plausible upper limit on the number of excess cases of cancer which could occur in a population after exposure for a specific period of time. -51- R&S145979 S ource: CH2MH1U, "BKK L a n d f ill Exposure C h a ra c te riz a tio n R e p o rt. West C ovina, C a lif o r n ia , " A ugust 15, 1988 Volume 1, p . 5*165 (F ig u re 5 .2 1 ) and Volume 1 FIGURE 7: Air M nitoring Programs, BKK Landfill, West Covina, CA (Based on CH2MHI1I Fig. 5-21 and Plat SAN BERNARDINO FREEWAY 1984 INDOOR . CONTROL HOME - 3 MILE RADIUS (CENTER OF SITE} .1 MILE RADIUS (BOUNDARY) LEGEND SCAQMD AMBIENT AIR MONITORING PROGRAM 0 Long-Term Sampling Locations (>1 Year) Q) Medium-Term Sampling Locations O Short-Term Sampling Locations (<2 Months) A 1982 EXPANDED MONITORING PROGRAM (A, B, D, E, FI and F2) 1984 EXTENDED MONITORING PROGRAM Priority I Houses (Evacuated) & Control Home H Priority II Houses (Evacuated) O Priority II Houses (Non-evacuatcd) I I , P late 15, Enlarged View of 1984 Extended Monitoring Program Numerical Estimations of Risk 1. Numerical Estimation - Individual Excess Lifetime Cancer Risk The risk calculation is expressed as: ECR -CxYRxEFxRFxURx 1/LT Where ECR - Excess lifetime cancer risk C - Concentration in /ig/m3 of the carcinogen; parts per billion were converted to micrograms per cubic meter g/m3) as follows (assuming 25C and 760 mm Hg pressure): /ig/m3 - ppb x molecular weight 24.45 m3//xmole YR - Years of residence associated with exposure EF - Exposure factor, i.e., percent of time spent at home RF - Retention factor, i.e., percent of measured concentration absorbed in the lungs UR - Unit risk value LT - Human individual lifetime in years. Assumptions for this calculation are the following: persons have an average adult body weight of 70 kg and breathe 20 m3 of air per day; persons are at home 80 percent of the time (that is, the residential scenario assumes an annual exposure fraction of 292/365 days); persons retain 100 percent of the measured concentration; persons have an average 70 years lifetime. -53- R & S 145981 a. Risk Characterization Using SCAQMD's 1983-1987 Ambient Vinyl Chloride Monitoring Program Data In 1977, SCAQMD measured ambient air at four plants which manufactured or used vinyl chloride in the Los Angeles Basin: Keysor-Century in Saugus; Union Carbide in Torrance; and B.F. Goodrich and Stauffer Chemical in Carson (SCAQMD, 1982). The B.K.K. Landfill received wastes containing vinyl chloride from these plants. In 1981, SCAQMD conducted limited sampling of landfill gas emissions at the B.K.K. Landfill and detected vinyl chloride at concentrations above the California ambient air quality standard of 10 ppb. Because vinyl chloride is a human carcinogen, it became the landfill gas contaminant of primary concern. Vinyl chloride is the only contaminant for which there are continuous monitoring data from 1981 to the present. SCAQMD began monitoring in residential neighborhoods around the B.K.K. Landfill: Station A, established in 1981, was located at the intersection of Marlena and Nogales Streets, 450 feet southeast of the property line; Station B, established in 1981, was located on Lynn Court, immediately adjacent to the southern property line; Station MY, established in June 1984, was located on Myra Court, 150 feet southeast of the property line. Because the detection limit for vinyl chloride was lowered from 10 ppb to 2 ppb in 1983, comparison with data prior to 1983 is limited. -54- R&S145982 Samples were collected as 24-hour continuous daily samples in Tedlar bags and analyzed at SCAQMD's laboratory by gas chromatography. Table 12 presents the monthly and annual geometric means of vinyl chloride at Stations A, B, and MY for the years 1983 through 1987. DHS staff calculated the geometric means from SCAQMD's daily measurements. Measurements of vinyl chloride below the detection limit of 2 ppb were assumed to be at the detection limit. Figure 8 was generated from this data, and shows that both the maximum value of vinyl chloride detected and the frequency of detection have declined since 1985. Applying the present risk calculation to the 1987 annual geometric mean of vinyl chloride from Station MY (the highest value), and assuming a 70-year exposure to this level of vinyl chloride, the individual excess lifetime cancer risk is estimated to be 1.5 x 10~s, or approximately 1 to 2 in 100,000. -55- R&S145983 IABLr 12 VINYL CHLORIDE IN AMBIENT AIR <ppb) - 1983-1987 FDNIHLY AND ANNUAL GEOMETRIC MEANS SCAOMD MONITORING STATIONS AROUND EXE LANDFILL, WEST COVINA, CA month station 1983 JAN FEB MAR APR MAY JUNE JULY AUG SEPT OCT NOV DEC A 3.8 3.6 2.3 2.1 2.6 2.3 3.4 2.5 3.5 2.9 2.2 2.7 ANNUAL 2.8 1984 3.1 2.8 3 2.5 3.2 2.8 ND 3.7 4.7 4.4 3.7 3.6 3.3 1985 3.9 3.4 4.7 3 2.6 2.9 2.9 4 3.2 3.2 2.6 3.7 3.3 1986 2.7 2.6 2.6 2.3 2.3 2.5 2.6 2.3 2.2 2.2 2.1 2 2.4 JAN FEB MAR APR MAY JUNE JULY AUG SEPT OCT NOV DEC B 3.4 2.8 2.5 2.4 2.1 2.1 3.7 3.1 2.5 3.4 3.4 4.2 ANNUAL 2.9 7 3.7 3.9 3.5 4.6 3.5 ND 2.3 2.7 3.6 5.1 3.8 3.8 3 3.1 2.5 . 2.5 2.3 2.3 2.3 2.7 2.5 2.8 2.3 2.8 2.6 2.1 2.5 2.2 2 2.1 2.1 2.2 2.1 2.2 2.1 2 2 2.1 JAN FEB MAR APR MAY JUNE JULY AUG SEPT OCT NOV DEC ANNUAL ND ND ND ND ND ND ND 4.1 4.5 5.3 5.1 3.8 4.5 6.6 4.4 4.5 3.8 3 3.9 4.1 4.8 4 3.9 3.9 6.3 4.3 3.1 3.8 3.2 2.3 2.7 3.2 3.2 3.2 2.6 2.6 3.3 2.8 3.0 ANNUAL TOTALS 2.8 3.9 3.3 2.5 1987 2 2.1 2.3 2.6 2.1 2.1 2.3 2.2 2.6 2.4 2.1 2.4 2.3 2.1 2 2 2.1 2 2 2 2.2 2 2 2 2 2.0 2.3 2.4 2.9 3 2.6 2.3 2 2.8 3.2 2.6 3.1 3.1 2.7 2.3 R&S145984 NOTE: DHS staff calculated monthly and annual geometric means from SCAQMD's daily measurements of vinyl chloride. ND " No data was received. Measurements below the detection limit of 2 ppb were assumed to be at the detection limit. Station A * Mariana & Nogales Streets; Station B Lynn Court; and Station MY - Myra Court, established June 1984. -56 FIGURE 8 VINYL CHLORIDE IN AMBIENT AIR 1983-1987 STATION A MONTHLY MONITORING DATA BKK LANDFILL, WEST COVINA, CA VINYL CHLORIDE - BKK - 1985" 1987 MAXIMUM VALUE VINYL CHLORIDE - BKK 1983-1987 OATS EBIML TO OR OCKIER THAN IMPS NOTE: DHS staff generated thasa figures from daily measurements of vinyl chloride by SCAQMD at Station A -57- R & S 145985 If a value of 1 ppb (that is, half the detection limit) is substituted for values of vinyl chloride below the detection limit, the 1987 geometric means by station would be: A, 1.4 ppb; B, 1.1 ppb; and MY, 1.4 ppb. The annual geometric mean of all three stations would be 1.3 ppb. Using the value from Station MY, 1.4 ppb or 3.6 pg/m3, the individual excess lifetime cancer risk would be 7.8 x 10"6, or approximately 8 in 1,000,000. Vinyl chloride emissions from the B.K.K. Landfill appear to have changed over time. Years used to compare the changes in vinyl chloride emissions are: - 1982, at which time the first health risk assessment was conducted; - 1983, at which time the detection limit for vinyl chloride was lowered to 2 ppb; - 1984, at which time homes were evacuated due to subsurface migration of landfill gas, leading to an improved landfill gas collection system; - 1987, at which time mitigation measures were further lowering vinyl chloride emissions from the facility. Table 13 evaluates the '70-year risk over these changing exposure periods. A one-year exposure period is defined for data from 1983 through 1986. The 1982 data represent the following: the initial seven-year period for which waste disposal records are available (1975-1982); the landfill expansion from 40 acres to 140 acres; and -58- R&S 145986 TABLE 13 INDIVIDUAL EXCESS LIFETIME CANCER RISK SCAQMD AMBIENT VINYL CHLORIDE MONITORING PROGRAM BKK LANDFILL, WEST COVINA, CALIFORNIA 1982b 3 Mg/m" (ppb) 1983c Mg/m3 (ppb) 19B4d Mg/m3 (ppb) 1985d Mg/m3 (ppb) 1986d Mg/m3 (ppb) 19B7d Mg/m3 (ppb) Total Cvc YR ECR 18.6 (7.3) 7 4.0 x 10*6 7.2 (2.8) 1 2.2 x 10'7 11.5 (4.5) 1 3.5 x 10'7 11.0 (4.3) 1 3.4 x 10"7 7.7 (3.0) 1 2.4 x 10'7 6.9 (2.7) 59 1.3 x 10'5 70 1.8 x 10*5 a: Calculated by ECR " Cyc xYRxEFxRFxURx 1/LT where ECR - Excaaa lifetime cancer risk Cvc " Concentration in MS/n3 of vinyl chloride YR * Years of residence associated with exposure EF - Exposure factor, l.a. percent of time at home (BOX) RF - Retention factor, l.a. percent of measured concentration absorbed In the lungs (100Z) UR - Unit risk value for vinyl chloride-. 2.7 x 10~6 (jig/m3)'1, taken from Table 3.IS, "Air Toxics Assessment Manual," California Air Pollution Control Officer's Association, October 1987, p. 3.5*28. Value current through June 1980. LT Human individual lifetime in years (70) b: Mean valua, Station A, Table II, "Ambient Air Monitoring and Health Risk Assessment for Suspect Human Carcinogens Around the BKK Landfill in West Covina," DHS-TSCF/CARB/SCAQMD, March 1983, p. 16 (Appendix B of this report), c: DHS staff calculated the annual geometric mean from daily measurements of vinyl chloride by SCAQMD at Stations A and B (Table 12 of this report). d: DHS staff calculated the annual geometric mean from daily measurements of vinyl chloride by SCAQMD at Station MY (Table 12 of this report). R&S145987 -59- the increased residential construction along the southern border. The 1987 measurements are projected for the remaining 59-year period, although mitigation measures may be expected to lower vinyl chloride emissions. Applying the present risk calculation to the data specified in Table 13, the individual excess lifetime cancer risk over the changing exposure periods % approximately 2 in 100,000. is estimated to be 1.8 x 10~s, or b. Risk Characterization Using DHS-TSCP/CARB/SCAQMD's 1982 Expanded Monitoring Program Data During July to October 1982, DHS-TSCP, CARB and SCAQMD conducted a 90-day study to monitor ambient air around the B.K.K. Landfill for nine VOCs. The study was the first health risk assessment of the landfill. A summary of the report as well as a copy of the report are provided in the Appendix. Three monitoring stations were located in residential neighborhoods around the landfill (A and B to the south; F to the north); two monitoring stations were located on the landfill (D at the entrance, E at the highest elevation); and SCAQMD's monitoring station in Pico Rivera, nine miles to the southwest, was selected as the control station C. The selection of Pico Rivera as a residential control site has since been questioned because of the influence from industrial emission sources in Pico Rivera. In 1982 it was considered to be the closest established monitoring station for which routine data had been -60- R&S145988 collected over a period of years, and an upwind location. Stations A, B, D, E, and F are shown in Figure 7. The study defined the exposure period as the previous seven years (1975-1982) reflecting the seven year period for which waste disposal records were available, the landfill expansion from 40 acres to 140 acres, and the increased residential construction along the southern border. Continuous 24-hour samples were collected in Tedlar bags Sunday through Thursday. Split samples were taken and analyzed by two laboratories, SCAQMD's laboratory and CARB's southern laboratory branch (Haagen-Smit). Of the nine compounds monitored, seven were detected. Kean values from each laboratory were reported. CH2MHill's 1988 report has conflicting information about the program's data for benzene. DHS-TSCP/CARB/SCAQMD reported that benzene was detected by one laboratory which had a detection limit of 2 ppb, but not by the second laboratory which had a detection limit of 20 ppb. Benzene was included in their health risk assessment. CH2MHill listed the detection limits for benzene from the two laboratories as 10 ppb and 20 ppb, and excluded benzene from its exposure assessment. CH2MHill did not document the discrepancy between the 2 ppb and 10 ppb detection limit for the one laboratory. For this risk characterization, data from Station A are used. Topographic and meteorologic data suggested that the location of R&S145989 -61- Station A received higher contaminant levels than the other stations (B, D, E, and F), and represented a "worst-case" scenario. Applying the present risk calculation to the 1982 Station A measured data, assuming the seven-year exposure period defined in the program (1975-1982) and an additive effect of the carcinogens, the individual excess lifetime cancer risk is estimated to be 1 in 10,000. this estimate includes the benzene data reported by one laboratory. Deleting the benzene data because of the discrepancies in detection limits reduces the estimated risk to approximately 5 in 100,000 (Table 14,). c. Risk Characterization Using EPA and DHS' 1984 Extended Monitoring Program Data (Indoor Air Monitoring, Priority I Evacuated Homes) In July 1984, 19 homes along the southern and southeastern perimeter of the B.K.K. Landfill were evacuated when methane, from lateral subsurface migration of landfill gas, was detected at concentrations above the lower explosive limit (50,000 ppm). The Southern California Gas Company detected and identified the methane gas from the landfill during a routine survey (every four years for residential distribution piping systems). The landfill gas served as a transport medium for VOC's deposited at the facility. EPA and DHS developed the "Extended Monitoring Program" to investigate the hazards: 10 homes and 1 control home were designated Priority I, requiring indoor air monitoring for 9 VOC's and total hydrocarbons; 51 occupied homes and -62- R & S 145990 TABLE 14 INDIVIDUAL EXCESS LIFETIME CANCER RISE* DBS-TSCP/CARB/SCAQMD 1982 EXPANDED MONITORING PROGRAM BKK LANDFILL, WEST COVINA, CA Carcinogen Molecular Weight C-Station A*5 ppb (ig/m3 Unit Riskc (Mg/m3)'1 Cancer Risk EPAd Clast Chloroethane (Vinyl Chloride) Perehloroethylene (FCE) Trichloroethene (TCE) 1,1-Dichloroethane (Vinylidene Chloride) 1,2-D1chloroethane (Ethylene Dichloride) Trichloromethane (Chloroform) Benrene 62.3 163.83 131.4 96.93 98.96 119.39 78.11 7.3 18.6 3,7 23.0 1 5.37 1.3 5.15 3 12.1 0.3 2.44 4.8 15.3 Total Excess Lifetime Clinear Risk Including Baniana Total Exeaaa Lifetime Cancer Riak Excluding Bencene 2.7E-6 5.8E-7 1.3E-6 5.0E-5 2.2E-5 2.3E-5 5.3E-5 4.0E-6 1.2E-6 5.BE-7 2.1E-5 2.IE-5 4.5E-6 6.5E-5 A C B2 C B2 B2 A 1.2Z-4 5.2E-5 a: Calculated by ECR "CxYRxEFxRFxURx 1/LT Whore ECR " Exeaaa lifetime cancer riak C " Concentration in it&ln? TR " Yeera of reaidanca aaaociatad with expoaure (7} EF " Expoaure factor, i.e. percent of time at home (80Z) RF " Retention factor, i.e. percent of meaaured concentration absorbed in the lungs (1D0Z) UR " Unit risk valua LT " Human individual lifetime in years (70) b: Mean values, Station A, Table II, "Ambient Air Monitoring and Health Risk Assessment for Suspect Hum in Carcinogens Around the BKK Landfill in West Covina." DBS-TSCF/CARB/SCAQMD, March 1983, pg, 16. (Appendix B of this report). c: Values taken from Table 3.13 of the "Air Toxics Assessment Manual," California Air Pollution Control Officers Association, October 1987, pgs. 3.3-24 to 3.3-28. Values current through June 1989. d: EPA weight of evidence classification: A, sufficient evidence in humans; Bl, sufficient evidence in animals, limited in humans; B2, sufficient evidence in animals, inadequate in humans; C, limited evidence m animals, inadequate in humans. Taken from EPA's Integrated Risk Information System (IRIS), June 1989. R&S 145991 -63- 10 control homes were designated Priority II, requiring monitoring for vinyl chloride; and 90 subsurface landfill gas probes were installed onsite and offsite to monitor for total hydrocarbon levels. Field technical support and data quality assurance support for the program were provided by the EPA FIT contractor (Ecology and Environment, Inc.). Laboratory analyses were done by West Coast Analytical Laboratories, Data management support was provided by an EPA contractor. Tech Law. Priority I homes were monitored in October 1984 for the following nine VOC's: chloroform, 1,1-dichloroethylene, benzene, carbon tetrachloride, 1,2-dichloroethane, 1,1,1-trichloroe thane, perchloroethylene, trichloroethylene, and vinyl chloride. Composite 24-hour samples were collected in Tedlar bags and analyzed by gas chromatography-mass spectrometry. Data for Priority II homes were not available and not discussed by CH2MHill. CH2MHill prepared Table 15 as a summary of the data for the Priority I homes and the control home, and recorded the data for the program in Volume 5 Appendix H-2. CH2MHill did not list benzene, as seen in Table 15, because detections were attributed to laboratory contamination. No documentation or explanation of the laboratory contamination was provided. Data for benzene is added as a footnote to Table 15. Carbon tetrachloride and chloroform were not detected in any of the ten Priority I homes, and are not included in the risk -64- TABLE 15 (CH2MHILL) Table 6-13 SUMMARY OF 1984 INDOOR MONITORING IN PRIORITY I HOMES AND A CONTROL HOME Chemicals Priori^ H^s (10) a No. Median Maximum CoTnptrpo5l vH/vo)me No. Median Maximum 1.1- Dichloroethylene 1.2- Dichloroethane 1,1,l-Trichloroethane Carbon Tetrachloride Chloroform Perchloroethylene Trichloroethylene Vinyl Chloride 75 <1 75 3 75 4 75 <1 75 <1 75 2.5 75 1.5 75 <4 2 14 14 <1 <1 21 6 7 4 <1 4 <1 43 4 <1 4 <1 4 1.5 4 <1 4 <4 <1 <1 4 <1 <1 2 <1 <4 Notes: Data source is the 1984 Extended Monitoring program. Values presented with < symbol are detection limits. Slumber of samples. Source: CH2MH111, Table 6**13, "BKK Landfill Environmental Exposure Characterization Report, Meat Covina, California," Auguit 13, 19S8, Volume 1, F. 6-45. Benrene data in CH2MH111 Volume 5, Appendix B-2, 19B8, are the following: Priority I homes * 70 samples, median value 7 ppb, maximum value 29 ppb; Control home * 2 samples, 4 and 6 ppb. Carbon tetrachloride and chloroform were not detected in any of the 10 Priority I homes. A detection limit of 4 ppb for vinyl chloride is not substantiated by recorded values in Volume 5, Appendix H-2. R&S 145993 -65- characterization; the values in Table 15 for carbon tetrachloride and chloroform are the detection limits for the compounds. A detection limit of A ppb for vinyl chloride in Table 15 is not substantiated by recorded values in Volume 5, Appendix H-2: a value of 1 ppb is recorded for one home and a value of 2 ppb is recorded for three homes. Because the concentrations detected in the Priority I homes appear somewhat similar to the concentrations detected in the control home, analysis of variance (ANOVA) was performed to determine if there was a difference. ANOVA is a statistical technique that investigates the contribution of one or more factors to the variation in an outcome of interest. For the seven compounds detected in the Priority I homes (vinyl chloride, 1,1-dichloroethylene, 1,2-dichloroethane, 1,1,1-trichloroethane, perchloroethylene, trichloroethylene, and benzene), 3-way ANOVA shows that concentrations detected in the Priority I homes were significantly higher than concentrations detected in the control home (p <0.039). Excluding benzene, 2-way ANOVA of the six compounds shows a significant difference in the concentrations detected in the Priority I homes (p <0.006). Both analysis controlled for sample date/calendar period, indicating that the difference was not due to the day the sample was taken. (Appendix E contains a more detailed description of the analyses.) Whether or not there were additional sources of the compounds within the homes cannot be determined from the available data. R&S145994 -66- Table 16 applies the present risk calculation to the six carcinogens detected in the Priority I homes. (1,1,1-Trichloroethane, a Class D carcinogen, is not included in the risk calculation; the inhalation reference dose is 192 ppb.) A one-year exposure period of January to December 1984 is assumed since all evacuated homes were allowed to be reoccupied by December, and elevated levels of methane and landfill gas may have been present for a short time prior to being detected by the routine survey. Assuming an additive effect of the carcinogens, the individual excess lifetime cancer risk is estimated to be 2 in 100,000 including benzene, and approximately 6 in 1,000,000 excluding benzene. d. Risk Characterization Using CARB and SCAQMD's 1985 Los Angeles Basin Air Toxics Monitoring Program Data Pursuant to California's toxic air contaminant program (Health and Safety Code, Section 39650 et seq), CARB and SCAQMD initiated programs in 1985 to monitor selected VOC's at specific locations within the Los Angeles basin. Results were reported in "The Magnitude of Ambient Air Toxics Impacts From Existing Sources in the South Coast Air Basin" (SCAQMD, 1987). Air monitoring stations for SCAQMD were located in Anaheim, Azusa, Burbank, and Lennox; monitoring stations for CARB were located in El Monte, Long Beach, Los Angeles, Rubiodoux and Upland (Figure 9). Compounds selected for monitoring were: benzene, carbon tetrachloride, 1,2-dibromomethane, 1,2-dichloroethane, methylene chloride, perchloroethylene, toluene, 1,1,1-trichloroethane, -67- R&S 145995 TABLE 16 INDIVIDUAL EXCESS LIFETIME CANCER RISK* EPA and DHS 1984 EXTENDED MONITORING PROGRAM BKK LANDFILL, WEST COVINA, CA Carcinogen Molecular Height Median^ ppb nt/m3 Unit Risk* (Mg/*3)'1 Cancer Risk EPAd Class Vinyl Chloride Perchloroethylene Trichloroethene 1,1-Dichloroethene 1,2-Dichloroethane Banian* 62.3 163.83 131.4 96.93 98.9.6 78.11 4 10.2 2.3 17.0 1.5 8.1 1 4.0 3 12.1 7 22,4 Total Excess Lifetime Cancer Risk Including Benzene Total Excess Lifetime Cancer Risk Excluding Benzene 2.7 E-6 5.8 E-7 1.3 E-6 3.0 E-5 2.2 E-5 3.3 E-5 3.1 E-7 1.1 E-7 1.2 E-7 2.3 E-6 3.0 E-6 1.4 E-5 A C B2 C B2 A 2.0 E-5 5.8 E-6 a: Calculatad by ECR "CxYRxEFxRFxURx 1/LT where ECR - Excaas lifetime cancer risk C " Concentration In ng/m^ YR " Years of residence associated with azpoaura (1) EF " Exposura factor, l.a. parcant of time at home (801) RF " Ratantion factor, l.a. parcant of measured concantratlon absorbad In tha Lung* (100Z) UR - Unit risk valua LT - Human Individual Lifatima in years (70) b: Median value* taken from Table 6-13, "BKK Landfill Environmental Exposura Characterization Report, West Covina, California," CH2MH111. 1986, Volume I, p. 6-43, c: Values taken from Table 3.13, of tha "Air Toxics Assassmant Manual," California Air Pollution Control Officers Association, October 1987, pgs. 3.3-24 to 3.3-28. Value* currant through June 1989. d: EFA weight of evidence classification: A, sufficient evidence in humans; Bl, 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 EPA's Integrated Risk Information System (IRIS), June 1989. R&S 145996 Aft- UTH NORTHING (K>) FIGURE 9 (SCAQMD) FIGURE V-l AMBIENT AIR TOXIC MONITORING SITES IN THE SOUTH COAST AIR BASIN Source: South Coast Air Quality Management District, Figure V-l, "The Magnitude of Ambient Air Toxics Impacts From Existing Sources in the South Coast Air Basin," June 1987, p. V-2. -69- R & S 145997 trichloroethylene, chloroform, and vinyl chloride, (Table 17). Values obtained from these programs provide "background" levels in the Los Angeles air basin. Sampling methods and analysis were not described in the report. CH2MHill used data from the four SCAQMD monitoring stations in its 1988 report. This risk characterization uses data from CARB's El Monte station. Of all nine locations shown in Figure 9, El Monte appeared to be more representative of ambient air conditions which might exist around the B.K.K. Landfill. The Azusa station was not considered representative because of its proximity to mountains. With the exception of vinyl chloride, the carcinogens detected in ambient air near the B.K.K. Landfill have also been detected in ambient air in the Los Angeles basin. For the carcinogens detected near the B.K.K. Landfill, Table 18 applies the present risk calculation to the annual average ambient concentrations of those carcinogens also detected at El Monte Station in the Los Angeles basin. Assuming a 70-year exposure and an additive effect of the carcinogens, the individual excess lifetime cancer risk for the area near the El Monte Station is estimated to be approximately 7 in 10,000. R& S i 45998 Benzene emissions have the greatest cancer risk impact in the Los Angeles basin, corresponding to an upper-bound risk of 1 in 10,000 to 1 in 1,000 (SCAQMD, 1987). Benzene emissions are attributed almost -70- TABLE 17 (SCAQMD) TABLE V-l 1885 ANNUAL AVERAGE AMBIENT AIR CONCENTRATIONS OF VARIOUS TOXIC ORGANIC GASES IN THE SOUTH COAST AIR BASIN* (concentration in ppbv) Pollutant SCAQMD ARB Anahim Atuta Burbank Lannox El Lone LA Rubi- Upland Mont* Beach dottx BENZENE Av. Cone. Std. Drv. D*t*etion Limit Sample Sit*/# < DLC Data Category^ 1.7-2.8 1.6 2.0-4.0 24/10 B 1.0-2.6 .92 1.0-4.0 21/13 B 2.0-3.0 1.3 1.0-3.0 23/9 B 1.7-2.8 l.S 2.0-3.0 23/10 B 4.9 2.6 -5 39/0 A 4.1 1.9 .5 25/0 A 4.2 2.2 .5 23/0 A 2.5 1.3 .5 24/0 A 3.4 1.4 .5 22/0 A CARBON TETRACHLORIDE Av. Cone. Std. Dev. D*t*ction Limit Sample Si*/# < DL Data Category .12 .OSS 4)16 22/0 A .12 .036 .016 19/0 A .10 4)23 .016 20/0 A .11 .033 .016 20/0 A .095 4)24 .004 36/0 A .10 .014 .004 22/0 A .11 .016 .004 21/0 A .099 .015 .004 20/0 A .12 .073 .004 20/0 A CHLOROFORM Av*. Cone. Std. Dev. Detection Limit Sample Sic*/# < DL Data Catejory .04S-.20 .02-1.0 22/21 C .055-.29 .02-1.0 19/18 C .018-.24 - .077-.S 20/20 C .063-.27 .077-.89 20/18 C .063 .023 .02 36/0 A .082 .025 .02 22/0 A .11 .090 .02 21/0 A .053 .028 .02 20/0 A .071 .045 .02 20/0 A ETHYLENE DIBROMIDE Av*. Cone, (ppt) Std. Dev. (ppt) Detection Limit (ppt) Sample Sit*/# < DL Data Category 5-100 100 22/21 C 0-100 0 100 19/19 C 0-100 100 20/20 C 0-100 # 100 20/20 C 3-6 4 S 36/26 B 4-8 9.0 5 22/15 B 2-6 2.0 5 21/14 B 2-8 1.4 5 20/16 B 3-5 1.0 5 20/9 B ETHYLENE DICHLORIDE Av*. Cone. Std. Dev. Detection Limit Sample Sit*/# < DL Data Category 0-17 * 2.1-28 22/22 C 0-14 4.0-28 10/19 C 0-18 4.0-28 20/20 C 1.0-18 4.0-28 20/19 C R&S 145999 -71- TABLE V-l (continued) Pollutant S CA QMD ARB Anahim Acuta Burbank Lnnox El Long LA Rubi- Upland Monu Beach doux METHYLENE CHLORIDE Ave. Cone. Std. Dev. Detection Limit Sample Siie/# < DL Data Category 8.1 4.0-4.7 2.6 2.9 .006 .006 36/0 22/1 AA 3.8 2.2-2.3 3.0 1.9 .006 .006 21/0 20/4 AB 2.7-2.8 1.7 .006 20/3 B PERCHLOROETHYLENE Ave. Cone. Std. Dev. Detection Limit Sample Sica/# < DL Data Category 3.1 3.4 .3 33/0 A 2.0 1.8 .2 10/0 A 2.7 1.6 .2 20/0 A 3.3 3.8 .3 30/0 A 1.6 .86 .01 36/0 A 1.0 .86 .01 22/0 A 1.2 .91 .01 31/0 A .45 .32 .01 20/0 A .70 .48 .01 20/0 A TOLUENE Ave. Cone. Std. Dev. Detection Limit Sample Sice/# < DL Data Category 4.0-5.6 3.0 3.0-6.0 34/8 B 2.S-4.9 2.3 3.0-7.0 21/11 B S.6-6.7 3.0 8.0 33/8 B 3.S-S.3 4.2 .40-8.0 33/11 B I.I.l-TRICHLOROETHANE Ave. Cone. Std. Dev. Detection Limit Sample Site/# < DL Data Category 3.3 1.4 .33 33/0 A 2.0 1.7 .23 10/0 A 3.3 1.7 .23 20/0 A 2.8 1.8 .23 20/0 A 7.1 4.7 .02 36/0 A 3.0 2.1 .02 22/0 A 2.4 2.6 .02 21/0 A l.l .73 .02 20/0 A 1.6 1.1 .02 20/0 A TRICHLOROETHYLENE Ave. Cone. Std. Dev. Detection Limit Sample Site/# < DL Data Category .23-.35 .33 .20-.90 23/7 B 1G-.33 .26 .11-.90 19/8 B .39-.45 .72 .12-.22 20/7 B .20-.23 .22 .12-.IS 20/15 B .40 .28 .03 36/0 A .29 .20 .03 22/0 A .34 .22 .02 21/0 A .10 .06 .02 20/0 A .37 .17 .02 20/0 A VINYL CHLORIDE Ave. Cone. Std. Dev. Detection Limit Sample Site/# < DL Data Category 0-2.0 2.0 24/24 C 0-3.0 2.0 21/21 C 0-2.0 2.0 24/24 C 0-2.0 2.0 24/23 C -72- R&S146000 Pollutant TABLE V-l (continued) s cAQMD ARB Anahim A*u*a Burbank Lennox El Lone LA Rubi- Upland Monte Beach deux BENZOfA1PYRENE (from EPA monitoring network) Ave. Cone, (ng/m3) Std. Dev. Det. Lim. (ng/m3) Sample Sise/# < DL Data Category .75 .17 M 21/0 A .75 .0079 S3 18/0 A 1 Blank* indicate no data available. Range* of arithmetic annual average* defined a* follows: first estimate is the average assuming all sub-detection limit observations equal sero; second estimate is the average assuming all sub detection limit observations are equal to the detection limit concentration. Standard deviation* were calculated using only the observations above detection limits; if more than 00 percent of the observations were below detection limits, standard deviations were not calculated. ^ Detection limits for some SCAQMD-measured pollutant* reported as range because limits changed from sample to sample depending on analytical condition*. See text for further explanation. C 'Sample Sise/# < DL" s (the total number of samples taken over the year) / (total number of these samples with concentrations below minimum detectable limits). ^ Data Category codes for SCAQMD and ARB data are defined as: A - Most of the data above detection limits (>90%), C - Very few of the data point* are above detection limits (<10%), and B Several data points fall above and below detection limits. * * standard deviation not calculated for Data Category C. Source: South Coast Air Quality Management District, Table V-l, "The Magnitude of Ambient Air Toxics Impacts From Existing Sources in the South Coast Air Basin," 1987 Air Quality Management Flan Revision Working Paper No. 3, June 1987, Pgs. V-* to V-6. R & S 146001 -73- R&S146002 1 M TABLE IB INDIVIDUAL EXCESS LIFETIME CANCER RISK* CARCINOGENS DETECTED AT EL MONTE STATION, 1985 LOS ANGELES BASIN AIR TOXICS MONITORING PROGRAM AND ALSO DETECTED NEAR THE BKK LANDFILL. WEST COVINA, CA Carcinogen Molecular Weight Benzene Vinyl Chloride Perehloroethylene Trichloroethylene 1,2-Dichloroethane Chloroform 78.11 62.5 165.85 131.4 98.96 119.39 Total Excess Lifetime Cancer Risk El Monteb ppb ng/m3 Unit Risk0 (Mg/m3)-1 4.9 - 1.6 0.40 0.06 15.7 - 10.9 2.1 .3 5.3 2.7 E-6 5.8 E-7 1.3 E-6 2.2 E-5 2.3 E-5 Cancer Risk EPAd Class 6.7 E-4 - 5.1 E-6 2.2 E-6 5.5 E-6 A A C B2 B2 B2 6 .8 E-4 a: Calculated by ECR "CxYRxEFxRFxURx 1/LT whare ECR - Excess llfatlma cancar risk C - Concentration in *ig/m3 YR - Years of residence associated withexposure (70) EF - Exposure factor, i.e. percent oftime athome (801) RF " Retention factor, i.e. percent of measured concentration absorbed in the lungs (1001) UR " Unit risk value LT " Human individual lifetime in years (70) b: Valuas taken from El Monte Station, Table V-l, "1985 Annual Average Ambient Air Concentrations of Various Toxic Organic Gases in the South Coast Air Basin,- SCAQMD, 1987, pgs. V-4 to V-6, c: Values 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. Values current through June 1989, d: EPA weight of evidence classification: A, sufficient evidence in humans; Bl, 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 EFA's Integrated Risk Information System (IRIS). June 19B9, -74- equally to mobile sources (motor vehicles) and area sources (gasoline marketing, stationary gasoline engines, crude oil production, and agricultural burning). In two earlier characterizations, (the 1982 Expanded Monitoring Program and the 1984 Extended Monitoring Program) benzene could be excluded from the risk calculation because of discrepancies with the data. The data in this characterization suggest that risks presented by exposure to benzene are more significant from ambient sources than from the B.K.K. Landfill. e. Risk Characterization Using CARB's Modeling of 1987 Ambient Vinyl Chloride Concentrations Around the B.K.K. Landfill CARB used monitoring data from the B.K.K. Landfill in an air dispersion model to estimate population exposure to vinyl chloride for the purpose of proposing to identify vinyl chloride as a toxic air contaminant (CARB, 1990, Draft Document). CARB is the state agency responsible for identification of toxic air contaminants. A toxic air contaminant is subject to a different regulatory process than an ambient air quality standard. A toxic air contaminant is an air pollutant which may cause or contribute to increased morbidity or mortality, or which may pose a present or potential human health hazard (California Health and Safety Code Section 39655). Identification of vinyl chloride as a toxic air contaminant allows CARB to develop control strategies that reduce vinyl chloride air levels far below 10 ppb. -75- R&S146003 CARB used the Industrial Source Complex Short Term (ISCST) Gaussian model to estimate vinyl chloride concentrations and exposed population. This model does not allow direct inference of dist'nc . In this model, the B.K.K. Landfill was represented as an area source in the center of a grid of 41 one-square-kilometer cells (that is, a grid of approximately 25 square-miles). For each square-kilometer cell, annual average vinyl chloride concentrations were estimated using SCAQMD's 1981 meteorological data from Walnut Station, and SCAQMD's 1987 ambient vinyl chloride monitoring data from Station A, B, and MY (Table 19). Population estimates for each square-kilometer cell were determined from 1985 population census estimates. The 1,681 grid cells and associated population estimates were sorted from high to low by modeled vinyl chloride concentrations. Grid cell populations were then summed to determine the cumulative population exposed to a certain level of modeled vinyl chloride concentration. Table 20 shows the results of CARB's modeling. Using CARB's modeled vinyl chloride concentrations, and applying the present risk calculation, the individual excess lifetime cancer risk ranges from 7 in 100,000,000 for exposure to 0.01 ppb of vinyl chloride to 4 in 100,000 for exposure to 7 ppb of vinyl chloride (Table 21). R&S146004 -76- TABLE 19 (CARB) TABLE II-l SUMMARY STATISTICS FOR THE JANUARY 1987 THROUGH DECEMBER 1987 MONITORING DATA FOR VINYL CHLORIDE NEAR BKK LANDFILL (Concentrations reported in parts per billion (ppb)) Station 1 Station 2 Station 3 Number of samples Percent of Samples Below the LOD* Estimated Concentration forb Samples Below the LOD Estimated Mean*5 Concentration Maximum 24-Hour Concentration0 337 73 1.0 1.7 7 337 90 1.0 1.2 8 345 55 1.1 2.6 15 a - The SCAQMD's limit of detection (LOD) for vinyl chloride is 2 ppb. b - Gleit's method was used to estimate the concentration of samples below the LOD. c - California's Ambient Air Quality Standard for vinyl chloride is 10 ppb for a 24-hour averaging period. Source: California Air Resources Board, Table 11*1. "Technical Support Document. Proposed Identification of Vinyl Chloride as a Toxic Air Contaminant, Draft Report, Exacutiva Suninary and Fart A." Stationary Source Division, May 1990, p. A-7. Stations 1, 2, and 3 are Stations A, B, and MY respectively. R&S 146005 -77- TABLE 20 (CARB) Vinyl Chloride Concentretion (DBbl 0.01 0.05 0.1 1.0 2.0 3.0 4.0 5.0 6.0 7.0 TABLE 11*6 RANGE OF CUMULATIVE POPULATION EXPOSED TO VINTL CHLORIDE NEAR BIX Ranoe of Cumulative R onulatiofi_iDosefl Lower-Bound Estimate* Uoper-Boune. Eitimais 0 2.026.000 - 2.154.000 732,000 - 1.970.000 374.000 - 1.431.000 17,000 - 131.000 0 54.000 0 2S.000 0 20,000 0 14,000 0 7.000 0 2.500 a - The exposure estimate is bssed on a vinyl chloride emission rase of C.75 microgrems meter"4, seeT* o The exoosure estimate is based on a vinyl chloride emission rate of 3.32 micrograms meter'4, secT1 Source: California Air Raiources Board. Tabla 11*5, "Technical Support Document, Propoaad Xdantification of Vinyl Chlorida as a Toxic Air Contaminant, Draft Report, Executive Stannary and Part A". Stationary Source Division, May 1990, p. A-14. Modeled data is for an area approximately 25 miles-by-25 miles around the B.K.K. Landfill, West Covina, California. R&S146006 -78- TABLE 21 INDIVIDUAL EXCESS LIFETIME CANCER RISK* CARB MODELING OF 1987 AMBIENT VINYL CHLORIDE CONCENTRATIONS NEAR BKK LANDFILL, WEST COVINA, CA Modeled Vinyl Chloride Concentration ppb HS/" Cancer Risk .01 0.1 1.0 2,0 7.0 .03 0.3 2.6 3.1 17,9 6.3E-8 6.5E-7 5.6E-6 1.1E-5 3.9E-5 Calculated by ECR - Cvc xYRxEFxRFxURx 1/LT where ECR Excaaa lifetime cancer risk Cve Concantratlon In nt/a? of vinyl chloride YR Year* of raaldanca asaoclatad with axpoaura (70) EF Exposure factor, l.a, parcant of time at homo (80Z) RF Retention factor, l.a, percent of maaaured concantratlon abaorbod In the lungs (100Z) UR Unit risk value for vinyl chloride: 2,7 x 10' (pg/m3)*"*, taken from Table 3.13, "Air Toxics Assessment Manual", California Air Pollution Control Officer's Association, October 1967, p. 3.3-28. Value current through June 1989. LT Human individual lifetime in years (70) b: Modeled vinyl chloride concentrations in ppb are taken from Table II-5, "Technical Support Document, Proposed Identification of Vinyl Chloride As A Toxic Contaminant. Draft Report, Executive Suninary and Part A," CARB Stationary Source Division, May 1990, pg. A-1A. R&S146007 -79- 2. Numerical Estimation - Population Excess Cancer Burden The population excess cancer burden is calculated by multiplying the individual excess lifetime cancer risk in an exposed area by the population in the exposed area. The individual excess lifetime cancer risks estimated in the risk characterization scenarios of the B.K.K. Landfill are: 1987 Ambient Vinyl Chloride Monitoring, Station MY 1.5 x 10"5 1982-1987 Ambient Vinyl Chloride Monitoring 1.8 x 10"5 1982 Expanded Monitoring Program, excluding benzene 5.2 x 10"5 1984 Extended Monitoring Program, excluding benzene 5.8 x 10"6 Modeling of 1987 Ambient Vinyl Chloride 6.5 x 10"8 to 3.9 x 10*5 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). In actual fact, not all 40,000 persons are exposed to the levels of vinyl chloride suggested in these scenarios. Most residents are exposed to lower levels. CARB's Table 19 shows that in 1987 the proportions of samples below the detection limit of 2 ppb was 73 percent, 90 percent, and 55 percent for Stations A, B, and MY respectively. R&S146008 Based on the risk characterization scenarios, the most appropriate individual excess lifetime cancer risk to estimate population excess cancer burden is derived from monitored data at Station MY. Using the individual excess lifetime cancer risk of 1.5 x 10-5 associated with 1987 ambient vinyl chloride monitoring at Station MY, and the estimated -80- population within a one-mile radius of the B.K.K. Landfill, the estimated population excess cancer burden is 0.6, That is, in a population of 40,000 persons less than one additional case of cancer would be associated with exposure to vinyl chloride at 2.7 ppb for an entire 70-year period. Limitations and Uncertainties A risk number is an estimate of the risk of adverse health effects conditional on the methods and assumptions of the risk characterization, and the limitations and uncertainties of the data collection. CH2MH111 addressed the limitations and uncertainties of the data collection in its exposure characterization (CH2MH111, 1988). These included the following: only a few air monitoring data sets were judged to be appropriate for quantitative risk assessment based on a retrospective quality assurance review; 24-hour air samples were collected, providing data on average air emissions only; air monitoring data are primarily from residential stations in the south and southeast which represent nighttime ("worst-case"), air flow. detection limits for vinyl chloride and benzene have changed, limiting direct comparison of data over time; -81- R&S 146009 not all analytes were measured In all media, and some media (soil, particulates) were rarely sampled; demographics are based on the 1980 U. S. population census data and projections, although there has been considerable development around the B.K.K. Landfill. Limitations of this health risk assessment include the following: * use of data from 1982 through 1987 only; use of different summary statistics (that is, geometric means, arithmetic means, medians, and annual averages); use of June 1989 toxicity values. Uncertainties inherent in this health risk assessment include: / - the assumptions stated at the beginning of the risk characterization; the choice of unit risk values. The Class I Hazardous Waste Management Unit stopped accepting hazardous waste by December 1984, and was capped and closed in March 1989. Mitigation measures stipulated in the SAM Work Plan may be expected to reduce vinyl chloride emissions to levels and frequences below those detected in 1987. -82- R&S146010 Significance of the Risk Excess lifetime cancer risk is estimated in order to assess the potential impact of a particular exposure in addition to the relatively constant background level of cancer risk. An individual has approximately a one in three (3 x 10_1) risk of developing cancer during his or her lifetime. The ambient vinyl chloride monitoring data represent the most appropriate data t assess the excess cancer risk associated with the B.K.K. Landfill because vinyl chloride is not commonly detected in the Los Angeles air basin. Carcinogens such as benzene, perchloroethylene, and trichloroethylene are detected in ambient air both at the B.K.K. Landfill and in the Los Angeles basin. These compounds may present an additional cancer risk to people living near the B.K.K. Landfill but it is not possible with the present data to distinguish between exposure due to ambient levels and exposure due to the B.K.K. Landfill. Vinyl chloride is rarely detected in the ambient air, and therefore vinyl chloride more clearly represents the increased exposure associated with the B.K.K. Landfill. Based on the 1987 ambient vinyl chloride concentrations, and the methods and assumptions used in this health risk assessment, the individual excess lifetime cancer risk associated with exposure to the carcinogen detected in air around the B.K.K. Landfill is estimated to be approximately 1 to 2 individuals in 100,000 persons. This assumes everyone is exposed to vinyl chloride at the 1987 concentrations for an entire 70-year lifetime. Most residents are exposed to lower levels of vinyl chloride and most -83- R&SM6011 residents are not likely to stay at one place an entire lifetime. Mitigation measures stipulated in the SAM Work Plan may be expected to reduce vinyl chloride emissions from the B.K.K. Landfill. Currently, DHS and CARB are reevaluating the data on the carcinogenicity of vinyl chloride, in recent and past literature, for the purpose of identifying vinyl chloride as a toxic air contaminant, pursuant to the Health and Safety Code Section 39650 et seq. When this process is completed, a new unit risk value for vinyl chloride will be established. The new value is likely to b about 29 times greater than the value used in this health risk assessment. When this new value is adopted, DHS will prepare an addendum to this risk assessment, reflecting the changed unit risk value for vinyl chloride, updating toxicity values, and adding air monitoring data collected since 1987. -84- R&S146012 REFERENCES 1. Bogen, K.T. and Smith, M.T. "Risk Assessment for Exposure to Ambient Air in the Vicinity of the BKK Landfill in West Covina, 1978-1985." Unpublished paper. April 1986. 2. California Air Resources Board. "Technical Support Document, Proposed Identification of Vinyl Chloride as a Toxic Contaminant, Draft Report." Parts A and B. CARB, Stationary Source Division. May 1990. 3. California Department of Health Services. "BKK Reoccupancy and Relocation Criteria." Draft Memorandum From Epidemiological Studi s Section, Preventive Medical Services Division, to Angelo Bellomo, Chief, Southern California Section, Toxic Substances Control Program. October 30, 1984. 4. California Air Pollution Control Officers Association. "Air Toxics Assessment Manual. Toxic Air Pollutant Source Assessment Manual for California Air Pollution Control Districts and Applicants for Air Pollution Control District Permits." October 1987. 5. California Department of Health Services-Toxic Substances Control Program, California Air Resources Board, and South Coast Air Quality Management District. "Ambient Air Monitoring And Health Risk Assessment for Suspect Human Carcinogens Around the BKK Landfill in West Covina." Unpublished paper. March 1983. 6. CH2MHill. "BKK Landfill Environmental Exposure Characterization Report, West Covina, California." August 15, 1988. Volume I - Text; Volume II - Plates 1-17; Appendices Volume 1 F-l to F-3 (groundwater data). Volume 2 F-4 (groundwater data). Volume 3 F-4 and F-5 (groundwater data), Volume 4 F-5 (groundwater data) and G-l (surface water data), Volume 5 G-2 (surface water data), H-l and H-2 (air data), and I (soils data). 7. Crump, K.S. and Co. "Estimates of Carcinogenic Risk in the Vicinity of BKK Landfill." Unpublished paper. Ruston, Louisiana. March 1986. 8. Environmental Solutions, Inc. "BKK Landfill Site Assessment and Mitigation Work Plan. Book I, Subsurface: Site Characterization." March 15, 1988. 9. South Coast Air Quality Management District. "Vinyl Chloride in the South Coast Air Basin." May 1982. 10. South Coast Air Quality Management District. "The Magnitude of Ambient Air Toxics Impacts From Existing Sources in the South Coast Air Basin." 1987 Air Quality Management Plan Revision Working Paper No. 3. June 1987. R&S146013 -85- 11. Study Group on Risk Assessment Presentation. "Presentation of Risk Assessments of Carcinogens, Report of an Ad Hoc Study Group on Risk Assessment Presentation." American Industrial Health Council. Washington, D.C. July 1989. 12. U. S. Environmental Protection Agency. "BKK Update: Information about the BKK Landfill, West Covina, California." EPA Region 9. Issue No. 1, March 1985. 13. U. S. Environmental Protection Agency. "Superfund Public Health Evaluation Manual." EPA 540/1-86/060 (OSWER Directive 9285.4-1). October 1986. 14. U. S. Environmental Protection Agency. "Guidelines for Carcinogenic Risk Assessment." Federal Register. 51:33992 - 34003, 1986. 15. U. S. Environmental Protection Agency. "Integrated Risk Information System (IRIS)." Database access June 1989. 16. U. S. Environmental Protection Agency. "Risk Assessment Guidance for Superfund, Human Health Evaluation Manual Part A, Interim Final." EPA OSWER Directive 9285.701A. July 1989. 17. U. S. Environmental Protection Agency. "Health Effects Assessment Summary Tables, Third Quarter FT 1989." EPA OERR 9200.6-303-(89-3). July 1989. R&S146014 APPENDIX A R&S146015 SUMMARY OF THE THREE PREVIOUS HEALTH RISK ASSESSMENTS OF THE B.K.K. LANDFILL, WEST COVINA, CALIFORNIA Three previous health risk assessments have been performed evaluating residential exposure to seven carcinogens detected in ambient air around the B.K.K. Landfill. Risk estimates varied due to different assumptions and methods of risk calculation, as described in the following paragraphs. Copies of the three risk assessments are provided as Appendices A, B, and C. The seven carcinogens evaluated were: vinyl chloride, benzene, trichloroethylene (TCE), 1,1-dichloroethylene (vinylidene chloride), perchloroethylene (PCE), 1,2-dichloroethane (ethylene dichloride), and trichloromethane (chloroform). 1. "Ambient Air Monitoring and Health Risk Assessment for Suspect Human Carcinogens Around the BKK Landfill in West Covina", Department of Health Services-Toxic Substances Control Program/California Air Resources Board/South Coast Air Quality Management District (DHS-TSCP/CARB/SCAQMD), March 1983. (Appendix B) During July to October 1982, DHS-TSCP, CARB, and SCAQMD conducted a 90-day study to monitor ambient air around the B.K.K. Landfill for nine volatile organic compounds in response to continued concerns from neighboring residents. Twenty-four hour ambient air samples were collected in Tedlar bags on Sunday through Thursday at six sample stations. Figure 7 of this report (and Figure I of Appendix A) shows the locations of the stations: Stations A and B were located in residential areas south of the landfill, reflecting nighttime air drainage patterns; Station D was located at the entrance to th landfill; Station E was located at the highest elevation within the landfill, reflecting daytime transport; Station F was initially located in a residential area on the northeast side and on August 26, 1982, it was moved to the northwest in response to odor complaints from that area. Station C was located in Pico Rivera, nine miles southwest (upwind) of the facility, to estimate background levels. Stations A, B, D, and E were within 400 to 1,000 feet of the waste disposal area while Station F was 2,500 and 6,000 feet from the facility. The data given for Station F are an equally weighted average of the two locations. Split samples were taken and analyzed by two laboratories, SCAQMD's laboratory and CARB's southern laboratory branch, (Haagen-Smit). DHS considered the nine volatile organic compounds to be known or potential human carcinogens: vinyl chloride, benzene, perchloroethylene, trichloroethylene, 1,1-dichloroethylene, chloroform, 1,2-dichloroethane, chlorobenzene, and trans-1,2-dichloroethene. The report stated that chlorobenzene and trans-1,2-dichloroethene were not detected. The remaining seven chemicals were detected in concentrations near the analytical limit of detection. Elevated levels of the seven were found around the B.K.K. Landfill compared to the control community of Pico Rivera. Stations A, B, and D had consistently more elevated levels than Stations E and F. R&S146016 The risk assessment focused solely on the risk of cancer because the chemicals were detected in concentrations considered below their threshold for non-carcinogenic ,J toxic effects -- even at the highest concentrations detected. Excess cancer risks were derived by subtracting the average concentration of each substance at Station C from the average concentration of that substance at the B.K.K. Lanafill monitoring site. The exposure period was defined as the previous seven years, 1975 to 1982, since that time reflected the beginning of recorded waste deposits, the landfill expansion from 40 acres to 140 acres, and the increased residential construction along the southern border. The report did not identify slope factors or unit risk values used in the risk calculation. Individual excess lifetime (70-year) cancer risk was based on the following assumptions: no dilution in the measured concentrations at Stations A-F; exposure for 24 hrs/day, 365 days/year, for 7 years (1975-1982); 100 percent absorption in the lungs. The maximum individual excess lifetime cancer risk attributable to emissions from the B.K.K. Landfill for the previous 7 years was estimated to be approximately 5 per 100,000 (5 x 10_s). The population living within a one-mile radius of the B.K.K. Landfill property line was estimated to be approximately 7,700 persons. This number was derived by dividing the county assessor's plot maps into quadrants corresponding to monitoring Stations A, B, D, and F, and estimating the population within each quadrant from the 1980 census data. The population excess cancer burden was calculated for the population within each quadrant using the mean concentration difference for the respective station, then summing the derived excess number of cancers. No additional cases of cancer were suggested. 2. "Estimates of Carcinogenic Risk in the Vicinity of the BKK Landfill", K. S. Crump and Co., Inc., March 1986. (Appendix C) In March 1986, K. S. Crump, as a consultant to attorneys for the B.K.K. Landfill, performed a risk assessment on the seven carcinog ns detected in the DHS-TSCF/CARB/SCAQMD 1983 report. Crump identified epidemiologic data that he used to derive a human potency estimate for benzene, and the animal toxicologic data that he used in the linearized multistage extrapolation model to derive human potency estimates for the six other compounds. Exposure concentrations were taken from two air monitoring programs: the SCAQMD 1981-1985 ambient vinyl chloride monitoring program of the B.K.K. Landfill, supplemented by a University of Southern California 1980 residential monitoring program around the B.K.K. Landfill. The following assumptions were used: average air concentrations, from 12 SCAQMD stations and stations; exposure for 24 hours per day, 365 days per year, for 8 (1978-1985). 4 USC years R&S146017 According to Crump's methods, the lowest maximum likelihood estimate of total risk from all seven carcinogens was 2.5 x 10'6 and the highest upper 95 percent confidence limit estimate of total risk was 11 x 10-6 (Table 11 of Appendix B) . If typical year-round occupancy of a home were no more than 12 hours/day, Crump estimated the risk to range between 1.25 to 6 per million people exposed. 3. "Risk Assessment for Exposure to Ambient Air in the Vicinity of the BKK Landfill in West Covina, 1978-1985", K. T. Bogen and M. T. Smith, April 1986. (Appendix D) In April 1986, Bogen and Smith, as consultants to attorneys for the B.K.K. Landfill, performed a risk assessment on the seven carcinogens detected in the DHS-TSCP/CARB/SCAQMD 1983 report. Bogen and Smith identified relevant animal bioassay data and used a Monte Carlo Potency Analysis (MCPA) method to derive potency distributions for the seven carcinogens. The MCPA method uses the multistage model of cancer, but rather than a single upper-bound confidence value for potency, Monte Carlo simulation produced complete distributions for potency estimation error. The following assumptions were applied by Bogen and Smith to the data in the 1983 DHS-TSCP/CARB/SCAQMD report: 50 percent dilution in the measured concentrations at Stations A, B, D, and F due to dispersion in ambient air; exposure for 15 hours/day, 365 days/year, for 7 years (1978-1985); - 50 percent absorption in the lungs, based on a study cited by Bogen and Smith. Potency distributions were generated for each compound and each monitoring station and, again using a Monte Carlo procedure, the corresponding potencies were added to obtain a distribution of total Increased risk from all seven compounds. From the latter distribution, Bogen and Smith selected the 50th percentile value of 2.2 x 10-6 as a "best" estimate of increased lifetime cancer risk for the average individual living near the B.K.K. Landfill for the seven-year period. The "best" estimate value is a risk value as likely as not to overestimate the true level of average increased individual risk. Assuming the population of 7,700 exposed individuals from the DHS-TSCP/CARB/SCAQMD 1983 report, Bogen and Smith calculated a population excess cancer burden of 0.01 cases. R&S146018 Report TABLE 22 SUMMARY OF THE THREE PREVIOUS HEALTH RISK ASSESSMENTS OF THE BKK LANDFILL, WEST COVINA, CA Assumptions Methods Excess Cancer Risk "Ambient Air Monitoring and Health Risk Assessment for Suspect Human Carcinogens Around the BKK Landfill in Uest Covina.11 OHS-TSCP/CARB/SCAQMD 1983 "Estimates of Carcinogenic Risk in the Vicinity of the BKK Landfill." K.S. Crump t Co. 1986 - no dilution in 1982 measured concentrations at Stations A B C D E F - exposure for 24 hrs/day 365 days/yr, 7 yrs (1975-82) - 10QX absorption in the lungs - average air concentrations from 12 SCAOHD Stations and 4 USC Stations - exposure for 24 hrs/day 365 days/yr, 8 yrs (1978-85) individual excess lifetime cancer risk and population excess cancer burden 5 x 10'^ maximum likelihood and upper 95% confidence limit estimate 2.5-11 x 10'^ "Risk Assessment for Exposure to Ambient Air in the Vicinity of the BKK Landfill in West Covina, 1978-1985." Bogen t Smith 1986 - 50% dilution in 1982 measured concentrations at Stations A B D & F - exposure for 15 hrs/day 365 days/yr, 7 yrs (1978-85) Monte Carlo potency analysis method and Monte Carlo procedure; "best" estimate 2.2 x 10*^ - 50% absorption in the lungs a: All three health risk assessments evaluated residential exposure to concentrations of the following seven carcinogens: vinyl chloride, bentene, trichloroethylene, perchloroethylene, 1,1-dichloroethylene, 1,2-dichloroethane, and chloroform. 6109HS1SU APPENDIX B R&S146020