Document mq1Lo7ogqv7G9oz5zb85O8o2Z

FILE NAME Brakes BRK DATE 2001 DOC BRK118 DOCUMENT DESCRIPTION Journal Article - Malignant Mesothelioma and Asbestos Exposure Among Auto Mechanics Appraisal of Scientific Evidence 01/16/02 15:30 HOBIN AND SHINGLER 14104482368 Regulatory Toxicology and Pharmacology 34 170-177 2001 rtph.2001.1401 available online at http://www.ideallbrary.com on IDEALfi 002 Malignant Mesothelioma and Asbestos Exposure among Auto Mechanics Appraisal of Scientific Evidence Otto Wong * Applied Health Sciences Inc. P.O. Box 2078 San Mateo California 94401 Department of Epidemiology Tulane University New Orleans Louisiana and Department of Community and Family MedicineChinese University ofHong Kong Hong Kong Received March 24 2001 Key Words regulation causation case reports epi- In 1986 the U.S. Environmental Protection Agency EPA issued an official guideline on the prevention of asbestos disease among auto mechanics In the demiology control studies asbestos chrysotile brakes clutches auto mechanics malignant mesothe- lioma EPA guideline malignant mesothelioma was listed as a consequence of exposure to asbestos fibers from brake linings and clutch facings among auto mechan- INTRODUCTION ics EPA formulated its 1986 opinion by relying solely on a few outdated case reports and not on epidemiologic studies A review of the literature indicates that there are six epidemiologic studies providing relevant information on malignant mesothelioma among auto mechanics Three of the six studies had already been published by 1986 the year in which EPA Issued its guideline The results of the six studies were remarkably consistent in that all six studies re- ported no increased risk of malignant mesothelioma among auto mechanics The relative risks reported in the six studies ranged from 0.62 to 1.00 Based on a Regulatory policies and guidelines for occupational exposures are intended to prevent avoidable diseases among workers and are supposed to be based first and foremost on scientific evidence Definitive scientific ev- idence however may take years or even decades to ac- cumulate It is therefore the regulators responsibility to develop to update and to revise if necessary policies and guidelines in accordance with the latest available scientific data Unfortunately this is not always the case An example is the U.S. Environmental Protection Agency's EPA's guideline for the prevention of analysis of the combined data of all six studies asbestos disease among auto mechanics who are poten- consisting of approximately 1500 malignant mesothe- tially exposed to asbestos fibers from brake linings and Homa cases the mesothelioma relative risk for auto clutch facings mechanics is 0.90 95 confidence interval 0.66 1.23 In 1986 EPA issued an official guideline in which An application of Hill's causation criteria to epidemi ologic data of malignant mesothelioma among auto mechanics clearly demonstrates that auto mechanics do not have an increased risk of malignant mesothe lioma as a result of exposure to asbestos fibers from brake linings and clutch facings However in spite of the scientific evidence EPA has not modified or revised its 1986 guideline Occupational regulatory policies and guidelines when based on proper scien- tific evidence are invaluable and can prevent avoldable diseases in workers or other exposed individu als in the general public On the other hand it is the regulators responsibility to develop modify and revise policies and guidelines in accordance with the most relevant and the latest scientific data In this instance EPA as a regulator has not fulfilled its responsibility of providing the most accurate and update information to the workers or the general malignant mesothelioma was listed as a consequence of exposure to asbestos fibers generated from working with friction products such as brake linings and clutch facings among auto mechanics EPA 1986 In the 1986 EPA document several references were cited in support of the Agency's opinion on malignant mesothe lioma among auto mechanics All references cited were case reports Because not all malignant mesothelioma cases are related to occupational exposure to asbestos Peterson et al 1984 Pelnar 1988 using case reports as evidence for causation is not only inappropriate but also misleading For example based on the Finnish Tumor Registry malignant mesothelioma cases have been reported among the following occupations which do not entall asbestos exposures judge banker bookkeeper musician school teacher tailor student nurse midwife cook seamstress and maid Nurminen 1975 public 2001 Academic Press Based on these case reports one cannot conclude that 170 0273-2300 35.00 Copyright @ 2001 by Academic Press All rights of reproduction in any form resorved AP 01/16/02 15:30 HOBIN AND SHINGLER 14104482368 NO.287 NO.287 003 MALIGNANT MESOTHELIOMA IN AUTO MECHANICS 171 these occupations are at an increased risk of develop ing malignant mesothelioma Such a conclusion must be based on epidemiologic studies relevant to the occupations in question The 1986 EPA document did not cite any epidemiologic studies of malignant mesothe lioma among auto mechanics even though three epfdemiologic studies providing relevant information on malignant mesothelioma among auto mechanics had been published by 1986 see below Case reports are reports of isolated cases of diseases in individuals with certain characteristics or potential risk factors However the underlying population at risk is not defined in case reports and therefore no measure of disease frequency can be estimated Further more case reports do not involve any comparison to individuals without the characteristics or exposures and therefore cannot provide any measure of risk rel- ative to individuals with no exposure In its 1986 docu- ment EPA did not discuss the uncertainties of relying on case reports alone even though the limitations of case reports are well recognized by scientists and regulators alike For example in its monographs on carcinogenic ity evaluation the International Agency for Research on Cancer IARC 1989 discussed the uncertainties of case reports Case reports usually lack complete ascertainment of cases in any population definition or enumeration of the population at risk and estimation of the expected number of cases in the absence of exposure Thus case reports in or by themselves cannot be used as evidence for causation Case reports however do serve some useful purposes alerting researchers of the potential association be tween the exposure and disease in question and providing valuable information for priority setting in allocating research resources However it must be understood that case reports do not provide any definitive evidence for causation in ar by themselves A proper causation assessment must be based on appropriate epidemiologic studies With regard to the use of epidemiologic studies in causation assessment IARC 1988 remarked Co- hort and control studies relate individual exposure to the agent under study to the occurrence of cancer in individuals and provide an estimate of relative risk as the main measure of association Epidemiologic studies have both confirmed as well as refuted associations previously suggested by case reports Although it is prudent for regulators to Issue early warnings at the first sign of danger suggested by case reports it is equally prudent for regulators to revise their positions if subsequent epidemiologic studies prove otherwise In the case of malignant mesothelioma and asbestos exposure among auto mechanics as will be demonstrated below proper epidemiologic studies are available and they refute the association suggested by earlier case reports The following example illustrates the danger of relying on case reports In 1991 Woltowitz and R^delsperger reported several cases of malignant mesothelioma in garage mechanics at a clinic in Glessen Germany No information on the size of the underlying population of garage mechanics at risk was available and no measure of risk was provided Nevertheless based on the few cases alone Woitowitz and R^delsperger1991 concluded In summary we have found an increased Incidence emphasis added of mesothelioma among car mechanics exposed only to chrysotile Wong 1992 pointed out that the Woltowitz and R^delsperger1991 report was not an epidemiologic study but a case report As such it would not have been possible to calculate an incidence of mesothelioma among garage mechanics since the underlying population of garage mechanics at risk was undefined and unknown to the authors Furthermore no conclusion on the relationship between car mechanics and mesotheHoma should be drawn from such a case report Subsequent to this exchange in the literature Woitowitz and R^delsperger 1994 did complete an epidemiologic control study of mesothelioma and garage mechanics The analysis indicated that there was no in- creased risk of mesothelioma in garage mechanics see below Based on their 1994 epidemiologic investigation Woltowitz and R^delspergerreversed their earlier opinion based on the 1991 case report and concluded From these results there is no evidence that car me- chanics are exposed to increased risk of mesothelioma even if they do brake repairs This example serves to demonstrate the treacherous nature of relying on case reports for causality assessment Evidence for a causal relationship must be based on epidemiologic studies EPIDEMIOLOGIC STUDIES OF MESOTHELIOMA AMONG AUTO MECHANICS Because malignant mesothelloma is a relatively rare disease the study design of choice is control study The measure of risk in a control study is derived by comparing the proportion of cases individuals with the disease with exposure to that among the controls individuals without the disease In a large control study of malignant mesothelioma in North America McDonald and McDonald 1980 ascertained through 7400 pathologists in North America all fatal cases of malignant mesothelioma in Canada between 1960 and 1972 and all fatal cases of mesothelioma in the United States in 1972. Patients diagnosed with nonpulmonary malignant tumors at the same hospitals were selected as controls A one control ratio was used Cases and controls were matched with respect to sex age and year of death Employment histories of both cases and controls were obtained through a blinded 01/16/02 15:30 HOBIN AND SHINGLER 14104482368 NO.287 NO.287 172 OTTO WONG TABLE 1 Risk of Malignant Mesothelioma by Occupation in a Control Study in Canada and the United States 1900-1972 Occupation or industry Insulation Asbestos products and manufacturing Heating trades Shipyards Construction Industry Garage mechanics Source McDonald and McDonald 1080 Relative risk 48.0 6.1 4.4 2.8 2.6 0.9 interview Analysis was based on a comparison of the accupational exposure histories of 480 cases and their controls For insulators a significant increase of mesothe- lioma risk was found with a relative risk of fold For asbestos production such as mining and milling the relative risk was 6.1 Workers in heating trades furnaces boilers plumbing steam pipes and welding were reported to have a relative risk of 4.4 For shipyard workers the risk was 2.8 times that of the general population Table ) On the other hand there were 11 mesothe loma cases who had worked as garage mechanics com- parable to 12 controls who had done so In a correspondence one of the authors stated The equal numbers of garage workers in cases and controls indicates sic that no increased risk ofgarage work was found in our study letter from A. D. McDonald to O. Wong dated June 4 1986 The relative risk of mesothelioma for garage me- chanics based on this study was estimated to be 0.91 similar to the background risk of 1.00 for individuals with no occupational exposure to asbestos The corresponding 95 confidence interval 95 CI was 0.392.13 McDonald and McDonald 1980 concluded no increase in risk was found in garage workers certainly exposed to chrysotile from brake linings Incidentally the authors also stated For nearly half the male cases and for about % of female cases the tumor could be at- tributed to occupational exposure to asbestos of which a fifth were in shipyards This observation emphasizes the large number of mesothelioma cases that are not related to occupational exposure to asbestos In 1983 another control study of malignant mesothelioma and occupation that provided information on auto mechanics was reported by Teta et al 1983 Cases were identified primarily through the Connecticut Tumor Registry Connecticut State Health Department one of the oldest and most comprehen- sive tumor registries in North America The case ascertainment was supplemented by a search of records at the largest Veterans Administration hospital in the state The study consisted of 220 cases diagnosed between 1955 and 1977. Controls were randomly selected from the mortality registry in the state during the same time interval Medical demographic and occupational exposure information was obtained for both cases and controls Plumbers and pipefitters were found to have significantly increased risk relative risk of 3.87 A significantly elevated relative risk of 2.25 was also found for cabinetmakers and carpenters The relative risk of mesothelioma for automobile repair and related ser- vice was 0.65 The finding was based on 6 subjects who had worked as auto mechanics and the correspond- ing 95 CI was rather wide 0.08-5.53 Even though the study was relatively small the result indicated that there was no increase of mesothelioma associated with garage work which was consistent with the result reported in the much larger study by McDonald and McDonald 1980 In a control study conducted by epidemiologists at the National Cancer Institute NCI the occupational exposures of 259 mesothelioma patients diagnosed between 1975 and 1980 in New York State ex- clusive of New York City and Los Angeles County were compared to those of the controls Spirtas et al 1985 Significantly elevated relative risks were reported for workers in several occupations furnace or boiler installation or repair 4.5 95 CI 2.5-8.2 shipbuilding ship demolition or shipyard work 4.3 95 CI 2.5-7.4 and Insulation 3.2 95 CI 2.1-5.0 In contrast the relative risk for brake lining installation and repair was 1.0 95 CI 0.6-1.6 That is mesothelioma risk for work- ers engaged in brake lining installation and repair was the same as the general population In a second repart based on the same database Spirtas et al 1994 focused their analysis on attributable risk of asbestos exposure in general and no individual risk estimates were calculated for specific occupations separately However the numbers and percentages of cases and controls in each occupation were reported For several occupations a higher percentage of cases than controls was reported furnace or boiler Installation or repair 51 24.5 vs 39 7.3 insulation 83 39.8 vs 83 15.6 shipbuilding or repair 67 32.2 vs 40 7.5 and plumbing or heating 72 34.6 vs 125 23.5 On the other hand there were 33 15.8 cases and 72 13.5 controls who had engaged in brake lining work or repair The almost equal percentages of cases and controls indicated that there was no increased risk associated with brake lining work consistent with the more specific result presented in the earlier report Spirtas et al 1985 In recent control study conducted at the Insti- tute and Outpatient Clinic of Occupational and Social Medicine of the Justus University in Giessen Germany 16 4.9 of the 324 cases of mesothelioma were classified as motor vehicle mechanics compared to 16 mechanics 5.1 among 315 hospital controls and 12 mechanics 8.6 among 182 population controls Woltowitz and R^delsperger 1994 According to the authors the motor mechanics began their employment between 1925 and 1972. Based on a comparison to the combined hospital and population controls the relative 01/16/02 15:30 HOBIN AND SHINGLER 14104482368 NO.287 NO.287 005 MALIGNANT MESOTHELIOMA IN AUTO MECHANICS 173 TABLE 2 Risk of Malignant Mesothelioma by Occupation in a Control Study in British Columbia 1990-1992 Occupation Sheet metal workers Plumbers and pipefitters Shipbuilding workers not classified elsewhere Wolders Bricklayers plasterers and cement workers Miners drillers and blasters Construction foremon Stationary engineers and boilermakers Office clerks and secretaries Teachers and librarians Sales clerks Vehicle mechanics Source Teschke et al 1997 Relative risk 0.6 8.3 6.0 3.9 3.5 3.4 3.1 1.8 1.9 1.0 0.9 0.8 95 CI 1.5-108 1.5-86.3 1.2-22.7 0.8-21.8 0.0-14.0 0.8-13.1 0.9-11.0 0.5-5.0 0.5-3.5 0.2-3.7 0.4-2.1 0.2-2.3 risk for all motor vehicle mechanics was 0.87 95 CI 0.46 1.6M4ore specifically for motor vehicle mechanics definitely engaged in brake service the relative risk was 0.76 95 CI 0.28-2.05 The authors concluded From these results there is no evidence that car me- chanics are exposed to an increased risk of mesothelioma even if they do brake repairs In another recent control study in British Columbia the investigators at the University of British Columbia and the University of Washington compared the asbestos exposure histories of 51 cases of pleural mesothelioma to those of 154 population con- trols Teschke et al 1997 The mesothelioma cases diagnosed between September 1990 and August 1992 were identified through the British Columbia Cancer Agency Interviews to obtain exposure histories were conducted by a registered nurse and the exposure infor- mation was reviewed by an industrial hygienist The following significant risk ratios were reported for several occupational groups 9.6 for sheet metal workers 8.3 for plumbers and pipefitters and 5.0 for shipbuilding workers Table 2 In contrast there were 6 mesothe- loma cases and 20 controls who had worked as ve- hicle mechanics and the relative risk was 0.8 with a 95 CI of 0.2-2.3 Thus there was no increased risk reported for vehicle mechanics in the University of British University of Washington study The investigators also examined the risk for mechanics who were specifically involved in brake lining installation or repair Again no increased risk was found relative risk of 0.3 95 CI 0-1.4 Thus the authors concluded As with vehicle mechanics in the occupational analysis a history of brake lining installation or repair had a risk estimate below 1.0 Finally the Institute of Epidemiology and Clinical Research in Spain conducted a control study of mesothelioma and occupation Agudo et al 2000 The study consisted of 132 confirmed mesothelioma cases diagnosed in two provinces Barcelona and C^dizAge- and matched controls were selected from other pa- tients admitted to the same hospitals The occupational exposure histories of 132 mesothelioma cases were com- pared to those of 257 matched controls For occupations with at least 5 cases or a significant relative risk the numbers of cases and controls as well as rel- ative risks were reported Significantly elevated relative risks were reported for machinery fitters 3.59 machinery fitters and assemblers 4.07 electrical fitters 9.10 plumbers 7.49 and bricklayers 1.99 The authors reported 3 mesothelioma patients who had worked as vehicle mechanics compared to 14 controls Because the number of cases in vehicle mechanics was 3 less than 5 and the relative risk was not significant no risk estimate was presented in the report However based on the numbers presented by the authors the relative risk was estimated to be 0,62 95 CI 0.17- 2.25 Thus there was no increased risk of mesothelioma among vehicle mechanics in Spain The authors also stated Overall 37 of cases of mesothelioma in our population are attributed to a sure or almost sure occupational exposure to asbestos and this proportion comes up to 62 when occupations with any probability of exposure are included This observation underscores the high proportion of malignant mesothelioma cases not related to occupational exposure to asbestos ANALYSIS Based on these epidemiologic studies clearly there is no evidence to support or even to suggest an associa- tion between an increased risk of mesothelioma and ex- posure to brake linings or clutch facings among garage mechanics On the contrary the six studies reviewed above provide strong evidence that garage mechanics mesothelioma risk is similar to that in the general population None of the six studies reported any increased mesothelioma risk among auto mechanics Some of the individual studies were relatively small and the prec sion of the risk estimates might not have been as high as we would prefer as indicated by the wide 95 CIs Because of the consistency of the results the precision of the risk estimate can be improved by combining these studies through a analysis The primary purpose of the analysis was to provide a summary measure of risk with improved precision i.e. a narrower 95 CI analysis is a accepted procedure in reviewing and summarizing epidemiologic studies of individuals with similar exposures Wong and Raabe 1996 For example analysis was used by the Surgeon General's Committee 1964 in summarizing epidemiologic studies on smoking and cancer An obvious benefit of analysis is the increase in sample size and the narrow confidence interval of 01/16/02 15:30 HOBIN AND SHINGLER 14104482368 NO.287 NO.287 006 174 OTTO WONG TABLE 3 Individual Study Results and analysis of Malignant Mesothelioma among Auto Mechanica Study author and year Relative risk = 05 CT London School of Hygiene and Tropical Medicine United Kingdom McDonald and McDonald 1980 Connecticut State Health Department Teta et al 1983 U.S. National Cancer Institute Spirtas et al 1885 1994 Justus University Cormany Waitowitz and R^delsperger1994 University of British Columbia and University of Washington Teschke et al 1997 Institute of Epidemiology and Clinical Research Spain Agudo al 2000 Combined data of all six studies analysis 0.01 0.39-2.13 0.65 1.00 0.87 0.80 0.82 0.90 0.08-5.53 0.60-1.60 0.46-1.84 0.20-2,30 0.17-2.25 0.66-1.23 the summary risk estimate based on the pooled or combined data In reviewing studies for carcinogenic potential IARC 1989 commented When several epidemiological studies show little or no indication of an association between an agent and cancer the judg- ment may be made that in the aggregate they show evidence of lack of carcinogenicity Such a situation calls for the application of analysis With regard to the use of analysis in this context IARC stated In addition all studies that are judged to be methodologically sound should be consistent with a relative risk of unity for any observed level of exposure to the agent and when considered together should provide a pooled estimate of relative risk which is at or near unity and has a narrow confidence interval due to sufficient pop- ulation size The results of the six contral studies of mesothe- lioma are presented in Table 3. The relative risks reported in the six individual studies ranged from 0.62 to 1.00 The result of the analysis i.e. the summary relative risk based on all six studies is also presented in Table 3. The weights used in the analysis were Inversely proportional to the variance of the risk estimates in the individual studies Armitage and Berry 1994 In other words larger studies received more weight and vice versa According to the analysis of the combined data of all six studies consisting of approx Imately 1500 mesothelioma cases the mesothelioma relative risk for auto mechanics is 0.90 95 CI 0.66- 1.23 Thus Table 3 shows that all six studies individually or in aggregate demonstrate that auto mechanics are not at an increased risk of malignant mesothelioma when compared to the general population DISCUSSION More than three and half decades ago the criteria for assessing causation in chronic diseases such as can- cers was formulated by Hill 1965 and utilized by the Surgeon General's Committee in assessing the relationship between smoking and cancer Surgeon General's Committee 1964 as well as by IARC in the evaluation of carcinogenicity of substances IARC 1989 Hill's criteria include strength of association consistency of association specificity of association response or exposure relationship and temporality or la- tency In evaluating the causal relationship if any between exposure to asbestos fibers from brake linings and clutch facings among auto mechanics and malig nant mesothelioma Hill's criteria must be considered and applied directly to the relevant epidemiologic data With respect to strength of association the meta- analysis of the combined data from all six studies shows a summary relative risk of 0.90 meaning no increased risk Furthermore the narrow 95 CI 0.66-1.23 of the summary relative risk is indicative of the large underlying database and the precision of the summary risk estimate Furthermore the results of the individ- ual studies are remarkably consistent in that none of the studies shows an increased risk Specificity in both exposures and disease endpoints is one the most important criteria in causation assessment Wong 1993 If the subject matter is exposure to asbestos from friction products among auto mechanics we must base our evaluation on studies of auto mechan- tcs and not on other occupations For example it is not valid to apply results of studies of Insulators or shipyard workers to auto mechanics because workers in these vastly different occupations are exposed to differ- ent types of asbestos as well as to different concentration levels of asbestos In the studies reviewed above mesothelloma risk of not only all garage mechanics but also those specifically engaged in brake repairs was as- sessed Exposure relationship is yet another im- portant causation criterion Fiber measurement studies have indicated that garage mechanics are exposed to extremely low levels of asbestos as a result of the thermal transformation of asbestos fibers during the braking process The asbestos fibers in brake linings are entirely chrysotile fibers in a banded or encapsulated state During braking a temperature in excess of 700800 is reached and the chrysotile fibers break down to forsterite an anhydrous magnesium silicate which is nonfibrous Studies have shown that brake lining dust contains extremely little recognizable chrysotile fibers which are mostly embedded in the plastic bond- ing material and that the amount of free chrysotile fibers is less than 0.1 to % and most fibers are less than 0.5 ...min length Hatch 1970 Lynch 1968 Davis and Contam 1973 Williams and Muhlbaler 1982 01/16/02 15:30 HOBIN AND SHINGLER 14104482368 NO.287 = D07 MALIGNANT MESOTHELIOMA IN AUTO MECHANICS 175 TABLE 4 Weighted Average Exposures to Asbestos at Garages - Study authors and year R^/delspergeret al 1986 Kaupinnen and Korhonen 1987 1088 Cheng and O'Kelly 1986 NIOSH 1980a.b Location Germany Finland U.SU.S..A. A. Hong Pennsylvania Ohio U.S.A. Fiber concen" tration ficc 0,025 0.05 0.002 0.04 Industrial hygiene studies have demonstrated that the typical h weighted TWA exposures among auto mechanics at garages range from less than 0.002 to 0.05 fiber Table 4 R^delspergeret al 1986 Kauppinen and Korhonen 1987 Moore 1988 National Institute of Occupational Safety and Health 1980a Cheng and O'Kelly 1986 Thus the h TWA exposure to asbestos among auto mechanics is well below the safety standards mandated in most countries for example 0.1 fiber in the United States which should provide adequate protection to auto mechanics In fact according to the Committee on Hygienic Standards of the British Occupational Hygiene Society BOHS such fiber concentrations would have been categorized as negligible Levadle 1984 Given such extremely low exposures it is not surprising that none of the epidemiologic studies reported an increased mesothelioma risk among auto mechanics In Investigating occupational cancers an adequate time interval between exposure and the development of disease musbte allowed to account for the long latency of the disease Since brake linings and clutch facings have been in commercial use for decades latency is not a concern in control studies For example Woltowitz and R^delsperger1994 reported that the motor vehicle mechanics in their study began employment as mechanics between 1925 and 1972 which would have provided a more than sufficient time interval between exposure and disease development Thus the lack of an increased mesothelioma risk among auto mechan- ics cannot be attributed to an inadequate latency in the studies reviewed The application ofHill's causation criteria to epidemiologic data of mesothelioma among auto mechanics has clearly demonstrated that auto mechanics do not have an increased risk of malignant mesothelioma as a result of exposure to asbestos fibers from brake linings and clutch facinga It may be of interest to point out that there is no in- creased risk of lung cancer an asbestos cancer among auto mechanics In Its 1986 document on auto mechanics EPA cited one study in reference to lung cancer The study cited was a cohort study of workers at an amosite factory in Paterson New Jersey that supplied the U.S. Navy with asbestos insulation for pipes boilers and turbines during World War II Seidman al 1979 The authors characterized the workers exposure as in- tense work exposure to amosite asbestos This study which was based on workers with intense exposure to amosite was totally inappropriate for assessing risk in auto mechanics who are exposed to extremely low levels of chrysotile Wong 1993 reviewed cohort studies of auto mechanics in relation to lung cancer Individual cohort studies consistently indicated that there was no increased lung cancer risk the standard mortality ratios SMRs were 0.82 among bus garage mechanics in London Rushton et al 1983 Rushton 1987 1.15 among garage mechanics in Stockholm Gustavsson et al 1990 and 1.01 among auto mechanics in Denmark Hansen 1989 The summary SMR based on a analysis of all three cohort studies was 1.01 95 CI 0.80-1.26 Wong 1993 Similarly control studies reported no significantly elevated lung cancer risk ratios among auto mechanics from different loca- tions 1.06 in France Benhamou al 1988 0.9 in New Mexico Lerchen et al 1987 1.2 in Louisiana Florida Pennsylvania Virginia and New Jersey Vinels et al 1988 and 0.7 in nine metropolitan areas in the United States Detroit Chicago Philadelphia Pittsburgh New York Long Island San Francisco Birmingham and Atlanta Morabia et al 1992 Thus epidemiologic studies indicate that auto mechanics are not at an in- creased risk of lung cancer as a result of working with brakes and clutches However it should be pointed out that these studies on lung cancer in auto mechanics were published after EPA had issued its 1986 docu- ment CONCLUSION In 1986 EPA issued its guideline on the prevention of asbestos disease among auto mechanics In the guideline EPA's claim that auto mechanics were at an increased risk of developing mesothelioma was based on a few case reports published between 1965 and 1982. No epidemiologic studies were included in EPA's guideline As reviewed above three epidemiologic studies of malignant mesothelioma among auto mechanics had been published by 1986 McDonald and McDonald 1980 Teta et al 1983 Spirtas et al 1985 All three studies involved auto mechanics in the United States and none of the three studies reported an increased risk of malignant mesothelioma among auto mechanics It is not clear why EPA did not include these three studies in its guideline particularly in view of the fact that one of the studies was conducted by another federal health agency the National Cancer Institute Spirtas et al 1985 and a second one was funded by the National Cancer Institute and conducted by the Connecticut State Health Department Teta et al 1983 01/16/02 15:30 HOBIN AND SHINGLER 14104482368 NO.287 NO.287 D08 176 OTTO WONG Furthermore subsequent to the publication of EPA's 1986 guideline a second analysis of the NCI study had been published Spirtas et al 1994 and three additional new studies had appeared Woltowitz and R^delsperger1994 Teschke et al 1997 Agudo et al 2000 The Woitowitz and R^delsperger1994 paper was presented at the 1993 International Workshop on Health Associated with Chrysotile Asbestos held In Jersey Channel Island whose list of particiattendants included an official from U.S. EPA Again none of the additional new studies reported an increased risk of mesothelioma In spite of the remarkably consistent findings of no increased risk of malig- nant mesothelioma among auto mechanics from these studies EPA has not revised its 1986 guideline A recent May 2001 search of EPA's Web site reveals that the 1986 EPA guideline Gold Book is still on EPA's current list of asbestos publications available to the public Regulatory agencies such as EPA are charged with the responsibility of protecting public health It is therefore prudent for them to issue early warnings if a danger is suspected even in the absence of adequate scientific data However as discussed above this was not the case for EFA's 1986 guideline In this instance adequate scientific data were available but ignored As such EPA as a regulator has not fulfilled its responsibility of providing the most accurate and date information to the workers or the general public Occupational regulatory policies and guidelines when based on proper scientific evidence are invaluable and can prevent avoidable diseases in workers or other exposed individuals in the general public On the other hand regulatory polices and guidelines that are not based on the most complete and date scientific evidence are not only incorrect but also misleading It is the regulators responsibility to develop modify and revise policies and guidelines in accordance with the most relevant and the latest scientific evidence In particular the reluctance of regulators to revise policies and guidelines when new scientific data become available is Inexplicable REFERENCES Agudo A. Gonz^lezC. A. Bleda M. .. Ramirez J. Hern^ndez S L^pezF. Calleja A. Panad^sR Turnguet D Escolar A. Beltr^nM. and Gonz^lezE. 2000 Occupation and risk of malignant pleural mesothelloma A control study in Spain Am J. Ind Med 37 159 168 Armitage P. and Berry G. 1084 Statistical Methods in Medical Research third ed Blackwell Oxford Bonhamou S. Benhamou E. and Flamant R. 1988 Occupational risk factors of lung cancer in a French control study Br J. Ind Med 45. 231-233 Cheng V. K. I. and O'Kelly F. J. 1980 Asbestos exposure in the motor vehicle repair and servicing industry in Hong Kong J. Soc Occup Med 30 104 108 Davis J. M. and Coniam S. W. 1973 Experimental studies on the effects of heated chrysotile asbestos and automobile brake lining dust injected into the body cavities of mice Exp Mol Pathol 19 339 353 Environmental Protection Agency 1986 Guidance for PreventIng Asbestos Disease among Auto Mechanics EPA Washington DC Gustavsson P. Plato N. Lidstrom E. B. and Hogstedt C. 1990 Lung cancer and oxposure to diesel exhaust among bus garage workers Scand J. Work Environ Health 16 348 354 Hansen E. S. 1989 Mortality of auto mechanics a year follow- up Scand J. Work Environ Health 15 43 46 Hatch D. 1970 Possible alternatives to asbestos as a fraction materta Ann Occup Hyg 13 25 29 HUI A. B. 1965 The environment and disease Association or causation Proc R. Soc Med 58 205-300 International Agency for Research on Cancer 1989 ARC Monographs on the Evaluation of Carcinogenic Risks to Humans Decupational Exposures in Petroleum Refining Crude Oil and Major Petroleum Fuels Vol 45. World Health Organization Lyon France Kauppinen T. and Korhonen K. 1987 Exposure to asbestos during brake maintenance of automobile vehicles by different methods Am Ind Hyg Assoc J. 48 499 504 Lerchen M. L. Wiggins C. L. and Samet J. L. 1987 Lung cancor and occupation in New Mexico J. Natl Cancer Inst 79 839-645 Levadle B. 1884 Definitions for Asbestos and Other Related Silicates ASTM Special Technical Publication 834. American Soclety for Testing and Materials Philadelphia Lynch J. R. 1968 Brake lining decomposition products J. Air PolJut Cont Assoc 18,824 82618,824 826 McDonald A. D. and McDonald J. C. 1980 Malignant mesothe loma in North American Cancer 46 1650-1656 McDonald A. D. 1986 Letters to Otto Wong dated May 27 and June 4 1986 Moore L. L. 1988 Asbestos exposure associated with automotive brake repair in Pennsylvania Am Ind Hyg Assoc J. 48 A13 Morabia A. Markowitz S. Garibaldi K. and Wynder E. L. 1992 Lung cancer and occupation Results of a multicenter control study Br J. Ind Med 49 721 727 National Institute for Occupational Safety and Health 1980a Industrial Hygiene Report Asbestos at Allied Brake Shop Cincin- nati Ohio National Technical Information Service PB81-241879 NIOSH Washington DC National Institute for Occupational Safety and Health 1980b Industrial Hygiene Report Asbestos at Reading Brake and Alignment Service Reading Ohio National Technical Information Service PB81-24519 NIOSH Washington DC Nurminen M. 1975 The epidemiologic relationship between pleu- ral mesothelioma and asbestos exposure Scand J. Work Environ Health 1 128-137 Pelnar V. 1988 Further evidence of nonasbestos mesothelioma a review of the literature Scand J. Work Environ Health 14 141 144 Peterson J. T. Greenberg S D. and Buffler P. A. 1984 Nanasbestos malignant mesothelioma Cancer 54 951 900 R^delspergerK. Jahn H Br^...ckelB. Manke J. Peur R. and Woitowitz H. J. 1986 Asbestos dust exposure during brake re- pair Am J. Ind Med 10 63 72 Rushton L. Alderson M. R. and Nagarajah C. R. 1983 Epidemi- London Transport ologic survey of maintenance workers in Exccu- tive bus garagos and Chiswick Works Br J. Ind Med 40 340 345 Rushton L. 1987 Letter to Otto Wong dated November 17 1987 01/16/02 15:30 HOBIN AND SHINGLER 14104482368 NO.287 NO.287 Q09 MALIGNANT MESOTHELIOMA IN AUTO MECHANICS 177 Seidman H. Selikoff I. J. and Hammond C. 1979 Short asbostos work exposure and term observation Ann N. Y. Acad S330 S330 61-90 Spirtas R. Keehn R. Wright W. Stark A. Beebe G. and Dickson E. 1986 Mesothelioma risk related to occupational and other asbestos exposure Proliminary results from control study Am J. Epidemol 122 518 Spirtas R. Heineman E. F. Bersteln L. Beebe G. W. Keehn R. J. Stark A. Harlow B. and Benichou J. 1004 Malignant mesothelloma Attributable risk of asbestos exposure Occup Enviran Med 51,804 81151,804 811 Surgeon General's Committee 1064 Smokani d Hn ealg th U.S. Pub- Wz Health Services Washington DC Teschke K. Morgan M. S. Checkaway H. Pranklin G. SpinalII J. J. van Belle G. and Welss N. S. 1997 Mesothelioma surveillance surveillance to locate sources of exposure to asbestos Can 1. Pub Health 88 163-168 Teta M. J. Lewinsohn H. C. Melgs J. W. Viadone R A. Mowad L. 2. and Flannery J. T. 1983 Mesothelioma In Connecticut 1955 1977 Occupational and geographic association J. Occup Med 25 749-756 Vineis P. Thomas T Hayes R. B Blot W. J. Mason T. J. Pickle L. W. Corren P. Fantham E. T. H. and Schoenberg J. 1988 Proportion of lung cancers in males due to occupation in different areas of the USA Int J. Cancer 42 851 856 Williams R. L. and Muhlbaler J. L. 1882 Asbestos brake emissions Environ Res 20 70 82 Wollowitz H. J. and R^delspergerK. 1991 Chrysotile asbestos and mesothelloma Am J. Ind Med 18 551 553 Woitowitz H. J. and R^delspergerK. 1994 Mesothelioma among car mechanics Ann Occup Hyg 38 635 638 Wong O. 1982 Chrysotile asbestos mosothelloma and garage me- chardcs Am J. Ind Med 21 440 451 Wang O. 1999 Consideration of specificity in assessitnhge relation- ship between asbestos and cancer Am J. Ind Med 29 521 523 Wong O. and Raabe G. K. 1996 The application of analysis in reviewing occupational cohort studies Occup Environ Med 53 793-800