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FILE NAME Brakes BRK DATE 2005 DOC BRK146 DOCUMENT DESCRIPTION Journal Article - Abuse of Epidemiology Automobile Manufacturers Manufacture a Defense to Asbestos Liability Abuse of Epidemiology Automobile Manufacturers Manufacture a Defense to Asbestos Liability DAVID S. EGILMAN MD MPH MARION A. BILLINGS MSC Much of the debate about the relationship between from automobile brake work and asbestos exposure has been fueled by studies induced cancer that have been funded by corporations with billions at stake in tort litigation The authors explore how asbestos brake manufacturers have corrupted medical literature to escape liability analyzing studies funded by these companies to enable them to claim that work with asbestos brake linings never causes mesothelioma They reveal how the companies have redefined scientific criteria for the determination of manipulated effect relationships and scientific of an absence of effect data to give the impression of the But the absence of evidence is not evidence absence of an effect Key words mesothelioma health brake occupational asbestos corruption mechanics INT J OCCUP ENVIRON HEALTH 360-371 thousands of automobile and n recent years shade amateur mechanics have sought for asbestos disease from compensation the fact manufacturers of asbestos brakes Despite that these brakes are 40-70 asbestos the brake man- ufacturers have vigorously denied that they contributed of asbestos disease in any way to a single case The brake manufacturers have dismissed the fact that there is no known threshold of exposure associated with mesothelioma a rare cancer of the pleura or peri- peri- toneum and that in some cases the only documented are those that have occurred as a worker exposures brakes. Rather result of exposures to asbestos from the established scientific facts the than accept industry has funded scientists and lawyers to develop and methods for defending against lawsuits abrrgouugmhetntbsy workers and their household members who have developed mesothelioma as a result of exposure to asbestos in brakes To support their arguments the automobile manufacturers have hired consultants Received from the Department of Community Health Brown University Providence Rhode Island Address correspondence and reprint requests to David Egilman MD 8 North Mam Street Suite 404 Attleboro MA 02703 U.S.A degilman@egilman.com telephone 508 226-5091 mail degilman@egilman.com to reanalyze previously published hygiene and epi- demiologic studies Some manufacturers of asbestos brakes- epidemiologist including GM Ford Chrysler and Bendix- four notable examples of such have sponsored research since the late 1990s In 2001 Otto Wong an working for a California health fired the first salvo of their sciences company is couched as a cri- defense Although Wong's paper to asbestos tique of regulation of exposures brakes and EPA risk assessments Bendix an automo- bile brake manufacturer first presented it as an to defend against a laws by a worker expert report and who had been exposed to asbestos brake linings had contracted mesothelioma Three years later other of asbestos brakes GM Ford manufacturers Goodman et al to write a and Chrysler sponsored second related lung cancer analysis com- bined with a duplication of Wong's mesothelioma analysis The automobile companies then sponsored Hessel et al to write a third paper which was an extenof the NIH that had already sion of a paper by Spirtas been included in Goodman et al and Wong's metaanalysis Finally the industry subsidized an incom- to asbestos in plete analysis of historical exposures specific brake work. These companies have spent millions of dollars to these epidemiologic studies in order to greefnuetreatcelaims of causation and thereby avoid com- to victims and their families pensation payments the use of Accordingly all four papers demonstrate associated with the industry's involve- two practices research the redefinition of scien- ment in scientific tific criteria for the determination of cause of scientific data relationships and the manipulation In this paper we critique these methods drawing from the first three of the four papers cited examples of above The first section delmeates the process redefinition of scientific criteria for determination of causation followed by a more depth discussion of methods of scientific manipulation utilized in the studies by As a whole we Goodman et analyze the al Wong and Hessel value of this type of research in regard to its claims about the relationship to asbestos during brake work and between exposures induction of mesothelioma 360 REDEFINITION OF SCIENTIFIC CRITERIA FOR DETERMINATION OF CAUSE RELATIONSHIPS This method first developed by the tobacco industry parts involves two First industry lawyers and scientists redefine the type and amount of proof required to establish causation This is done by derogating legally that are unfavorable to unfavorable classes of evidence industries litigation and regulatory positions and insist- that evidence that does not exist or is favorable to ing essential to establish a industry is most important or effect relationship in court For example when suspect carcinogen carcinogen is found to cause cancer in human epidemiologic studies but not in animals companies that animal studies are required to prove causa- argue tion On the other hand when animal studies are posi- tive and human epidemiology is incomplete or nega- that human evidence is required tive companies argue before the government can regulate the substance and before workers and others can be compensated epidemiologic For example tobacco companies argue that human studies cannot establish causation but eipnsitdeeamdioolnolgyiecstablish some definitive association to tobacco smoke and cancer They between exposure studies cannot distin- have argued that link between the propensity to smoke guish a genetic of and the propensity to contract cancer This critique human epidemiologic studies is true but irrelevant since there is no biologic basis for such speculation On the other hand when early researchers failed to induce cancer in animals that were exposed to tobacco smoke tobacco companies insisted that only animal inhalation studies could prove causation After the famous beagle studies these companies emphasized the importance of mechanistic understanding as a causal require- ment They then argued that unless one could explain exactly how tobacco smoke caused cancer they had no scientific proof of causation.10 Some chemical manu- facturers have made comparable epistemological argu- ments when studies of their products have followed a similar fact pattern In the early 1970s for example when researchers failed to induce cancer in animals fol- lowing benzene exposure industry expert witnesses stated that these missing animal data were required to 12 establish that a substance was a human carcinogen The second element of this method is industry's insistence on direct causal evidence related to specific forms of exposure in individual cohorts of workers Human epidemiology is often lacking for most chemi- cancer effects Most chemical companies exposure animal or other therefore argue that these missing studies or human studies in which the exposed work- ers are exposed to the substance in question only a vir- tual impossibility are required to establish proof of a effect relationship In the latter case industry that animal and in vitro studies are rendered argues invalid as evidence of causation Since cancer effects have long latent periods and workers are generally sub- these studies ject to potential confounding exposures are rare and easily criticized When clear epidemio- logic evidence of causation exists as is the case of the relationship between asbestos and mesothelioma com- panies and their experts have argued that before an worker can even file a claim for compensation injured individ- two epidemiologic studies in similarly exposed uals that find a statistically significant doubling of the risk must be published in reviewed journals.13 Some Texas courts have accepted this argument and even appear to require the publication of human epidemiologic studies for subgroups of particular particular indus- rate ratios above two tries with statistically significant before a worker can even file a lawsuit.14 Greenland calls the use of this criteria a methodologic error that has become a social problem can be conThese stringent legal requirements trasted with the normal physician practice of assigning causation based on an analysis of all available evidence rate ratio or statistical requirements requirements with no specific In general practicing physicians attribute lung cancer causation to tobacco smoking if there is evidence of a regardless of brand history of smoking any cigarettes regardless for often unspecified time frames prior to disease diagnosis Practicing physicians would not check to see whether a published pee1-1 eviewed paper showed that smoking ten cigarettes per day caused a statistically sig- nificant doubling of the risk of contract ng lung cancer prior to making the determination that a patient's had caused or contributed to his or her smoking that all brands cancer Physicians also take for granted smoked contributed to disease causation even in the absence of studies evaluating individual brands The asbestos manufacturers and theu have constructed constructed an epistemological epistemological straw man experts evidence of causation is asserting that epidemiologic required in each and every worker cohort that has a to a harmful substance documented excess exposure before evidence of causation can be presented in court Companies argue that to prove causation both the type of asbestos and the nature of exposure same job not just comparable exposure must be clearly documented in an epidemiologic study as having a causal effect on the development of cancer Even the tobacco compa- nies have not gone so far as to argue that an expert cannot assert that Virginia Slims cause a specific lung cancer subtype e.g. bronchogenic cancer in women absent an epidemiologic study of smokers of that particular cigarette showing a statist cally significant twofold increased risk in that particular cohort of female smokers for that particular subtype of lung cancer Yet the asbestos companies and then experts cohort studies are needed to estabargue that separate lish causation for the same disease for each fiber type and each product composed of that fiber despite the VOL NO 4 DEC 2005 www.ijoeh.com Abuse of Epidemiology 361 fact that almost all workers are exposed to more than one fiber type from more that one product As a result companies and their experts attempt to show that exposures to asbestos from their product are somehow different or even irrelevant Manufacturers argue that exposures to asbestos from their products are quantitatively or qualitatively unlike other asbestos expo- sures For example asbestos in their products is bound or degraded or decomposed or results in too low an exposure to cause mesothelioma.13 Unfortu- nately some courts have adopted aspects of this reason- ing.17 In the case of chrysotile asbestos only fiber type that industry still claims does not cause mesothelioma argument that the particular particular type of asbestos in a company's product is different from other types is now generally recognized as the amphibole hypothe- 18-23 sis It is important to note that product manufac- turers who used amosite fiber made similar arguments by claiming that there was insufficient epidemiologic evidence to establish that amosite caused mesothelioma.24 MANIPULATION OF SCIENTIFIC DATAANALYSIS AND EXPOSURE DATA MISREPRESENTATION Manipulation of scientific data and misuse or reinterpretation of standard scientific reasoning is ubiquitous in the automobile sponsored asbestos studies The most common are selection of inappropriate studies for analysis selective presentation of study data differential determination bias inadequate sample size comparison of an exposed cohort with an inappropriate control group and misuse of confidence intervals Here we present these strategies illustrated with specific examples from the Bendix Ford General Motors and Daimler- Chrysler studies levels hundreds of times higher than current exposure permissible limits Wong cites some data from a 1987 Finnish study by Kauppinen and Korhonen by listing fiber concentrations as 0.05 fibers cc.2cc.626 This average study also found however that the grinding of brake linings produced asbestos concentrations as high as 125 fibers Kauppinen and Korhonen reported expo- sures up to 8.2 cmduring the cleaning of passenger- car drum brakes using a compressed aijret to remove brake dust Unfortunately this is still a common prac- tice in many nations including the United States Averconcentrations were between 0.1 and 0.2 cmfor age truck and bus repair The only data point Wong chose to report from this study represented average average exposures during passenger repair Contrary to Wong's mus leading data selection and analysis this study demon- strated that average asbestos concentrations in Finland may comply with TWA limits but also showed that peak often exceeded the OSHA excursion limit.26 exposures Wong also selectively excerpts information from a paper by Agudo et al whom he quotes stating Overall 37 of cases of mesothelioma in our population are attributed to a sure or almost sure occupational to asbestos and this proportion comes up to exposure 62 when occupations with any probability of expo- sure are included In turn Wong concludes that this observation underscores the high proportion of malig- nant mesothelioma cases not related 10 occupational exposure Wong makes this assertion but omits Agudo et al.'s subsequent qualifying sentence which states Around 40 of cases of mesothelioma in our could be due to causes other than occupa- population of tional exposure to asbestos although possibility in traditionally haz- other occupational exposures ardous scenarios cannot be ruled out Manipulation of Meta analysis Inappropriate Study Selection and Selective Presentation of Data Selective Presentation ofExposure Data In his article Wong outlines the lack of exposure argument as described in the previous section In doing so however he fails to report studies indicating that work with asbestos brake linings leads to exposures that have resulted in asbestos cancers in other occupa- tional and occupational settings.25 Wong not only studies whose results contradict his ignores exposure industry position he also misrepresents the results of the studies he does report He states that studies have shown that brake lining dust contains little recognizable chrysotile fibers and extrapolates from a few studies to claim that current exposures are extremely low It is true that only some studies have examined decomposed used brakes the heaviest exposure to asbestos occurs during the sanding and grinding of new brakes Of course current exposures do not reflect past exposures or risk Studies of workers previous job activities reveal Industry researchers can often influence influence results by careful selection of the epidemiologic studies they decide to evaluate Studies favored by the industry perspective those with negative results in regard to the relationship between exposure and cancers are included and others are ignored or derogated and then excluded Goodman et al and Wong reanalyzed a series of epidemiologic studies claiming that they failed to find an association between brake work and an increased incidence of mesothelioma.56 Both howevTI disregard numerous methodologic problems in the individual studies they chose to incorporate in their analyses and ignore study limitations noted by the orig- inal authors Furthermore these authors selectively omit key information that undermines their conclu- sions and evidence Goodman et al first attempt to evaluate the quality of 11 studies with potentially relevant information 362 Egilman Billings www.ijoeh.com www.ijoeh.com INT J OCCUP ENVIRON HEALTH about the relationship between brake work and mesothelioma The authors use a created point scale to evaluate the studies the rating system allowed for negative scores The highest ranked study of two purported studies based on personal communications by Goodman and Hessel themselves a 5 out of 9. The scores for the rest of the studies included in the analysis are unimpressive 3 4 1 1 1 and 2 out of 9. Goodman et al excluded studies that scored minus 1 the rating system allowed for negative scores but none of the included studies achieved a passing grade of 60 based on normal academic standards Goodman et al seem to believe that evaluating the studies in such a way somehow mitigates their underlying methodologic errors and inadequacies Unfortunately revealing errors is not the same as fixing them and these studies which were never designed to assess mesothelioma risk to exposed workers are beyond repair After this elaborate quality evaluation Goodman et al performed a analysis using the same studies that Wong had reviewed three years before They excluded two cohorts The first of these was a study of 685 automobile mechanics that reported two mesothe- liomas The second found a statistically significant excess of mesothelioma in mechanics with a reported rate ratio.2 Furthermore Goodman and his colleagues present the data entirely out of context The original authors of the underlying studies did not design them to examine the specific issue of exposure to asbestos during brake work and subsequent incidence of mesothelioma The extraction therefore of occasional study participants who happen to be automobile mechanics not only lacks statistical power but cannot be independently used as concrete evidence proving the absence of a relation- ship between a complicated exposure and a potential outcome Due to the inherent difficulty in determining asbestos exposure especially in the case of brake work due to the large number of amateur brake jobs and time brake work that can easily go unnoticed when determining exposure cohort studies must be specifi- cally designed to address the issue of mesothelioma among those exposed to brake dust Until such studies are conducted it is wrong to conclude that epidemio- logic studies fail to establish a relationship between brake work and asbestos cancer The converse however is not true To paraphrase Karl Popper finding a thousand white swans does not prove that all swans are white the discovery of a single black swan dis- hypothesis proves that This is particularly true when a researcher is relying on studies of all bird species all SIC codes to determine the color of swans risk in brake workers As Lemen has shown there are plenty of black swans in the context of asbestos cancer he has documented more than 220 published cases of mesothelioma in users of friction products.25 The automobile manufacturers have spent millions of dollars to reanalyze studies that were never designed to determine mesothelioma risk in brake mechanics On the other hand they have access to a cohort of their own and their dealers workers whose work involves the installation and repair of brakes They are perfectly situated to use other demographically similar employ- ees who work at these same facilities as a control popu- lation In many cases they have access to medical and workers compensation records records that would allow them to efficiently conduct such a study Why haven't they done so Wong and Goodman et al both exclude evidence from other epidemiologic studies that contradict their conclusions Hansen for example examined the mor- tality of automobile mechanics and found an excess mortality from mesothelioma.32 The study reported a single case of mesothelioma over a year period among approximately 20,000 automobile mechanics yet because of the rarity of the disease the authors concluded that asbestos exposure is known to occur during the replacement of brake linings and the single case of pleural mesothelioma is an indication that this exposure has not been negligible Differential Exposure determination Bias In his analysis Wong relied primarily on casecontrol studies that were fraught with problems of dif ferential exposure determination bias Asbestos expo- sure is difficult to determine since many individuals are unaware of their exposures especially in secondary cases in which an individual might inhale asbestos fibers from the clothing of a spouse or parent returning home from asbestos work In the case of brake work many individuals engage in time or amateur mechanic work yet otherwise otherwise engage in other careers and may therefore be classified as unexposed if determination is based on a classical epidemiologic determination of regular occupation Of course the direction of any potential or actual bias is a key issue in analyzing its potential effect on the results of a study Random exposure misclassification biases results towards the null However as we discuss below in this case because exposure is more often missed in the exposed cohort the misclassification is likely to lead to an inverse relationship between exposure and disease In the case of mesothelioma in which the time between diagnosis and death is usually a matter of months retrospective study designs such such as con- Or perhaps their lawyers have already conducted such a stuchy and kept it secret As has been noted in tobacco litigation company lawyers often contract with experts to conduct studies If the stuches stuches are unfavorable the company does not have to produce these in liu- The brake manufacturers lawyers have funded and actually gation 31 helped conduct some studies related to brake exposures VOL NO 4 OCT 2005 www.ijoeh.com www.ijoeh.com Abuse of Epidemiology 363 trol studies often require the interviewing of surrogates spouse children etc to determine exposure Direct interviews of cases or controls are far more likely to uncover prior brake exposure than are interviews with surrogates Individuals who did not work primarily as automobile mechanics are likely to be misclassified as unexposed if surrogate interviewees are unaware of any time or amateur brake work done earlier in life Since mesothelioma cases are more likely to be deceased at the time of interview than controls a dif- determination ferential bias may show that the exposed have less risk than the unexposed Next- kin interviews are particularly subject to this result since brake exposures often occur among shade tree occasional or even high school mechanics in automo- bile repair courses These exposures are more likely to be reported by patients themselves than by relatives particularly children of patients In many of the studies the researchers determined exposure from direct inter- view of controls in comparison with greater reliance on interviews with survivors of mesothelioma patients Next interviews were therefore used more often to estimate exposure in mesothelioma patients than in controls Since direct interviews are more likely to elicit a history of exposure to brakes than next inter- views brake exposures are systematically more likely to be recorded for controls than cases Goodman et al acknowledge the problem of next interview bias but omit any discussion of the fact that the consequence of this bias is a result showing that brake work protects against mesothelioma This phenomenon is demonstrated by the fact that most of the studies Wong and Goodman et al selected had rate ratios ofless than one Wong's overall point estimate was 0.90 95 confidence interval 0.66-1.23 while Goodman et al determined that exposure to brake dust produced a statistically sig- nificant and important reduction in the rate of mesothelioma of 0.67 95 confidence interval 0.53-0.84 in all studies combined The finding that brake work reduces the risk of mesothelioma is a sign of systematic error in this analysis because exposur to asbestos brakes cannot reduce the risk of developing mesothelioma by 33 That is however what these selected analyzed data showed Other Bras Issues The study conducted by Agudo and others published in 2000 demonstrates how differential differential exposure determination can bias results when exposure histories of cases who are dead or too sick to be interviewed directly are more likely to be determined by surrogate interviews than are exposure histories for controls.33 | They found combined RRs of 0.92 95 CI 55 1.5565 studies and 0.81 95 CI 0.52-1 28 Tier II studies 1.56^finTier I Forty percent of cases were deceased at the time of the study and thus researchers determined their exposures through member interviews Among the control group however the researchers directly inter- viewed all but one participant Cases therefore may have been less likely to be classified as exposed which would bias the resulting risk ratios to be less than one In addition the researchers considered only occupa- tions that had been held for at least six consecutive months meaning that workers with exposures from time or amateur brake jobs were omitted This random misclassification biased the results of the study towards the null The authors also assumed assumed without ques- tion that brake work puts an individual at risk for asbestos exposure by placing brake mechanics in the risk of exposure category in their analysis The rate ratio for this entire category of exposed work- ers was elevated at 2.59 but the analysis of a small number of individuals within the category of risk occupations i.e. the brake mechanics cannot lead to any sound conclusions The study published in 1994 by Spirtas and others exposure provides additional evidence that determma- tion bias is a real threat to study validity.34 In the study younger cases had a higher attributable risk for mesothelioma from asbestos exposure than did older cases This is likely to have resulted from more accurate individuals who exposure assessment among younger were better able to remember more recent exposure events Spirtas et al did not include independent analyses of the members of the cohort who reported brake lining work or repair 105 of711 because of the lugh rate of multiple asbestos exposures m this group.31 Unlike the authors of the original study Wong fails to note these brake exposures or the original authors exclusion of these workers and relies on these rejected data in his analysis The automobile manufacturers paid Hessel et al to update the Spirtas cohort and reanalyze its brake- worker data in 2004. The results of the analysis pre- sented by Hessel and colleagues reveal the methodologic problems with the use of the NIII data set First the analysis of Hessel et al indicated that occupa- tional brake work prevented workers from developing mesothelioma regression beta was -0.184 In addition their analysis found that higher levels of exposure to asbestos among workers performing occupational brake work were more protective regression beta was -0.307 In other words these authors found a dose- response relationship between exposure to asbestos- lined brakes and reduced risk of mesothelioma Of course brake work cannot reduce workers risk for con- tacting mesothelioma and it certainly can't do this in a -dependent manner The unbelievable dose-response relationship is further evidence that the study suffered from systematic error Hessel and his colleagues also examined six other job categories of 364 Egilman Billings www.ijoeh.com INT J OCCUP ENVIRON HEALTH asbestos workers all of whom have been found to have developed induced mesothelioma or other asbestos disease in other studies includ- ing workers exposed to asbestos insulation in furnace or boiler installation or repair building demoli- tion plumbing or heating repair elevator instal- lation or repair production of asbestos textiles and previ- production of paper products In contrast to ous cohort studies Hessel et al found no increased risk of mesothelioma in workers performing these jobs They found elevated odds ratios for shipbuilding and repair work OR 6.04 CI 3.74-9.75 and insulation work OR 3.38 CI 2.20-5.17 While elevated these odds ratios are orders of magnitude lower than those found in cohort studies of these same two groups For example Selikoff found that about 10 of insulators died from mesothelioma giving an approximate rate ratio of 1,000 Thus unless one is willing to believe that brake work protects against mesothelioma and that previous cohort studies of other job categories are wrong Hessel et al have provided results indicating that their method biases results to the null and reverses actual effects of exposure turning harmful exposures into beneficial ones Teschke et al used an classification scheme that may also have biased results towards the null The authors stated In addition grouping of occupations was likely to result in differential misclassification usually biasing risk estimates to the null value Wong omitted this critical fact The study is also another example of differential determindeaterm-ina- tion bias authors determined exposure histories for 13.6 of controls histories of exposure were obtained through next interviews compared with 33 of cases The study also had a higher participation rate among controls which could lead to selection bias and interviewers were not blinded to the control status of the interviewee possibly leading to interviewer bias The Woitowitz and Rodelsperger study focused solely on the issue of a relationship between automobile mechanic work and mesothelioma Part of this study is of no value in determining the relationship between any asbestos exposure and mesothelioma because the authors used lung cancer patients as con- trols Exposure status is likely to be similar among the control group and the cases which would lead to little discernable difference in risk between the two groups despite any real association that may exist between brake work and mesothelioma Since asbestos exposure is known risk factor for lung cancer any mesothe- lioma control study with lung cancer patients as the control group will almost certainly produce results at or below the null This study demonstrates this effect well since the researchers used population controls controls as well as lung cancer patients as controls The odds ratio OR for hospital controls was 0.75 almost half that for population controls 1.32 Rather than report both results Wong presented an average OR of 0.87 Goodman et al published both ORs but included only the lower average in their analysis.56 McDonald and McDonald conducted a control study published in 1980 examining mesothelioma cases from Canada and the United States Like the Woitowitz and Rodelsperger study this study relied on an inappropriate control group control subjects were patients in cases diagnosed by pathologists in which pulmonary metastases were present from a pulmonary malignant tumor 19 For example the control group may have included patients who had died from mesothelioma or other induced malig- nancies such as laryngeal or colon cancer.50.51 The choice of such controls biased results towards towards the null In addition the study eviewed occupational status only ten years prior to death Since mesothelioma has a minimum latency period of about ten years this study did not necessarily address any subject's most relevant exposures McDonald et al subsequently compared fiber burdens between control and mesothelioma patients and found no statistically significant difference between the amounts of chrysotile amosite or crocido- lite52 This is further evidence that controls were not adequately chosen since they were clearly exposed to as much asbestos as the 99 mesothelioma patients This misclassification biases the results to the null Both Wong and Goodman et ignore other studies that reveal mesothelioma risk to manufacturing workers Since these authors base their argument for lack of risk on fiber length and the general issue of whether or not chrysotile can ever cause mesothelioma they are clearly relevant And while they are also compromised by numerous methodologic and other problems they do show increased rates of mesothelioma in brake manufacturing workers 53,54 Dodson has critiqued the short fiber argument elsewhere.55 The risk to manufacturing workers is relevant to the question of risk to repair workers since the fiber used in the manufacture of brakes is the same length as that in new brakes If there is relevar ce to the short- fiber argument at all it relates to exposures from used brakes Brake workers are exposed to fibers from both new and used brakes from tooling parts as well as blow of brake dust In 1982 McDonald and Fry published results of a study of a Connecticut chrysotile asbestos manufacturing factory and concluded that The failure to find a single mesothelioma among 1469 deaths in 4738 employees of the largest and oldest asbestos factory in the state suggests that chrysotile in the manufacture of friction products was not responsible for the problem In a study of three plants mcluding the Connecticut plant McDonald et al reported only 0.1 cases of mesothelioma per 1,000 individuals in chrysotile asbestos factories over the course of approx- VOL NO 4 OCT 2005 www.ijoeh.com Abuse of Epidemiology * 365 imately 40 years 100,000 or 10 per million per year They then asserted that This finding supports much other evidence that amphibole are mainly responsible for mesothelioma whereas chrysotile has little or no mesothelioma potential The authors present this evidence however without discussing the expected population rate for comparison Teta et al report an expected rate of 2.2 cases per million each year for the total population and 4 per million for Connecticut.56 Comparisons with expected population rates are also problematic since at least half of all mesothelioma cases are caused by occupational expo- sures to asbestos The unexposed expected rate is no higher than 1 per million.57 For a true comparison to be drawn it would have to be with only those cases that were not occupational since the risk of mesothelioma among automobile mechanics should not be compared with the risk of workers in other occupations known to cause the disease but with those who were not occupa- tionally exposed The rate reported by McDonald et al is therefore at least more than double the expected rate McDonald's data thus support the claim that chrysotile asbestos causes mesothelioma The McDonalds research suffered from other more serious problems In 1983 Teta et al described findings from the state of Connecticut cancer registry and reported three mesothelioma deaths in the same Connecticut factory and during the same time frame used in the McDonald study One year after the publica- tion of Teta's paper in 1984 McDonald et al published their final report on the plant This final report however did not report the full data from the original cohort which included both men and women but reported data from the male portion of the cohort only Two missed cases occurred in women who were members of McDonald's cohort McDonald et al reported that they had found not a single case of mesothelioma in this plant and failed to mention the cases Teta cited from the state of Connecticut registry.5 In their 1982 paper McDonald and Fry claimed their data were reliable in large part due to the existence of the very same registry They stated The opportunity for recognition of mesotheliomas was also very good at the chrysotile friction materials plant as the state of Connecticut has maintained a renowned cancer regis- ter Clearly this would hold true only if the authors had checked the registry prior to the publication of their paper unfortunately it appears that they had not done 59,60 Teta et al claim they informed them of the discrepancy and in 1986 McDonald tried to explain the omission away.59 McDonald stated that she and her col- leagues omitted the cases because mesothelioma had not been indicated on two of the deceaseds death cei- tificates the primary measure of outcome in their study and that they excluded the third case because he had terminated work prior to the beginning date of their study However in 1986 by the time McDonald had commented on these discrepancies at least two other cases of mesothelioma in the plant had been reported on death certificates see Table , cases 1 and 2 Both fit the initial cohort definition and the first left employment before there was any alleged amphibole use These cases occurred after the termination termination date of the McDonald study We are now aware of at least six additional mesothelioma cases in workers from the plant four of whom had no other possible exposures to asbestos Table ) At least four of these cases are known to the main sponsors of the McDonalds research since members of the Quebec Asbestos Mining Association QAMA were sued by three of them Therefore there were a total of at least nine mesotheliomas in this factory which used chrysotile until 1957 only Perhaps by unfortunate coincidence all of these cases occurred before or after the begin- ning and ending dates of the McDonalds studies or the diagnoses were not reported on the death certificates Death certificates in general are often inadequate means of determining a mesothelioma diagnosis due to the strong possibility of other related conditions becoming the primary causes of death e.g. cardiac arrest and because mesothelioma is frequently misci- specific agnosed Mesothelioma was not added as code until 1968.61 The study was conducted ICD in the 1970s mostly examining data from prior decades in which mesothelioma was a known disease that was frequently not accurately diagnosed In addition the Connecticut registry was an excellent source of data for a comparison of expected and plant rates To make the data compatible the registry should have been used to determine the mesothelioma rates for the plant work- ers Had they done so McDonald et al would not have missed the two mesothelioma cases that occurred during their selected observation period Of course the most important result of the exposure to chrysotile at this plant is the death of nine workers from mesothe lioma in a population of about 4,500 workers Although the McDonalds et al stressed the importance of this cohort in asserting that chrysotile did not cause mesothelioma these nine cases provide additional evi- dence that chrysotile causes mesothelioma Despite the fact that Teta is a author of one of the manufacturer papers and works for the company that generated three of these papers the manufacturer researchers failed to use of these studies or data to assess the hazard of expoany sure to chrysotile brakes Other industry researchers have also failed to use this information in assessing chrysotile risks Recently Crimp and Berman completed a risk assessment for asbestos for the EPA To some extent this was an update of a previous assess- Some anthophyllite was used beginning in 1957 and about 100 pound of crocidolite were used experimentally in the laboratory from 1964 to 1972.5 366 Egilman Billings www.ijoeh.com www.ijoeh.com INT J OCCUP ENVIRON HEALTH TABLE Mesothelioma Case in a Chrysotile Brake Manufacturing Plant Case 1 Date of Birth 5/20/1908 Date of Diagnosis 5/21/1980 Raymark Job Work Dates Description 1926-1937 Office worker Shipping clerk Other Exposures None no known home repair friction or additional occupational exposures Case 7/7/1914 9/3/1985 =: 1940-1985 = Unknown Unknown Death Certificate Autopsy Left lobar pneumonia mesothelioma Malignant mesothelioma Case 3 4/21/1930 3/24/1994 1983-1984 Unknown Was also exposed to asbestos in the Navy and had other occupational exposures including EB American Linen Supply Upjohn and U.S. Rubber Respiratory failure mesothelioma Case 4 9/15/1918 9/16/1996 1937-1962 1970-1968 Plant worker None worked in security and sales for other occupations no known home repair or friction exposure Respiratory failure mesothelioma Case 5 10/12/1991 5/24/1999 1940-1941 Carding spinning room laborer None truck driver and woodworker for other occupations Mesothelioma Case 6 9/23/1930 3/14/2000 1965-1985 Machine operator None no known home repair friction or additional occupational exposures Lung cancer Autopsy report mesothelioma Based on Lewinsohn's Connecticut expected rate of 4 mesothelioma cases per million the expected number of cases is 14 observed number is 9 therefore the RR is 6.4 and p < 0.05 ment they had done for the Asbestos Information Association an asbestos industry industry lobby and public relations front in 1984. Berman and Crump ignored the published mesothelioma cases from the friction plant that McDonald had acknowledged in 1986 and based their response analysis on the assumption that there were no cases in that plant Perhaps the most interesting of the changes between the 1986 KL value estimates and the cur- rent KL value estimates involves the friction products plant in Connecticut McDonald et al 1984 Although a relatively small positive exposureresponse was estimated from this study in the 1986 Health Effects Update the best current estimate is that this is essentially a negative study no excess risk attributable to asbestos .68 Teta served as an official reviewer of Berman and Crump's paper and although the omitted cases were noted in 1983 along with the need for further follow on this cohort Teta recommended that the EPA adopt the Berman model before the cohort follow was performed.65 performed.65 The Berman model did not incorporate these 1983 data and we have reported our partial follow of this population in this paper Berman and Crump also relied on dose estimates from QAMA studies about which the authors themselves stated It remains doubtful however whether conversion of particle dose estimates the only measure of exposure in the QAMA studies to a fibre equivalent can have much epidemiological validity Inadequate SampleSample Size Because of the broad nature of most of the studies examining mesothelioma risks among many different occupational groups the numbers used by Wong from each study i.e. the number of garage mechanics in each study is usually less than 25. Hessel et al the highrated study in Goodman et al.'s analysis reports an OR for brake workers based on only two cases after controlling for insulation and shipbuilding exposure and on a single case after controlling for all other potential asbestos exposures Any conclusions elative to safety based on these tiny sample sizes are reckless Use ofInappropriate Control Group It is extremely difficult to find a comparable comparable control group for hospitalized mesothelioma cases Due to the Iarity of the condition mesothelioma cases are often referred to large medical centers Some hospital con- trols who do not have rare diseases will not reflect the true demographics of the desired denominator popu- lation Patients with mesothelioma are often referred from rural or suburban to urban hospitals for diagno- sis or treatment Patients from these urban environ- ments are likely to be overrepresented in the control VOL NO 4 OCT 2005 www.ijoeh.com Abuse of Epidemiology 367 group and are more likely to have been exposed to brakes than the rural or suburban neighbors of the cases controls that more accurately reflect the demographics of the cases This effect helps explain how all but one of the studies Wong and Goodman et al analyzed found that brake work reduced the risk of the development of mesothelioma Misuse of Confidence Intervals Almost all of the studies reviewed report confidence intervals that include a rate ratio greater than one.56 When risk ratios are being calculated on small samples point estimates cannot be considered particularly accu- rate and examination of confidence intervals is more important in determining risk Wong and Goodman et al however mention these confidence intervals only in passing and base their entire analysis on point estimates DISCUSSION Despite the clear methodologic problems with the abovementioned studies used in their analyses Goodman et al and Wong present them as unquestionable evi- dence of the absence of an association between brake work and mesothelioma.5,6 None of the studies used was designed specifically to examine this association bringing in the possibility that unknown confounders could be at play Despite this Wong presents the studies under the heading of Epidemiologic Studies of Mesothelioma among Auto Mechanics and Goodman et al title their paper Mesothelioma and Lung Cancer among Motor Vehicle Mechanics A analysis As we have shown a study that is not designed specifically to determine brakework exposure is likely to be fraught with bias due to the complexity of exposure determination The World Trade Organization issued a ruling on the matter in September 2000 after extensive expert testimony led to a conclusion that chrysotile asbestos does produce a real risk of mesothelioma to mechanics.67 The ruling allowed European countries to ban the use of containing brakes Both papers omit this information as well After publication of Wong's paper but before the pub- lication of that of Goodman et al considerable evidence emerged from studies conducted in Australia by Leigh et al supporting an association between automobile mechanic work and mesothelioma Of the approximately 6,000 individuals in Australia's extensive mesothelioma death registry 1.2 were automobile mechanics For many the only source of asbestos exposure was brake- lining repair In a number of individuals examined only chrysotile asbestos fibers were found indicating that chrysotile exposure alone can cause malignancy.69 On the whole Wong and Goodman et al fail to adequately address the issue of the relationship between brake work and mesothelioma The small numbers of individuals pulled from larger studies from which Wong reports risk ratios to support his argument lack statistical power as well as epidemiologic meaning due to the large amount of potential bias The analyses begin to the address the problem of a lack of statistical power However since the data used for the analysis are handpicked from the literature to the exclusion of contrary evidence and those that are included are likely to suffer from various types of bias the results reported are not reliable Until prospective cohort studies specifically designed to determine asbestos exposure from brakelining installation and repair are conducted definite conclusions about the magnitude of this risk cannot be made It is clear that a risk exists Moreover the entire argument addressed by these analyses regarding the risks of chivsotile is specious in light of the following undisputed facts Chrysotile causes lung cancer 2. Chrysotile causes asbestosis 3. Chrysotile used in the United States is contami- 75 nated with tremolite amphibole 76 4. Products made from chrysotile contain tremolite Chrysotile is concentrated in the pleura 6. Populations with mixed exposures to amphiboles and chrysotile have double the rate of mesothelioma of those exposed to amphibole alone 7. repair workers get substantial airborne asbestos exposures from grinding brake and clutch parts and blowing out dust from brake assemblies.25 Almost all brake workers have had some exposure to amphibole with or as well as chrysotile Thus even if chrysotile alone is not a cause of mesothelioma it acts synergistically with amphiboles to increase the inc dence of this cancer CONCLUSION The methods utilized by the asbestos and related indus- tries redefinition of scientific criteria for deter- mining effect relationships and the manipula- manipula- tion of scientific data and scientific inferences obscured the true picture regarding asbestos exposure and mesothelioma In contrast to their experts opinions the relationship between exposure to asbestos and mesothelioma has long since been recognized by the industry executives who retained Goodman et al and Wong.5,6 In his 1973 private presidential address to brake manufacturers Ike Weaver the Chair- man of the Asbestos Study Committee of the Friction Materials Standards Institute an industry trade organi- zation noted the importance of this phenomenon I know of no way any of us can be absolutely sure that his friction products regardless of whether they are sold as original equipment or on the replace- 368 ' Egilman Billings www.ijoeh com INT J OCCUENVIRON HEALTH ment market will not be subjected to additional operations or alterations in the field that could result in excessive exposure of workers or bystanders to airborne asbestos fibre I have been appalled to learn of a number of instances where this problem has occurred and some of these cases involved people that certainly might have been expected to know better . If this kind of thing occurs in fabrication operations of major OE original equipment customers it appears to me there can be no argument about the need for educational measures to reduce chances of unnecessary exposure during grinding drilling or cutting operations To those who argue that labeling or other types of warning need not apply to replacement materials because fabricators or appliers handling replacement quantities are exposed relatively intermittently I say emphatically this just ain't necessarily so Large volume replacement users present major potential hazards and even small job shops can needlessly expose people to high fibre concentrations if operations are performed without controls Despite the secret industry acknowledgement of risk and high exposures Goodman et al and Wong manipulate epidemiologic science to conclude that exposure to asbestos from brakes does not induce asbestos- related malignancies As we and others have noted absence of evidence is not evidence of absence in other words failing to find an association does not pro- vide any evidence that an association does not exist Once it is generally accepted that a substance can cause disease in humans all that is required to establish cau- sation is documentation of exposure to that substance For example the OSHA benzene standard did not require epidemiologic evidence of cancer risk in every sector covered by the standard.83 In the case of vinyl chloride chemical companies themselves removed the compound as a propellant in hair sprays based on animal studies alone because of the risk of unlimited liability The asbestos industry and the automobile industry rather than hiding behind a dust cloud of misleading science should do the same and stop using asbestos in brakes worldwide References 1. 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