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FILE NAME Brakes BRK DATE 2016 DOC BRK248 DOCUMENT DESCRIPTION Letter to the Editor RE Response Exposure Vehicle Mechanics Chrysotile & Mesothelioma Ann Occup Hyg 2016 Vol 60 No. 4 528-530 mew015 vey f DOMI MINA MVS M|INA ILLU 0 MKA 7 LETTER TO THE EDITOR Editorial Note Letters to the Editor are peer reviewed to ensure that the arguments are reasonable and clearly expressed However letters may express a particular opinion rather than a balanced interpretation Authors of papers commented on are invited to reply but neither the journal nor peer reviewers should be assumed to support the arguments made Downlade Thinking about Occupation and Exposure Relationships Vehicle Mechanics Chrysotile and Mesothelioma from htp:/anyg.oxfrdjualsg/ Kay Teschke htp:/anhyg.oxfrdjournals.org/ School of Population and Public Health University of British Colombia 2206 East Mall Vancouver British Columbia V6T 1Z3 Canada mail kay.teschke@ubc.ca kay.teschke@ubc.ca htp:/anyg.oxfrdjuls/ Submitted 16 December 2015 revised 20 February 2016 revised version accepted 10 March 2016 at Mcaster University The 2015 paper by Garabrant et al 2016 Mesothelioma among Motor Vehicle Mechanics An The first question addresses the statement at the beginning of the review paper Garabrant et al 2016 Libra y Updated Review and analysis includes our 1997 paper Teschke et al 1997 as a tier l study in the are studies of motor vehicle repair activities and brake repair activities appropriate settings to examine the analysis risks of mesothelioma from chrysotile exposure on March About a decade after our paper Teschke et al The issue of interest is whether chrysotile asbestos 1997 was published it came to my attention that causes mesothelioma It may be reasonable to study it had been used regularly in litigation related to jobs or tasks to investigate this question but note that 31 2016 mesothelioma in people who had worked as vehicle mechanics or in brake repair I do not normally accept the jobs or tasks are being used as surrogates of chry- sotile exposure It is important to consider whether legal work but agreed to take part as an expert witness in one case to point out some problems in interpretation of epidemiological evidence such as ours in these cases It seems possible that this new analysis will be used in the same way as our individual paper they are good surrogates Some occupations are syn- onymous with extensive exposure to certain agents For example it would be a rare wood furniture maker who did not have daily high exposure to hard wood dust and an exceptional asbestos insulator without daily so I thought it may be useful to present the issues in a more public forum I will focus on two questions high exposure to amphibole asbestos For such jobs the association between the occupation and a disease . 'The Author 2016. Published by Oxford University Press on behaofltf he British Occupational Hygiene Society 528 Letter the Editor " 529 may be virtually equivalent to the association between Other occupational groups such as chrysotile tex- its predominant exposure and that disease Many jobs tile workers may be more appropriate occupations have much more variable exposures For example some to study The most reliable epidemiological study nurses are regularly exposed to anesthetic gases and would measure chrysotile exposure and assess the others are rarely or never exposed Examining the rela- exposure relationship not count on an tionship between nursing and spontaneous abortion occupation or task to act as an exposure surrogate is not equivalent to examining exposure to anesthetic Even with exposure analyses data quality gases and that outcome Because exposures are so varia- can make a profound difference in the strength of an ble within the occupation any true exposure observed relationship for example a fold stronger relationship will be attenuated or not observable when examined instead via an occupation analysis relationship between chrysotile and mesothelioma was observed with better exposure data Burdorf and Downlade In the case ofvehicle mechanics brake repair work not consistently performed Three studies Woitowitz and R^delsperger 1994 Teschke et al 1997 Rake Heederik 2011 The second question addresses an issue that is raised in litigation and workers compensation is it et al 2009 cited in the analysis Garabrant appropriate to require evidence of elevated associa- from et al 2016 included information on subjects brake tions between an occupation and a disease to ascer- repair work separately from vehicle mechanic occupa- tain whether someone incurred the disease as a result tion at least 34 of the vehicle mechanics reported no of exposures in that occupation brake repair work Yet of the 16 studies included in the The answer must be no Answering yes requires that analysis Garabrant et al 2016 12 examined every person who has a disease arising from workplace htp:/anyg.oxfrdjuls only the vehicle mechanic job or even broader job cat- exposure provide epidemiological evidence that their egories such as garage workers auto repair and related specific job has an elevated risk ofthat disease Ofcourse services and auto engineers It is reasonable to expect it is impossible to study every occupation relathat many in these categories had chrysotile exposures tionship In addition even where a job has been studied at similar to background levels in the population the potential for variable exposures within a job to dilute What about brake repair work itself Four stud- ies Woitowitz and R^delsperger 1994 Teschke the relationship is probable for many jobs and would preclude a person with high exposures from having their Mcaster et al 1997 Hessel et al 2004 Rake et al 2009 in occupational disease recognized simply because others University the analysis reported on brake repair The era in the same job were not similarly exposed The question of potentially etiologic exposure in these studies was is whether the exposure caused the disease A job cannot { ibrary dominantly long prior to 1980 a period when vehicle mechanics largely worked in gas stations and brake cause disease its exposures may It may be helpful to think of this in another way work was one possible task of many within the job Studies of chrysotile miners and textile workers have on March The frequency of exposure was likely to be intermit- found elevated risks of mesothelioma International tent though it possible that rare subjects may have Agency for Research on Cancer 2012 whereas stud- worked in specialized brake shops and done this task ies ofvehicle mechanics and brake repair workers typi- 31 repeatedly every day all day for most of their careers cally have not Garabrant et al 2016 Does this mean 2016 Interpretation of the results of the studies included that vehicle mechanics and brake repair workers are in the analysis Garabrant et al 2016 should somehow immune to the effects of asbestos that they acknowledge the likelihood that many vehicle mechanics had done no brake repair work and that of those who had most would have done so infrequently are especially resistant superhuman No they simply work in a job that has very varied exposures so detecting occupation relationships is difficult In as part of a broad array of activities This means that both the vehicle mechanic occupation and the brake other words the effects of chrysotile are not properly assessed via the surrogate measures of exposure vehi- repair task are unlikely to be good surrogates of chry- sotile exposure Associations between the occupa- tion or task and mesothelioma were likely attenuated cle mechanic or brake repair For people with mesothelioma have been exposed to chrysotile in their job the first question by subjects with background or low exposure levels to ask is whether chrysotile causes mesothelioma 530 + Lettetro the Editor International Agency for Research on Cancer 2012 so the next question is whether they had sufficient exposure to cause mesothelioma For some the answer Hygiene saw this letter prior to it being accepted for publication will be yes and for others the answer may be no The REFERENCES question of what constitutes sufficient exposure is not simple to answer In some jurisdictions workers compensation boards have a presumption in favor of compensation where a person has any workplace exposure to asbestos and a diagnosis of mesothelioma Others Burdorf A Heederik D. 2011 Applying quality criteria to exposure in asbestos epidemiology increases the estimated risk Ann Occup Hyg 55 565-8 Garabrant DH Alexander DD Miller PE et al 2016 Mesothelioma among motor vehicle mechanics an updated consider duration of exposure and intensity of exposure Note that exposure appropriately is the focus review and analysiAsnn Occup Hyg 60 8-26 Hessel PA Teta MJ Goodman M et al 2004 Mesothelioma among brake mechanics an expanded analysis of a case- Downlade DECLARATION I was the first author of one of the studies reviewed in from the Garabrant et al article In 2011-2012 I acted as control study Risk Anal 24 547-52 International Agency for Research on Cancer 2012 Arsenic metals fibres and dusts a review of human carcinogens In Monographs on the evaluation of carcinogenic risks to humans IARC Monograph No. 100C Lyon France IARC Press an expert witness at the request of the Ruckdeschel Rake C Gilham C HatchJ et al 2009 Occupational domes- Law Firm in a mesothelioma case to explain prob- tic and environmental mesothelioma risks in the British htp:/anyg.oxfrdjuls lems with interpretation of epidemiological studies such as ours This is also the motivation for this let- ter I wrote the letter its contents are solely mine and I received no funding related to it No one other than reviewers and editors of the Annals of Occupational population a control study Br J Cancer 100 1175-83 Teschke K Morgan MS Checkoway H et al 1997 Mesothelioma surveillance to locate sources of exposure to asbestos Can J Public Health 88 163-8 Woitowitz HJ R^delspergerK. 1994 Mesothelioma among car mechanics Ann Occup Hyg 38 635-8 htp:/anhyg.oxfrdjounals.org/ at Mcaster University Libray on March 31 2016