Document LJMXXqQn61MOgD4REQR3Y5z8w

i> J Polite talicy is 'ed and dity or form to sion. : 1 ident to believe tarcinopossible e undethodblok for any absolute [early all andean ' This n- .ssenit or even substance isk factor i declines. substances afe at low vival The the assistune what the case of other subrapolations igh level o from big! seyond th; to misinfo imates ar 1 unrealis No Excess Lung Cancers ... This landmark study confirms the fmdtags of other less extensive research which has found no excess mortality risks resulttag from low-level exposures to chrysotile asbestos. For example, Churg (1986) discovered that residents ofchrysotile mining communities who were exposed to fibre levels from 200 to 500 times higher than those common in most North American cities showed no evidence ofa higher taddence of asbestos-related disease. Other studies examining work place exposures have corroborated these findings. Newhouse & Sullivan (1989) conducted a 40 year mortality study in a factory productng chcysotile-based friction materials. They concluded that despite exposure levels substantially higher than those currently found, chrysotile asbestos was processed with no detectable excess mortality. Similar findings have also been observed in studies of chrysotile exposure In die asbestostament industry (Ohlson & Hostedt, 1985;Thomas et al, 1982; Weill eial, 1979). The Liddell, McDonald & McDonald report not only supports these previous findings, but it makes a significant new contribution to our understanding of the nature of the threshold level of exposure responsible for inducing chrysotile-related disease. In terms of its implications for industrial hygiene policy, the study provides compelling evidence that the controlled-use approach to chrysotile asbestos Is not only feasible, but given that current exposure levels around the world are frequently l free or less, it is the most logical regulatory option. Previous Data on Chrysotile Exposure Support New Findings Although tha Uddoll, McDonald & Mcdonakl *tu tha largaaft and moat thorough cohort study to . a number of scientific antecedents support Its conclusions. Churg, A. Lung.ri$&fto$ content in long-term residents ofa chrysotile town, American Review of Respiratory Disease, 1986,134(1): 125-1 Study comparing health effects in residents ofchrysotile mining towns, wbe anfrom 200 to 500 times higher than in most North American cities. In higher levels, no evidence ofhigher asbestos-relateddisease wasfound Newhouse, M.L. and Sullivan, K.R.A mortality study ofworkers tnanufu friction materials '.1941-86. British Journal of Industrial Medicine 46(3): 176-179 The authors confirm that there was no excess mortalityfrom lung cance asbestos-relatedtumours or chronic respiratory disease. Ohlson, C.G. and Hogstedt,C Lung cancer among asbestos cement wi . ASwedisb cohort study and review. British Journal of Industrial Mo 1985,42(6): 397-402. A cohortstudy of1176asbestos-cement workers in a Swedishplant using chi asbestosfoundno excess mortality atexposures ofbetween 10-20f/mt. * Thomas, HE, Benjamin, Lt.Hwood, P.C. and Sweetnam, P.M.. Furtherfolk study ofworkersfrom an asbestos cementfactory. British Jour Industrial Medicine, 1982,39(3): 273-276. Afollow-up study of1,970 workers in an asbestos-cementfactory using cht] only showed no significant StandardMortality Ratio (SMR) excesses. The cau /faith investigated included neoplasms and cancers ofthe lung pleura one, trointestinal tract. Weill,a, Hughes, J. and Waggespack, (I. Influence ofdose andfibre typ respiratory malignancy risk in asbesos cement manufacturing. Ame Review ofRespiratory Disease, 1979,120(2): 345-354. An investigation of5,645 asbestos-cement manufacturing workers fount increased mortality resultingfrom chrysotile exposures ofapproximately 15f years. 2 HWBUI0012239 Policy considerations... which there are no detrimental health effects, many scientists are recommending that we rethink our approach to risk assessment. As such, legislators are asked to recognize the limitations of the linear model as a basis for regulatory policy. quently been used as the principal ii ment for determining chrysotile exj limits and regulatory policy. The res that once a risk estimate is calculate published, regardless of its valid: accuracy, it can be used as a platfo justify unwarranted and extreme acti " stringent regulation andfright eningpublicity have led topublic anxiety and chemophobia... the cost ofcleaning upphantom hazards will be in the hundreds of billions ofdollars with minimal benefit to human health. In the meantime, real hazards are not receiving adequate attention." P. Abelson Associate Editor, Science Scientific limitations of the Linear Model There are a number of serious problems which can arise from applying the linear model of risk assessment which extrapo lates from high dose exposures to much lower ones. Any of a number of experi mental flaws can alter the slope of the dose-response curve arid result in an inac curate estimate of risks at the low end of the exposure scale. Experimental errors, and the effects of insufficiently large data pools or slight variations in chemical composition are magnified many times over as data from very high doses is extrapolated to very low doses. The end result is that predictions based on the lin ear model have resulted in gross exagger ations of the actual health risks and car cinogenicity of many substances at low levels of exposure. This has clearly been the case for asbestos. The actual number of asbestos-related cancers observed in the U.S. is more than 20 times less than the original estimates based on the linear extrapolations of Dr. Irving Selikoff and the U.S. Department of Health Education and Welfare (HEW). Despite these and other serious limitations as well as the existence of other more real istic interpretations of the data, extrapola tions from high dose exposures have fre All Substances are Potential Toxins Supporters maintain that it is prudi err on the side of caution. They bi that although at low doses no car genic effect may be observed, it is po that these effects exist, but are t tectable with current data and metho gy. In theory, this is true. Zero risk fo substance cannot be proven with abs certainty, nor will it ever be. Clear substances are potential toxins ant never be proven to be without risk, includes exposures to common and t tial substances such as salt, water or oxygen. At very high doses any subs can be carcinogenic and the risk f will always decline as the dose dec Conversely, even the most toxic subst such as arsenic are not only safe a doses, but necessary to our survival challenge for regulators, with the: tance of scientists, is to determine level of safety is acceptable. In the c chrysotile asbestos and many other stances, the linear model of extrapoh has proven ineffective. The high ta uncertainty in extrapolating from doses to much lower ones is beyond which is acceptable. It has led to misi mation, unrealistic risk estimates ultimately to ill conceived and unre; regulations. HWBUI0012240 U.S. Study Links Fiberglass to Lung Disease Pom prolonged exposure to fiberglass adversely affect pulmonary functions or produce radiographic abnormalities In humans ? A recent study by researchers at the University of Southern California (USC) School of Medicine concluded drat com mercial rotary spun fiberglass appears to produce human disease that is similar to asbestosis. The study, conducted by K. KUbum, D. Powers and R.H. Warshaw was published in the October issue of The British Journal ofIndustrial Medicine. it examined 284 workers at an appliance factory where refrigerator doors and cabi nets were insulated with fiberglass sheet ing and loose rotary spun fiberglass.Workers with exposures of twenty years or more were evaluated on a num ber of tests of respiratory functioning including lung volumes, chest x-rays and physical examination. Apostmortem analysis of one workerwho died just prior to the study showed a sub stantial accumulation of glass fibres in the lungs. A transmission electron microscopy examination showed that each lung contained approximately 178,000 fibres. Charles Rossiter, former professor at the London School of Hygiene and Tropical Medicine who currently acts as a consul tant to the insulation industry disputes the study's conclusions. He argues that the study does not adequately recognize the compounding effects of smoking and that the control group was not represen tative. Me Rossiter does nonetheless urge the Man Made Mineral Fibre industry to undertake further study Into the health effects onusers. Jim Merchant, a leading American authority and director of the Occupa tional and Environmental Health Department at the University of Iowa believes that this study is " in line with what we know about fiberglass". Mr. Merchant warns that "this may have a lot of Implications for people who work in building and construction." Other major American and European cohort studies of the occupational health risis for workers in the Man Made Mineral Fibre (MMMF) manufacturing sector have found lung, trachea and bronchus cancer rates in excess of those expected The researchers found that in addition to eye and throat irritation in about 20% of the population studied, expiratory flows, which indicate pulmonary dysfunction, were significantly Impaired. 43 workers also had evidence of pneumoconiosis on chest radiographs. The authors believe that 36 (13%) of these pulmonary opaci ties or plural abnormalities were due to fiberglass exposure. Source*: Macati, GJL, Interilac. P,, Stone, ft. * Heoderaoo, Y.L., Mortality among a Cohort ofUSD Man-Mad* Mtrmal Nbr* Workon; 1983 PoOottHip. ]. Occ. Med 32,394- 604, 1990. Simoiuio, L ct *L 71* mainnad* mintrnl flbrt European Historical Cohort study: EsUnrlon oflb* Fottouwp. Sand. J. Work, Ear. Hhh, 12, Suppl 1,34-47,196 Code of Practice for Synthetic Mineral Fibres In response to recent human and ani mal data, representatives from the Quebec Federation of Labour (QFL), with the support of the Canadian Labour Congress have written a draft Code of Practice for die use of Synthetic Mineral Fibres (SMF). The code would Include descriptions of SMF, summaries of their health effects, as well as recommenda tions for proper monitoring, safe work practices and exposure limits. The code would detail work practices based on the different risk factors accorded to various fibres. A number of recent studies (see article U.S. Study...) have found evidence that exposures to some types of SMFs can have serious health effects, including eye and throat irritation, pulmonary dys function, non-mallgnant disease and cancer. Oespite the growing concerns of scientists, regulators and the labour movement, some industry representatives such as Frank Cereghlni, manager of Occupational Health and Safety at Owens-Corning/Flberglass Canada maintain that insulation fibres are not carcinogenic. A new Code of Practice is Intended to eliminate the inter-provincial Inconsis tencies which exist in worker protection policies across Canada and provide guidelines for government policy and industry practices.! A THIASMSTOS INSTlTUTf 1002 Sherbrooke Street Wtn Surre 1750, Montreal (Quebec) Canada H3A }L6 IHephonc: (514)844-3956 U*l: u55 60565 (INSTAM) Telecopier: (5141844-1361 HWBUI0012241