Document ZnKwDYNK7jVzOEMY6qo6YKxmO

Federal Register / Vol. 51, No. 119 / Friday, June 20,. 1980 / Rules and Regulations 22625 E. Effects of Cigarette Smoking and education, were not farmers, were alive Asbestos Exposure - as of January 1,1987, and had a history This section discusses scientific . of occupational exposure to dust, fumes, evidence describing ihe influence of vapors, gases, chemicals, or radiation. smoking on the risk from asbestos- The age-standardized lung cancer related disease. Because several studies mortality rate for non-smoking controls (Ex8. 2-5; 84-190; 84-47) were cited in (i.e., the baseline rate) was 11.3 deaths the November proposal as evidence of a per 100,000 man-years; the rate for multiplicative effect of asbestos smoking controls was approximately 11 exposure and cigarette smoking with times higher (122.8 per 100.000 man- regard to producing increased lung years). The lung cancer mortality of non cancer risk, several commenters, smoking asbestos workers was 5 times including the Asbestos Information higher (58.4 deaths per 100,000 man- Association (Ex. 328), argued that OSHA years) than that of non-smoking controls overstated the risk of lung cancer in its (11.3 deaths per 100,000 man-years). qualitative risk assessment by failing to distinguish between the lung cancer risks for asbestos-exposed smokers and nonsmokers. While the scientific data are discussed here, Section VI (Significance of Risk) contains OSHA's response to comments dealing with how the lung cancer risk for asbestosexposed smokers should be evaluated from a regulatory perspective. . Hammond et al. (Ex. 84-047) found that the lung cancer mortality of asbestos workers who smoked was 601.6 per 100.000 man-years, a value that is also about five times higher than the baseline rate of lung cancer mortality for smoking controls. Selikoff et al. (Ex. 84-190) examined the effeclB of cigarette smoking and asbestos exposure among 582 amosite production workers. 567 of whom had Asbestos-Related Malignant Disease smoking histories. Ab in the study by Several studies were cited in the November proposal as evidence that asbestos-exposed workers who smoke have a higher risk of lung cancer mortality than either asbestos-exposed . nonsmokers (Selikoff, Churg, and Hammon et al. (Ex. 84-047), the age and cause-specific mortality rates were compared within each smoking status category defined by the American Cancer Society cohort. Selikoff et al. (Ex. B4--190) concluded as follows; Hammond, Ex. 2-5; Selikoff, Seidman, Here asbestos exposure greatly multiplied and Hammond, Ex. 84-190; Hammond, the already high risk that would have been Selikoff, and Seidman, (Ex. 84-047). The reduced ability of smokers to clear particles from their lungs, compared present with cigarette smoking alone, . ; . This increased risk is very much the same as that seen among asbestos Insulation workers (who smoked). This observation indicates with the ability of non-smokecs to do so, ' that the increased risk of death from lung as suggested by Cohen et al. (Ex. 84- cancer among cigarette-smoking asbestos 031), may help to explain the higher lung cancer risk of asbestos workers who smoke. The Agency also determined that there is no evidence of an association workers is a specific Interaction rather than coincidental, and not, for example, the result of other agents in the environment of the construction trades." (Ex. 84-190). between cigarette smoking and an In the November proposal, OSHA increased risk of either mesothelioma or presented two ways of calculating the gastrointestinal cancer. probability that any single case of lung To exemplify the multiplicative effect . cancer In a person with, known exposure of asbestos exposure and cigarette to asbestos could.be attributed to the smoking in producing an increased lung asbestos exposure. The first way, cancer risk, OSHA discussed two' proposed by Enterline (Ex, 84-128), was . studies at length (Hammond et al. Ex. based only on relative risk estimates. 84-047; Selikoff et at., Ex. 84-190). The Using data from Selikoff et al. (Ex. 84-. Hammond et al. study (Ex. 84-047) 090) on asbestos insulation workers, examined Ihe smoking histories of 8,220 Enterline estimated that there was a of 12,051 asbestos insulation workers probability of 75 percent that lung with a followup of 20 or more years . cancers were attributable to asbestos since initial exposure. In late 1988, 8,841 exposure; this probability applied both of these workers were either current or to smoking and non-smoking asbestos past cigarette smokers, 488 had a history workers. However, in the case of of pipe or cigar smoking, and 891 had asbestos workers who smoked, OSHA never smoked regularly. The mortality of. deems it inappropriate to dichotomize these workers was observed during the causation in terms of smoking or period 1987-1976. The comparison asbestos exposure because of the population, drawn from the American synergistic effect between cigarette Cancer Society's long-term prospective smoke and asbestos. OSHA therefore study, consisted of 73,763 white men presented its method of calculating the who had no more than a high school - probabilities of causation in the November publication (Table 8 and Table 7, 48 FR 51110). Although OSHA's calculations differ from Enterline's calculations of attributable risk by including a factor for synergism, the two probability estimates do not differ by a great extent. According to OSHA's calculations, asbestos exposure contributes to 79.4 percent of lung cancer deaths among asbestos-exposed workers who smoke, and 77.2 percent of lung cancer deaths among nonsmoking asbestos workers. Lung Disease and Chest X-ray Abnormalities In the study by Hammond et al. (Ex. 84-047) discussed above, it was also reported that asbestos insulation workers who smoked one or more packs of cigarettes per day had an asbestosis mortality rate 2;4 times higher than that of asbestos insulation workers who had. never smoked regularly. Selikoff et al. (Ex. 84-190), however, observed no increased risk of death from asbestosis among amosite production workers who smoked compared to their nonsmoking co-workers. Weiss (Ex. 84-097) conducted a chest x-ray and questionnaire survey of 100 asbestos textile workers. Chest roentgenograms were examined for evidence of pulmonary fibrosis. Two asbestos exposure groups were defined; those with less than 20 years of exposure and those with 20 or more years of exposure. The age-adjusted. prevalence of pulmonary fibrosis among smokers and non-smokers was 40 and 23 percent, respectively. None of the 11 non-smokers with less than 20 years of asbestos exposure had pulmonary fibrosis, in contrast to 29 percent of the smokers with less than 20 years of exposure to asbestos. The median duration of exposure to asbestos was similar for these two groups. Based on these findings, Weiss (Ex. 84-097) concluded that both asbestos exposure and cigarette smoking were associated ' with pulmonary fibrosis and that asbestos workers.who smoked had a. higher prevalence of fibrosis relative to that among nonsmoking asbestos workers. Weiss did.not indicate whether the difference in the prevalence of pulmonary fibrosis between smokers and nonsmokers was statistically significant. OSHA tested the significance of the reported difference using a chi-square test of proportions and did not find a significant difference (p greater than 0.1). This study and its findings were criticized by Kilbum (Ex. 84-237) because Weiss used a definition of pulmonary fibrosis that differed from the standard International Labour Office GLEASON-000873