Document KJkYZ3XEMvQ00dae72JxZaNG6

22618 Federal Register / Vol. 51, No. 119 / Friday, |une 20, 1986 / Rules and Regulations fluctuations caused by the small size of risk. The upper limits of the 95 percent members and retirees of the California the cohort or the possible confounding confidence intervals of the SMRs for local of the United Association of effects of smoking may have been respiratory cancer for the three lowest Plumbers and Pipefitters. The interim responsible for this unexpected result. exposure categories ranged from report was based on 6.398 (89.8 percent) More likely, lung cancer risk may have approximately 115 to 150. indicating, in of the 7,121 deaths. No specific been underestimated for the highest OSHA's opinion, that the presence of an information was available on cigarette exposure category by Finkclstein's excess risk of mortality from lung cancer smoking habits or on asbestos exposure exclusion of any lung cancer deaths that could not be ruled out for the cohorts in levels. Expected numbers of deaths might have occurred during the 20 years these exposure categories. were calculated from cause-specific from onset of exposure to the beginning of the followup.period. In addition to Berry.and Newhouse (Ex. 84-021) proportionate mortality rates by 5-year studied the mortality of a large cohort of age and 5-year calendar period groups showing dose-response relationships friction material production workers among U.S. while males. For between asbestos exposure and the whose asbestos exposures were mesothelioma, the expected number of excess risk from lung cancer and relatively low (generally less than 1 f/cc deaths was estimated on the basis of mesothelioma, OSHA notes that to 5 f/cc) and of short duration. death certificate information for Finkelstein's study presents evidence Cumulative exposures for the cohort approximately 10 percent of the U.S. that an excess risk for these diseases averaged less than 50 f/cc-years. Only population. Further analysis conducted exists at cumulative exposures that non-significant increases in mortality after the interim report confirms the would be permitted by lifetime exposure from lung cancer were observed: interim report findings (Ex. 168-A). to the 2-fcc standard. however, mortality from mesothelioma The most striking finding from this Rubino et al. (Ex. 84-006) studied the was significantly elevated compared report is that 15 mesothelioma deaths mortality of 952 male Italian chrysolite with that of controls. Most of the occurred in this group, while only 2 were miners and millers. The mortality mesothelioma victims had been exposed expected. A significant (p less than 0.05) experience of the overall cohort was to asbestos levels exceeding 5 f/cc; their excess number of lung cancer deaths compared with that of nonexposed cumulative exposure estimates were not was also observed (587 observed. 408 Italian males. Compared with reported. A sizeable portion of the expected). Other smoking-related cancer nonexposed Italians, the overall cohort cohort was studied for a relatively short sites had PMRs at or near expected had statistically significant excesses of followup period between onset of levels. The investigators concluded: mortality from laryngeal cancer, exposure and the end of the study. For nonmalignant respiratory diseases, and example, the followup period for 33 "It is likely that exposure to asbestos is responsible for at least part, if not all. of the non-asbestos-related causes, but not percent of the men was less than 20 excess number of lung cancers in this group: from lung cancer. However, there were years. Because of the short followup 1. The excessive number of deaths due to some trends showing increasing lung cancer risk with increasing length of followup and increasing cumulative exposure. Using the methodology presented in Ex. 84-338, OSHA determined that this study had only a 33.5 percent power to detect a 50 percent period used, OSHA does not believe that the non-significant increases in lung cancer mortality found by these investigators contradict the findings from other studies, which show that low-level exposure to asbestos has resulted in excessive mortality from lung lung cancer is consistent with the elevated number of mesothelioma deaths that points to widespread asbestos exposure. 2. If cigarette smoking hod [emphasis added) played an important role in causing excess lung cancer deaths, we would expect the PMR for bladder cancer, another smoking-related. . . (malignancy) that has increase in lung cancer risk among cancer. not been linked to asbestos exposure, to also workers with 20 or more years of followup. Generally, it is considered desirable for studies to have at least an 80 percent power to detect a 50 percent Of the few epidemiologic studies submitted to the docket after the publication of the November proposal, four provide additional information on ' be elevated. There were 40 deaths due to bladder cancer whereas 40.4 were expected (PMR =>.99), suggesting no Increase in risk for cancers of this site." (Ex. 188-A, pp. 3-4.) increase in disease. the risk of lung cancer mortality and/or This study, although it is an interim Wei)l et al. (Ex. 84-208) studied mesothelioma mortality among workers report, is significant for two reasons. mortality among 5,645 men having at exposed to asbestos. The first (Cantor, First, the excess number of deaths from least 20 years of latency since first Ex. 16B-A; Cantor et al, Ex. 188-B) is mesothelioma add to the already exposure in either of two asbestos only an interim report on a considerable weight of evidence for a cement plants. Each worker's proportionate mortality study and has causal relationship between asbestos cumulative dust exposure during the 20 no estimates of cumulative exposure. exposure and an increased mortality years after the onset of exposure was Two other studies similarly give no risk from this rare cancer. Second, estimated in terms of mpef-years. Based estimates of cumulative exposure; one despite the lack of data on smoking on the conversion factor of 1:1.4 (Nicholson and Selikoff. Ex. 162-C) habits for the cohort, the study suggests suggested by Hammad et al. Ex. 84-277), investigates the risks of recent that asbestos exposure, and not the Five cumulative exposure categories exposures of limited duration, while smoking, was the principal cause of the would be equivalent to 14 or fewer f/cc- another (Zoloth and Michaels. Ex. 183- observed excess in lung cancer years. 15-70 f/cc-years, 71-140 f/cc- E) investigates the effects of intermittent mortality. years, 141-280 f/Cc-years, and 281 or asbestos exposure. The fourth study Nicholson and Selikoff (Ex. 162-C) more f/cc-years. Neither respiratory (Seidman, Ex. 261-A) is an update of a investigated mortality among 1,918 male cancer mortality nor any other cause of previous study (Seidman et al., Ex. 84- shipyard workers who were employed death was increased among workers in 087) and was discussed earlier in this on January 1,1967 and who were first the three lowest exposure categories. section. employed before January 11,1957. More Weill et al. noted that the relatively high Kenneth P. Cantor, of the National than 80 percent of the cohort was proportion (25 percent) of the cohort that Cancer Institute, submitted an interim employed for less than 20 years. was lost to followup and assumed to be report (Ex. 168-A; Cantor et al., Ex. 168- Although no estimates of exposure alive may have led to an B) on his proportionate mortality study levels were given, the authors state that: underestimation of respiratory cancer of 7,121 deaths identified among "in terms of time from onset of exposure GLEASON-000866