Document a4nyJ173O8kXqpoEpZwLDy5my

Federal Register / Vol. 51, No. 119 / Friday, June 20, 1986 / Rules and Regulations_______ 22617 were not available at the time this study Overall deaths were significantly (p was published. Workers were classified less than 0.001) elevated (SMR-167), as as having worked less than 1 month, 2 were deaths from all cancers (SMR-2B7), months, 3-5 months, 6-11 months, 1 from all "asbestos" diseases (SMRr-396), year, or 2 or more years. Workers in all from noninfectious lung disease (SMR- of these exposure categories had 489), and from lung cancer (SMR-541). excessive mortality from lung cancer. Colorectal cancer mortality was also This study demonstrates that workers significantly (p less than 0.05) increased with exposures of relatively short (SMR-185). In addition, 17 deaths from duration arc at excess risk of lung mesothelioma were observed, a finding cancer. of.great significance given the rarity of This mortality study was updated to include both a. longer followup period and exposure estimates (Seidman, Ex. 261-A). The updated analysis included ths disease. A strong cumulative doseresponse relationship was evident for both lung cancer mortality and mortality from all "asbestos" diseases. an additional 593 cases involving deaths Dement et al. (Exs. 84-036, 84-037) occurring during the period from 5 to 40 estimated individual cumulative years after onset of work. To increase the comparability of this study with exposures for 768 workers employed at a chrysotile textile plant during 1930- others, Seidman re-analyzed the results 1975. Mean exposure levels were of the earlier study by using death rates estimated for these workers on the basis for white males from New Jersey to of 5,952 industrial hygiene samples. The calculate Standardized Mortality Ratios following exposure categories were (SMRs). Cumulative exposure to defined: less than 1,000 f/cc-days, 1,000- asbestos was estimated for each worker 10:000 f/cc-days and 10,000-40,000 f/cc- using work history records and exposure days. As explained in the November measurements taken in 1967,1970, and proposal, OSHA calculated thut these 1971 from two similar amositc insulation categories of cumulative exposure are production plants. These exposure data were collected and reported by NIOSH roughly equivalent to the following exposure categories: less than 2.7 f/cc- (Ex. 2-12). Workers were progressively years; 2.7-27.4 f/cc-years. 27.4-109.6 f/ assigned to the following cumulative cc-years, 109.6-274 f/cc-years, and exposure categories during the 35-year greater than 274 f/cc-years. The first followup period: less than 6.0 f/cc-years, three of these exposure categories fall 6.0- 11.9 f/cc-ycars, 12.0-24.9 f/r.c-years, within at or below the lifetime 25.0- 49.9 f/cc-years, 50.0-99.9 f/cc-years cumulative exposure permitted by the 2- 100.0- 149.9 f/cc-years, 150.0-249.9 f/cc- f/cc standard. Fifteen or more years years. and 250 or more f/cc-years. The after the onset of exposure, use of exposure data from plants other standardized mortality ratios (SMRs) for . than that from which the cohort was lung cancer among white males were derived is appropriate in this study since 140, 279 (p less than 0.05), and 352 (p the exposure measurements were from "plants of the same company where the same products were made utilizing the same machinery, fiber and production processes" (Ex. 261-A, p. 5). The investigators indicated that their less than 0.05) in the First three exposure categories, respectively, demonstrating the existence of a dose-response relationship. Dement et al. (Ex. 84-037, p. 432) concluded that: "Based on data from this study, significantly elevated exposure estimates may be on the high side for two reasons: (1) Dustier areas tend to be sampled more often than other areas, and (2) a concerted effort mortality risks are predicted for lung cancer and for asbestosis at cumulative exposures of 100 fibers/cc-years in the textile industry." OSHA considers that was made to have respiratory protection these observations of excess risk from used by workers in the plant from which low cumulative exposures are well- . the study cohort was taken. Furthermore, Dr. Morion Corn, former Assistant Secretary for OSHA and supported because of the careful estimation of exposure histories for members of the cohort in this study. testifying on the behalf of thc.Building Henderson and Enterline (Ex. 84-048) and Construction Trades Department, studied the mortality of 1,075 retired commented that the Tyler, Texas plant, asbestos production workers. Mean where some of the exposure data were estimated exposures for the cumulative obtained, was ". : . one of the most exposure categories were 62, 162, 352, contaminated asbestos facilities I've 606, and 976 mpef-yeafs. Based on the ever been in" (Tr. 7/3, p. 67). Therefore, recommended conversion factor of 1:1.4 it is likely that the exposure estimates for asbestos production (discussed in were overestimated, leading to an the November proposal), 62 mpef-years underestimate of excess risk for workers is roughly equal to 87 f/cc-years. a in each of the cumulative exposure cumulative exposure permitted by the 2 categories. f/cc standard. An SMR of 197.7 for respiratory cancer was observed for workers in this cumulative exposure category. This observed excess __ mortality risk is not as high as observed by Dement et al. (Exs. 84-036. 84-037); however, the authors of the Demenl.et al. study suggested that this difference may be the result of the fact that Henderson and Enterline studied retirees, which constitute a select group of survivors; only 8 of the 35 lung cancer deaths observed by Dement et al. (Ex. 84-37) occurred among persons 65 or older. McDonald et al. (Ex. 84-065) studied the mortality of 11,379 workers exposed to chrysotile mining and milling. Based on a conversion factor for these operations of 1:3 for mpef to f/cc. the exposure classifications developed by the authors would correspond to the following exposure categories: less than 90 f/cc-years, 90-699 f/cc-years. and 900 or more f/cc-years. Although they did observe an increased incidence of pneumoconiosis (SMRs 298,1081, and 5400, respectively), McDonald et al. (Ex. 84-005) observed less lung cancer risk for these exposure categories than other investigators (SMRs were 93,118, and 225, respectively). Regarding the different findings between the studies by McDonald et al. (Ex. B4-065) and Dement et al. (Exs. 84-036, 64-037) on lung cancer risk from low exposures. Dement et al. suggested that differences in the characteristics of airborne fibers, as well as the presence of a competing risk of pneumoconiosis among miners in the McDonald et al,, study, could account for the differences in lung cancer mortality reported in these two studies. Finkelstein (Ex. 84-240) studied the mortality of 339 men who had been employed at an Ontario asbestos cement factory for 9 or more years. Each cohort member was classified as having accumulated 8-69 f/cc-years, 70-121 f/ cc-years, or 122-420 f/cc-years of asbestos exposure during the 18 years following onset of exposure. Cohort mortality was analyzed by cumulative exposure, starting 20 years after onset of exposure, and was compared to that of non-exposed Ontario men. Approximate relative risks for lung cancer mortality for the three exposure categories were 8.5.16.3, and 7.4, respectively. Mesothelioma mortality rates per 1000 man-years were 1.9, 4.9, and 11.9, respectively, showing a clear doseresponse relationship between asbestos exposure and mesothelioma.'Finkelstein suggested several explanations for the unexpected decrease in excess lung cancer mortality in the highest exposure category: he argued that statistical GLEASON-000865