Document 5kXgqKRkBdjjdMvRMz3J6qE0D

22634 Federal Register / Vol. 51. No. 119 / Friday, June 20, 1980 / Rules and Regulations microscopy for the counting of fibers 84-90] studies in the calculation of KL. exposure) derived from several sources. longer than five micrometers, have been The ma[or objection to the use of these Although the use of average data and utilized in Great Britain and the United studies'was the lack of concurrent- overall (average) levels of risk may not States only since 1964 [Ayer et a).. 1965, exposure information on the cohorts. For be as desirable as risks broken down by Ex. 64-253] and have been standardized example, Dr. Crump noted that: cumulative exposure! nevertheless, the in the United States only since 1972 . [Leidel], 1979, Ex. 84-62] and even later in Great Britain. In any case, sampling The CPSC (1983) Panel placed these two studies in a separate category because of the weakness of the exposure estimates. The estimates of KL from these data are nevertheless valid and reasonable. OSHA predicted a Ku of 0.02 for the ' has occurred only in a few of the Seidman et at. study also Involved brief cohort, with an uncertainly band of - worksites studied, and then only occasionally. In addilion, variability in work activities and in sampling circumstances add considerable uncertainty to knowledge of dose. Some of the epidemiologic studies. . including those by Dement et al. [Ex. 8435], Liddell et al. [Ex. 84t59] and Henderson and Enterline. [Ex. 64-48], include measured air concentrations at the exposure site and used job histories of thestudy population to estimate exposure. In these cases the doseresponse curve was calculated by estimating total asbestos exposure (in mppef-years or in fiber-years/cc) according to the time that an individual spent at a job with a measured exposure. A conversion factor for converting from mppcf to f/cc was employed on a study-by-study basis, depending on the data available. Other epidemiological studies,' for example those by Selikoff et al. [Ex. 84-90] arid Seidman et al. [Ex. 84-67], did not have direct industrial hygiene measurements for the studied worker population. For these studies, exposure estimates were derived' from industrial hygiene surveys of similar work operations and processes for which industrial hygiene data were available. OSHA has evaluated these exposures (less than four years) exclusively, which.makes it less suitable than other studies for estimating the effect of long term exposures [Ex. 237A, p. 2G|. Dr. Weill also expressed reservations about including the Selikoff et al. and Seidman et al. studies in the overall estimation of risk (Tr. 6/19, p. 164]. Though it is true that CHAP did characterize the Selikoff et al. and .Seidman et al. studies as having "Level 2 exposure data" (no job histories or industrial hygiene measurements available for the cohort, exposure estimate made from best available sources), CHAP still computed KL for these two studies with the information available. And, during crossexamination, Dr. Nicholson, a member of CHAP, indicated that CHAP did not weigh the Kt values from these two studies differently from those in other studies when deriving estimates of the final potency [Tr. 6/19, p. 148], Dr. Weill emphatically stated that inclusion of the studies in the risk analysis was "not a fatal flaw (Tr. 6/19, p. 184]. . OSHA offered a fujl description of the exposure data used in these two studies in Exhibit 84-392. Since that time, however, new and more complete, information on exposures for the Seidman et al. cohort have come to light (0.008 to 0.30). The.value 0.02 is only twice the best estimate of an overall KL of 0.01 and falls well within the range of overall uncertainlty given for the overall Kl, that is, 0.003 to 0.03. Thus, OSHA has not adjusted the original value of Kt computed for this cohort. The Seidman et al Update. During the course of the hearing, the testimony of ' several witnesses strengthened OSHA's . confidence in using results from the Seidman et al. study of 820 insulatlori manufacturing workers. As.discussed in Exhibit 84-392, while no data exist on air concentrations at the time the Paterson factory operated, data do exist on air concentrations in two plants that manufactured the same products with similar fiber and machinery. One of these plants, in Tyler, Texas, opened in 1954 and operated until 1971. The other, in Port Allegheny, Pennsylvania, opened in 1964 and closed in 1972. Similar efforts to control dust in these newer plants were apparently made as were made in the Paterson, New Jersey plant. During 1967,1970, and 1971, asbestos fiber concentrations in these plants were measured by the U.S. Public Health Service and were published by NIOSH (Ex. 2-12]. Participants in the rulemaking differences and has dealt with their which strengthen the' case for including criticized the assumption that these implications on a study-by-study basis. the results of the KL calculation in the exposure data were representative of Uncertainties associated with these overall estimates of risk. This new the exposure conditions in the Paterson measurements constitute much of the information is discussed below. plant. Dr. Crump expressed his concern range of variability surrounding the Kt's. Although no new evidence has been over the use of these data. He stated: Taken as a whole, the asbestos studies contain data of unusually high quality, which has enabled OSHA to make the brought forward on the Selikoff et al. study of insulation workers. OSHA still believes it is appropriate to include the OSHA thus derived exposure estimates from measurements made 21 to 31 years later in the other plants in Texas and risk estimates with a high degree of . Kl from this study in determining the Pennsylvania. The reasonablenessof these confidence. overall level of risk. It is the largest of estimates is open to question. It Is certainly - There was considerable discussion during the rulemaking about the individual Kt's for many of the studies . that went into the estimation of the . overall lung cancer risk, particularly the Inclusion/exclusion of several of the all the studies (17,800 workers) and also reports the largest number of lung cancer death's (652) and deaths from mesothelioma (180). Excluding this study would mean excluding 45% of all the asbestos-related lung cancer deaths and plausible that the exposure measurements In these plants made after the dangers associated with asbestos became known were less, and perhaps far less than exposures experienced 21-31 years earlier under wartime conditions [Ex. 237A, p. 13). Btudie's in this calculation. The 84% of all the mesothelioma deaths from Dr. Morton Com,.former Assistant discussion below deals first with the the overall analysis. OSHA believes It Secretary for OSHA. who appeared at comments on and adjustments to would be a serious error to eliminate OSHA's hearing on behalf of the individual KL's and then discusses the such a large portion of the available . Building and Construction Trades impact of their inclusion in the overall data, when appropriate estimates of the Department was hired by the companies estimate of lung cancer risk. exposure levels of these workers are who owned the plants to recommend The Selikoff et al. and Seidman et al. available. and install control measures in the two ' Studies. Several participants in the OSHA calculated the Kj. from the plants in the late 1960's. At the hearings ' hearing criticized OSHA for including Selikoff et al. data based on average he was asked to comment on the the results from the Selikoff et al.. 1979 values (for duration of exposure, level of reasonableness of using data from Tyler, [Ex. 84-67) and Seidman et al., 1979 [Ex. exposure and time since onset of Texas and Port Allegheny to estimate GLEASON-000882