Factories
The mortality experience is published of 1074 Johns Manville retirees. Eight deaths from mesothelioma were observed among workers in the textile, maintenance, cement shingle and sheets, insulation, and cement pipe departments experiencing direct and indirect exposures to mixed types of asbestos fibers (Henderson and Enterline, 1979; Enterline et al., 1987). The members of this cohort are estimated to have 750 f/ml-yr cumulative exposure, the highest average level reported in the literature (Hodgson and Darnton, 2000). At a textile plant in Pennsylvania, chrysotile with some amosite and crocidolite were used. Exposure for each man was estimated. Fourteen deaths were recorded of 5135 subjects, though undercounting of mesothelioma cases was a possibility. The risk of mesothelioma was higher for those exposed to processes when even small quantities of amphiboles were used (McDonald et al., 1983b). In addition to the asbestos cement plant workers reported in the same article, a small group of Italian women who worked in the textile industry, mainly exposed to chrysotile, and compensated for asbestosis had six deaths due to mesothelioma (Germani et al., 1999). Chrysotile asbestos was the primary form used in a factory in Rochdale, UK, between 1932 and 1968, though some crocidolite was used (total 2.6%). Exposure data were largely derived from static particle counts, not fiber determinations, but the risk of mesothelioma appeared to be increased from the observation of 10 cases (Peto et al., 1985). A mortality study of workers employed at a factory producing friction products was completed from 1941 to 1986. Other than two short periods before 1944 when crocidolite was used on one particular contract, only chrysotile had been used. Asbestos exposures were high (>20 f/ml) especially before the 1931 Asbestos Regulations, but since 1970, levels had been less than 1 f/ml. Thirteen deaths due to mesothelioma were found, 11 in those with known contact to crocidolite. For the other two cases, the diagnosis was uncertain in 1 person, and the occupational history is unclear in the other cases (Berry and Newhouse, 1983; Newhouse and Sullivan, 1989). Of approximately 10,000 subjects of Factory A covering over 6 decades, an estimated 120 mesothelioma cases were found (Browne and Smither, 1983; Newhouse et al., 1985). In a mortality study for 1940-1975 among 3276 workers of a plant using chrysotile and amphiboles, 17 cases of mesothelioma were observed (Robinson et al., 1979). A cohort of 889 men and 1077 women employed at a factory in Grugliasco, Italy, worked with various types of asbestos, including crocidolite, and "exposure in this factory almost approached experimental conditions." Thirty-seven pleural and peritoneal mesothelioma cases and many deaths from asbestosis are reported (Pira et al., 2005).