Amosite (Insulation)
Exposure to another commercial amphibole, fibrous grunerite (commonly called "amosite" from the acronym AMOS, representing Asbestos Mines of South Africa), has resulted in an excess risk of mesothelioma. It is unclear in some occupational studies that the exposures are to asbestiform mineral. Among 3212 amosite miners in South Africa (51,000 person-years with cumulative exposure of 24 f/ml-yr), 4 mesotheliomas were found (Sluis-Cremer et al., 1992; Hodgson and Darnton, 2000). Mesothelioma was diagnosed in 17 men among 820 workers exposed to amosite in a factory located in Paterson, NJ. The incidence among those with short-term work exposures showed a strong relationship with advancing time (Seidman et al., 1986). The worker cohort in New Jersey had cumulative amosite exposure of 65 f/ml-yr (Hodgson and Darnton, 2000). A study of a cohort involved in amosite insulation manufacturing at Tyler, TX, reported 6 mesotheliomas among 130 workers (Levin et al., 1998). Two mesothelioma cases were found among 12 exposed workers at an Ontario factory manufacturing amosite asbestos insulation materials under poorly controlled environmental conditions (up to 640 f/ml in 1973) (Finkelstein, 1989a). Another cohort with exposure to cummingtonite-grunerite, a mineral that is closely related to amosite, had one case of mesothelioma diagnosed by needle biopsy (McDonald and McDonald, 1978). Workers at one factory of Cape Industries Ltd. (Factory D) producing insulation boards containing amosite had no reported mesotheliomas among approximately 1500 workers (Browne and Smither, 1983).