Mortality from asbestos-associated disease in Libby, Montana 1979–2011

Abstract

Research on asbestos exposure in Libby, MT, has focused on occupational exposure in vermiculite mining and processing, but less attention has been paid to asbestos-related mortality among community members without vermiculite mining occupational history. Our study reports on asbestos-related mortality in Libby over 33 years (1979–2011) while controlling for occupational exposure. We calculated sex-specific 33-year standardized mortality ratios (SMRs) for Libby residents who died from 1979 to 2011 with an asbestos-related cause of death. Decedent address at time of death was geocoded to confirm inclusion in the Libby County Division. We controlled for past W.R. Grace employment by including and then removing them from the SMR analysis. Six hundred and ninety-four decedents were identified as having at least one asbestos-related cause of death and residing in our study area boundary. Statistically significant (P<0.05) 33-year SMRs, both before and after controlling for W.R. Grace employment, were found for: male and female non-malignant respiratory diseases, female COPD, and asbestosis for both sexes combined. Eighty-five men and two women were matched to employment records. We observed elevated asbestos-related mortality rates among males and females. SMR results for asbestosis were high for both sexes, even after controlling for past W.R. Grace employment. These results suggest that the general population may be experiencing asbestos-related effects, not just former vermiculite workers. Additional research is needed to determine whether SMRs remain elevated after controlling for secondary exposure, such as living with vermiculite workers.

Risk of cancer associated with residential exposure to asbestos insulation: a whole-population cohort study

“…2,14 Rates of death from asbestos-associated diseases-including non-malignant respiratory diseases, chronic obstructive pulmonary disease, and asbestosis-are increased in the community of Libby, MT, USA, although at substantially lower levels than in people exposed occupationally to asbestoscontaining vermiculite. 7 The association we recorded between living in an affected residential property and mesothelioma in men is modest compared with that noted in studies of occupational or para-occupational exposure to asbestos. For example, among amosite asbestos miners in Tyler, TX, USA, peritoneal mesothelioma had a standardised mortality ratio of 21•5 (95% CI 8•62-44•2) and pleural mesothelioma had a standardised mortality ratio of 222 (12•7-361).…”

“…3 Elevated risks have also been seen in family members of occupationally exposed workers 5 and in communities living near asbestos-related industries. 6,7 Far less is known about the risk of primarily domestic exposure. 5,[8][9][10] In particular, there is no scientific evidence on the risk of cancer associated with living in a house containing loose-fill asbestos insulation.…”

Lung Cancer in an Orthoprosthetist Using Vermiculite

“…The mine of Libby, Montana, USA, was one of the most important sources of vermiculite worldwide between 1920 and its closure in 1990. 2 Contamination of Libby's vermiculite with amphibole asbestos has been described elsewhere with its consequences in terms of asbestos-related occupational and environmental morbidity and mortality. Cases of mesothelioma have been reported among former employees of the mine.…”

Asbestos in High-Risk Communities: Public Health Implications

“…ARDs from LAA seem to have distinctive features. Occupational exposure to vermiculite and/or residence in Libby is associated with mesothelioma [ 49 , 50 ] and ARD mortality [ 51 ], but also appears to provoke more progressive pleural disease than other fiber types [ 52 ]. Other unusual features include increased frequency of antinuclear autoantibodies (ANAs) [ 53 , 54 ] and systemic autoimmune disease [ 55 ], which have not described in other asbestos-exposed groups.…”