Nonoccupational exposure to chrysotile asbestos and the risk of lung cancer

Heavy industrial exposure to asbestos causes lung cancer and mesothelioma, but it remains unknown whether much lower environmental exposure to asbestos also causes these cancers.

Nevertheless, regulatory agencies, including the Environmental Protection Agency (EPA), have assessed the risk of lung cancer by extrapolating known risks from past industrial exposure to asbestos to today’s much lower environmental asbestos levels (roughly
100,000 times lower). The researchers also tested the EPA’s model for predicting the risk of asbestos-induced lung cancer in a population of women with relatively high levels of nonoccupational exposure to asbestos.

Mortality among women in 2 chrysotile asbestos-mining areas of the province of Ouebec was compared with mortality among women in 60 control areas, and age-standardized mortality ratios were derived. With the help of an expert panel, they estimated past exposure to asbestos among women in the mining areas and used these data with the EPA’s model to predict the relative risk of lung cancer. They then compared this prediction with the observed mortality ratios.

They found no measurable excess risk of death due to lung cancer among women in two chrysotile-asbestos- mining regions. The EPA’s model overestimated the risk of asbestos-induced lung cancer by at least a factor of 10.

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