Radiographic Evidence of Nonoccupational Asbestos Exposure from Processing Libby Vermiculite in Minneapolis, Minnesota

Abstract

Background: Community exposure to asbestos from contaminated vermiculite ore from Libby, Montana, occurred in many processing sites in the United States, including a densely populated urban residential neighborhood of Minneapolis, Minnesota.Objective: We examined exposed community residents who never worked at the plant or never lived with a plant worker for radiographic evidence of lung changes consistent with asbestos exposure.Methods: We obtained posteroanterior chest radiographs to identify the prevalence of pleural abnormalities consistent with pneumoconiosis, as determined by consensus of two National Institute for Occupational Safety and Health–certified B-reader radiologists. We estimated cumulative asbestos exposure (fibers per cubic centimeters × months) with air dispersion model data and activity-based modeled exposure estimates for vermiculite processing waste contact. We modeled associations between pleural abnormalities and asbestos exposure using multiple logistic regression to adjust for year of birth, sex, and potential occupational asbestos exposure.Results: Radiographs were obtained for 461 participants. The prevalence of pleural abnormalities by B-reader consensus was 10.8%. A history of direct contact with the waste and ever playing in the waste piles was associated with pleural abnormalities {odds ratio [OR] 2.78 [95% confidence interval (CI): 1.26, 6.10] and 2.17 (95% CI: 0.99, 4.78), respectively, when adjusted for background exposure}. The regression coefficients for log-transformed measures (fibers per cubic centimeters × months) of background exposure and activity-based exposure were 0.322 (95% CI: 0.078, 0.567) and 0.063 (95% CI: –0.013, 0.139), respectively, when adjusted for each other, and 0.283 (95% CI: 0.104, 0.463) for cumulative exposure from all sources.Conclusion: These results support the hypothesis that community exposure to asbestos-contaminated vermiculite originating from Libby, Montana, is associated with measurable effects based on radiographic evidence.

Naturally Occurring Asbestos: Potential for Human Exposure, Southern Nevada, USA

“…The evidence of fibrous amphiboles on car tires and on clothing after recreational activities shows that they can be brought back to family members and thus increase the risk of exposure for other populations besides those directly exposed through outdoor dust emissions. Because health effects may occur even at low levels of exposure to fibrous amphiboles (Alexander et al, 2011;Hillerdal, 1999), our data indicate a potential public health threat in southern Nevada. Any potential future land-use projects should carefully determine the risks to both workers and the regional populations because disturbances to these natural desert surfaces cause increased dust emissions (Goossens et al, 2012).…”

HRCT/CT and Associated Spirometric Effects of Low Libby Amphibole Asbestos Exposure

“…33,34 Lower exposure has also been associated with pleural changes in a more recent study, but there were indicators of potential exposure misclassification. 36,37 A study of spirometry results from a community screening program of Libby residents demonstrated increased odds ratios between parenchymal changes and DPT as well as LPT only based on chest radiographs and restrictive spirometry (FEV 1 /FVC greater than lower limits of normal and FVC less than lower limits of normal). 36,37 A study of spirometry results from a community screening program of Libby residents demonstrated increased odds ratios between parenchymal changes and DPT as well as LPT only based on chest radiographs and restrictive spirometry (FEV 1 /FVC greater than lower limits of normal and FVC less than lower limits of normal).…”

The Worldwide Pandemic of Asbestos-Related Diseases

“…The most notable recent US example is in Libby, Montana, where significant rates of asbestos-related diseases have been observed among community residents who never worked in the vermiculite mining operations; the vermiculite ore was contaminated with as much as 25% amphibole asbestos. Asbestos-related disease has also been found in communities around industrial plants that produced vermiculite from the Libby ore (2,57). An increase in mesothelioma has been documented in communities with asbestos mining in South Africa (48), Australia (14,27), Italy (31) and Quebec (6).…”