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


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          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.

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          Cancer Mortality and Incidence of Mesothelioma in a Cohort of Wives of Asbestos Workers in Casale Monferrato, Italy

          Background Family members of asbestos workers are at increased risk of malignant mesothelioma (MM). Although the hazard is established, the magnitude of the risk is uncertain, and it is unclear whether risk is also increased for other cancers. Few cohort studies have been reported. Objective The “Eternit” factory of Casale Monferrato (Italy), active from 1907 to 1986, was among the most important Italian plants producing asbestos-cement (AC) goods. In this article we present updated results on mortality and MM incidence in the wives of workers at the factory. Methods We studied a cohort of 1,780 women, each married to an AC worker during his employment at the factory but not personally occupationally exposed to asbestos. Cohort membership was defined starting from the marital status of each worker, which was ascertained in 1988 from the Registrar’s Office in the town where workers lived. At the end of follow-up (April 2003), 67% of women were alive, 32.3% dead, and 0.7% lost to follow-up. Duration of exposure was computed from the husband’s period of employment. Latency was the interval from first exposure to the end of follow-up. Results The standardized mortality ratio (SMR) for pleural cancer [21 observed vs. 1.2 expected; SMR = 18.00; 95% confidence interval (CI), 11.14–27.52] was significantly increased. Mortality for lung cancer was not increased (12 observed vs. 10.3 expected; SMR = 1.17; 95% CI, 0.60–2.04). Eleven incident cases of pleural MM were observed (standardized incidence ratio = 25.19; 95% CI, 12.57–45.07). Conclusions Household exposure, as experienced by these AC workers’ wives, increases risk for pleural MM but not for lung cancer.
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            Vermiculite, Respiratory Disease, and Asbestos Exposure in Libby, Montana: Update of a Cohort Mortality Study

            Background Vermiculite from the mine near Libby, Montana, is contaminated with tremolite asbestos and other amphibole fibers (winchite and richterite). Asbestos-contaminated Libby vermiculite was used in loose-fill attic insulation that remains in millions of homes in the United States, Canada, and other countries. Objective This report describes asbestos-related occupational respiratory disease mortality among workers who mined, milled, and processed the Libby vermiculite. Methods This historical cohort mortality study uses life table analysis methods to compare the age-adjusted mortality experience through 2001 of 1,672 Libby workers to that of white men in the U.S. population. Results Libby workers were significantly more likely to die from asbestosis [standardized mortality ratio (SMR) = 165.8; 95% confidence interval (CI), 103.9–251.1], lung cancer (SMR = 1.7; 95% CI, 1.4–2.1), cancer of the pleura (SMR = 23.3; 95% CI, 6.3–59.5), and mesothelioma. Mortality from asbestosis and lung cancer increased with increasing duration and cumulative exposure to airborne tremolite asbestos and other amphibole fibers. Conclusions The observed dose-related increases in asbestosis and lung cancer mortality highlight the need for better understanding and control of exposures that may occur when homeowners or construction workers (including plumbers, cable installers, electricians, telephone repair personnel, and insulators) disturb loose-fill attic insulation made with asbestos-contaminated vermiculite from Libby, Montana.
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              Environmental exposure to Libby Asbestos and mesotheliomas.

              Thirty-one cases of mesothelioma resulting from exposure to Libby Asbestos have been identified from Libby, Montana. Eleven cases not previously reported are the subject of this report. These cases are in non-occupationally exposed people, appearing to have resulted from exposure to contamination of the community, the surrounding forested area, and areas in proximity to the Kootenai river and railroad tracks used to haul vermiculite. These exposures are considered to be of a low degree of magnitude, but are similar to those in Western Australia's crocidolite mine at Wittenoom Gorge. An epidemic of mesothelioma can likely be expected from this type of asbestos contamination over the next 20 plus years. Copyright 2008 Wiley-Liss, Inc.

                Author and article information

                Environ Health Perspect
                Environmental Health Perspectives
                National Institute of Environmental Health Sciences
                12 October 2011
                January 2012
                : 120
                : 1
                : 44-49
                [1 ]Division of Environmental Health Sciences, School of Public Health, University of Minnesota, Minneapolis, Minnesota, USA
                [2 ]Minnesota Department of Health, St. Paul, Minnesota, USA
                [3 ]Department of Environmental and Occupational Health, Colorado School of Public Health, Aurora, Colorado, USA
                Author notes
                Address correspondence to B.H. Alexander, Division of Environmental Health Sciences, University of Minnesota, School of Public Health, Room 1260, Mayo Building, 420 Delaware St. SE, Minneapolis, MN 55455 USA. Telephone: (612) 625-7924. Fax: (612) 625-4936. E-mail: balex@ 123456umn.edu
                Copyright @ 2011

                This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

                : 06 February 2011
                : 12 October 2011

                Public health
                lung diseases,asbestos,community exposure,amphibole,pleural abnormalities,libby vermiculite


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