Abstracts: ISEE 21st Annual Conference, Dublin, Ireland, August 25-29, 2009: Poster Presentations
Background and Objective:
Asbestos contaminated vermiculite ore from Libby Montana was processed at the Western Mineral Products/W.R Grace processing plant in a densely populated urban residential neighborhood of Minneapolis, Minnesota, from 1936 to 1989. Waste rock from piles at the plant was made available to the community for use in yards, gardens and driveways.
To evaluate potential effects of community exposure to asbestos from contaminated vermiculite we recruited current and former community residents who never worked at the plant or lived with a plant worker, and were first exposed before 1980. Subsequent to an informed consent process, participants completed a self- administered questionnaire to supplement previously collected information, and were evaluated at regional clinics with occupational health expertise. Each participant completed a pulmonary function test and one PA chest x-ray to be evaluated using the NIOSH B-reading protocol. X-rays were read by two radiologists certified as NIOSH B-readers. Of particular interest in this analysis was intense, intermittent exposures experienced by community members, usually children, from playing on piles of vermiculite waste. We evaluated the prevalence of pleural abnormalities with respect to exposure to the waste. Prevalence odds ratios, adjusted for age, sex and history of jobs with potential asbestos exposure were estimated with multiple logistic regression.
Clinic visits were completed by 461 individuals. Prevalence of any pleural abnormalities, as determined by at least one B-reader, was 15% overall. Those who ever reported playing in the piles of waste rock had a prevalence of 19% compared to 12% for non-pile players. Adjusted prevalence odds ratios for pleural abnormalities and reporting ever playing in a waste rock pile was 2.0 (95% CI = 1.1–3.6).
These analyses support the hypothesis that community exposure to asbestos contaminated vermiculite is associated with measurable changes on x-rays.