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Mineral Fiber Toxicology
Citation:
Gavett, S. Mineral Fiber Toxicology. International Conference on Mesothelioma in Populations Exposed to Naturally Occurring Asbestiform Fibers, Honolulu, HI, November 09 - 10, 2015.
Impact/Purpose:
This abstract provides a summary of recent studies examining the relative toxicity, pathological responses, and biological mechanisms of action of Libby amphibole and naturally occurring asbestos samples usin several in vitro and in vivo methods. The studies are part of EPA's Libby Action Plan to address risk assessment efforts in Libby, Montana and other EPA regions where asbestos exposure is a concern.
Description:
The chemical and physical properties of different forms of mineral fibers impact biopersistence and pathology in the lung. Fiber chemistry, length, aspect ratio, surface area and dose are critical factors determining mineral fiber-associated health effects including cancer and asbestosis. The length and aspect ratio of fibers are especially critical, with many studies demonstrating that greater toxic effects occur with longer fibers or greater aspect ratios. However, given a sufficient dose, shorter or lower aspect ratio fibers may still exert certain toxic effects such as acute inflammation or initial fibrotic changes. A mine in Libby, Montana, was the world’s leading source of vermiculite for 70 years until its closure in 1990. The Libby vermiculite co-existed with various amounts of amphibole asbestos, which led to exposure of miners, other workers, and residents. The influence of fiber characteristics on lung cell responses was examined using Libby amphibole (LA) and amosite asbestos in several in vitro and in vivo models. Comparative toxicology of LA with other site-specific naturally occurring forms of asbestos give new insights into mechanisms of asbestos-induced inflammation, fibrosis, and tumorigenesis.