Legal exposure to asbestos-like material linked to lung damage 25 y...( Men and women who worked in a plant ...),Health

Men and women who worked in a plant that processed vermiculite tainted with asbestos-like fibers that originated from a mine in Libby, Montana, show high prevalence of scarring and thickening of the membrane that lines the chest wall some 25 years after the plant stopped using the materialeven those who were exposed at or below current legal levels.

Vermiculite is a mineral that expands to nearly 20 times its original size when rapidly heated and has a number of consumer applications, from gardening products to loose-fill home insulation. The Libby vermiculite was first suspected of causing lung damage in the late 1970s, when researchers documented a cluster of bloody pleural effusions among workers who handled it. At one time, the Libby mine produced up to 80 percent of the vermiculite used around the world.

In 1980, researchers examined 513 individuals who worked at a plant that processed Libby vermiculite and found pleural changes or interstitial fibrosis in 2.2 percent of the overall cohort. In this follow-up study, a research team led by James Lockey, M.D., the principal investigator of the 1980 report, found that the unadjusted prevalence in the still-living members of the original cohort was 28.7 percent for pleural changes and 2.9 percent for interstitial fibrosis.

The findings are published in the second issue for March of the American Thoracic Societys American Journal of Respiratory and Critical Care Medicine.

The high prevalence surprised even Dr. Lockey, senior researcher at the University of Cincinnati. I expected to see a higher rate of x-ray changes, but was surprised at the percentage, he said. We found that even low levels of exposure to asbestos-like fibers can cause thickening of the membrane that lines the chest wall.

Of the 431 workers from the original group who were still living, 280 participated in the follow-up study and were interviewed about their lung health and work history, including p
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