Researchers examined recent chest X-rays of 236 people who worked at a plant in Marysville, Ohio, that until 1980 used vermiculite ore mined in Libby, Mont., that contained asbestos fibers.

Of the 236 workers tested, 62 (26.3 percent) showed pleural plaques, or scarring of the chest wall lining. The occurrence was as high as 44.1 percent in workers with the largest and heaviest exposure to the vermiculite ore. The percentage of workers with pleural plaques was 5.1 percent in those with the lowest levels of exposure.

Pleural plaques are usually considered markers of previous exposure to asbestos fibers. Because of the previous exposure to asbestos, there is a potential increased risk for other asbestos-related lung changes, including scar tissue within the lungs and certain types of cancer such as mesothelioma.

Preliminary results of the study were presented in San Diego May 24, 2005, at the annual International Conference of the American Thoracic Society.

"Our study shows that cumulative exposure to vermiculite from Libby is associated with a significant increase in pleural changes," said study leader James Lockey, MD, professor of occupational and pulmonary medicine at the University of Cincinnati College of Medicine.

"There is clearly a relationship with increasing exposure, but the pleural changes also were seen in the low-exposed workers," said co-author Amy Rohs, MD, a fellow in occupational and pulmonary medicine at University of Cincinnati.

About 0.2 percent of the general population with minimal history of exposure to respiratory hazards shows signs of pleural plaques, Dr. Lockey noted. "I was surprised at the significant increase in overal
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Contact: Richard Puff
richard.puff@uc.edu
513-558-4553
University of Cincinnati
24-May-2005