March 14, 2008, Cincinnati, Ohio - New research from the University of Cincinnati (UC) confirms that workers who were exposed more than two decades ago to low levels of an asbestos-like mineral have an increased risk of developing lung disease.

The mineral in question is vermiculite, a mineral with a fluffy, flaky structure. Previous studies carried out on the substance indicate that the vermiculite mined in Libby, Montana contained elevated levels of an asbestos-like fiber that could become airborne and inhaled during manufacturing processes that use the mineral.

The study was carried out over a 25-year period, and followed workers at a plant which until 1980 had used vermiculite mined in Libby. Current chest x-rays indicated that one fifth of the workers who were exposed to low level airborne fibers have showed changes in the lining of their lungs.

For workers exposed to high levels of airborne vermiculite, 54% of workers had lung changes as recorded by chest x-rays.
Senior research investigator James Lockey, MD says the study shows that the asbestos-like mineral in Libby vermiculite can cause chest x-ray changes at low levels of exposure that were previously not thought to have an effect.

Lockey, a UC professor of pulmonary and environmental health, says that the health effects of exposure are not immediate for manufacturing workers exposed to Libby vermiculite, but they should ensure their doctors are aware of the past exposure.

Once inhaled, the body has great difficulty expelling the asbestos-like fibers. They tend to lodge in lung tissue, causing chronic inflammation that eventually leads to lung disease or asbestos cancer.

Headed by Lockey, the UC research team conducted their 25-year study on workers who had worked with lawn care products containing the vermiculite mined in Libby. Of the original 513 workers the study started with, around 84% were still alive at the end of it, and a total of 280 workers participated fully in the study over the 25 year period.

In the study, workers underwent chest x-rays and interviews to answer questions about their job history and lung health. The chest x-rays were reviewed separately by three independent radiologists.

Among the findings were results indicating that the exposure to Libby vermiculite had caused thickening of the pleural membrane that surrounds the lungs. In cases of asbestos exposure, changes such as these can precede the development of asbestosis or mesothelioma.

Before the Libby vermiculite mine closed in 1990 it had provided up to 80% of the world’s supply of the mineral, which was widely used in home insulation, construction materials, gardening products, and packing materials. Vermiculite is now mined from sources that are not contaminated with the asbestos-like fibers.

James Lockey says the UC study highlights the need to consider the dangers not only of asbestos, but also of asbestos-like minerals that contaminate some natural mineral sources.

This entry was posted on Monday, March 17th, 2008 at 5:15 pm and is filed under Asbestos Exposure, Jobsite Exposure, Montana. You can follow any responses to this entry through the RSS feed. Responses are currently closed, but you trackback from your own site.