By Ben Harder
A new study of the residents of Libby, Mont., confirms that even people who don’t work with asbestos can have lung abnormalities caused by the mineral. The “striking, very disturbing” findings indicate that asbestos released from mining or manufacturing operations may pose health threats to entire communities, says Christopher P. Weis of the Environmental Protection Agency in Denver.
Research in the late 1970s linked high rates of the lung cancer mesothelioma among miners working for W.R. Grace & Co. in Libby to their inhalation of asbestos from the town’s vermiculite mine. Studies elsewhere found that workers who processed Libby’s vermiculite, a mineral used in insulation and potting soil, also have high rates of mesothelioma and other lung problems. The government subsequently issued warnings and regulations to reduce occupational asbestos exposures.
In the early 1980s, the Reagan administration halted investigations of asbestos-related health problems in Libby. The data available at that time didn’t indicate to environmental regulators that non-occupational exposures to asbestos could be dangerous.
Renewed investigations, spurred in part by newspaper reports about health problems among Libby residents, have “changed our perspective on that completely,” says Weis. Libby residents, he says, “have clearly been exposed to high concentrations of asbestos and [consequently] are at higher risk for both noncancer and cancer-related disease.”
Since 1999, Weis and his colleagues with the Agency for Toxic Substances and Disease Registry in Atlanta and other government agencies have X-rayed the lungs of 6,668 people who had lived in Libby for at least 6 months before 1991, by which time vermiculite mining had ceased there. The volunteers also answered questions about whether they had participated in any of 29 activities that might have exposed them to asbestos. These included working in the town’s mine, living with a miner, using vermiculite insulation, and playing on a ball field near a vermiculite plant.
The researchers found that the more asbestos-linked activities a volunteer reported, the more likely that person was to have abnormalities in the pleura, or lining, of the lung. Scientists consider pleural abnormalities indicative of asbestos exposure. Ten percent of residents with one reported route of exposure showed pleural abnormalities on their X rays, while nearly 20 percent of those with six or seven routes of exposure–and 35 percent of those with 12 routes or more–showed similar abnormalities.
Even residents who couldn’t recall participating in any activities that might have exposed them to asbestos had a 6.7 percent chance of having pleural abnormalities, the researchers report in an upcoming Environmental Health Perspectives. That incidence is the highest reported to date among people who don’t work with asbestos.
The study confirms that dangerous asbestos exposure in Libby extended beyond workplaces, says William S. Beckett, who studies environmental medicine at the University of Rochester in New York. Precisely how much disease resulted or is likely to develop from community exposure to asbestos isn’t yet certain because most pleural abnormalities don’t actually interfere with lung function, Beckett adds.
“Community exposures can’t be ignored,” says Philip Harber of the University of California, Los Angeles. What’s more, since threats from asbestos may linger in an environment long after mining or processing of asbestos-containing material ceases, Harber says the new findings imply that “asbestos concerns are not just a thing of the past.”
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