Exposure to asbestos in rocks may cause cancer

Reported by Susan Aldridge, PhD, medical journalist

People living close to natural sources of asbestos run an increased risk of mesothelioma, according to a new study.
It is well known that occupational exposure to asbestos is the cause of the rare cancer mesothelioma. Asbestos fibers attack the layers of membrane covering the lung. The disease takes 30 to 40 years to develop following exposure. Now researchers at the University of California, Davis, show that living near rocks containing asbestos can also cause the disease.

They looked at nearly 3,000 mesothelioma cases and found that around half had no obvious occupational exposure to asbestos. But living near asbsestos containing rocks could explain the occurrence of the disease. In fact, the odds of developing mesothelioma decreased by 6.3 per cent for every 10 kilometers away from an asbestos source. California has more naturally occurring asbestos sources than any other state. The researchers believe that some people living in areas with asbestos containing rocks may have even higher exposures than those who have been exposed occupationally.

Source
American Journal of Respiratory and Critical Care Medicine October 2005