The study - the largest to examine the question - will be published this fall in the American Journal of Respiratory and Critical Care Medicine.
Exposure to asbestos in the workplace, particularly in shipyards, has long been recognized as a risk factor for mesothelioma, a rare form of cancer affecting the lining of the lung. But in the new study, researchers found a consistent and dose-dependent association between mesothelioma and residential proximity to ultramafic rock, the predominant source of naturally occurring asbestos.
"Our findings indicate that the risks from exposure to naturally occurring asbestos, while low, are real and should be taken seriously," said Marc Schenker, professor and chair of the UC Davis Department of Public Health Sciences and the study's senior author. "This study provides important supportive evidence that naturally occurring asbestos causes mesothelioma - and public efforts should now shift to understanding the risk and how we can protect people from this preventable malignancy."
To put the mesothelioma risk in perspective, the disease kills about the same number of Americans each year as passive smoking. About 2,500 people a year die from mesothelioma in the United States, according to National Institute of Occupational Safety and Health statistics. About 3,000 deaths a year are attributed to exposure to secondhand tobacco smoke, according to U.S. Environmental Protection Agency statistics.
Ultramafic rock is distributed throughout the Sierra Nevada, Coast Ranges and Klamath Mountains in Northern and Central California, and has been a source of increasing concern as new housing developments cut through these areas. Of most concern are the areas of ultramafic rock associated with tremolite asbestos.
In their ambitious study, Schenker an
Source:University of California, Davis - Health System