A California study finds that people who live near rocks containing asbestos may have a greater risk of getting a rare type of cancer.
Mesothelioma, a cancer of the cells lining the chest, is only known to be caused by breathing in asbestos fibers and has been strongly linked to workplace exposure.
The Sacramento Bee reports that researchers from Harvard and the University of California at Davis examined almost 3,000 cases of mesothelioma diagnosed in the state between 1988 and 1997. They compared them with 3,000 cases of pancreatic cancer matched for age, sex and other characteristics.
The survey found that the mesothelioma victims were more likely to live near ultramafic rock, a type of rock that is likely to contain asbestos. The same association was not shown with pancreatic cancer.
The researchers say that cancer risk appears to drop by 6.3 percent for every 10 kilometers (6 miles) of distance from rocks where asbestos occurs naturally.