Release 99-03      
January 15, 1999 


Joe Irvin
Jerry Martin
(916) 322-2990

ARB Issues Proposition 65 Notice for Airborne Asbestos in El Dorado County

The California Air Resources Board today notified El Dorado County health officials that airborne levels of asbestos fibers exceeding levels specified in Proposition 65 guidelines have been detected around the Weber Creek serpentine rock quarry, near Rescue.

ARB Executive Officer Michael Kenny, said, "The ARB has conducted monitoring around the quarry as part of our ongoing efforts to assess the public's exposure to asbestos in El Dorado County. The concentrations we found are greater than those typically measured in other areas of El Dorado County and point to the need to ensure that effective measures are in place at sources of asbestos emissions to protect public health."

ARB sampling data released today showed the average range of risk of mesothelioma (a form of cancer caused by exposure to asbestos) is 22 to 290 potential cancers per million people continuously exposed for 70 years. State law establishes a level of 10 excess cancer cases per one million people exposed for a 70 year lifetime as the threshold for Proposition 65 notices. To put these risk numbers into perspective, in California normal cancer rates are about 200,000 cancer cases in a population of one million people. A risk estimate of one-in-one million means that one extra cancer case may occur above the expected 200,000 cancer cases over a period of 70 years.

Air monitoring has been conducted in El Dorado County in cooperation with a task force of state and local officials that has spearheaded efforts to determine the extent and possible public health threat from asbestos. Serpentine rock, which sometimes contains asbestos, is common throughout California and, in fact, is the designated state rock. Asbestos emissions can be caused by vehicles passing over unpaved roads or parking lots which contain serpentine rock, or blown by wind from other nearby sources. While undisturbed serpentine asbestos is not health threatening, asbestos fibers can be released and become airborne when the rocks are crushed or broken.

The ARB has been monitoring around Weber Creek Quarry because of the possibility that its operations could result in significant emissions. The ARB also is stepping-up efforts to ensure that Weber Creek Quarry, and other similar facilities, are implementing the best available control measures to minimize fugitive dust and is developing guidelines for reducing the risks of asbestos exposure to construction operations, quarries, and unpaved roads.

More information on emissions and health impacts from naturally occurring asbestos can be obtained on the ARB website at or call (916) 322-2990.

        The Air Resources Board is a department of the California Environmental Protection Agency.  ARB's mission is to promote and protect public health, welfare, and ecological resources through effective reduction of air pollutants while recognizing and considering effects on the economy.  The ARB oversees all air pollution control efforts in California to attain and maintain health based air quality standards.

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