Resurfacing Recommended for Asbestos-Laden Roads
Crushed or broken serpentine in gravel roads and driveways can release cancer-causing asbestos fibers into the air. The health concern is serious enough for the state's Department of Toxic Substances Control to now recommend those roads be resurfaced.
Serpentine, California's state rock, occurs naturally in 44 of 58 counties. The greenish rock contains asbestos, a cancer-causing silicate mineral. Amphibole asbestos, which has been found in El Dorado County, is especially deadly. When serpentine rock is broken or crushed, it can release minute fibers that can lodge deep in the lungs. Those fibers can cause the almost-always fatal mesothelioma, a cancer that invades membranes in the chest and other body cavities.
The U.S. Environmental Protection Agency considers stone containing more than one percent of asbestos to be unsafe. California law states serpentine gravel can't have more than five percent asbestos.
The DTSC based its resurfacing recommendation on a 2002 study of a serpentine gravel road near Garden Valley in northeastern El Dorado County. The agency sampled air near Slodusty Road under a variety of conditions, including no traffic, minimal traffic and average traffic. The research showed there were significant concentrations of airborne asbestos at all points near the road whenever traffic was present.
The following summer the DTSC resurfaced Slodusty Road with limestone aggregate. The air study was duplicated and results indicated a 98 percent reduction in airborne asbestos concentrations.
Before resurfacing, the DTSC estimated the risk of cancer at Slodusty Road at 3 in 1,000 five feet from the road and 3 in 100,000 190 feet from the road.
To learn more about the study and its conclusions, read the following below.
