U.S.G.S. releases report on rock and soil in El Dorado Hills, Calif.
SAN FRANCISCO – Today, the U.S. Geologic Survey released an independent analysis of rock and soil in El Dorado Hills, Calif.
The U.S. Environmental Protection Agency requested the U.S.G.S. analysis to answer mineralogical questions related to EPA’s October 2004 assessment of exposures to naturally occurring asbestos during sports and play activities in El Dorado Hills. The report, titled Mineralogy and Morphology of Ampiboles Observed in Soils and Rocks in El Dorado Hills, California, is available on line at 
“This study contributes important information to the scientific understanding of naturally occurring asbestos,” said Daniel Meer, Chief of the Response, Planning, and Assessment Branch in the Superfund Division of the EPA’s Pacific Southwest region. “The EPA continues to advise that a common sense approach to controlling exposure to dust in naturally occurring asbestos areas is a prudent course of action for California counties with naturally occurring asbestos deposits and for residents of those areas. Reducing exposures reduces the risk of developing asbestos-related disease.”
The USGS collected samples of rock, soil, and settled dust residue in the areas of El Dorado Hills where the EPA assessment was conducted. Selected air samples from the EPA 2004 effort were also examined. The samples were analyzed using a number of sophisticated test methods to determine the chemistry, mineral composition and mineral form of the amphibole asbestos structures detected.
The USGS report provides further geological characterization to augment the exposure data collected by the EPA. The USGS study documents the presence of respirable amphibole structures, including actinolite and tremolite, in soil and settled dust samples.