A new study should help move the debate over living near asbestos veins from whether the situation is potentially dangerous to how people should best respond to the hazard, the study's lead scientist said Tuesday.
Dr. Marc Schenker, a UC Davis public health scientist, said the findings strongly support the hypothesis that low-level, non-workplace exposures to naturally occurring asbestos cause mesothelioma, a rare and highly lethal cancer of the lining of the chest.
While the odds of getting the disease are low, they are comparable to the risks of getting lung cancer from breathing secondhand tobacco smoke, a hazard that has captured much more attention from public health officials, he said.
Mesothelioma kills at least 2,500 people a year in the United States, compared with an estimated 3,000 deaths attributed to secondhand tobacco smoke, Schenker said.
"Public efforts should now shift to understanding the (mesothelioma) risk, and how we can protect people from this preventable malignancy," said Schenker, who chairs the UCD Department of Public Health Services.
The scientist joined fellow researchers and lung health advocates at a university press conference in Sacramento on Tuesday to speak in detail for the first time about a study that links living near asbestos-bearing rocks in California with higher rates of the rare cancer.
In areas closer to rocks that frequently contain asbestos - mainly serpentine - the researchers found more cases of mesothelioma, while farther away, they found fewer and fewer.
In California, serpentine, a greenish rock with a waxy surface, occurs mainly near earthquake faults in the Sierra foothills, the Coast Range and the Klamath Mountains.
Many of the asbestos areas are in the path of some of the most rapidly growing areas in the state, creating a potential hazard as housing and road construction tear into the veins and release fibers, which are small enough to reach deep into the lung, yet large enough to lodge there for life and cause cancer 20 to 40 years later.
Schenker called for more aggressive efforts in educating the public, reducing exposures and pinpointing where the most dangerous types of asbestos occur.
Public health advocates embraced his recommendations. But Marcella McTaggart, air district chief of El Dorado County, said the study contains too many holes to support local efforts at reducing dust at construction sites in the foothills.
Earl Withycombe, who follows asbestos issues for state and regional branches of the American Lung Association, said the work points clearly to the need for more research that will better quantify the risks.
Withycombe wants to see more measurements done that are aimed at assessing the health impacts of gardening, rototilling, horseback riding, or riding on off-road vehicles in regions with naturally occurring asbestos.
Residents also need to know the type and concentration of asbestos fibers they may be breathing daily, simply by living near areas of disturbed asbestos rock and soil, Withycombe said.
EPA officials said the findings support the agency's decisions in recent years to investigate El Dorado Hills and other areas of the country laden with asbestos-containing rock.
"The study by a respected researcher who is unaffiliated with the EPA underscores and reinforces our concern about the potential risk to environmental exposure to naturally occurring asbestos," said Dan Meer, an EPA official who supervised air test studies at schools and parks in El Dorado Hills.
EPA test results released in May showed that bicycle riding, playing baseball and other everyday recreational activities at the town's Community Park kick up fibers of a particularly toxic type of asbestos in concentrations many times higher than if there were no activity in the area.
One thing the study does not do, Schenker said, is provide enough information to tell a young family whether to live near naturally occurring asbestos.
"The risk to any individual is actually quite low," the scientist said, so families would have to weigh what risks they might face in other locations, as well as the exact nature of the mineral near their homes and their own personal risk tolerance.
What he hopes the study will do is provide more tools for people to take steps toward preventing new cases of a cancer clearly caused by asbestos exposure.
The latest, peer-reviewed asbestos study by Schenker, UC biostatistician Laurel Beckett, and others from UC Davis and Harvard University was posted online last month by the American Journal of Respiratory and Critical Care Medicine, and is expected to be printed in the journal this fall.
Researchers looked at almost 3,000 California cases of mesothelioma and compared their geographic distribution with pancreatic cancer - a control strategy to designed to rule out such risk factors as genetics and lifestyles.
Other scientists who track the issue have called the work provocative, but not conclusive.
So far, most asbestos research in the United States has focused on exposures on the job, such as to insulation workers handling asbestos- containing materials or, more recently, on asbestos exposures to people living near mines and mineral processing plants.
This is the first large study to look at patterns strictly related to where asbestos may be found naturally in the ground, and its implications could be broad.
While much of the recent interest in asbestos risks has involved construction stirring up fibers in El Dorado County, Withycombe stressed that El Dorado Hills is not unique in California or the United States. At least 40 states have some deposits of natural asbestos, he said.
Sen. Deborah Ortiz, D-Sacramento, said the UCD study boosts her push for better identification and public disclosure of confirmed or suspected asbestos areas, on a par with other geologic hazards such as flooding and earthquakes.
Her proposal, Senate Bill 655, would require state geologists to map "asbestos hazard zones," and local government would have to account for the zones in land-use decisions. Developers wanting to build in these areas would have to investigate the extent of asbestos before breaking ground. The measure cleared the Senate last month but faces tough opposition from the building industry.
The Bee's Carrie Peyton Dahlberg can be reached at (916) 321-1086 or firstname.lastname@example.org.