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  • Not every asbestos fiber resides in El Dorado County.

    At times it may seem so, with media and regulatory attention glued to the foothills construction in naturally occurring veins of asbestos. But public health concerns are emerging in several Northern California communities in scenarios as varied as the landscape.

    "El Dorado County has plenty of asbestos, but there are plenty of other places that are just as much of a concern," said Rick Fears, a state geologist with a new program that inspects proposed school sites for the fibrous minerals and other toxic substances.

    While the focus in El Dorado County's chaparral hills is large-scale housing tracts, asbestos in the jam-packed Bay Area is more often a red flag in redevelopment projects and underground work.

    In northwestern California, the issue is the many miles of backroads surfaced with crushed asbestos-containing rock called serpentine, which is native to the Klamath Mountains.

    On the Central Coast, the Salinas Valley topsoil so hospitable for lettuce and broccoli also hosts an abundance of asbestos fibers that eons of erosion have washed down the western slope of the Diablo Range, creating a potential breathing hazard for farmers tilling fields.

    On the east side of the Diablos, near Coalinga, air pollution regulators are worried for the thousands of off-roaders roaring about the federal Clear Creek Management Area, near the world's largest known asbestos deposit.

    Earlier this month, federal land managers closed 30,000 acres of the popular dirt-bike playground during the dry season at the urging of the U.S. Environmental Protection Agency. Recent EPA air tests indicate that motorcyclists are inhaling asbestos levels as high as nine times the legal exposure limits for industry.

    In the past five years, the concerns in El Dorado have prompted agencies to adopt policies governing construction and mining statewide.

    As a result, asbestos protection in California has widened considerably. What had been almost exclusively a worker safety issue in the demolition and remodeling of old buildings with asbestos-containing construction materials has expanded to a health issue for the public at large in breaking ground for new development.

    State environmental regulators routinely screen for asbestos at proposed public school sites within 10 miles of areas state geologists have flagged "asbestos hazard zones."

    Asbestos has turned up at 11 of 14 proposed school sites sampled so far, according to the state Department of Toxic Substances Control. Results on 12 more are expected later this year.

    Developers planning to excavate more than an acre in an asbestos zone must test for the minerals and have a dust-mitigation plan approved by local air pollution regulators before breaking ground. El Dorado County supervisors are scheduled today to vote on a stricter measure that would impose asbestos dust-controls on projects as small as a backyard swimming pool.

    And, as of 2001, gravel sold for covering roads, playgrounds, parking lots and other surfaces must be verified as virtually asbestos-free by a state-certified testing laboratory.

    Not long ago the California Geological Survey issued site-investigation guidelines to geologists who increasingly are asked to inspect properties for asbestos prior to land-use decisions, property acquisitions and development.

    Last week, state Sen. Deborah Ortiz, D-Sacramento, chairwoman of the Senate Health committee, amended a bill to require that cities and counties address naturally occurring asbestos in general plans that guide land-use decisions. Ortiz also added a requirement that state geologists compile maps identifying "asbestos hazard zones."

    "More and more we are being asked, 'Does it occur here?' said John Clinkenbeard, geologist with the California Geological Survey, which does the mapping.

    Another amendment would require property sellers within the asbestos zones to disclose the designation to prospective buyers.

    Asbestos is a family of silicate minerals that readily separate into thin but strong fibers remarkably resistant to heat. The invisible, needle-like fibers are hazardous because they can be inhaled deeply, penetrate lung tissue and even migrate through the wall of the lungs and stomach. The fibers can remain in the body for decades and eventually cause diseases - including mesothelioma, a lethal tumor of the lining of the chest and abdominal cavities; asbestosis, a widespread scarring of the lungs; and lung cancer.

    In California, asbestos typically occurs in and around serpentine, a greenish rock with a waxy luster used as a decorative stone in landscaping.

    Serpentine and other rocks in the ultramafic group are the predominant but not exclusive source of asbestos, distributed mostly along the Sierra Nevada foothills north of Yosemite, the Coast Ranges and the Klamaths.

    Air pollution officials in serpentine regions said that new rules requiring builders to monitor dust levels, watering down sites and covering exposed veins when they are done can vastly reduce asbestos exposure.

    As the East Bay Municipal Utility District bores a water supply tunnel through the Berkeley Hills, excavators are wearing respirators, air monitors and white protective clothing in the event their drills tear into asbestos veins. Likewise, every truckload of dirt is sampled and all tires are sprayed clean before leaving the site of the $33 million project - a bypass replacing the section of Claremont Tunnel that crosses the active Hayward Fault.

    "We're going by a conservative approach, assuming it is there," said Susan Suzuki, a health and safety specialist with the utility.

    Halfway through the dig, the air and soil analyses have yet to find the mineral fibers, utility officials said.

    Bridge contractors employed many of the same safeguards in recent earthquake safety work at the base of the Golden Gate's southern approach, where serpentine is abundant, according to records filed at the Bay Area Air Quality Management District.

    One mile south, in the Presidio, hazardous materials workers cleaning up an old Army dump a few years ago were instructed to remove and contain not only buried building debris that contained asbestos but also the underlying natural deposits of asbestos.

    Similarly, developers of a 27-acre South San Francisco business park, to be leased by the biotechnology giant Genentech, have naturally occurring asbestos to worry about in addition any chemical contamination remaining from more than a century of paint manufacturing that had occurred there on Oyster Point.

    These are among the 22 construction projects within the broken belts of serpentine ringing the Bay Area that air-quality regulators have monitored in the past few years. The hundreds of acres of artificial fill rimming the bay itself also contains asbestos from crushed serpentine, including some from the rubble removed after the 1906 earthquake, according to air district records.

    None of the Bay Area investigations on record has turned up the particularly toxic amphibole asbestos - mainly tremolite and actinolite - that has been found along with the more common chrysotile type in portions of El Dorado County and elsewhere in the Sierra foothills.

    The finding of amphibole asbestos - namely the tremolite and actinolite varieties - was a key driver in the federal EPA's choice of El Dorado Hills for its largest investigation of the fibrous minerals in California, said Dan Meer, an EPA official who supervised the tests, which showed significant exposures to children riding bikes and playing baseball.

    "We are not aware of any other place in the state where you have this converge of rapid development and large-scale disturbance of tremolite-bearing terrain," Meer said.

    But the Bay Area regulations are no less protective for chrysotile, which scientists say is harmful but significantly less potent than amphibole asbestos in causing mesothelioma.

    When the wind speed exceeded 25 mph, builders of the newly finished Ramblewood Park School in San Jose had to shut down, said Larry Aceves, superintendent of the Franklin-McKinley School District.

    Unlike their counterparts in the Sierra foothills, school officials in the fully developed Bay Area usually can't turn to an alternative, asbestos-free site.

    Workers had to haul off hundreds of truckloads of soil and replace it with clean fill. Street sweeper trucks continuously cleansed the residential streets. The asbestos-mitigation work accounted for $4 million of the $16 million cost to build the elementary school, he said,

    "I didn't mind going the extra yard for these kids," Aceves said.

    Graphic: Asbestos in California [116k JPG]

    About the writer:

Study cites asbestos impact

Published: Tuesday, Jun. 28, 2005 - 8:10 am
Last Modified: Monday, Aug. 21, 2006 - 2:26 pm

People who live near the kind of rocks that can contain asbestos are more likely than other Californians to contract a rare cancer, according to a study being published in the nation's leading respiratory medical journal.

The study by University of California, Davis, and Harvard University researchers has been eagerly awaited by federal officials trying to understand possible links between the rocks beneath our feet and asbestos-related diseases.

It could be "a huge part of the puzzle," said Dan Meer, one of several EPA officials who had heard the study's results described at public meetings.

Still, they and others characterized the work as only a start toward a better understanding of the possible dangers of weathering, digging or other dust-releasing activity in asbestos belts.

In studies like this, "interpretation is always a little bit delicate," said Michel Camus, a University of Montreal associate professor whose past work has suggested U.S. risk models may overstate some asbestos dangers.

While the new study is both "eye-opening" and "disturbing," he said, it's still likely that the environment is responsible for only a very small proportion of mesothelioma cases in North America.

The study could hold special interest for foothills communities, including El Dorado Hills, where elevated levels of asbestos fibers have been measured in the air around joggers, bicyclists and others pursuing dust-raising activities. It's still unclear whether people are breathing in enough of those fibers to become ill, and if so, how much of an upsurge that might create in an already uncommon cancer.

Workplace exposure to asbestos can cause a sometimes fatal disease, asbestosis, along with lung cancer and mesothelioma, the swiftly lethal tumor of cells lining the chest and other cavities.

Experts estimate that mesothelioma strikes just one or two people in a million every year in the United States.

Even so, it's often a focal point in tracing asbestos' effects because, unlike lung cancer, it doesn't have a number of other widely established causes, and, unlike asbestosis, very large exposures aren't needed to trigger disease.

Mesothelioma was the disease tracked in the new, peer-reviewed study awaiting publication in the American Journal of Respiratory and Critical Care Medicine and quietly posted online by the journal late last week.

The research team concluded that the risk of getting mesothelioma appeared to decline by 6.3 percent for every 10 kilometers farther away someone lived from possible asbestos veins.

"It seems unlikely to be due to chance," said Laurel Beckett, an expert in biostatistics at the UC Davis School of Medicine and one of the study's co-authors.

The apparent geographic component of the disease is "much weaker" than its well-known occupational causes, Beckett added, making it clear that more work is needed to probe just what's behind the numbers.

The study stressed that for the purposes of this analysis, researchers made a number of assumptions that have potential flaws. For example, they used the last job held to estimate roughly how great someone's workplace exposure to asbestos might have been, but they didn't have full work records.

They used each person's address at the time of diagnosis to determine possible proximity to asbestos, but they didn't have records for how long the person might have lived there or where else he or she had lived.

And since there is no map showing where all the asbestos in California lies, researchers used state maps of "ultramafic" rock, where veins of asbestos often form. It too is an imperfect indicator; large swaths of ultramafic rock are likely to be asbestos-free, and the fibrous mineral also can be found in other rocks.

Researchers drew their conclusions from reviewing nearly 3,000 cases of mesothelioma that that were reported to the state's cancer registry as being diagnosed between 1988 and 1997.

For comparison, they looked at the same number of pancreatic cancer cases drawn from the registry, matched for age and gender and diagnosis date. The pancreatic cancers were not more common closer to ultramafic rock, but the mesotheliomas were.

Interestingly, the distance needed to make a difference was relatively small. "Ten (kilometers) is about 6.2 miles," said Beckett. "That says that if you were standing on top of an asbestos rock and started running, your risk would drop as soon as you ran the first 10K race."

The medical journal's online posting put study authors in an awkward position, because some had been advised that talking to reporters before the print publication, expected in September, could result in the article's being yanked, said Claudia Morain, spokeswoman for the UC Davis cancer center.

The warning hadn't reached Beckett but did forestall comment from senior author Dr. Marc Schenker, chairman of the medical school's department of public health sciences.

The bind left some key issues unclear, including underlying estimates of how likely mesothelioma was found to be overall in different locations.

Those familiar with the issues stress that knowledge about environmental causes of disease builds up slowly, study by study, as each new finding brings investigators a little closer to the truth.

Dr. John Balmes, head of the Northern California Center for Occupational and Environmental Health, called the new paper "important enough to get into the best pulmonary journal," but added, "I don't think it's a landmark."

Balmes, a specialist in lung and environmental diseases who teaches at both UC Berkeley and UC San Francisco's medical school, said that on their own, studies like this one don't prove anything. Instead, they raise important questions that call for more work. This study will make "an incremental contribution" to figuring how out safe - or unsafe - it is to live near asbestos-bearing rock.

That assessment was shared by the federal Environmental Protection Agency. Today, the only federal standards for asbestos were designed to limit workplace exposure, said Lisa Fasano, a spokeswoman for the EPA's San Francisco office.

"There was never a standard developed for people living near naturally occurring asbestos," she said. "We need to continue to collect more information like this so we can finally make a determination on possible risks to residents."

Schenker has said his study was inspired by a 1998 investigation by The Bee that raised health questions about asbestos dust from dirt roads and construction sites in the foothills.

About the writer:

  • Bee staff writer Chris Bowman contributed to this report. The Bee's Carrie Peyton Dahlberg can be reached at (916) 321-1086 or

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Read more articles by Carrie Peyton Dahlberg -- Bee Staff Writer

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