Central Coast Field Office

Naturally Occurring Asbestos

The United States Environmental Protection Agency (US EPA) no longer maintains an information web site about Naturally Occurring Asbestos.  They can be contacted at (415) 744-1730 or 1-800-231-3075.

U.S. Forest Service Pacific Southwest Region - Naturally Occurring Asbestos

What is Asbestos?
  • Asbestos is a group of six different fibrous minerals which occur naturally in soil and rock in some areas.
  • Asbestos fibers are hard to see with the naked eye.
  • Chrysotile asbestos is the main type found in the Clear Creek Management Area (CCMA).
  • Asbestos fibers are resistant to heat and have been used in a variety of man-made products for insulation and heat-resistance.
  • Asbestos fibers are very tough and stay in the same harmful form in the environment for a long time. 
Why is there Asbestos in CCMA?
  • CCMA is located on a formation of naturally occurring serpentine rock and soil which contains high concentrations of asbestos.
  • Asbestos mining activities in the area also contributed to the asbestos at CCMA
  • In areas where there is naturally occurring asbestos from serpentine rock, the percentages of asbestos in the soil range from 1% to as much as 50% in areas where asbestos has been mined. 
How does Asbestos enter the environment?
  • During geological processes, the crushing of serpentine rock results in asbestos which is more readily available to the environment.
  • The mining industry and roads built to support mining have broken up the asbestos causing it to disperse.
  • Asbestos fibers are further dispersed in the environment by wind and water.
  • Asbestos fibers stay suspended in the air for lengthy periods but ultimately settle onto the soil.
How does Asbestos get into my body?
  • Asbestos fibers in the air can get into your lungs when you breathe.
  • Asbestos fibers that get into your mouth can be swallowed into the stomach.
  • Asbestos fibers are not likely to penetrate the skin.
How might my family or I be exposed to Asbestos while visiting CCMA?
  • If you ride motorcycles or other Off-Highway Vehicles (OHVs), camp, hunt, or collect rocks, you can be exposed to asbestos fibers on dusty trails, especially during the dry season.
  • Because motorcycles raise considerable dust, if you watch motorcycle races you may inhale asbestos fibers.
  • If you are camping in especially dry and dusty areas you could be exposed to asbestos fibers which are in the air and soil at the camping areas.
  • Water in the creeks and pools of the CCMA may contain asbestos fibers and heavy metals.
  • Asbestos fibers in dust and mud from CCMA can remain on your clothes and vehicles when you leave CCMA.
How is the level Asbestos measured?
  • Asbestos is measured by the number of fibers(f) that are present in a cubic centimeter (cc) of outdoor air, or f/cc.
  • Asbestos fiber levels are monitored by the BLM. 
How could Asbestos affect my health?

Most of the information on the health effects of asbestos in humans comes from studies of people who were regularly exposed to high levels of asbestos in the workplace.  Any exposure to asbestos involves some risk, but for people who are exposed to low levels of asbestos for short periods the risk should be minimal.

Asbestos has been known to cause cancer in humans who have been exposed to high levels on a regular basis.  The two most common cancers found in these situations are lung cancer and mesothelioma - a rare cancer of the lining that surrounds the lung and stomach.

Smoking cigarettes dramatically increases the chance of getting lung cancer from asbestos exposure.

The non-cancer health effect most commonly associated with high levels of asbestos exposure is asbestosis which is scarring of the lung tissue.

  • If you have asbestosis, your lungs cannot expand or contract like normal lungs, which makes it difficult to breathe.
  • Asbestosis is only seen in people who received regular, high level exposure to asbestos.
  • Both cancer and asbestosis can take twenty to thirty years or more to develop after exposure.
Is there a medical test to determine whether I have been exposed to Asbestos?

There area no tests to determine effects from low level asbestos exposure.

  • Chest X-rays are only useful for identifying damage from exposure to asbestos from much higher exposure than you would receive from a visit to CCMA.
  • Because asbestos-related diseases take many years to develop, effects from recent, low dose exposure cannot be seen on a chest x-ray.
Precautions to take if you visit the Clear Creek Management Area:
  • Avoid areas where it is dusty or windy.
  • Never drink the water from the streams or springs.
  • Wash any vehicle that has been used at CCMA before returning home.
  • Wash clothing worn at CCMA separately from you other clothes.
  • If digging in dry dirt, try to minimize the amount of dust that is distributed.
  • Do not ride OHVs around the campground; they create dust.
  • If riding an OHV in a group, spread out along the trail and don't ride in another rider's dust.


Information Courtesy of:

U.S. Department of the Interior, Bureau of Land Management 
U.S. Environmental Protection Agency
ATSDR, Agency for Toxic Substances and Disease Registry
California Department of Health Services, Environmental Health Investigations Branch 

Bureau of Land Management
Central Coast Field Office
940 2nd Avenue
Marina, CA 93933
Phone: (831) 582-2200
Fax: (831) 582-2266
Office Hours: 7:30 a.m. - 4:00 p.m., M-F
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