Study Re-Examines Safety of California Asbestos Site

The Clear Creek Management Area near Hollister, California (spanning San Benito and Fresno Counties) is home to one of the largest natural asbestos hazards in the world.  31,000 acres of exposed serpentine (a type of rock which contains naturally occurring asbestos) were once used for outdoor recreational activities by thousands of enthusiasts each year.   

The land is owned and controlled by California’s Bureau of Land Management (BLM).  It was open for public use by hikers, campers, rock climbers, ATV riders and more until 2008 when it was closed due to unsafe levels of airborne asbestos.   

The EPA mandated a public health assessment of the property that year to determine the risk of asbestos exposure due to recreational use of the land and the study recommended that the area be closed to minimize the danger to the public.

Asbestos exposure can cause mesothelioma, a deadly and aggressive type of cancer that kills roughly 3,000 Americans every year.  When asbestos fibers become airborne, they can be inhaled or ingested into the body.  Once inside, these fibers embed themselves in the soft tissue lining the respiratory system, heart, and digestive tract. 

As a natural response to these foreign bodies, the body then begins to build clusters of tissue around the intruders (called asbestos bodies) in order to isolate the fibers.  However, these asbestos bodies can then turn cancerous.  Once diagnosed with mesothelioma, patients typically have less than two years to live.  There currently is no cure for the disease.

Recently, the safety of the Clear Creek Management Area has been re-examined.  A new study entitled “Preliminary Analysis of the Asbestos Exposures Associated with Motorcycle Riding and Hiking in the Clear Creek Management Area (CCMA) San Benito County, California," sponsored by International Environmental Research Foundation examined the air quality of the area to determine the levels of free-floating asbestos. 

The study was authorized by the Off-Highway Motor Vehicle Recreation (OHMVR) Division of the California State Parks Department and authored by Richard Wilson of the Physics Department at Harvard University in addition to several other researchers. 

The OHMVR requested the study look into motorcycle riding because a previous 1979 study had found that people engaged in that activity suffered asbestos exposure rates 3% higher than people practicing other activities (even ATV riding).  However, authors of the study were quick to point out that other recreational activities “such as swimming, hiking, and snow skiing are over a 100-fold more dangerous."

The study used OSHA’s acceptable level of airborne asbestos fibers as a baseline for comparison.  OSHA has established a maximum level of 0.1 fibers of asbestos fibers per liter of air for workplace safety.  The latest Clear Creek study used random air testing and discovered levels ten times less than that (0.01 fibers per liter.)  That falls in line with the World Health Organization’s own estimated ambient level of airborne asbestos (between 0.001 and 0.01 fibers per liter.)

Daphne Greene, deputy director of the OHMVR Division, said that while the study was commissioned to assess whether or not the land could be opened once more without posing an unnecessary public health risk, the organization wasn’t yet willing to do that.  At least one group (the American Motorcyclists Association--AMA) is pressuring Greene and the BLM to reopen the land but Greene is determined to put the safety of everyone above the desires of the few and is unwilling to make recommendations until all of the data has been reviewed.  For now, the area remains closed for recreational use.