EXPOSURES TO NATURALLY-OCCURRING ASBESTOS FROM SPORTS AND PLAY ACTIVITIES IN EL DORADO HILLS, CALIFORNIA: WHAT WE DID, WHAT WE FOUND, AND WHY WE ARE SO UNPOPULAR

U.S. EPA Region 9 used activity-based sampling (ABS) to measure asbestos levels in the breathing zone of individuals simulating sports and play activities at three schools and a community park in El Dorado Hills, California. El Dorado Hills is a rapidly growing residential community built on a serpentine rock formation with deposits of naturally-occurring asbestos (NOA). Over 400 air samples were collected while EPA contractors simulated activities that included biking, jogging, baseball, baseball field maintenance, basketball, soccer, gardening, and playing in a toddler playground. Air samples were analyzed by the ISO 10312 TEM method and the Phase Contrast Microscopy Equivalent (PCME) fiber size classification (> 5 microns long, 0.25 – 3.0 microns wide, > 3:1 aspect ratio) was used to evaluate the exposures.

Results: Amphibole asbestos (actinolite-tremolite series) was detected in almost all personal exposure and ambient air samples. Activities which disturbed the soil produced elevated asbestos concentrations in the breathing zone. The highest concentrations were produced by activities in an elementary school garden, where amphibole asbestos concentrations in the child’s breathing zone were 62 times greater than concurrent ambient air levels. The exposures of children are of particular concern because their life expectancy exceeds the latency period for asbestos-related disease.

Observations: In the absence of documented disease, EPA’s sampling effort and results were very controversial in the community. The Agency’s motives were questioned, and stakeholder groups, including a national trade association, raised issues which included whether Region 9 counted structures which do not chemically or structurally meet the definition of “asbestos”. El Dorado Hills landed squarely at the nexus of geology, medicine, risk assessment, and public policy.