Elcrs based on the oehha unit risk for the adult

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ELCRs based on the OEHHA unit risk for the adult motorcycle, ATV, and SUV riders equaled or exceeded 1E-04, for maximum air concentrations, when the rider is exposed for more than 5 days/year (Table 6D). The ELCRs for the adult camper that camps for more than 1 day/year exceeded 1E-04, for maximum air concentrations (Table 6D). The ELCRs for adult campers for maximum air concentrations all exceeded 1E-04 as did the ELCR for child campers for maximum air concentrations and high estimate exposures. The ELCRs for adult hikers (30 year exposure duration) for maximum air concentrations also exceeded 1E-04. Additionally, the ELCR for adult fence builders/repairer equaled or exceeded 1E-04 for maximum air concentrations. Asbestos cancer risks for child hiking, vehicle cleaning, and post-decontamination driving scenarios were all less than 1E-04, with many minimum asbestos concentrations exhibiting risks of less than 1E-06. ELCRs for recreational users and BLM workers indicate unacceptable cancer risks for OHV riders, especially those in trailing positions, using EPA’s Superfund risk assessment guidance as a standard. The ELCRs based on the OEHHA unit risk were almost an order of magnitude greater than the U.S. EPA’s IRIS-based ELCRs. However, child hiking and most adult hiking, vehicle cleaning, and post-decontamination driving activities were within or less than EPA’s risk management range, indicating that these risks could, potentially, be mitigated through appropriate management decisions. Background The CCMA, located in San Benito County, California, is an approximately 76,000 acre area that contains the New Idria Serpentine Formation. This 30,000 acre geological area, which has been designated a Hazardous Asbestos Area (HAA) by the Bureau of Land Management (BLM), has soils with large amounts of naturally occurring asbestos. The CCMA is one of four geographically distinct areas of the Atlas Asbestos Mine Superfund Site. It is managed by the BLM, Hollister, California. The naturally barren slopes, bald ridges, network of bulldozed mining trails, and isolated location make the CCMA a popular location for recreational use by OHV users, hunters, hikers, and campers, including many families with children. Since the 1970’s investigators have studied asbestos dust exposures of recreational users and BLM employees within the HAA (Cooper et al., 1979, Popendorf and Wenk, 1983). The “Human Health Risk Assessment for the Clear Creek Management Area” was developed for the BLM by PTI Environmental Services (1992) to assess the potential hazards and risks posed to public health associated with the inhalation of airborne asbestos generated during OHV use, as well as other uses that generate less dust. The current work is part of the task to update BLM’s 1992 Human Health Risk Assessment (HHRA). This study differs from the BLM study in using transmission electron microscopy, rather than phase contrast microscopy, to analyze air samples for asbestos. In addition, this study specifically evaluates asbestos exposures to children. Children were not actually used during the
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