SITE INFORMATION AND CORRESPONDENCE 1993-1995

Home Browse Search

F. Amador March 1, 1993 Page 5 Dermal absorption of PCBs from soil should be based on the results of recent laboratory studies. Wester et al . (1990a) found approximately 20% of PCBs in mineral oil were dermally absorbed over a 24 hour period when applied to the skin of a rhesus monkey. Under similar experimental conditions, Wester et al . (1990b) found 3% dermal absorption of DDT from a soil matrix. These chemical-specific factors should be used instead of the default value of 10% . (It is appropriate to use 10% for organic compounds lacking data. ) For inorganic chemicals, use a value of 0 . 1% for cadmium and 3% for arsenic (Wester et al . , 1992a and 1992b) . Otherwise, use the 1% default value for inorganics. 10 . Table 7-13 . California cancer potency factors (Cal/EPA, 1992) must be used. When these are not available, IRIS or HEAST should be consulted. Reference doses (RfDs) should be obtained from IRIS or HE4ST, not derived from Applied Action Levels. When inhalation RfDs are not available, oral RfDs can be converted to equivalent inhalation RfDs using standard assumptions for inhalation rate and body weight. The uncertainties in this procedure should be noted. Section 8, Environmental Risk Assessment 1. Page 8-2 . The report and summary of field notes for the reconnaissance conducted on June 18 , 1992 , or other field surveys, should be included as an appendix. 2 . The environmental risk assessment eliminates the potential for exposure to surface and subsurface soils in Areas I and III based on the reasoning that the asphalt cover precludes contact with soils by wildlife. Will removal of the asphalt cover be prohibited in the deed restrictions in order to prevent exposure to wildlife in the future? Based on the aerial photograph (Figure 8-1) and the site description, it appears the site is in an industrialized setting which has little if any native vegetation. In its present state, it is unlikely to provide suitable habitat for wildlife. 3 . As the Environmental Risk Assessment has noted, riparian habitat bordering Mormon slough, located about 300 feet from the site, is an important area for wildlife. The special status species listed in Table 8-1, such as the valley elderberry longhorn beetle, the Swainson ' s hawk, and the California hibiscus, are associated with such riparian habitat.