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HEALTH RISK ASSESSMENTS • <br /> - 3 - <br /> Pages 7 and 8 of Section 6 contain the condensed risk and hazard <br /> soil exposure. Pages 8-11 show how the condensed equations were derived. Page 14 <br /> contains the condensed risk and hazard equations for air e <br /> how they are derived. xpoe, wh while pageions srl 1x14 show <br /> The dermal absorption fractions (ABS) are <br /> DTSC anticipates adding an ABS found in Table 3, which is attached to the memo. <br /> value for organophosphates of about 50%. If it is <br /> necessary to use an organophosphate ABS for your site, then 50% should be used. <br /> Table 2 contains some of the chemical data required by the risk and hazard equations. <br /> Section 7: Summation of Risk/Hazard for all media <br /> Staff will look at the health risk from each type of exposure, as well as the overall health <br /> risk at the site. In general, a risk of less than 10' probably does not require any further <br /> work, while a risk over 104 will probably require a cleanup. Site-specific decisions will be <br /> made when risks fall between 10-6 and 104. <br /> For the hazard value, if the summation of all hazard numbers is less than 1.0, it is usually <br /> considered that no health-based hazard is present. However, staff will still need to make <br /> site-by-site decisions. <br /> Ecological Screening Evaluation <br /> This section is not required as part of the health risk assessment. <br /> General Requirements <br /> The health risk assessment must clearly show all values used and assumptions made. It is <br /> strongly recommended that two tables be included. The fust should contain a listing of each <br /> chemical found at the site, the maximum concentration, and the toxic and environmental <br /> values used in the risk equations. The source of all information should be cited. <br /> A second table should show the risk values for each chemical for each exposure media <br /> (water, air, soil), and the hazard values for each chemical for each exposure media. A <br /> summary statement should follow detailing the summed risk and summed hazard for the site. <br /> Any questions regarding the health risk assessment must be directed to Regional Board staff, <br /> not to DTSC staff. <br /> If you have any questions, I can be reached at (916) 255-3104. <br /> WENDY WYE ILS <br /> Ag Regulatory Unit <br /> Attachment <br />