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SECTIONTHREE T®chatcal Approach <br /> 3.9.6 Assess Toxicology of Chemicals of Concern <br /> The toxicity assessment will use toxicity values developed and/or approved by U S EPA and the State <br /> of California to characterize the potential carcinogenic and non-carcinogenic effects of the chemicals of <br /> concern <br /> The toxicological data regarding the contaminants of concern are obtained from various data bases <br /> The hierarchy of toxicity values to be used in the assessment is as follows <br /> 0 Cancer potency factors(slope factors) or chronic reference doses (RfDs) promulgated into <br /> Califorrna regulations <br /> o Slope Factors (SFs) or chronic RfDs used to develop environmental criteria promulgated <br /> into California regulations <br /> o Integrated Risk Information Data Base(IRIS,U S EPA) <br /> o The most current edition of U S EPA's Health Effects Assessment Summary Tables <br /> (BEAST,U S EPA ECAO) <br /> o Toxicity values not available through any of the aforementioned sources will be obtained <br /> through the Office of Scientific Affairs(OSA) "Helpline " <br /> Tins toxicity information is summarized to assess the following <br /> a Dose-response relationships with respect to site-specific exposures that may be associated <br /> with potentially harmful health effects <br /> o Species differences with regard to both dose-response and target-organ relationships <br /> o Attenuation factors which may be used to adjust estimates of contaminant absorption and <br /> uptake through the intestinal tract or across the skin <br /> o The validity of long-term animal studies to evaluate the carcinogenic potential of a <br /> particular chemical <br /> Other data bases, including CIEMLINE, Toxh ne, Chenucal Abstracts, and available literature may be <br /> researched, of necessary, to evaluate toxicity of key chemicals of concern Table 3-8 provides proposed <br /> toxicity values for the potential chemicals of concern <br /> The toxicity assessment considers both carcinogenic risks and non-carcinogemc hazards posed by the <br /> . chemicals of concern The potency of potential carcinogens is quantified as a SF, that relates the dose <br /> of a chemical to the lifetime incremental excess cancer risk, expressed as a unitless probability In <br /> ® nigor rmo®rAwmcKTotmmoRTD ti7-nuG4w7w=4AwvA 3-7 <br />