Can the oral RfDs in the SL Table be applied to dermal exposure?
Not directly. Oral RfDs are usually based on administered dose and therefore tacitly include a GI absorption factor. Thus, any use of oral RfDs (or CSFs) in dermal risk calculations should involve removing this absorption factor. Consult the Risk Assessment Guidance for Superfund, Part A, Appendix A, for further details on how to do this. (See also RAGS Part E.) Note that the SL table displays the GIABS used in dermal SL calculations. • The exposure variables table in the SL background document lists the averaging time for non-carcinogens as “ED*365.” What does that mean? ED is exposure duration, in years, and * is the computer-ese symbol for multiplication. Multiplying ED by 365 simply converts the duration to days. In fact, the ED term is included in both the numerator and denominator of the SL algorithms for non-cancer risk, canceling it altogether. See RAGS for more information. • Where did the inorganic lead SL value in the Table come from? EPA has no consensus RfD or CSF for inor
Related Questions
- The exposure variables table in the SL background document lists the averaging time for non-carcinogens as "ED*365." What does that mean?
- For manganese, IRIS shows an oral RfD of 0.14 mg/kg-day, but the SL Table uses 0.024 mg/kg-day. Why?
- Can the oral RfDs in the SL Table be applied to dermal exposure?
