Document O15kbmEVpnN99B03vkX2bZdrQ

From: B fW 4 J R*41y on 01/20/2002 09 22 AM To: ASNppQonvirorcorp com, rhamsigenvironccrp :cm cc: M Ann Sradly/STB/DUP@OUP *ohn R 8owman/AE/DuPont@QuPont Subjsct: 10 ug/L m Environ Hazard Narrativa ------------------------- Fcrvrarded oy Barnard j RetiiyiAE/CuPcni on 01/20/2002 09 23 A M ---------- From: Bernard J Reilly on 01/20/2002 09 2i AM To cc: Subject: Gerald L Kennedy/AE/DuPont@DoPont Robert W Rickard/AE/DuPont@OuPont David M Rurak/AE/DuPontjgDuPont, M Ann 8raaley/S"rB/0UP@0UP, John R Bowman/AE/DuPontOuPont. Andrea V Maiinowaki/AE/DuPont@OuPont. Paula L Durst/STB/DUP@DUP, Heatber h jores/STB/DLP@DUP 10 ug/L in Environ Hazard Narrative I had thought there would not be significant changes between the draft EN V IR O N PFO A Hazard Narrative we reviewed a couple weeks ago and the final that we got late Thursday, 1/17. and that the feedback we got from E N V IR O N mid-last week was that the 14 ug/L in drinking water from the RfD analysis would remain the bottom line. However, the final version has changed the Margin of Exposure (M OE) for the cancer end-point risk-specific dose from 300 In the draft to 1000 in the final version. Using traditional exposure assumptions (20% drinking water), this results in a drinking water number of 1 0 ug/L. Obviously this is lower than the 14 ug/L that is based on the RfD analysis. If I am reading this accurately, I need to correct my representations to EPA Region 3 , 1told them the 14 ug/L would not be changed. Is there a reason I can offer? Recall this report has been and will be the sole basis for the Safe Drinking W ater Act Order that will require us to provide alternative sources if the concentration if the O rder is exceeded when we gather samples. EPA and Dr. Staats now have this report. Is there an argument that 14 ug/L still is the proper number? -B erm e From page 30 ot'Final Report In summary, the risk-specific dose obtained from MOE analysis (14 pg/kg BW-day) is similar to the RfD derived from monkey data (2 pg/kg-day; see Table 3). The RfD derived from the monkey study would also be protective of the potential carcinogenicity o f PFOA. Because the responses in monkey are thought to be more relevant to potential responses in humans, a drinking water concentration based on the negative findings in the monkey study is recommended The RfD corresponds to an allowable water concentration of 70 ug/L, while the risk-specific dose corresponds to an allowable water level of 50 pg/L. When deriving acceptable drinking water concentrations for Maximum Contaminant Levels (MCLs), the contribution of intake trom drinking water to total intake by all routes is considered. In the absence of specific data regarding the contribution to PFOA in drinking water to total exposure, the default assumption of 20 a source attribution from drinking water could be used. Hence, drinking water criteria protective against all non-cancer and cancer health effects potentially associated with PFOA exposure would be 10 pg/L or 14 pg/L, based on the risk specific dose o f 50 pg/L or an RfD of 70 pg/L. 0000.72 EDD0330154