1. Superfund Advisory Committee January 23, 2014 Tetrachloroethylene: Cancer Risk Values Office of Research and Standards Sandra Baird, Ph.D. 1

2. Road Map Brief HistoryProcessDecisionsDerivationShortform and Proposed Reg. Values 2

3. Brief History 2012 US EPA final based on liver tumors Derived values for leukemia and liver 2008 MassDEP based on leukemia and liver 2008 US EPA draft based on leukemia 2010 NRC Review lacked consensus on leukemia 2011 US EPA Interagency draft based on leukemia 3

4. Why did we review PCE? Basis of US EPA 2012 value different from – MassDEP’s 2008 and 1990 – US EPA 2008 and 2011 NRC Committee did not reach consensus US EPA 2012 two IURs >10-fold different US EPA 2012 liver-based IUR differed substantially from US EPA 2008 liver and leukemia-based IUR 4

5. ORS Process Review recent data, primary literature, models MassDEP Health Effects Advisory Committee Authors of US EPA Harmonized PBPK model Address concerns from NRC & interested parties – High leukemia background rate – Dose response – NTP data – Relevance to humans – Up to date PBPK model 5

6. Decisions US EPA harmonized PBPK model should be used JISA 1993 bioassay should be used not NTP 1986 Leukemia data should be used to derive PCE cancer risk values Total metabolized PCE should be used for interspecies extrapolation instead of total PCE 6

7. Leukemia Endpoint Background rate high but… – Treated animal rate higher Earlier and more severe in treated animals Statistically significant dose-response NTP & JISA No data to rule out relevance to humans 7

8. Derivation JISA 1993 (0, 50, 200, 600 ppm) Males and Female Rats Harmonized PBPK model Total Metabolized Dose 8

9. Cancer Risk Values Inhalation and oral values are based on same extrapolation from inhalation studies Inhalation unit risk (IUR) 3 x 10 -6 per ug/m 3 Oral cancer slope factor (CSF) 2 x 10 -2 per mg/kg/day 9

10. Method 3 Short-Form 2008-20122014 Unit Risk (per ug/m 3 ) 1 x 10 -5 3 x 10 -6 Residential (ug/m 3 ) No Significant Risk (NSR)2 8 Imminent Hazard (IH)10 50 Workplace (ug/m 3 ) No Significant Risk (NSR)10 40 Imminent Hazard (IH)60 200 10

11. Risk Conc. Back- ground Indoor Air Concentration (ug/m 3 ) Target Air Conc. Risk Conc. Back- ground DEP pre-2008 Tox ValueDEP 2014 Tox Value Proposed Target Indoor Air Concentration and GW-2 Standard Target Air Conc. GW-2 = 50 ug/LGW-2 = 20 ug/L 5 10 0.04 11 0.2 44 15 11

12. Thank You! More information on tetrachloroethylene cancer risk values will be posted on MassDEP Chemical page http://www.mass.gov/eea/agencies/massdep/toxics/sour ces/chemical-research-and-standards.html Questions? Comments? Sandra.Baird@state.ma.us 617-654-6587 12

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14. Risk Conc. Back- ground Indoor Air Concentration (ug/m 3 ) Target Air Conc. Risk Conc. Back- ground DEP pre-2008 Tox ValueDEP 2014 Tox Value Proposed Target Indoor Air Concentration and GW-2 Standard Target Air Conc. GW-2 = 50 ug/LGW-2 = 20 ug/L 5 10 0.04 11 0.2 44 15 Risk Conc. Back- ground US EPA 2012 Tox Value Target Air Conc. GW-2 = 30 ug/L 7.8 4 8 14

15. Method 3 Short-Form 2008-20122014US EPA Unit Risk (per u/m 3 ) 1 x 10 -5 3 x 10 -6 3 x 10 -7 Residential (u/m 3 ) No Significant Risk (NSR) 2840 Imminent Hazard (IH) 1050400 Workplace (u/m 3 ) No Significant Risk (NSR) 1040180 Imminent Hazard (IH) 602001800 15