1. PERCHLORATE Kevin Mayer U.S. EPA, Region 9 Background and History Occurrence Toxicity Regulatory Status

2. Regulation Determination Whether or Not to Regulate Toxicity – Referred to National Academy Of Sciences for second Peer Review. Final 2004/05? Analytical Method – Improvements in progress by EPA and Commercial Labs Treatment Technologies – Full Scale Commercial Units Operating with Multiple Methods….COST Occurrence - National Data in 2004

3. EPA Analysis External Peer Review EPA Analysis Internal Review Only Other Analysis (e.g.,World Health Org) External Review Process DATA Increasing Complexity Over Time Final Reference Dose Provisional Reference Dose Third Tier Analysis EPA’s SCIENTIFIC PROCESS

4. What is a REFERENCE DOSE (RfD)? Science Based Only, Not a Regulation DOSE is mg Chemical per kg body wt. / day RfD = No or Lowest Observed Effect Level Uncertainty Factors

5. Human Differences: Sensitive Populations Animal Studies to Human Effects Short Term Studies to Long Term Effects Lowest-Observed-Effect-Level (LOAEL) to No-Observed-Effect-Level (NOAEL) Database deficiency Serum Hormone Data Results Typical Factors for Uncertainties Magnitude of 1, 3 or 10

6. Perchlorate TOXICOLOGY - 1992 Blocks Iodide Uptake into Thyroid, Disrupts Production of Hormones Used as Human Drug Since 1950's EPA Provisional Reference Dose 1992-95 4 to 18 ppb in Drinking Water No Data on Children's Health or Chronic Effects 1000x Uncertainty Factors

8. TOXICOLOGY - 2002 Draft EPA Toxicity Assessment in 2002 Set RfD at 0.00003 mg/kg-day Drinking Water Equivalent = 1 ppb for Adults Studies from 1997 to 2001 Used to Measure Impact – Animal & Human Only 300x Uncertainty Factors Perchlorate EPA Focused on Sensitive Populations and Chronic Effects – Animal Studies

9. Thyroid Hormone Regulation T 4, T 3 PP-TH PA TTR/TBG Liver T4T4 T 4 -Gluc UDPGTs Certain Tissues T4T4 T3T3 Deiodinases Hypothalamus Pituitary I 2 + TyrosineI-I- T 4, T 3 TRH TSH Thyroid MIT DIT I-I- T4T4 T3T3 Brain Biliary Excretion Deiodination I - TrappingOrganic Binding-coupling Proteolysis, T 4, T 3 release Perchlorate Thiocyanate Nitrate PTU, Methimazole Sulfonamides Mancozeb, Thiourea Aminotriazole PCBs? Thiram Ah-receptor Pb-like induction Positive Negative

10. Human Clinical Data – 200 ppb

11. Perchlorate TOXICITY EPA Schedule January - June 2002 External Peer Review Expected Final Draft in Spring 2003 2003/04 National Research Council Review 2005 (approx.) Final Reference Dose on Integrated Risk Information System (IRIS)

12. NO Federal Standard. Only Site-Specific decisions under CERCLA, RCRA, SDWA As data gaps filled, perchlorate moves to the regulatory determination process EPA may make “off-cycle” regulatory determination when data become available -- rather than wait until next CCL regulatory determination in 2006 EPA may issue Health Advisory as a guidance in the interim, before a determination to regulate can be made. Perchlorate REGULATORY STATUS

13. MAXIMUM CONTAMINANT LEVEL (MCL) – Fully Enforceable Drinking Water Standard under SDWA EPA has 24 Months to Propose an MCL and an MCLG (non-enforceable MCL GOAL) Within 18 to 27 Months After the Proposal, EPA Must Publish a Final Rulemaking (MCL) Considerable Expert and Public Input Is Involved at Each Stage. The Regulatory Process

14. Perchlorate Arizona… 14 ppb California… 6 ppb Massachusetts… 1 ppb Maryland… 1 ppb New Mexico… 1 ppb (monitoring only) New York… 5 ppb and 18 ppb Nevada… 18 ppb Texas… 4 ppb, 7 ppb or 10 ppb State and Tribal Advisory Levels REGULATORY STATUS

15. Perchlorate Treatment Systems are Operating Various Types of Biological Systems Full Scale, Commercially Available Ion Exchange – Regenerate or Dispose Reverse Osmosis for Small Systems TREATMENT TECHNOLOGIES

16. Ion Exchange San Gabriel Superfund Site Baldwin Park, CA Fluidized Bed Bioreactors at Aerojet Superfund Site Rancho Cordova, CA

17. Nevada - 1998

18. Texas - 2002

19. California - 2004