Moffett RAB TCE Update

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Moffett RAB TCE Update
Restoration Advisory Board
Former NAS Moffett Field
January 14, 2010
Dan Stralka, U.S. EPA
BRAC Program Management Office West

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Moffett RAB TCE Update

  1. 1. TCE Update Former NAS Moffett Field Restoration Advisory Board Meeting January 14, 2010 Dan Stralka Regional Toxicologist EPA Region 9
  2. 2. TCE Update • Significance of TCE at Superfund sites • EPA drinking water standard for TCE is 5 ppb • No similar EPA standard for vapor intrusion pathway and indoor air • EPA currently reassessing TCE toxicity • Integrated Risk Information System (IRIS) process • Chronology of TCE Toxicological Assessment • What’s New in the Draft 2009 TCE Toxicological Review • Questions 1
  3. 3. Integrated Risk Information System - IRIS Why is IRIS Important? Risk Assessment and Risk-Based Cleanup Levels (PRGs) Risk Assessment Risk Management 1. Hazard Identification IRIS (What type(s) of toxicity?) Identify Regulatory Options 2. Dose-Response (How much exposure produces toxicity?) Evaluate public health, 4. Risk Characterization economic, social & political (How much risk?) consequences 3. Exposure Assessment (How much are people exposed?) Agency Decisions & Actions 2
  4. 4. What is Involved in an IRIS Assessment? • Review scientific literature for toxicity data – identify useful (scientifically valid) studies • Analyze the relevant data – identify critical studies, toxicities – quantitative modeling of dose-response • Write a toxicological review • Calculate toxicity values for risk assessment – cancer potency factors – non-cancer reference doses • Publish on IRIS database 3
  5. 5. Current IRIS Development Process 4
  6. 6. Steps of Risk Assessment • Hazard Identification – what type(s) of toxicity can the contaminant cause? • Dose-Response Assessment – what amounts of exposure (doses) produce toxicity? • Exposure Assessment – to how much are people exposed? • Risk Characterization – how much risk are people experiencing? The first 2 steps are the main focus of IRIS. 5
  7. 7. Hazard Assessment Health Effects associated with TCE • Non-cancer • Cancer – Acute effects-neurological – Kidney – Various organ systems – Liver • Liver – Lymphoma • Kidney • Mode of Action – Immunological – Mutagenic – Reproductive – through metabolites – Developmental 6
  8. 8. TCE Toxicity Assessment Chronology • Purpose: Identify potential health effects of TCE and how much exposure to TCE causes harmful effects • 1985-87: 1st EPA TCE Health Assessment & Addendum • 1989: withdrawn from IRIS • 2000: “State of the science” papers published • Aug 2001: Draft EPA TCE assessment update - pubic comment and external peer review • Dec 2002: EPA Science Advisory Board (SAB) independent peer review report • Feb 2004: EPA hosts Symposium on New Science • Sep 2004: National Research Council (NRC) consultation on “Key Scientific Issues” • Jul 2006: NRC issues report “Assessing the Human Health Risks from TCE” 7
  9. 9. TCE Timeline (continued) • 2009: EPA interagency consultation • Oct 2009: EPA Federal Register Notice soliciting EPA SAB review panel nominations • Nov 2009: EPA releases updated Draft TCE Tox Review Assessment - external review draft • Jan 2010: IRIS TCE Tox Review Listening session on Jan 26 • Feb 1, 2010: 90-day comment period ends • Apr 2010: EPA SAB peer review on specific issues • 2010 -11: EPA SAB review report, revisions, final EPA review, other federal agencies, and White House discussion • 2011 & beyond?: Final TCE Toxicity Assessment on IRIS • Where to go for more information: http://www.epa.gov/ncea/ and click on the TCE link 8
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  12. 12. What’s New in the Draft 2009 TCE Toxicological Review • Cancer and Non-cancer values • Values for both oral and inhalation • Account for multiple sites of cancer • Mutagenic mode of action for kidney cancer 11
  13. 13. Possible TCE Indoor Air Screening Levels DRAFT – For Discussion Only Indoor Air 2009 EPA EPA Draft 2009 Tox Review Screening Level Proposed Plan (subject to change) (micrograms per cubic meter) (MEW/Moffett Field) Cancer Cancer Endpoint (10-6) (10-6) non-cancer Residential Screening Level 1 0.24 - 0.96 5.2 (24 hrs/day) Commercial Screening Level 5 2.5 - 9.8 17.5 (10 hrs/day) 12
  14. 14. TCE Update: Take Home • There are still several outstanding scientific and policy questions to resolve on TCE toxicity reassessment. • Finalization of TCE toxicity reassessment is still over a year or more away. • EPA has Five-Year Review process and will assess impact of any changes that revised TCE toxicity values have on health-based screening values and risk management decisions at each Superfund Site. 13
  15. 15. Questions? Dan Stralka Regional Toxicologist 415.972.3048 Stralka.Daniel@epa.gov Where to go for more information on TCE: www.epa.gov/ncea/ and click on TCE link

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