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

1. TCE Update
Former NAS Moffett Field Restoration
Advisory Board Meeting
January 14, 2010
Dan Stralka
Regional Toxicologist
EPA Region 9

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
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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
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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
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5. Current IRIS Development Process
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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.
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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
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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”
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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
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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
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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)
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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.
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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