Impending IRIS Updates May Lower Soil Cleanup Levels
1. Impending IRIS Updates Potential Impacts on Site Cleanup Florida Chamber Environmental Permitting Summer School July 22, 2010 Chris Saranko, PhD, DABT Environmental Planning Specialists csaranko@envplanning.com
2. Overview The toxicological properties of several of the most widespread and problematic chemicals dealt with at waste cleanup sites in Florida are under consideration by the EPA’s IRIS program – potentially resulting in more stringent cleanup requirements Regulation of carcinogens – the crux of the problem Linear vs. non-linear modes of action Florida’s statutory target risk limits Chemicals affected Inorganic Arsenic Hexavalent Chromium Polycyclic Aromatic Hydrocarbons (PAHs) 2,3,7,8-TCDD (Dioxin)
3. EPA’s IRIS Program IRIS – Integrated Risk Information System Widely used resource for information on the effects of chemicals on human health Database for EPA “toxicity factors” used by EPA and state environmental agencies (including FDEP) in human health risk assessments and risk-based screening levels High profile re-assessments have historically moved at a snail’s pace The current administration has made a commitment to expedite this process
5. Cancer - Linear or Non-Linear? EPA Guidelines for Carcinogen Risk Assessment (updated 2005) Long-awaited changes recognizing that all chemical carcinogens are not created equal Provided guidance for the agency to consider a chemicals “mode of action” (MOA) in determining: Whether or not that MOA is relevant to humans; and If relevant, which dose-response models are most appropriate to characterize potential cancer risks to humans (the linear vs. non-linear argument) EPA has been reluctant to meaningfully implement these guidelines
6. Florida’s Statutory Requirements F.S. §§ 376.30701, 376.81 In establishing soil cleanup target levels for human exposure to each contaminant found in soils from the land surface to 2 feet below land surface, the department shall apply the following, as appropriate: calculations using a lifetime cancer risk level of 1.0E-6; a hazard index of 1 or less; and the best achievable detection limit. However, the department shall not require site rehabilitation to achieve a cleanup target level for an individual contaminant that is more stringent than the site-specific, naturally occurring background concentration for that contaminant.
7. Arsenic Naturally occurring and widely dispersed - 20th most abundant element Found in fossil fuels at low levels – concentrated in combustion wastes (e.g. coal ash) Historically used in agriculture Common chemical of concern for site assessment and remediation
8. Health Basis for Arsenic Regulation Arsenic regulated by EPA as a carcinogen EPA toxicity values based on human exposure to arsenic in drinking water In the later half of the 20th century, aid organizations worked to bring clean drinking water to people in rural south and east Asia Many residents of this region previously drank from surface water sources with high bacterial loads This region has high levels of natural arsenic (50 – 3,000 ppb) Chronic health effects took years to appear Extent of problem only recently became clear (~60 million people affected) Long-term (chronic) health effects Skin lesions, Blackfoot disease Cancer (skin, liver, lung)
10. EPA Arsenic Regulatory Activities Ext. Draft IRIS Oral CSF (Lung / Bladder) Standard 50 ppb MCL 50 ppb MCL 10 ppb Final IRIS Value IRIS Oral CSF (Skin Cancer) Draft IRIS Tox. Review June 2010 Feb 2010 April 2010 2001 1999 201? 1998 1976 1942 2007 2005 SAB As Workgroup SAB Review NAS Report (50 not health protective) Full SAB Meeting
11. Draft EPA Cancer Slope Factor EPA Office of Water is lead agency Oral CSF Current value = 1.5 per mg/kg-day Proposed value = 27.5 per mg/kg-day “Theoretical” Drinking Water Risks Current 1×10-4 cancer risk - 2 ppb Proposed 1×10-4 cancer risk - 0.1 ppb Theoretical risk from Arsenic at 10 ppb MCL = 1.1 ×10-3 Proposed changes to CSF not likely to have an imminent effect on MCL ~18-Fold Higher!
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14. Industrial RSL = 0.09 mg/kg (currently 1.6)Both residential and industrial values are below natural background levels across Florida Potentially below detection limits
16. Arsenic Bioavailability University of Florida “monkey study” FDEP adopted a 33% bioavailability factor Site-specific studies can be placed at UF (~$50k) Bioavailability can’t counter 18X toxicity change
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18. Does not consider negative cancer data in animals and weak or negative epidemiological studies
23. Time Frame At June meeting, full SAB referred the review back to the SAB As Workgroup for additional consideration of issues raised in public comments Unclear how much longer SAB review could take Changes would be immediate for soil cleanup at EPA lead sites FDEP changes would require Chapter 62-777, F.A.C. revision MCL changes (if any) years away
24. Chromium Naturally occurring - 21th most abundant element Average concentration in earth’s crust 100 ppm (lower in FL) Oxidation (valence) state is critical !! Chromium III Most abundant and stable in environment Almost non-toxic (industrial soil SCTL 1,000,000 ppm) Chromium VI Almost all chromium ore is processed to Chromium VI compounds Carcinogen (industrial soil SCTL 470 ppm – based on inhalation)
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26. New animal studies from NTP indicate it can induce cancers following oral administration
27. NJ and CA have developed oral cancer slope factors for CrVI
28. NJ cancer slope factor applied in EPA RSL table (starting 12/09)
33. Industrial SCTLs = 12 mg/kg (currently 470) Comparisons with Background Residential values are below natural background levels across Florida Industrial values higher or lower than background depending on area
69. Implications for Florida Sites Exact timeframe for these changes at federal level is currently uncertain Some more imminent than others Arsenic / PAHs > Chromium VI > Dioxin Even less certainty with FDEP 62-777 will be re-opened eventually, but when? Dealing with these uncertainties at new sites with one or more of these chemicals will be a challenge
