Science and Decisions Advancing Risk Assessment (2009) / Chapter Skim
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Appendix E: Environmental Protection Agency Program and Region Responses to Questions from the Committee
Appendix E: Environmental Protection Agency Program and Region Responses to Questions from the Committee
Pages 367-398
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From page 367... ...
. What improvement in EPA risk assessment practices would you find particularly helpful in the short term (2-5 years)
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From page 368... ...
First, are assessment activities that support the development of national ambient air quality standards (NAAQS) for the 6 "criteria" air pollutants, and, second, those conducted in consideration of emissions controls for hazardous air pollutants (HAPs or air toxics)
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From page 369... ...
Human exposure and/or health risk assessments and ecological risk assessments are performed during the periodic reviews of these standards. The process under which exposure and/or risk assessments are performed for the criteria pollutants is largely driven by statutory language and legislative history and involves substantial external peer and public review.
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From page 370... ...
Hazardous Air Pollutants The hazardous air pollutants (HAPs or "air toxics") are 187 substances listed in CAA (e.g., benzene, methylene chloride, cadmium compounds, etc.)
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From page 371... ...
Risk assessments for HAPs may include quantitative sensitivity analyses of exposure as mentioned above, and also include qualitative discussion of contributing uncertainties. However, the dose response information provided in IRIS (or other sources of dose response information)
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From page 372... ...
• As described above, the single greatest challenge in risk analysis for most hazardous air pollutants is the need to rely primarily on animal or limited human data for the development of hazard and dose response assessments. The interpretation and implications of such data for potential risk is typically one of the greatest sources of uncertainty in such assessments.
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From page 373... ...
Thus, any guidance on prioritization of recommendations or on those circumstances where potentially more resource intensive approaches are suggested, would be useful. The "key issues and challenges" discussions in Part I of this submission (for both the NAAQS process and hazardous air pollutants)
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From page 374... ...
(NRC 1983, 1994) in assessing aggregate and cumulative risks (hazard, dose response, exposure assessment and risk characterization)
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From page 375... ...
Consistent with Departments of Interior and Commerce regulations governing federal agency responsibilities relative to listed species, EPA consults with the U.S. Fish and Wildlife Service and National Marine Fisheries Service (the Services)
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From page 376... ...
We also manage the Superfund program to respond to abandoned and active hazardous waste sites and accidental oil and chemical releases as well as encourage innovative technolo gies to address contaminated soil and groundwater. This chapter provides a perspective on site-specific risk assessments conducted within the Superfund program.
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From page 377... ...
Risk assessment plays a critical role in determining that these criteria are met. Risk Assessment in the Superfund Program The Superfund program uses risk assessment to determine whether remedial action is necessary at a specific site and to determine the levels of remedial action where actions are required.
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From page 378... ...
Within the Superfund program we follow the basic risk assessment paradigm developed in the 1983 Framework document, i.e. the four steps of hazard identification, dose response assessment, exposure analysis, and risk characterization.
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From page 379... ...
The supplemental guidance document, "Standard Default Exposure Factors" (OSWER Directive 9285.6-03, March 25, 1991) , presents the Superfund program's default exposure factors for calculating RME exposure estimates (EPA 1991a)
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Probabilistic Risk Assessment Guidance Development of the OSWER probabilistic risk assessment guidance illustrates the process used in the Superfund program to develop guidance to address uncertainty (EPA 2001b)
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From page 381... ...
As part of the community involvement, results from both assessments were shared and the results discussed regarding the relative impacts of varying exposure assumptions in a probabilistic assessment on the decision. The Region presented the data incorporating the point estimate and showing that when other exposure assumptions were used the risk remained above the risk range described for Superfund above.
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From page 382... ...
Sensitive and Vulnerable Subpopulations (e.g., Children, Elderly, Tribes, Endangered Species) Children A common question asked of EPA is why Superfund risk assessments evaluate "dirt eating kids": Why should Superfund sites be cleaned up to levels such that children can safely "eat" the soil there?
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From page 383... ...
EPA has developed soil ingestion rates that are used as "default exposure assumptions" for adults and children. For young children (6 years or younger)
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From page 384... ...
Within the Superfund program there is extensive communication with the community regarding the remedial investigation, risk assessment, remedial actions, and Superfund process. One of the challenges that is faced at all sites is the explanation of complex scientific concepts such as hydrodynamic modeling, groundwater issues, changes in the understanding of the toxicity of chemicals, and application of ranges of toxicity values.
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From page 385... ...
Toxicity Data In the Superfund program, we rely on NCEA including the Integrated Risk Information System (IRIS) and the Superfund Technical Support Section as the source for toxicity values.
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From page 386... ...
Mixtures Typically at Superfund sites we evaluate exposures to multiple chemicals through multiple pathways. EPA program offices and regional risk assessors have a great need for both assessment information and risk assessment methods to evaluate human health and ecological risks from exposure to chemical mixtures.
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From page 387... ...
EPA Risk Assessment Guidelines and other Agency guidance. OW also does assessment of human health risk from microbial disease, from consuming drinking water, using water for recreation, and consuming aquatic organisms, and from contact with waste water.
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From page 388... ...
in 1996; this was specifically to highlight risks to children from pesticides. As pesticides are found in drinking water source waters, OW adopts the risk assessments done under FQPA by the Office of Pesticides Programs, at least as far as hazard identification and dose response; exposure assessment will differ given the purview of the legislation under which the risk assessment is conducted.
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From page 389... ...
In order to regulate a contaminant in drinking water, EPA must establish the following: the contaminant can adversely affect public health; the contaminant occurs or is likely to occur in public water systems at levels that can affect public health; and there is a meaningful opportunity for public health improvement as a result of the regulation. In answering these questions OW conducts quantitative risk assessments to determine nonenforceable Maximum contaminant level goals (MCLGs)
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From page 390... ...
. CWA requires that States and authorized Tribes designate uses for waterbodies (such as drinking water source water, fishable/swimable waterbody)
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From page 391... ...
The SDWA Amendments mandate that EPA consider risks to groups within the general population that are identified as being at greater risk of adverse health effects; these include children, the elderly, and people with serious illness (Safe Drinking Water Act [1996]
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From page 392... ...
OW may not delay these actions to await data generation or method development. Under SDWA OW is concerned with contaminant mixtures in drinking water in response to requirements of the Safe Drinking Water Act Amendments of 1996, including mixtures of DBPs and of Contaminant Candidate List chemicals (e.g., organotins, pesticides, metals, pharmaceuticals)
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From page 393... ...
Future Directions: Addressing Gaps, Limitations, and Needs The 1983 NRC paradigm for human health risk assessment for chemicals and radiation remains adequate. The 1998 paradigm for ecological risk assessment remains adequate.
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From page 394... ...
I: Human Health Evaluation Manual, Supplemental Guidance, "Standard Default Exposure Factors." Interim Final. OSWER Directive 9285.6-03.
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From page 395... ...
I -- Human Health Evaluation Manual (Supplement to Part A) : Community Involvement in Superfund RiskAassessments.
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From page 396... ...
2003b. Human Health Toxicity Values in Superfund Risk Assess ments.
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From page 397... ...
Standards Documents from Review Completed in 2008–Staff Papers. Technology Transfer Network National Ambient Air Quality Standards, U.S.
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From page 398... ...
2000. Daily soil ingestion estimates for children at a Superfund site.
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