Presented to MIT Air Quality Symposium on Air ToxicsAugust 4, 2004

Presented to MIT Air Quality Symposium on Air ToxicsAugust 4, 2004

EPA Risk Assessment Practices Evaluation

EPA Risk Assessment Practices Evaluation

Kerry L. Dearfield, Ph.D.Senior Scientist for Science Policy

Office of the Science AdvisorUnited States Environmental Protection Agency

Kerry L. Dearfield, Ph.D.Senior Scientist for Science Policy

Office of the Science AdvisorUnited States Environmental Protection Agency

Risk Assessment Risk Assessment

Risk assessment is a process where information is analyzed to determine if an environmental hazard might cause harm to exposed persons and ecosystems.

Paraphrased from “Risk Assessment in the Federal Government” (National Research Council, 1983)

What Is Risk? What Is Risk?

Definition: Probability of harm or loss

Risk = Hazard x Exposure

NRC Risk Assessment Paradigm NRC Risk Assessment Paradigm

Risk Assessment

Risk Management National Research Council, 1983

Dose-Response Assessment

HazardIdentification

RiskCharacterization

ExposureAssessment

Statutory and LegalConsiderations

Public HealthConsiderations

RegulatoryDecisions

SocialFactors

EconomicFactors

ControlOptions

Environmental Risk Analysis Environmental Risk Analysis

• Nature of effects• Potency of agent• Exposure• Population at risk

– Average risk– High-end risk– Sensitive groups

• Uncertainties of science• Uncertainties of analysisIdentify, Describe, Measure

• Social importance of risk• De minimis or acceptable risk• Reduce/not reduce risk• Stringency of reduction• Economics• Priority of concern• Legislative mandates• Legal issues• Risk perceptionEvaluate, Decide, Implement

Risk Assessment Risk Management

Comments Submitted to OMB Comments Submitted to OMB

• In early 2003, an OMB FR Notice (Feb 3, 2003; 68 FR 5492-5527) asked for comments on Federal Agencies’ risk assessment practices

• Comments submitted were forwarded to EPA to consider

General Nature of Comments General Nature of Comments

• EPA is being criticized for its risk assessment practices

• Generally, the nature of these criticisms are:• EPA must not intermingle policy judgments within the

scientific assessment of risk• Risk assessments should not rely on conservative (“worst

case”) assumptions that distort outcomes and yield estimates that grossly overstate risk

• Risk assessments should acknowledge the presence of considerable uncertainty

EPA Risk AssessmentTask Force

EPA Risk AssessmentTask Force

• EPA senior managers requested a Task Force examine EPA risk assessment practices; effort under Office of the Science Advisor auspices and has broad Agency representation

• Collect and analyze criticisms of our risk assessment practices• Determine fact from fiction• Reassess our intent• Consult with some expert group(s) regarding our

practices

EPA Risk AssessmentTask Force (cont.)

EPA Risk AssessmentTask Force (cont.)

• Task Force reviewed criticisms and grouped them according to common themes (e.g., conservatism, use of worst-case scenarios, susceptibility, uncertainty)

• Published Staff Paper in March 2004 (on OSA web site)

• FR Notice: March 25, 2004 (FR 69: 15326 – 15328); closed June 23, 2004

Document as Staff PaperDocument as Staff Paper• Document is an EPA Staff Paper• Presents the perspectives of EPA risk assessors

on how they understand risk assessment is conducted at the Agency

• Also presents staff recommendations for EPA and interested stakeholders to consider for how EPA can move forward to strengthen and improve its risk assessment practices

• Staff paper as it stands does not represent EPA policy

Staff Paper Opens DialogueStaff Paper Opens Dialogue• Most important, the Staff Paper will serve as

a vehicle for opening a broad dialogue among EPA staff, EPA managers, and external parties about the practice of risk assessment at EPA

• Paper represents the first step in a multi-step process; FR notice asks for comments on what issues/practices we need to focus on for refinement/improvement

Risk Assessment at EPA Risk Assessment at EPA

• EPA conducts risk assessment in order to provide the best possible scientific characterization of the risk in question, based on a scientifically sound, rigorous analysis of available information and knowledge.

• Risk assessment informs decision makers about the science implications of the risk in question.

EPA Risk Assessment Approach EPA Risk Assessment Approach

• Confidence in our risk assessments is critical.

• Approach is to use to fullest extent site- and chemical-specific data relevant to the decision needed.

• Without such information, we use defaults to ensure we cover the uncertainty of the remaining data or lack of data.

EPA Risk Assessment Approach (cont.)

EPA Risk Assessment Approach (cont.)

• The data and information we use in developing risk assessments has inherent uncertainty and variability.

• Due to the general uncertainty and variability of the data, information, and methodologies EPA assesses, we tend to take a more health and environmentally protective stance to ensure we do not underestimate risk.

Look At Issue for Air Toxics Look At Issue for Air Toxics

• Exposure assumption: use of 70 year exposure for HAPS (the “porch potato”)

HAPs Exposure Assessment:Conservative Issue

HAPs Exposure Assessment:Conservative Issue

Are they too conservative? Closer look at “Porch Potato” example for air toxics:

• Clean Air Act – specifically identify risk to individual most exposed (IME) as a critical decision variable for Hazardous Air Pollutants (HAPs)

• Agency Benzene action specifies Agency consider risks for lifetime exposure, e.g., 70 years (54 FR 38044, 1989)

“Porch Potato” Risk Assessment Approach 1

“Porch Potato” Risk Assessment Approach 1• For screening purposes, usually use 70 years as

lifetime exposure; if not pass screen, perform more refined assessment

• Refined assessment presents range of risk estimates using a distribution of exposure periods (which includes IME & 70 years) and models of exposures where people actually live

• Risk assessment portrays what is known about the range of plausible risks, even though there are always limited data

“Porch Potato” Risk Assessment Approach 2

“Porch Potato” Risk Assessment Approach 2• Also, need to take into account that people are

not stationary for 70 years, 24 hours/day, seven days/week, i.e., they are generally mobile

• Need to present differences in indoor exposures vs. outdoor exposures

• Range of risk estimates try to account for these variables, but cannot account for all aspects

“Porch Potato” Risk Assessment Approach 3

“Porch Potato” Risk Assessment Approach 3• It should be noted that many people spend a

majority of time at home – annual average concentration at home is indicative of exposure concentration

• Long-term average indoor and outdoor concentrations are nearly equivalent for many outdoor pollutants (although not all)

• People have been known to live in one location for much of or their entire lives

“Porch Potato”Risk Management

“Porch Potato”Risk Management

• Risk managers consider the range of risk estimates presented and decide which is the basis for acceptable risk

• When the decision is based on the 70 year lifetime exposure, it is a policy choice based on legal and policy constraints (usually considering the IME and using the Benzene action to support the 70 years exposure)

EPA Risk Assessment Recommendations

1

EPA Risk Assessment Recommendations

1 • Encourage the development of the specific data necessary to more accurately assess potential risks, including mode of action data.

• When we don’t have the specific data, we must continually look for opportunities to increase our certainty and confidence in the defaults and assumptions we use, i.e., encourage the derivation of more data-derived defaults.

EPA Risk Assessment Recommendations

2

EPA Risk Assessment Recommendations

2 • Focus on better communication of the data, assumptions and defaults used in our risk assessments, including how we deal with uncertainty.

• A major method to help address uncertainty is use of probabilistic analysis. We use it now for exposure, but we now need to explore the feasibility of probabilistic analysis for all phases of risk assessment.

EPA Risk Assessment Recommendations

3

EPA Risk Assessment Recommendations

3 • Transparency in risk assessment and risk

management practices is crucial• Continued use of planning and scoping before

and during a risk assessment – need this dialogue between risk assessors and risk managers

• Encourage work on a decision making framework

Other Risk Assessment ConcernsOther Risk Assessment Concerns• Cumulative effects on infants and children of

pesticide residues and other substances that have a common mechanism of toxicity

• Need to address cumulative effects of multiple stressors vs. single chemical risk assessments

• Need to characterize risk to infants, children, pregnant women, the elderly, or other populations that are identified as likely to be at greater risk

Reach Out EffortsReach Out Efforts• Staff Paper placed on EPA web site• Formal notice and comment via the FR• Direct meetings with interested stakeholders• Workshops with EPA’s Science Advisory

Board (and other groups, e.g., BOSC, NAS) on promising areas for further development of risk assessment practices

• Symposia at professional societies

Reach Out Efforts (cont.)Reach Out Efforts (cont.)• Society of Toxicology (SOT): proposal for a CCT

(Contemporary Concepts in Toxicology) workshop on probabilistic approaches for all phases of risk assessment.

• Society for Risk Analysis (SRA): proposal for a symposium at annual meeting on issue of compounding defaults (“conservatism”) in risk assessment.

• Society of Environmental Toxicology and Chemistry (SETAC): discuss the organism-level vs population-level assessment issue at annual meeting.

Office of the Science AdvisorWeb Site

Office of the Science AdvisorWeb Site

www.epa.gov/osa

Also contains SPC materials

The End The End

Thank you very much