NRC Report Suggests Improvement for EPA Risk Assessment Process

Dec. 9, 2008
A new report from the National Research Council (NRC) identifies improvements EPA could make to enhance its risk assessment process, which the committee said is bogged down by unprecedented challenges and should be streamlined to ensure the appropriate use of available science and technical accuracy.

EPA’s risk assessments estimate the potential adverse effects posed by harmful chemicals found in the environment in order to protect public health through four steps: hazard identification, exposure assessment, dose-response assessment and risk characterization. But the challenges of risk assessment have become increasingly complex, especially considering the issues of multiple exposure, multiple risks and susceptibility of different populations.

EPA therefore asked the Research Council to identify improvements it could make to enhance risk assessment. In turn, the committee presented recommendations and a proposed framework for risk-based decision making to provide a template for risk assessment in EPA and strengthen the scientific basis, credibility and effectiveness of future risk management decisions.

An Expanded Framework

The committee found that EPA is struggling to keep up with demands for hazard and dose-response information, is challenged by a lack of resources and should focus more attention on the formative stages of risk assessment, such as planning, scoping and problem formulation. This includes defining a clear set of options for consideration and involving decision makers, stakeholders and risk assessors upfront to evaluate whether the design of the assessment will address the problems.

The committee proposed that EPA adopt an expanded, three-phase risk assessment framework that begins with enhanced problem formulation and scoping to identify the risk management options and types of technical analyses required to evaluate and discriminate among the options. The second phase involves planning, hazard identification, exposure assessment, risk characterization, deciding whether the assessment is appropriate and allowing discrimination among risk management options, while the final phase examines the relative health or environmental benefits of the proposed risk management options for the purpose of reaching a decision.

The goal of the new approach is to assure that risk assessments are focused on the right questions, use the best available science and address the needs of decision makers.

Dose-Response Assessments

The committee also recommended that EPA adopt a unified approach for the dose-response step of risk assessment, which estimates the amount of a chemical that would lead to an adverse health effect.

Currently, dose-response assessments are conducted differently for chemicals that produce cancerous effects and those that produce other health effects. But according to the committee, the current noncancer assessment process, while valuable in certain public-health situations, does not provide decision makers with information on varying estimates of risk at different exposure levels, nor does it allow for adjustment of background exposures and underlying disease that may lead to increased risk. Rather, it provides a distinct line between possible harm and safety for all populations.

The committee suggested unifying the cancer and noncancerous dose-response assessment approaches to include assessments of background disease processes and exposures, possible vulnerable populations and modes of action that may affect a chemical's dose-response relationship in humans. This unified approach would incorporate advances in scientific knowledge and provide clearer estimates of population risk – information that is most useful for decision making, including informing risk trade-offs or cost-benefit analyses.

The Challenge

EPA’s current institutional structure and level of resources may pose a challenge to implementation of the report's recommendations, which are equivalent to major transformations in the agency's culture, the committee said. It would require a commitment to leadership, cross-program coordination and communication and training to ensure the requisite expertise.

According to the report, EPA should initiate a senior-level strategic re-examination of its risk-related structures and processes to make sure that it has the institutional capacity and resources to implement the committee's recommendations. In addition, EPA should develop a capacity building plan that includes budget estimates required for implementation.

For the full report, visit

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