Superfund:

Improved Reviews and Guidance Could Reduce Inconsistencies in Risk Assessments

RCED-94-220: Published: Aug 10, 1994. Publicly Released: Sep 9, 1994.

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Pursuant to a congressional request, GAO reviewed the Environmental Protection Agency's (EPA) risk assessment process for Superfund hazardous waste sites, focusing on: (1) whether these assessments adhere to EPA guidance or vary by region; and (2) how EPA monitors the quality and consistency of these risk assessments.

GAO found that: (1) most of the 20 risk assessments reviewed generally adhered to EPA guidance, were prepared consistently among the 10 EPA regions, identified which contaminants were present, and used similar assumptions in measuring human exposure to hazardous contaminants; (2) some risk assessments were not completely accurate and did not follow EPA guidance for estimating contamination levels, adequately describe the assumptions' inherent weaknesses, or calculate the total risk of exposure; (3) EPA has used many different assumptions in estimating exposure, future site uses, residual contamination amounts, and the ways people absorb contaminants through their skin; (4) although EPA has conducted annual quality assurance reviews to monitor the quality and consistency of risk assessments, these reviews produce only summary descriptive information and do not analyze inconsistencies among risk assessments; (5) EPA could improve its risk assessments and better meet regional staff needs by analyzing assessment inconsistencies; and (6) identifying assessment inconsistencies would not require significant additional funding, since EPA already collects the necessary information in its annual reviews.

Recommendations for Executive Action

  1. Status: Closed - Implemented

    Comments: EPA's Hazardous Site Evaluation Division is now using its annual risk assessment review to monitor consistency of individual risk assessments with national practices. Officials have completed this analysis for risk assessments prepared in FY 1992, and are in the process of analyzing assessments prepared during FYs 1993 through 1995.

    Recommendation: The Administrator, EPA, should ensure that the agency's quality assurance reviews be used to identify and reduce inconsistencies in risk assessments by analyzing individual risk assessments to determine whether they are consistent with national practices.

    Agency Affected: Environmental Protection Agency

  2. Status: Closed - Implemented

    Comments: EPA's Hazardous Site Evaluation Division has provided national data and regional reports to its regions that demonstrate their level of consistency with requirements for risk assessments that were completed in FY 1992. EPA also plans to conduct this analysis for risk assessments prepared in FY 1993 through FY 1995 and distribute the results to regional offices.

    Recommendation: The Administrator, EPA, should ensure that the agency's quality assurance reviews be used to identify and reduce inconsistencies in risk assessments by providing the results of this analysis to the regions.

    Agency Affected: Environmental Protection Agency

 

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