An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »

Risk Assessment

Risk Assessment Guidance for Superfund (RAGS): Part A

RAGS Part A is one of a three-part series: Part B addresses the development of risk-based preliminary remediation goals; and Part C addresses human health risk evaluations of remedial alternatives. RAGS Part A: Human Health Evaluation Manual provides guidance on the human health evaluation activities that are conducted during the baseline risk assessment - the first step of the Remedial Investigation/Feasibilty Study (RI/FS). The baseline risk assessment is an analysis of the potential adverse health effects (current or future) caused by hazardous substance releases from a site in the absence of any actions to control or mitigate these releases (i.e., under an assumption of no action). The baseline risk assessment contributes to the site characterization and subsequent development, evaluation, and selection of appropriate response alternatives. The results of the baseline risk assessment are used to help determine whether additional response action is necessary at the site, modify preliminary remediation goals, help support selection of the "no- action" remedial alternative, where appropriate, and document the magnitude of risk at a site, and the primary causes of that risk.

Baseline risk assessments are site-specific and therefore may vary in both detail and the extent to which qualitative and quantitative analyses are used, depending on the complexity and particular circumstances of the site, as well as the availability of applicable or relevant and appropriate requirements (ARARs) and other criteria, advisories, and guidance. After an initial planning stage, there are four steps in the baseline risk assessment process: data collection and analysis; exposure assessment; toxicity assessment; and risk characterization.

The potential users of Part A are the individuals actually conducting health risk assessments for sites, who frequently are contractors to the EPA, other federal agencies, states, or potentientially responsible parties. It is also targeted to EPA staff, including those responsible for review and oversight of risk assessments (e.g. technical staff in the regions) and those responsible for ensuring adequate evaluations of human health risks (i.e., RPMs).

Related Resource

EPA's Ecological Assessments of Hazardous Waste Sites: A Field and Laboratory Reference Document

RAGS Part A Guidance Document

You may need a PDF reader to view some of the files on this page. See EPA’s About PDF page to learn more.