6    A RISK APPRAISAL PROTOCOL FOR DEVELOPING
CLEANUP CRITERIA IN THE RESTORATION OF
CONTAMINATED SITES
Daniel Kofi Asante-Duah, Senior Project Engineer,
International Technology (IT) Corporation,
Irvine, California 92714.
INTRODUCTION AND BACKGROUND
Hazardous waste sites may pose significant risks to the public because of the potential health and
environmental effects, and to the Potentially Responsible Parties (PRPs) because of the financial
liability stemming from their effects. To ensure public health and environmental sustainability, decisions relating to hazardous waste management should be based on a systematic and scientifically valid
process, such as is offered by risk assessment.
The Comprehensive Environmental Response, Compensation, and Liability Act of 1980, as
ammended (CERCLA, or "Superfund"), establishes a national program for responding to releases of
hazardous substances into the environment. The U.S. EPA recognizes the use of risk assessment to
facilitate decisions on whether or not remedial actions are needed to abate site-related risks, and also
in the enforcement of regulatory standards. Risk assessment techniques have been used in various
regulatory programs employed by Federal, State and local agencies.
The main objectives of this presentation are to:
• Discuss an approach for strategizing health and environmental risk assessment and site
restoration plans for potentially contaminated sites.
• Evaluate a case-specific risk assessment and develop target cleanup criteria for this subject site.
The emphasis will be on the use of health risk assessment techniques to support management
decisions in the development of Remedial Action Plans (RAPs) in hazardous waste site restoration
programs.
THE RISK APPRAISAL PROTOCOL
Although specific forms of risk assessment may differ considerably in their detail, they share the
same general logic. The overall risk assessment hierarchy is comprised of the elements shown in Figure
1. Further discussion of the basic elements are presented in the risk analysis literature.'"4
Health Risk Assessment
Important factors to consider in assessing risks and in setting up site cleanup criteria for a potentially contaminated site are discussed by several authors.2"6 The health risk assessment consists of the
process flow shown in Figure 2.4 The toxicity assessment is conducted as part of a risk assessment to
quantitatively and qualitatively assess the potential for adverse human health effects from exposure to
the chemicals of potential concern. The quantitative portion of the toxicity assessment entails identifying the relevant toxicity indices such as the Acceptable Daily Intakes (ADIs), the Reference Doses
(RfDs), and the Slope Factors (SF), or Cancer Potency Factors (CPFs). The qualitative aspect of the
HAZARD
IDENTIFICATION
EXPOSURE-RESPONSE
EVALUATION
EXPOSURE
ASSESSMENT
Figure 1.    Basic elements of risk assessment.
45th Purdue Industrial Waste Conference Proceedings, © 1991 Lewis Publishers, Inc., Chelsea, Michigan 48118.
Printed in U.S.A.
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