SYMPOSIA PAPER Published: 01 January 1992

Estimating Risk at a Superfund Site Contaminated with Radiological and Chemical Wastes


This paper describes the methods and results for estimating carcinogenic and noncarcinogenic effects at a Superfund site that is radiologically and chemically contaminated. Risk to receptors from disposal of waste in soil and resulting contamination of groundwater, air, surface water, and sediment is quantified. Specific risk assessment components which are addressed are the exposure assessment, toxicity assessment, and the resulting risk characterization. In the exposure assessment, potential exposure pathways are identified using waste disposal inventory information for soil and modeled information for other media. Models are used to calculate future radionuclide concentrations in groundwater, soil, surface water and air. Chemical exposure concentrations are quantified using site characterization data. Models are used to determine concentrations of chemicals in surface water and in air. Toxicity parameters used to quantify the dose-response relationship associated with the carcinogenic contaminants are slope factors and with noncarcinogenic contaminants are reference doses. In the risk characterization step, results from the exposure assessment and toxicity assessment are summarized and integrated into quantitative risk estimates for carcinogens and hazard indices for noncarcinogens. Calculated risks for carcinogenic contaminants are compared with EPA's target risk range. At WAG 6, the risk from radionuclides and chemicals for an on-WAG homesteader exceeds EPA's target risk range. Hazard indices are compared to unity for noncarcinogenic contaminants. At WAG 6, the total pathway hazard index for the on-WAG homesteader exceeds unity.

Author Information

Temeshy, A
Bechtel National, Inc., Oak Ridge, TN
Liedle, JM
Bechtel National, Inc., Oak Ridge, TN
Sims, LM
Bechtel National, Inc., Oak Ridge, TN
Efird, CR
Bechtel National, Inc., Oak Ridge, TN
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Developed by Committee: D18
Pages: 231–244
DOI: 10.1520/STP23844S
ISBN-EB: 978-0-8031-5213-7
ISBN-13: 978-0-8031-1445-6