Department of Environmental & Aquatic Animal Health - Research Programs & Projects

Environmental Toxicology and Risk Assessment

Risk assessment is the process by which the probability or likelihood of some adverse effect of a contaminant to humans or the environment is estimated. Currently, considerable effort is focused on this topic because assessment of contaminant-associated risk is mandated in key federal laws including the Resource Conservation and Recovery Act (RCRA) and the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA). Risk assessment is also implied by the phrase "unreasonable risks" in the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) and the Toxic Substance Control Act (TSCA). In its present form, risk assessment involves four steps:

1. The identification of a potential hazard (e.g., low, but detectable, concentrations of lead in drinking water) 

2. The formulation of a plausible exposure scenario (e.g., human exposure from drinking water)

3. Identifying some exposure-effect relationship for predicting the level of effect (e.g., epidemiological studies of lead's effect on children exposed through drinking water) 

4. Combining the information from the first three steps to estimate the risk of an adverse effect (e.g., less than 1 in 1,000,000 exposed individuals will display an adverse effect as a consequence of the low levels of lead in the drinking water).