Health Risk Characterization
A risk estimate indicates the likelihood of occurrence of the different types of health or environmental effects in exposed populations. Risk assessment should include both human health and environmental evaluations. Ecological impacts include actual and potential effects on plants and animals. The numbers produced from the risk characterization, representing the probability of adverse health effects being caused, must be evaluated. To assess the overall potential for noncarcinogenic effects posed by more than one chemical, a hazard index approach has been developed based on Environmental Protection Agency’s Guidelines for Health Risk Assessment of Chemical Mixtures. This approach assumes that simultaneous subthreshold exposures to several chemicals could result in an adverse health effect. For carcinogens, risks are estimated as the incremental probability of an individual developing cancer over a lifetime as a result of exposure to the potential carcinogen.