ABSTRACT
This chapter introduces both general principles to protecting the sensitive individual, including the use of two specific uncertainty factors, and mechanistic toxicology and epidemiology information as the basis for identifying a sensitive subpopulation. Health Canada and the United States (U.S) Environmental Protection Agency (EPA) and others have developed guidance, which provides some limited advise on identifying the sensitive subpopulation for human health risk assessment. As more fully described by the US EPA, dose–response analysis for potentially susceptible subpopulations is often done as part of the overall dose–response analysis for health effects for any particular chemical. In risk assessment, high-quality human toxicology and epidemiology data that focus on no-observed-adverse-effect level information are optimum and can be used to directly calculate an Reference dose or reference concentration, with animal studies providing supporting evidence. Sensitive populations can sometimes be identified from epidemiology studies and understanding of toxicokinetics and toxicodynamics or by an understanding of the underlying mechanism of toxicity.
