ABSTRACT
Dose-response assessment is the quantitative evaluation of toxicity as a function of exposure. Risk characterization integrates source assessment, exposure assessment, and dose-response assessment into a statement of the types and magnitudes of adverse effects that the contaminant may cause, qualified by probability of occurrence and uncertainty associated with the estimates. A key decision in preparing a risk assessment is the selection of suitable toxicity data for a given route of exposure. Risk assessments review available toxicological studies and evaluate the relevance of the derived toxicity values to the environmental exposure scenario. Agency for Toxic Substances and Disease Registry's Toxicological Profile for 1,4-dioxane derives oral and inhalation minimal risk levels for various durations of exposure. For chemicals that are considered to be known, probable, or possible carcinogens to humans, the cancer risk assessment is an important component of environmental risk assessment.
