The risk assessment process consists of four primary steps. Hazard identification evaluates the potential for a xenobiotic to induce a toxic hazard. Dose-response assessment characterizes the relationship between doses and incidences of adverse effects. Exposure assessment estimates the intensity, frequency, and duration of exposures. Risk characterization estimates the incidence of health effects under various types of exposure. Procedures for risk assessment are generally different for carcinogenic effects and non-carcinogenic effects. With