US EPA

The human health risk assessment is supported by methodology for utilizing toxic effects in animals consisting of carcinogenic and noncarcinogenic responses as a result of chronic, subchronic and acute exposures. ne of the initial steps in a risk assessment activity involves the estimation of exposure levels. hese estimates are typically based on either direct environmental measurements or predictions obtained from fate and transport models. he decision to develop assessment of risk from chronic exposure based on a nonthreshold model is made if a chemical demonstrates carcinogenic activity in animal bioassays and/or in human epidemiological studies. In the absence of any positive human epidemiologic data, it is assumed that a substance which induces a statistically significant carcinogenic response in animals has the probability to cause cancer in humans. he carcinogenic potential of 2,3,7,8-TCDD has been established based on chronic exposure in rodents. n addition, 2,3,7,8-TCDD has also been shown to be a liver cancer promoter in rodents. n the risk assessment on dioxins based on chronic exposure in experimental animals, 2,3,7,8-TCDD is regarded as a carcinogenic substance. arcinogenic data from animal bioassays are utilized for the assessment of risk for the purpose of estimating the likelihood of 2,3,7,8-TCDD being carcinogenic for humans and to determine the magnitude of the potential impact on public health.

Mukerjee, D., J. Stara, AND J. Schaum. RATIONALE FOR ASSESSMENT OF RISK ASSESSMENT OF RISK FROM EXPOSURE TO 2,3,7,8-TCDD. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-86/524 (NTIS PB90232133).

Chemosphere, 15(9-12):1805-1813, 1986