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MECHANISM OF DIOXIN TOXICITY: RELATIONSHIP TO RISK ASSESSMENT
Citation:
Birnbaum, L. MECHANISM OF DIOXIN TOXICITY: RELATIONSHIP TO RISK ASSESSMENT. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-95/026, 1994.
Description:
Risk characterization involves hazard identification, determination of dose/response relationships, and exposure assessment. mprovement of the risk assessment process requires inclusion of the best available science. ecent findings in the area of dioxin toxicity have led to a major effort to reassess its risk. 2,3,7,8tetrachlorodibenzo-p-dioxin (TCDD), commonly referred to as "dioxin," is the most toxic member of a class of related chemicals including the polyhalogenated dibenzo-p-dioxins, dibenzofurans, biphenyls, naphthalenes, azo- and azoxy-benzenes, whose toxicities can be expressed as fractional equivalencies of TCDD. hese chemicals exert their effects through interaction with a specific intracellular protein, the Ah receptor. hile binding to the receptor is necessary, it is not sufficient to bring about a chain of events leading to various responses including enzyme induction, immunotoxicity, reproductive and endocrine effects, developmental toxicity, chloracne, tumor promotion, etc. ome of these responses appear to be linear at low doses. mmunotoxicity and effects on the reproductive system appear to be among the most sensitive responses. he Ah receptor functions as a transcriptional enhancer, interacting with a number of other regulatory proteins (heat shock proteins, kinases, translocases, DNA binding species). nteraction with specific base