title: 2,3,7,8-Tetrachlorodibenzo-p-dioxin: a potent inducer of  -aminolevulinic acid synthetase.
abstract: 2,3,7,8-Tetrachlorodibenzo-p-dioxin, a toxic contaminant frequently formed during the synthesis of the herbicide 2,4,5-trichlorophenoxyacetic acid, was shown to be a potent inducer of hepatic delta-aminolevulinic acid synthetase in the chick embryo. As little as 4.66 x 10(-12) mole of the contaminant per egg produces a significant increase in the activity of the enzyme. Induction of the enzyme is related to the dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin and, in contrast to that produced with other drugs, is prolonged in time, with 70 percent of the maximum induced activity present 5 days after a single dose. This contaminant is implicated as the likely causative agent in an outbreak of porphyria cutanea tarda in workers in a factory where 2,4,5-trichlorophenoxyacetic acid was being synthesized.
mesh_terms: D000624:5-Aminolevulinate Synthetase / Q000378:metabolism*; D000818:Animals; D002642:Chick Embryo; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D004147:Dioxins / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004790:Enzyme Induction / Q000187:drug effects; D006846:Hydrocarbons, Halogenated / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D008099:Liver / Q000201:enzymology
chemical_list: D004147:Dioxins; D006846:Hydrocarbons, Halogenated; D003609:Dactinomycin; D003513:Cycloheximide; D000624:5-Aminolevulinate Synthetase