Polychlorinated dibenzodioxins and polychlorinated dibenzofurans.

Polychlorinated dibenzodioxins and polychlorinated dibenzofurans (dioxins) are contaminants with long biological half-lives. The most toxic dioxin, 2,3,7,8-tetrachlorodibenzodioxin (TCDD), has a half-life in humans of 9 years. A tolerable daily intake (TDI) of 10 pg/kg body wt/day has been recommended, which was derived from steady-state concentrations of TCDD at the no-observed-adverse-effect level in animal studies.

Short-term toxicological studies with impromidine (SK&F 92676): a specific histamine H2-receptor agonist.

Impromidine is a specific, potent histamine H2-receptor agonist. The present paper describes the results of acute and short-term repeated-dose toxicity studies with impromidine in rodents and dogs. The intravenous LD50 was 9.