Elimination of various polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs and PCDFs) in rat faeces

A defined mixture (of a composition characteristic of that present in incinerator fly ash) of polychlorinated dibenzo-p-dioxins and -furans (PCDDs and PCDFs) was subcutaneously administered to rats and the elimination of the unchanged congeners via faeces was measured. 1) All congeners administered could be found in faeces. 2) The rates of elimination via faeces were rather different for the different congeners. 3) The most toxic congeners, 2378-T4CDD and 12378-P5CDD, were present in unmetabolized form in faeces to < 4% and < 8% of the administered dose within the first week. Thus, parenteral administration clearly minimizes contamination of the animal quarters when compared with corresponding oral dosing. 4) The rate of unchanged elimination was apparently especially pronounced for the higher chlorinated PCDDs and PCDFs. The highest excretion rate was found for 1234678-H7CDD (up to 30% of administered dose). 5) No obvious differences were observed in the rates of elimination of the unchanged substances via faeces of the 2378-substituted or the non-2378-substituted isomers.Abbreviations Used PCDDs PCDFs polychlorinated dibenzo-p-dioxins, and -furans - T4CDDs T4CDFs tetra-chlorinated dibenzo-p-dioxins, and -furans - P5CDDs P5CDFs penta-chlorinated dibenzo-p-dioxins, and -furans - H6CDDs H6CDFs hexa-chlorinated dibenzo-p-dioxins, and -furans - H7CDDs H7CDFs hepta-chlorinated dibenzo-p-dioxins, and -furans - OCDD OCDF octa-chlorinated dibenzo-p-dioxin, and-furan - DMSO dimethyl-sulfoxide