Relative abilities on a molar basis of hexafluoro-, hexachloro- and hexabromobenzenes to decrease liver uroporphyrinogen decarboxylase activity and cause porphyria in female rats.

Virgin female Agus rats were fed a diet containing hexahalogenated benzenes (700 nmol/g of food) for 70 days. The liver concentrations of these compounds were then determined and correlated with any depression in uroporphyrinogen decarboxylase activity and increases in porphyrin levels (indicating the induction of porphyria). Hepatic concentrations of the compounds corresponded to the series F greater than Cl greater than Br. However, depression of decarboxylase activity and increase in porphyrin levels were Cl greater than Br greater than F, (hexachlorobenzene and hexabromobenzene increased porphyrins by 513- and 17-fold respectively) suggesting that at its site of action in the liver hexabromobenzene may be more porphyrogenic than the chlorine analogue. This may suggest a relationship between the strength of the carbon-halogen bond and the induction of porphyria.