Hexachlorobenzene toxicity in pigs

Hexachlorobenzene Toxicity in Pigs. den Tonkelaar, E. M., Verschuuren, H. G., Bankovska, J., de Vries, T., Kroes, R., and van Esch, G. J. (1978). Toxicol. Appl. Pharmacol. 43 , 137–145. A 90-day toxicity study was carried out in which pigs received 0.05, 0.5, 5.0, and 50 mg/kg/day of hexachlorobenzene (HCB). Special attention was given to the induction of porphyria and microsomal liver enzymes and the concentration of HCB in blood and tissues. Animals given the highest dose (50 mg/kg) showed clinical signs associated with porphyria and died during the experiment. At lower dosages these signs were not observed. An increased excretion of coproporphyrin was found in the 5.0- and 0.5-mg/kg groups, as well as induction of microsomal liver enzymes accompanied by increased liver weight (at 5.0 mg/kg) and characteristic histopathological changes in the liver. The concentration of HCB in blood and tissues was elevated at all dosages. Concentrations in fat were approximately 500 times greater than those in blood, while the concentration in liver was higher than in the kidneys and brain. Under the conditions of this experiment, a no-effect level was judged to be 0.05 mg/kg/day of HCB.