Elimination of porphyrins and their precursors in rats pretreated with hexabromobenzene.

The elimination times of porphyrins and their precursors and of hexabromobenzene (HBB) itself were studied in female rats given 15 mg HBB by stomach tube every other day for 4 months. The concentrations of HBB in the blood, liver and adipose tissue were in the ratio 1:1.5:25, 24 hr after the last dose. Two weeks after the end of treatment, HBB was no longer detectable in the tissues. In animals given a single oral dose of 16.6 mg HBB/kg body weight, HBB was no longer detectable in adipose tissue 12 days after dosing. The half-life of HBB in adipose tissue was about 2.5 days in the animals given HBB for 4 months, and at the end of the treatment the concentrations of porphyrin in the liver, urine and faeces were increased to about 1000, 600-700 and 60-70 times the control values. The amounts of delta-aminolaevulinic acid and porphobilinogen in the urine of treated animals were 6-7 times those in controls. After the end of HBB treatment, it took almost 1.5 yr for delta-aminolaevulinic acid and porphobilinogen excretion to return to normal. Nearly 2 yr were needed for complete elimination of the accumulated liver porphyrins.