COMBINED EFFECTS OF MERCURY AND HEXACHLOROBENZENE IN THE RAT

The objective of the present study was to assess the potential interac tive effects of two Great Lakes chemical contaminants, hexachlorobenze ne (HCB) and mercury (HgCl2). Groups of 10 female Sprague-Dawley rats were administered by gavage single doses of HCB (400, 600 mg/kg b.w. i n corn oil), HgCl2 (10.0, 12.5 mg/kg b.w. aqueous) or combinations of both followed by observation for clinical signs of toxicity for 14 day s. Five animals from treatment groups died before the termination of t he study; one animal each in 600 mg HCB, 400 mg HCB + 10 mg HgCl2, and 600 mg HCB + 10 mg HgCl2, and two animals in 600 mg HCB + 12.5 mg HgC l2. The surviving animals were necropsied at the termination of the st udy, and hematological, clinical chemistry, histopathological and tiss ue residue analyses were performed. Relative liver weights were increa sed in both low and high dose groups of HCB but not in animals treated with HgCl2 alone. Co-administration of HgCl2 did not alter the HCB ef fects on the liver weight of the animals. Serum cholesterol levels wer e increased in all the groups receiving HCB but not HgCl2. No interact ive effects on other serum parameters were seen in animals administere d with both chemicals. Mild to moderate morphological changes occurred in the liver, thyroid, thymus, ovary and bone marrow of rats exposed to HCB or HCB + HgCl2, and in the kidney of HgCl2 or HgCl2 + HCB treat ed animals. More severe histological changes occurred in the groups re ceiving both chemicals. The histological effects appeared to be additi ve. It was concluded that co-administration with HCB and HgCl2 resulte d in additive effects in some of the endpoints measured but no synergi sm or antagonism was observed.