Hexachlorobenzene residues and effects on esterase activities in pre-weanling rats after a reciprocal transfer between HCB-treated and control dams.

Female Wistar rats were divided into two groups. One group was fed ad libitum powdered rat chow containing 80 ppm hexachlorobenzene (HCB) and the other was fed HCB-free diet 2 weeks before mating until the termination of the experiment. Immediately after parturition, the pups were randomly culled to 10 per litter and 5 pups were reciprocally transferred between HCB and control dams. All pups within same paired litters were sacrificed on the 16th to 17th day and on the 20th to 23rd day after birth. Liver esterase activity toward indophenyl, thiophenyl, and p-nitrophenyl acetates was determined. The liver to body weight ratio, liver esterase activity and HCB residues were significantly higher in pups nursed by HCB-fed dams than in those nursed by control dams. The HCB residue in the liver, kidney, spleen, heart and brain was analyzed by gas-liquid chromatography. At about the weaning time, the HCB residue levels in pups transferred after parturition from HCB fed to control dams were similar to those in pups which remained with the control dams. The results demonstrated that HCB in tissues at about weaning time was obtained largely through milk. In addition, transmission of HCB through milk had greater effects on esterase activities in suckling pups than placental transmission. The pups born to HCB-treated dams and nursed by the control dams were similar to the pups born and nursed by the same control dams.