Hexachlorobenzene and Pentachlorobenzene Accumulated during Pregnancy is Transferred to Pups at the Accumulation Ratio in Dams

Abstract

Hexachlorobenzene (HCB) and pentachlorobenzene (PECB) were used to clarify how the rate at which lipophilic environmental pollutants are metabolized will affect their transfer to pups. In this study, the ratio of PECB/HCB transference to fetuses and suckling pups was investigated in rats fed a diet containing HCB (35.1nmol/100g diet) and PECB (351nmol/100g diet). The amounts of HCB and PECB transferred to fetuses were 0.44% and 0.15% of the amounts consumed by their dams, respectively, and the PECB/HCB concentration ratio in fetuses was 3.4. In pregnant rats on the day before parturition, the PECB concentrations in organs and fat tissue were 3 to 4 times higher than those of HCB. After parturition, PECB rapidly disappeared from the body of nursing rats during the lactation period, especially when compared with HCB. On day 2 after birth, HCB and PECB concentrations in the stomach contents of suckling pups were highest, and the PECB concentration was 3.5 times higher than that of HCB. HCB in the stomach contents decreased gradually (T_1/2=5.7 d) and PECB decreased rapidly (T_1/2=2.8 d) during the 15 d after birth. These findings indicate that the PECB/HCB transferred to fetuses and suckling pups was the same ratio found in the blood of their dams.