Transfer of 2,4,5,2',4',5'-hexachlorobiphenyl and 2,2-bis-(p-chlorophenyl),1,1,1-trichloroethane (p,p'-DDT) from maternal to newborn and suckling rats.

Pregnant rats were given a small dose of 14C-2,4,5,2',4',5'-hexachlorobiphenyl (HCB) and 3H-DDT intraperitoneally. The transfer of HCB and DDT through the placenta and milk was then investigated. Transfer through the placenta was 2.7 and 1.5% (respectively) of the initial doses; transfer through milk was 39.2 and 21.5%. HCB is obviously more transferable than DDT through the placenta and milk, the ratio of the amount of HCB transferred through milk to the amount transferred through the placenta agrees with that for DDT. Concentrations of HCB and DDT in the whole suckling rat increases rapidly and is similar to the sigmoidal growth curve and change in lipid concentration. Therefore, the concentrations of the chemicals in the maternal tissue generally decrease in comparison with those of nonpregnant rats.