Effects of pure chlorobiphenyls (2,4',5-trichlorobiphenyl and 2,2',4,4',5,5'-hexachlorobiphenyl) on the reproductive capacity in female mice.

The effects of two pure chlorobiphenyls (2,4',5-trichlorobiphenyl and 2,2',4,4',5,5'-hexachlorobiphenyl) on the reproductive capacity in female mice have been studied. The results obtained show that females given 0.5 mg 2,5',5-trichlorobiphenyl (TCB)/day or 0.5 mg 2,2',4,4',5,5'-hexachlorobiphenyl (HCB)/day for six consecutive days, starting on the first day of pregnancy, have significantly lower frequencies of implanted ova than the control females, whereas the frequency of implanted ova does not differ either between females given 0.05 mg/day of TCB or HCB and the control females, or between females given TCT 0.05 mg/day or 0.5 mg/day and those given the corresponding dose of HCB. Females given 0.5 mg/day of TCB or HCB, respectively, also have significantly higher contents in the livers of cytochrome P-450, on Day four of pregnancy, than the control females. The results also show that, under the experimental conditions used, neither the frequency of pregnancies nor the number of implanted ova per pregnant female differ significantly between the different groups.