Effects of DDT on reproduction in multiple generations of beagle dogs.

The effects of chronic oral exposure to 1, 5, and 10 mg of technical DDT/kg/day on: 1) age at puberty, length of gestation, fertility, success of pregnancy, litter size, and lactational ability of dams; 2) viability, survival to weaning, sex distribution and growth of pups; and 3) morbidity, mortality, organ/body weight ratios, gross and histologic abnormalities in all animals were studied through three generations of Beagle dogs. There were a total of 135 adult female and 63 adult male dogs in the project which produced 650 pups. There were no statistically significant differences among control and DDT-treated dogs in any of the reproductive variables, with the exception of age at puberty of the females. DDT-treated females had their first estrous cycles 2 to 3 months earlier (P less than .001) than the control dogs. Selected DDT-treated females, held for a second breeding period, had normal anestrous periods between their first and second estrous cycles. There was no effect of DDT on survival, growth, and sex distribution of pups, nor was there any influence on morbidity, mortality, gross or histologic findings in any of the dogs. All organ/body weight ratios were normal, with the possible exception of an increase in liver/body weight ratio in some DDT-treated animals.