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Effects of dieldrin on reproduction in the rat Virgo, Bruce Barton


The effects of chronic ingestion of technical dieldrin on reproduction in the rat were studied by determining the number of litters, the number and the viability of young born to animals exposed to dietary concentrations of 0, 13, 25, 37 and 53 ppm. Dieldrin had no effect on the reproductive success of the males. In the females dieldrin had no effect on fertility and did not significantly reduce litter sizes but evidence is presented which suggests the litter size reduction is real. Exposure of the dam during lactation reduces the survival of suckling young. It is suggested that the major cause of this mortality is acute poisoning from dieldrin secreted in the milk, although the growth responses of the young indicate that starvation resulting from decreased lactation may also be involved. None of the mortality is caused by increases in maternal aggression or neglect. Exposure during gestation alone also reduces the post-partum survival of young. The probable physiological mechanisms involved in the various effects are discussed.

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