Effects of DDT on stable laboratory mouse populations

Four stable laboratory mouse populations were established; each contained approximately 400 mice of both sexes and all ages postweaning living in a single cage, as well as neonates caged in separate nesting boxes with their dams. Two were used to determine the effects of continuous exposure to a dietary level of 100 ppm DDT while the other two served as controls. The results indicated a significant decrease (p less than or equal to 0.05) in neonatal survival (lactation index) within 20 wk after the beginning of exposure to the toxicant in one of the exposed populations and by 30 wk in the other. This deleterious effect of the DDT continued through each succeeding generation. On the other hand, improved postweaning survival in DDT-fed mice was noted. Histological examination showed no tumors in test or control animals; other pathology was seen more frequently in control than in test animals.