Diesel exhaust affects the abnormal delivery in pregnant mice and the growth of their young.

To clarify the toxic effects of diesel exhaust (DE) on delivery in mice and on growth of young, C57Bl-strain females were exposed to 0.3, 1.0, or 3.0 mg diesel exhaust particles (DEP)/m3 or filtered clean air (control) for 4 mo (12 h/day, 7 days/wk). After exposure, some females from each group were examined by necropsy, and the remainders were mated with unexposed males. Estrous females for necropsy who had been exposed to 1.0 mg DEP/m3 had significantly lower uterine weights than the control estrous females. In the mated females, 9.1, 10.0, or 25.0% (0.3, 1.0, or 3.0 mg DEP/m3 of the pregnancies resulted in abnormal deliveries (abortion and unable delivery), but this was not significant. The rate of good nest construction by delivered females exposed to 3.0 mg DEP/m3 was significantly lower. Young were weighed at 11, 14, and 21 days, and weekly from wk 4 to 9 after birth. Body weights of male young of dams exposed to 1.0 or 3.0 mg DEP/m3 were significantly lower at 6 and 8 wk of age. Body weights of female young of dams exposed to 1.0 or 3.0 mg DEP/m3 were also significantly lower at 6, 8, and 9 wk. Vaginal orifices of young female mice whose dams were exposed to 0.3 and 1.0 mg DEP/m3 opened significantly earlier. The young were killed at 30 or 70 days during deep anesthesia, and their body weights, organ weights, and body lengths were measured. Anogenital distance (AGD) of 30-day-old males whose dams were exposed to 0.3 mg DEP/m3 was significantly shorter than that of the controls. Weights of thymus and ovary in 30-day-old females whose dams were exposed to 3.0 mg DEP/m3 were significantly lower. In 70-day-old males of dams exposed to 3.0 mg DEP/m3, body weights were significantly lower and AGD was significantly shorter. Weights of adrenals, testes, and seminal vesicles in 70-day-old males with dams exposed to 1.0 mg DEP/m3 were significantly lower. In 70-day-old females with dams exposed to DE, body weights in the 3.0-mg DEP/m3 group were significantly lower, and weights of adrenals, liver, and thymus in the 1.0-mg DEP/m3 group were significantly lower. Thymus weights in 70-day-old females with dams exposed to 0.3 mg DEP/m3 were significantly lower. Crown-rump length (CR) in 70-day-old females with dams exposed to 1.0 or 3.0 mg DEP/m3 was significantly shorter. These results show that toxic substances in DE might cause abnormal delivery in mice, and that exposed females affected the growth and sexual maturation of their young.