Effect of oral and inhalation exposure to cadmium on the oestrous cycle in rats.

Female rats were administered by gavage an aqueous solution of CdCl2 for 14 weeks, 5 days per week, at doses of 0.04, 0.4, 4 and 40 mg Cd/kg/day or exposed by inhalation to CdO for 20 weeks (5 h per days, 5 days per week) at concentrations of 0.02, 0.16 and 1 mg Cd/m3. A pronounced increase in the mean duration of the oestrous cycle mainly due to lengthening of dioestrus was noted already 6 weeks after treatment of females given per os 40 mg Cd/kg or exposed to a concentration of 1 mg Cd/m3. No changes in the mean duration of the oestrous cycle were found in other experimental groups, although in the 0.16 mg Cd/m3 group an increased percentage of females with oestrous cycles lasting over 6 days was shown 18 weeks after exposure. Since Cd-induced lethality and decrease in body weight gain were observed in females given by gavage 40 mg Cd/kg or exposed by inhalation to a concentration of 1 mg Cd/m3, it is concluded that exposure to cadmium does not affect the sexual cycle unless other overt signs of Cd-toxicity are induced.