Reproductive toxicity of chronic lead exposure in the female cynomolgus monkey

The effect of chronic lead (Pb) exposure on menstrual function and circulating concentrations of luteinizing hormone (LH), follicle stimulating hormone (FSH), estradiol (E2) and progesterone (P4) were studied in female nulliparous cynomolgus monkeys (n = 32). Pb acetate (1500 micrograms/kg BW/day) was administered by capsule to monkeys in teh following groups; exposure from birth to 10 years (lifetime, n = 8), postnatal day 300 to 10 years (adolescent, n = 8), and postnatal days 0 to 400 (childhood, n = 8). Monkeys in the control group (n = 8) received gelatin capsules containing the vehicle only. Reproductive assessment of these monkeys was performed between 9 and 10 years, during which time the blood Pb levels in the lifetime and adolescent exposure groups were approximately 35 micrograms/dL. No overt signs of Pb-induced toxicity were found in the general health or menstrual function. However, Pb treatment significantly suppressed circulating levels of LH (P less than 0.042), FSH (P less than 0.041), and E2 (P less than 0.0001) during the menstrual cycle. Pb treatment had no effect on plasma concentrations of P4. These data indicate that chronic Pb exposure results in subclinical suppression of circulating concentrations LH, FSH, and E2 without producing overt signs of menstrual irregularity.