REPRODUCTIVE TOXICITY OF CHRONIC LEAD-EXPOSURE IN THE FEMALE CYNOMOLGUS MONKEY

The effect of chronic lead (Pb) exposure on menstrual function and cir culating concentrations of luteinizing hormone (LH), follicle stimulat ing hormone (FSH), estradiol (E2) and progesterone (P4) were studied i n female nulliparous cynomolgus monkeys (n = 32). Pb acetate (1500-mu- g/kg BW/day) was administered by capsule to monkeys in the following g roups; exposure from birth to 10 years (lifetime, n = 8), postnatal da y 300 to 10 years (adolescent, n = 8), and postnatal days 0 to 400 (ch ildhood, n = 8). Monkeys in the control group (n = 8) received gelatin capsules containing the vehicle only. Reproductive assessment of thes e monkeys was performed between 9 and 10 years, during which time the blood Pb levels in the lifetime and adolescent exposure groups were ap proximately 35-mu-g/dL. No overt signs of Pb-induced toxicity were fou nd in the general health or menstrual function. However, Pb treatment significantly suppressed circulating levels of LH (P < 0.042), FSH (P < 0.041), and E2 (P < 0.0001) during the menstrual cycle. Pb treatment had no effect on plasma concentrations of P4. These data indicate tha t chronic Pb exposure results in subclinical suppression of circulatin g concentrations LH, FSH, and E2 without producing overt signs of mens trual irregularity.