In utero exposure to organochlorines and age at menarche.

BACKGROUND To examine the effect of in utero exposure to polychlorinated biphenyls (PCBs) and dichlorodiphenyldichloroethylene (DDE) on age at menarche in offspring, we conducted a cohort study over two generations. METHODS Female participants (and their offspring) in a Michigan angler cohort in which organochlorine levels had been determined previously were studied. Of their 213 female offspring aged 20-50 years, 151 participated in the study (71%). We retrospectively determined age at first menstrual bleeding. Based on repeated maternal serum measurements between 1973 and 1991, we extrapolated PCB and DDE serum levels at the time of pregnancy. To estimate the association between in utero PCB and DDE exposure and age at menarche, we used linear regression analyses controlling for birth date period, maternal age at delivery, birth weight, breastfeeding, education status and maternal height. RESULTS An increase in the in utero DDE exposure of 15 micro g/l reduced age at menarche by 1 year (P = 0.04). There was no association with maternal PCB exposure. When controlling for estimated body size at menarche, the DDE association was no longer significant, based on a subsample of 102 women. CONCLUSION The DDE effect on age at menarche encourages further research about in utero exposures. Prospective studies including the offspring's DDE level before menarche are of particular interest.