Organochlorine exposure and age at natural menopause

Background. The effect of potential endocrine-modulating organochlorines on menopause has not been extensively examined. Methods. We evaluated the associations of plasma polychlorinated biphenyls (PCBs) and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) with age at natural menopause. We analyzed data from 1407 women in a population-based, case-control study of breast cancer that was carried out in 19931996 in North Carolina. Results. The adjusted hazard ratio estimating the rate of onset of natural menopause was 1.4 (95% confidence interval = 0.9-2.1) for the top decile of DDE compared with values below the median. This association is similar in magnitude to the association between smoking and menopause (hazard ratio 1.4 [1.1-1.9]). No association was seen with PCBs. Conclusions. The suggested effect of DDE on timing of natural menopause encourages further research to corroborate these findings and evaluate potential mechanisms. Prospective studies, in which exposure measurements are taken before menopause, would be particularly useful.