Abstract
ISEE-0327 Background: Environmental exposures may alter timing of puberty, a factor related to later reproductive function, breast cancer, and other chronic diseases. The Breast Cancer and Environment Research Centers (BCERCs) are investigating environmental exposures and puberty in females. We hypothesize that hormonally active exposures because of their weak biologic activity may alter age at pubertal onset, although their effects may be modified by adiposity (the major source of prepubertal estrogen). Methods: A multi-ethnic cohort of 6-8 year old girls was established at three national BCERC sites. At baseline, urine specimens from 1151 girls were analyzed for biomarker panels of hormonally active chemicals (9 phthalate, 8 phenol, and 3 phytoestrogen metabolites). Breast development stages from physical examination, and covariate information including body mass index (BMI), diet, and selected characteristics were collected. We calculated multivariate adjusted prevalence ratios (aPR) for the association of baseline biomarker measurements with breast stage (stage B2+ [any] vs. B1 [none]) at first annual follow-up (N = 948). Results: Breast development (B2+) was present in 25% of girls. Three biomarkers had small but significant effects on breast stage in BMI-biomarker interaction models. For example, the likelihood of being B2+ decreased monotonically across quintiles of enterolactone (aPR = 0.92 [0.83-0.98] vs 1st [reference]) among girls with BMI-percentile ≥ median. BP-3 showed an inverse association and 2,5-dichlorophenol a positive association among high BMI-percentile girls; there was no association in low-BMI girls. Modification of the biomarker-B2+ association was observed with selected dietary factors that may be related to hormonal mechanism of the exposures. Conclusion: Preliminary results from this longitudinal study suggest that environmental exposures may be associated with pubertal developmental if considered jointly with body size distribution or dietary factors. Longer follow-up may provide further insight on effects of weak hormonal agents in relation to female puberty.
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