Prepubertal and pubertal endocrine-disrupting chemical exposure and breast density among Chilean adolescents

Abstract

Background: During puberty, mammary tissue undergoes rapid development, which provides a window of heightened susceptibility of breast composition to the influence of endogenous and exogenous hormones. Exposure to endocrine-disrupting chemicals (EDC) may affect breast development and composition and the risk of developing breast cancer in adulthood. Methods: We evaluated the associations between breast density and urinary concentrations of phenols and phthalates collected at Tanner 1 (B1) and Tanner 4 (B4) in 200 Chilean girls. Total breast volume (BV), fibroglandular volume (FGV), and percent dense breast (%FGV) were evaluated at B4 using dual X-ray absorptiometry. Generalized estimating equations were used to analyze the association between concentrations of EDC biomarkers across puberty and breast density. Results: The geometric mean %FGV was 7% higher among girls in the highest relative to the lowest tertile of monocarboxyisooctyl phthalate [1.07; 95% confidence interval (CI), 1.01–1.14]. Monoethyl phthalate concentrations at B4 were positively associated with FGV (highest vs. lowest tertile: 1.22; 95% CI, 1.06–1.40). Bisphenol A displayed a U-shaped association with FGV; girls in the middle tertile had at least 10% lower FGV than girls in the lowest or highest tertiles. Monocarboxyisononyl phthalate showed a nonlinear association with BV. No other statistically significant associations were observed. Conclusions: Our results suggest that the developing breast tissue is susceptible to select EDCs during childhood and adolescence. Impact: This study may spur further investigations into environmental influences on breast development during puberty andhowshifts in pubertal breast density track through the life course to modify breast cancer risk.