Associations of Peripubertal Serum Dioxin and Polychlorinated Biphenyl Concentrations with Pubertal Timing among Russian Boys

Abstract

BACKGROUND: Dioxins, furans, and polychlorinated biphenyls (PCBs), dioxin-like and nondioxin-like, have been linked to alterations in puberty. OBJECTIVES: We examined the association of peripubertal serum levels of these compounds (and their toxic equivalents (TEQs)) with pubertal onset and maturity among Russian boys enrolled at ages 8-9 years and followed prospectively through ages 17-18 years. METHODS: At enrollment, 473 boys had serum dioxin-like compounds and PCBs measured. At the baseline visit and annually until age 17-18 years, a physician performed pubertal staging [Genitalia (G), Pubarche (P), and testicular volume (TV)]. 315 subjects completed the follow-up visit at 17-18 years of age. Pubertal onset was defined as TV > 3 mL, G2, or P2. Sexual maturity was defined as TV > /=20 mL, G5, or P5. Multivariable interval-censored models were used to evaluate associations of lipid-standardized concentrations with pubertal timing. RESULTS: Medians (interquartile ranges) of the sum of dioxin-like compounds, TEQs, and nondioxin-like-PCBs were 362 pg/g lipid (279-495), 21.1 pg TEQ/g lipid (14.4-33.2), and 250 ng/g lipid (164-395), respectively. In adjusted models, the highest compared to lowest TEQ quartile was associated with later pubertal onset (months; 95% CI) [TV 11.6 (3.8, 19.4); G2 10.1 (1.4, 18.8)] and sexual maturity [TV 11.6 (5.7, 17.6); G5 9.7 (3.1, 16.2)]. However, the highest compared to the lowest quartile of nondioxin-like-PCBs, when co-adjusted by TEQs, was associated with earlier pubertal onset [TV -8.3 (-16.2, -0.3)] and sexual maturity [TV -6.3 (-12.2, -0.3); G5 -7.2 (-13.8, -0.6)]; the nondioxin-like-PCB associations were only significant when adjusted for TEQs. TEQs and PCBs were not significantly associated with pubic hair development. CONCLUSIONS: Our results suggest that TEQs may delay, while nondioxin-like-PCBs advance, the timing of male puberty.