Behavioral sexual dimorphism in school-age children and early developmental exposure to dioxins and PCBs: a follow-up study of the Duisburg Cohort

Abstract

Background: Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) are persistent organic pollutants that have been characterized as endocrine-disrupting chemicals (EDCs).

Objectives: Within the Duisburg birth cohort study, we studied associations of prenatal exposure to PCDD/Fs and PCBs with parent-reported sexually dimorphic behavior in children.

Methods: We measured lipid-based and WHO2005-TEQ (toxic equivalents established in 2005 by the World Health Organization)-standardized PCDD/Fs and PCBs in maternal blood samples and in early breast milk using gas chromatography/high-resolution mass spectrometry. At the child's age of 6-8 years, parents (mostly mothers) reported sex-typical characteristics, preferred toys, and play activities using the Pre-School Activities Inventory (PSAI), which was used to derive feminine, masculine, and difference (feminine - masculine) scores. We estimated exposure-outcome associations using multivariate linear regression. A total of 91-109 children were included in this follow-up.

Results: Mean blood levels of summed WHO2005-TEQ-standardized dioxins (ΣPCDD/Fs) were 14.5 ± 6.4 pg/g blood lipids, and ΣPCBs were 6.9 ± 3.8 pg/g blood lipids, with similar values for milk lipids. Regression analyses revealed some highly significant interactions between sex and exposure-such as for ΣPCBs in milk, pronounced positive (boys: β = 3.24; CI = 1.35, 5.14) or negative (girls: β = -3.59; CI = -1.10, -6.08) associations with reported femininity. Less pronounced and mostly insignificant but consistent associations were found for the masculinity score, positive for boys and negative for girls.

Conclusions: Given our results and the findings of previous studies, we conclude that there is sufficient evidence that these EDCs modify behavioral sexual dimorphism in children, presumably by interacting with the hypothalamic-pituitary-gonadal axis.

Citation: Winneke G, Ranft U, Wittsiepe J, Kasper-Sonnenberg M, Fürst P, Krämer U, Seitner G, Wilhelm M. 2014. Behavioral sexual dimorphism in school-age children and early developmental exposure to dioxins and PCBs: a follow-up study of the Duisburg Cohort. Environ Health Perspect 122:292-298; http://dx.doi.org/10.1289/ehp.1306533.

Figure 1

Partial regression plots of the PSAI feminine scores for ΣPCDD/F + PCB in maternal milk for boys and girls. Data points are the adjusted residuals of the multiple linear regression analyses where the ­exposure variable was left out (Table 4).