Possible association of prenatal exposure to endocrine disruptors with sex-typical development and autism traits – Results from the Duisburg birth cohort study

Abstract

Background: Polychlorinated biphenyls (PCB), dibenzo-p-dioxins and dibenzofurans (PCDD/F) are characterized as endocrine disruptors (ED) that assumedly influence steroid hormones. During pregnancy brain development depends on hormones, especially fetal testosterone (fT) which plays a crucial role for the male-typical brain differentiation. Studies have found relations between fT and empathy, analytical thinking and sex-typical play behaviour. The causes of autism spectrum conditions (ASC) are yet unclear, however some researchers see them as an extreme form of the male brain. ED might influence fT which in turn might influence sex-typical behaviour and autistic traits. Aims: Within the Duisburg birth cohort study we investigated the effects of prenatal exposure to PCB and PCDD/F on sex-typical behaviour and autism traits. Methods: WHO2005-TEqs of PCB and PCDD/F (pg/g lipid base) in maternal blood were used as a measure for exposure. At 8-10 years of age the mothers of 97 children (52 boys) filled out the “Empathy-Systemizing-Quotient” (EQ-SQ), assessing sex-typical cognition. At 9-11 years of age the mothers of 102 children (54 boys) completed the “Social Responsiveness Scale” (SRS), an autism rating scale. Results: Exposure to PCB and PCDD/F was within background levels (e.g. medianPCB = 6.85 ± 3.88). We found negative correlations between PCB levels and the EQ (rs = -.320, p < .05) in girls and negative correlations between PCDD/F levels and the SQ (rs = -.330, p < .05) in boys. The SRS was inversely related to PCDD/F levels (rs = -.301) and PCB levels (rs = -.265, all p < .01). When analyzed separately, correlations were no longer significant in boys but in girls. Conclusions: We found significant associations of prenatal background exposure to PCB and PCDD/F with sex-typical behaviour and autistic traits. The causes of ASC are still unknown, however it is assumed that they are multifactorial and environmental factors such as ED that alter fetal steroid hormone levels might be an important factor.