By Roberta Attanasio
Persistent environmental pollutants – such as DDT, dioxins and polychlorinated biphenyls – are a major global health threat. These toxic chemicals resist degradation and persist in the environment for long periods of time. They can be transported by wind and water across international boundaries, and reach regions far from where they are produced or used. People are exposed to these chemicals mostly by eating contaminated fish, meat, and dairy products and, once exposed, may develop a variety of adverse health effects, including birth defects, dysfunctions of the immune and reproductive systems, damage to the central and peripheral nervous systems, and certain cancers.
Now, results from a study (Behavioral Sexual Dimorphism in School-Age Children and Early Developmental Exposure to Dioxins and PCBs: A Follow-Up Study of the Duisburg Cohort) published on March 1, 2014 in the scientific journal Environmental Health Perspectives, show that school-age boys and girls exposed to low levels of persistent organic pollutants during fetal life exhibit behavioral changes related to sexual dimorphism – boys show more feminine behavior and girls show less feminine behavior.
The study was carried out using the Duisburg cohort, which consisted of 232 healthy pregnant women living in Duisburg, Germany, from September 2000 through October 2002. Duisburg is located in an area that was an important agglomeration for heavy industries. The researchers collected blood samples at 28-43 weeks of gestation and then, after the babies were born, breast milk samples. For the study, all samples were analyzed for presence of dioxins and polychlorinated biphenyls, which are also known endocrine-disrupting chemicals.
Once the children reached the age of 6-8 years, parents were asked to report their play behavior, which is known to show profound differences related to gender.
For the study, the play behavior was characterized on the basis of “24 items grouped into three categories: preferred toys (e.g., guns, dolls), preferred activities (e.g., playing house, fighting), and behavioral characteristics (e.g., enjoys rough and tumble play, likes pretty things).”
For each of these items, parents reported the perceived frequency of occurrence during the preceding month (never, hardly ever, sometimes, often, very often).
The researchers found linear dose-response relationships between exposure and outcome – thus, they conclude that low levels of prenatal environmental exposure to dioxins and polychlorinated biphenyls modify behavioral sexual dimorphism in school-age children. Their article has been selected by the Children’s Environmental Health Network (CEHN) as one of the “Articles of the Month” (April 2014 issue). The summary presented by CEHN includes the discussion of the potential policy implications related to the new findings.