Prenatal Exposure to Persistent Organic Pollutants: Influence on Masculine and Feminine Behavior in School-Age Children
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.
Persistent organic pollutants are numerous and are very significantly affecting behavior, developmental effects, and other physiologic pathogenic effects that plague society, but this organic class of pollutants is also greatly complicated by additive and synergistic effects of inorganic persistent pollutants, especially toxic metals. The toxic metals do not break down in the environment either, and are ubiquitous globally. They have been mined from buried deposits for many centuries, concentrating them into products for dispersal around the globe to inevitably degrade as pollution. The more toxic metals mined, the more they are available to add their pathogenic effects by building up in the environment with its load of the persistent organic contaminants. Mixtures of toxic chemicals, even at chronic low dose levels, are understudied compared to the normal scientific lab research of trying to understand the toxic effects of single toxicants. Lab research has to simplify the mixtures by singling out single toxicants in order to clarify how each chemical individually is pathogenic. The pathologic complexities of mixtures are very difficult to tease out. Environmental persistence of toxic chemical means that they don’t break down to diminish their potential effects over time. Metals pollution is persistent and very harmful to society.