The effects of exposure to environmental chemicals on child development

Several chemical compounds are resistant to degradation and end up in the food chain. One group of these chemicals are polychlorinated biphenyls (PCBs), i.e. used as plasticizers. Although PCBs have been banned since 1985, 17 years later they were still detectable in all pregnant women in our study. The aim of this thesis was to determine whether exposure to PCBs, and similar environmental chemicals, during pregnancy is associated with neurological and hormonal development until adolescence.
In our study, in which healthy mother-child pairs participated, we found that higher exposure to environmental chemicals is associated with poorer motor development at the age of 3 months. At 3, 18, and 30 months of age, we found both negative and positive effects on neurological development. Exposure to environmental chemicals was also found to be both positively and negatively related to motor and cognitive outcomes during adolescence, although it did not result in an abnormal development. We also found that PCBs influence thyroid hormone metabolism, essential for normal brain development, during fetal life. A final important finding was that higher exposure to PCBs during pregnancy is associated with advanced pubertal development in both boys and girls.
There is growing evidence that new chemicals, like bisphenol A, also have endocrine disrupting effects. Our finding that relatively low exposure to environmental chemicals is related to developmental outcomes as long as 13 to 15 years after exposure, underlines the importance of exercising extreme caution when it comes to using existing chemicals and to introducing new ones.