Prenatal PCB exposure linked to children's ADHD symptoms.
Sagiv, SK, SW Thurston, DC Bellinger, PE Tolbert, LM Altshul and SA Korrick. 2010. Prenatal organochlorine exposure and behaviors associated with attention deficit hyperactivity disorder in school-aged children. American Journal of Epidemiology http://dx.doi.org/10.1093/aje/kwp427.
A study of children born near a PCB-contaminated harbor in Massachusetts finds that prenatal exposure to banned persistent organic pollutants – specifically PCBs and DDE – may be linked to attention-deficit/hyperactivity disorder (ADHD).
The results are consistent with previous human and animal studies that have found links between PCB levels and ADHD-like behaviors, such as inattention and impulsivity. This may be the first time the behaviors are associated with DDE exposure.
Even though the mothers lived near a potential source of PCBs, levels measured in the children’s umbilical blood at birth were low compared to other populations. These data suggest that even low level exposure during pregnancy can have long-term effects on children’s behavior and development.
ADHD is a common behavioral disorder marked by impulsive behavior, overly active movement and lack of attention. It is currently estimated that approximately 5-10 percent of children in the United States have ADHD.
Organochlorines – such as PCBs and DDT – are persistent organic pollutants (POPs). The chemicals are long-lived, can collect in fat and have been banned in many countries because of associated health effects. PCBs were commonly used as electrical insulators. They can cross the placenta from mother to fetus and are linked to behavoior effects. DDE is a breakdown product of the powerful insecticide DDT, which is well known to harm wildlife and for its role to control mosquitoes that carry malaria.
The Harvard researchers determined problem behaviors using a teacher-administer scale rather than clinically diagnosing ADHD. They evaluated the relationship between the behaviors and pollutant levels measured in umbilical cord blood at birth among 607 children aged 7 to 11 years old. When pregnant, the mothers lived near a polluted harbor in New Bedford, Massachusetts.
They found that ADHD-like behaviors increased 26 - 79 percent for those with the highest level of four types of PCBs measured in the blood as compared to those with the lowest level of chemicals. Similar relationships were also observed for DDE. These relationships persisted even after controlling for potential confounders, such as smoking habits, socioeconomic status, and blood lead levels.
