In the study, researchers at Columbia University followed 253 pregnant mothers in New York City. They tracked the mothers and their children from before birth until age 9. The researchers focused on an air pollutant called polycyclic aromatic hydrocarbon (PAH). This chemical is a byproduct of burning fossil fuels. PAHs are found in car exhaust, tobacco smoke, home heating systems and even some foods, such as smoked meats.
The goal of the study was to see whether PAHs affect child development and result in symptoms. Those symptoms can include inattention and behavior issues. In a previous study, the same researchers had already found a possible link between exposure to PAHs and developmental delays.
To measure PAH exposure, the researchers tested the umbilical cord blood of mother and child at the time of birth. They also measured the level of PAH in the mothers’ own blood. Urine samples from the children were also tested when the children were 3 or 5 years old.
Behavior checklists were used to see if the children had ADHD symptoms. The researchers found that children were more likely to show signs of ADHD if they were born to women who had higher levels of PAHs in their blood when they gave birth.
The results of the study suggest that a pregnant woman’s exposure to pollution might contribute to ADHD symptoms in her child. But the researchers caution that more data is needed. They specifically note they did not look at the role of other factors like stress, noise level and other pollutants. The study was also limited to nonsmoking mothers in a single neighborhood.
In the end, it may not be possible to connect environmental factors to ADHD. To learn more, view a slideshow about the possible causes of ADHD.
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About the author
About the author
Geri Coleman Tucker is a freelance writer and editor and a former deputy managing editor for