Breathing bad air while pregnant may increase risk of ADHD in kids

A new study finds exposure to vehicle exhaust in utero can lead to behavioral issues in young children, especially children who grow up in low-income households.

The study, which followed 351 babies born to African-American and Dominican women in New York City, has implications for greater Los Angeles, where the impacts of air pollution are disproportionately borne by low-income residents and people of color.

Between 1998 and 2006, researchers with Columbia University’s Mailman School of Public Health recruited pregnant women for a long-term study of children’s health. When the women gave birth, researchers took samples of cord blood and analyzed them for exposure to air pollution. Specifically, they were interested in the tiny particles that make up vehicle exhaust. Once inhaled by a pregnant woman, they are so small they can pass into her blood stream, into her placenta, and damage the brain of a developing fetus.

As the women raised their children, the researchers kept track of them. Every year or so, they asked the women questions to determine their level of poverty: Had they ever struggled to afford food? Clothing? A place to live?

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When the kids turned nine, the researchers checked in with them again. This time, they asked the mothers to fill out a survey to find out if the children were displaying symptoms of Attention Deficit Hyperactivity Disorder, or ADHD.

In their study, published in Environmental Research, the Columbia scientists found both prenatal exposure to vehicle exhaust and poverty increased symptoms of ADHD in the nine-year old children.

“Each of those independently was linked to more symptoms of ADHD in the children, but when combined, the effect was far greater,” said lead author Frederica Perera.

Carrie Breton, a professor of preventative medicine at USC who studies environmental health and was not involved in the study, said scientists are increasingly interested in whether poverty and stress increase a person’s vulnerability to the negative effects of chemical exposures.

Both Breton and Perera suggested that addressing childhood poverty and exposure to air pollution would help decrease the risk of children developing ADHD.