Prenatal exposure to polycyclic aromatic hydrocarbons, or PAH, a component of air pollution, raises the odds of behavior problems associated with attention deficit hyperactivity disorder, or ADHD, at age 9, according to researchers at the Columbia Center for Children’s Environmental Health at the Mailman School of Public Health. Results are published online in the journal PLOS ONE.
The researchers followed 233 nonsmoking pregnant women and their children in New York City from pregnancy into childhood, and found that children born to mothers exposed to high levels of PAH during pregnancy had five times the odds of a higher-than-usual number and degree of symptoms that characterize ADHD — specifically inattentive-type ADHD at age 9 — compared with children whose mothers did not have high PAH exposure. The study is the first to explore the connection between prenatal PAH and ADHD in school-age children over time.
“This study suggests that exposure to PAH encountered in New York City air may play a role in childhood ADHD,” says lead author Dr. Frederica Perera, director of the Center and professor of Environmental Health Sciences at the Mailman School. “The findings are concerning because attention problems are known to impact school performance, social relationships, and occupational performance.”
The Centers for Disease Control estimates that around 10 percent of American children ages 4 to 17 have ADHD in one of three types: inattentive ADHD, in which children have a hard time focusing and are easily distracted and disorganized; hyperactive and impulsive ADHD; or a combination of the two. Little is known about what causes ADHD, but, in addition to genes, environmental factors are known or suspected to play a role.
The current findings build on the Center’s previous studies linking prenatal PAH exposure with behavioral and cognitive issues, including associations with developmental delay at age 3, reduced IQ at age 5, and symptoms of anxiety/depression and attention problems at ages 6 and 7.
The study was supported by the National Institute for Environmental Health Sciences (NIEHS) and the U.S. Environmental Protection Agency (US EPA) (grants NIEHS/EPA P01ES09600/R82702701, NIEHS/EPA P01ES09600/RD832141, NIEHS/EPA P01ES09600/RD834509, NIEHS R01ES08977), the John & Wendy Neu Family Foundation, the New York Community Trust, and the Blanchette Hooker Rockefeller Fund.