Exposure to pollution during pregnancy ups a child's risk of developing attention deficit hyperactivity disorder, more commonly known as ADHD, according to a new study. Specifically, researchers focused on the influence of polycyclic aromatic hydrocarbons (PAHs), a main component of dirty air.
Researchers at Columbia University's Mailman School of Public Health followed 233 pregnant women, who were non-smokers, and their children in New York City from pregnancy into childhood. The results showed that children born to mothers exposed to high levels of PAHs during pregnancy were five times more likely to exhibit symptoms that characterize ADHD than those who weren't subjected to PAHs. And for kids aged 9, they in particular demonstrated inattentive-type ADHD, according to the findings detailed in the journal PLOS ONE.
"This study suggests that exposure to PAH encountered in New York City air may play a role in childhood ADHD," lead author Frederica Perera said in a statement. "The findings are concerning because attention problems are known to impact school performance, social relationships, and occupational performance."
The Centers for Disease Control and Prevention (CDC) estimates that around 10 percent of US children ages 4 to 17 have some form of ADHD. There are three types: inattentive ADHD, hyperactive and impulsive ADHD, or a combination of the two. The characteristics of inattentive ADHD are perhaps the most widely known, in which kids have a hard time focusing and are easily distracted and disorganized.
Scientists still don't know what exactly causes ADHD, but genetics and environmental factors are suspected to be involved. This study demonstrates that air pollution may be one of those environmental factors that plays a part.
PAHs, the US Environmental Protection Agency describes, are chemicals that are either natural or man-made. They are created from the burning of fossil fuels or even garbage. They are also of particular concern because they can linger in the air for long periods of time.
In order to measure the amount of PAHs in the study participants' system, the researchers used urine samples of kids aged 3 to 5, and then to assess their ADHD behavioral problems, they relied on the Conners' Parent Rating Scale.
The current findings build on previous findings from the CDC 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.