A new study suggests that prenatal exposure to air pollution increases children's risk of developing attention deficit hyperactivity disorder (ADHD) by the time they turn 9 years old.
Researchers from Columbia University's Mailman School of Public Health in New York City looked at the data of 233 nonsmoking pregnant women and their children for the study. Urine samples were collected after the mothers gave birth to measure the levels of polycyclic aromatic hydrocarbons (PAH) in the body. When the children turned 3 to 5 years old, the researchers collected urine samples and had them undergo an assessment to determine if they have ADHD.
The analysis showed that children of pregnant women exposed to high levels of polycyclic aromatic hydrocarbons (PAH) are 500 percent more likely to show symptoms of ADHD at age 9 than those who had lesser exposure to the chemical. About one-third of the 250 children were exposed to high levels of prenatal air pollution.
PAHs are chemicals that are naturally present in the environment, but they can also be man-made. These chemicals are formed when coal, gas, and garbage are partially burned. They are also used to manufacture plastics, dyes, pesticides, and some medicines. Humans are often exposed to it by breathing contaminated air such as cigarette or tobacco smoke, eating foods grown from contaminated soils, or consuming grilled meat. Early research showed that mice exposed to PAHs even for a short period of time had birth defects, and kidney and liver damage.
The recent study, however, is the first to study a possible link between PAH and ADHD in children.
"This study suggests that exposure to PAH encountered in New York City air may play a role in childhood ADHD," said lead author Frederica Perera, DrPH, PhD, 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 researchers called for policymakers to implement new policies that can help in cutting the levels of PAH pollution such as anti-idling for public transportations and use of cleaner fuels.
"We do see that policies can make a difference, and air pollution is the responsibility of policymakers," she told Live Science.
Further details of the study were published in the Nov. 5 issue of PLOS ONE.
