A new study suggests a pregnant woman’s exposure to polycyclic aromatic hydrocarbons (PAHs), the toxic air pollution caused in part by vehicle emissions, coal burning and smoking, may be bad for her child’s brain.
In a small study, researchers found a powerful relationship between prenatal PAH exposure and disturbances in parts of the brain that support information processing and behavioral control.
Investigators from the Institute for the Developing Mind at Children’s Hospital Los Angeles (CHLA) and colleagues at Columbia University’s Center for Children’s Environmental Health believe the exposure may contribute to slower processing speeds and behavioral problems, including attention-deficit hyperactivity disorder (ADHD) symptoms.
The study is published online by JAMA Psychiatry.
PAHs are caused by the incomplete combustion of organic materials. In addition to outdoor air pollution, sources of indoor air pollution caused by PAHs can be cooking, smoking, and space heaters.
PAHs can cross the placenta and damage fetal brains, and animal experiments suggest prenatal exposure can impair behavior and learning, according to study background.
Bradley S. Peterson, M.D., of Children’s Hospital Los Angeles, and coauthors conducted an imaging study that included 40 minority urban school-aged children born to Latin (Dominican) or African-American women.
The children were followed from the fetal period to ages seven to nine years old. Their mothers completed prenatal PAH monitoring and prenatal questionnaires.
The authors found an association between increased prenatal PAH exposure and reductions in brain white matter in children (later in childhood) that was confined almost exclusively to the left hemisphere of the brain and involved almost its entire surface.
Reduced white matter surface on the left side of the brain was associated with slower processing during intelligence testing and behavioral problems, including ADHD symptoms and conduct disorder problems, according to the results.
The neurodevelopmental outcomes in children were measured through intelligence testing and a behavior checklist.
Since the study findings were limited to a minority population with a high level of poverty and low educational attainment, the results may not be applicable to other populations.
However, impoverished urban minority populations are typically disproportionately exposed to air pollutants.
“Our findings raise important concerns about the effects of air pollutants on brain development in children, and the consequences of those brain effects on cognition and behavior,” said Peterson.
“This is the largest MRI study to date of how early life exposure to air pollutants, specifically PAH, affect the developing mind,” said Peterson, who is also a professor of pediatrics and psychiatry at Keck School of Medicine of the University of Southern California.
“Our findings suggest that PAH are contributors to ADHD and other behavioral problems due to the pollutants’ disruptive effects on early brain development.”
Source: JAMA Networks