Exposure to air pollution during pregnancy may alter the structure of the fetal brain in a harmful way, new research from Barcelona Institute for Global Health (ISGlobal), Spain, and Erasmus University Medical Center of Rotterdam, the Netherlands, revealed. These potentially lasting brain abnormalities could impair concentration and cognitive function in school-age children.

In a first, the study established a relationship between air pollution exposure and difficulties with inhibitory control, which is the ability to regulate self-control over temptations and impulsive behavior. 

"Although specific individual clinical implications of these findings cannot be quantified, based on other studies, the observed cognitive delays at early ages could have significant long-term consequences such as increased risk of mental health disorders and low academic achievement, in particular, due to the ubiquity of the exposure," said lead author Mònica Guxens who is a researcher at ISGlobal and Erasmus University Medical Center.

The researchers used data from a population-based birth cohort set up in Rotterdam from 2002 to 2006. During the fetal life of 783 children, residential levels of air pollution were calculated by utilizing land-use regression models. Collected data also included levels of nitrogen dioxide, coarse particles, and fine particles. Structural neuroimaging and cognitive function exams were conducted when the children were 6 and 10 years old.  

The analysis of the data and the scans revealed children who were exposed to higher particulate matter levels during fetal life had thinner cortex in several brain regions of both hemispheres. The exposure to fine particles during pregnancy was linked to structural alterations of the cerebral cortex in the child's brain and these alterations "partially mediated the association between exposure to fine particles during fetal life and impaired child inhibitory control."

The study added "such cognitive impairment at early ages could have significant long-term consequences."

A particularly concerning observation was the average levels of fine particles were actually much lower than the current limit set by the European Union, while the average levels of nitrogen dioxide were right at the safe limit. Only 0.5 percent of the pregnant women were exposed to levels considered unsafe. Thus, even when around “safe” levels, Guxens cautioned "we cannot warrant the safety of the current levels of air pollution in our cities." 

The study also mentioned the damage endured by the developing brain could lead to mental health problems such as addictive behavior and attention-deficit/hyperactivity disorder. John Krystal, editor of Biological Psychiatry, felt there should be more awareness about how the brain is damaged by smoke and environmental toxins just as much as other organs.

"Air pollution is so obviously bad for lungs, heart, and other organs that most of us have never considered its effects on the developing brain. But perhaps we should have learned from studies of maternal smoking that inhaling toxins may have lasting effects on cognitive development," said Krystal.