Scientists from the Institute of Global Health of Barcelona (ISGlobal) and the Erasmus Medical Center Rotterdam have associated residential exposure to air pollution during pregnancy with brain abnormalities that can contribute to a reduction in the cognitive capacity of children of school age.
The study, published in Biological Psychiatry, shows that the levels of pollution that were associated to brain alterations were within the range considered safe. The research showed for the first time a relationship between exposure to air pollution and difficulties in inhibitory control – ability to regulate self-control and impulsive behavior.
This is associated with mental health problems such as addictive behavior and attention deficit hyperactivity disorder (ADHD). On the other hand, exposure to fine particles during fetal life was associated with a thinner brain cortex in several regions of both hemispheres, which is one of the factors that would explain the deficiencies observed in the inhibitory control.
The research team used a population cohort in the Netherlands to study pregnant women and their children. They determined the levels of residential air pollution during the fetal life of 783 boys and girls. The data was obtained from air monitoring campaigns, and included levels of nitrogen dioxide and coarse and fine particles. The morphology of the brain was evaluated from magnetic resonance imaging performed when the children were between 6 and 10 years of age.
The relationship between exposure to fine particles, structural alterations of the brain and inhibitory control was observed despite the fact that the residential levels of fine particles did not exceed the limits established by the European Union –only 0.5% of pregnant women were exposed to levels considered unsafe. On average, residential levels of nitrogen dioxide were just at the safety limit.
Children are the most vulnerable
These findings complement previous studies that associate “acceptable” levels of air pollution with other complications, including cognitive decline and fetal growth. “Therefore, we cannot guarantee that the current levels of pollution in our cities are safe,” said Mònica Guxens, study coordinator and researcher at ISGlobal and the Erasmus University Medical Center.
The brain of the fetus is particularly vulnerable, as it has not yet developed the mechanisms to protect itself from environmental toxins or to eliminate them. “Although the clinical consequences of these findings at the individual level cannot be quantified, other existing studies suggest that cognitive delays at an early age could have considerable long-term consequences, including an increased risk of mental disorders and lower academic performance, given the ubiquity of the exhibition,” Guxens said.