A new study suggests that unborn babies exposed to ‘safe’ levels of air pollution are prone to developing brain abnormalities that might contribute to cognitive impairment later in life.

Via Flickr/wissenschaftsjahr

Scientists from the Netherlands have observed that exposure to fine particles during fetal development is linked to a thinner cortex — the exterior layer of the brain that regulates self-control over impulsive behavior. Such cognitive impairment at early ages could have significant long-term consequences.

“We observed brain development effects in relationship to fine particles levels below the current EU limit,” lead author Dr. Mònica Guxens, of the Barcelona Institute for Global Health (ISGlobal), Spain, a center supported by the “la Caixa” Foundation, and Erasmus University Medical Center, the Netherlands, said in a statement.

Other recent studies have associated acceptable air pollution levels with other complications such as cognitive decline and fetal growth development.

The team of researchers used a population-based cohort in the Netherlands, which observed pregnant women and their children from fetal life onward. The researchers assessed the levels of home air pollution during the fetal life of 783 children and collected data by air pollution monitoring campaigns, measuring levels of nitrogen dioxide, coarse particles, and fine particles.

Scientists also scanned the brains of children between the ages of six and ten and discovered abnormalities in the thickness of the brain cortex, the precuneus and rostral middle frontal region. That’s despite the fact that the levels of fine particles and nitrogen dioxide measured in their homes were acceptable by EU standards.

“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,” Dr. John Krystal, editor of Biological Psychiatry, said in a statement. “But perhaps we should have learned from studies of maternal smoking that inhaling toxins may have lasting effects on cognitive development.”

The paper suggests that the fetal brain is very vulnerable during pregnancy because it hasn’t yet developed the mechanisms for removal of, or protection against, environmental toxins.

“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,” Guxens added.

The study was published in Biological Psychiatry.