Even the finest particles of air pollution at home may affect the development of a fetus' brain. It can have long-term consequences including impaired child inhibitory control - impairment in the ability to pay attention to relevant stimuli.
"We observed brain development effects in relationship to fine particles levels below the current EU limit," said lead author Mňnica Guxens, MD, of Barcelona Institute for Global Health (ISGlobal), Spain, a center supported by the "la Caixa" Foundation, and Erasmus University Medical Center, the Netherlands. This finding adds to previous studies that have linked acceptable air pollution levels with other complications including cognitive decline and fetal growth development. "Therefore, we cannot warrant the safety of the current levels of air pollution in our cities," said Dr. Guxens.
Exposure to fine particles during fetal life was associated with a thinner outer layer of the brain, called the cortex, in several regions. The study showed that these brain abnormalities contribute in part to difficulty with inhibitory control, the ability to regulate self-control over temptations and impulsive behavior, which is related to mental health problems such as addictive behavior and attention-deficit hyperactivity disorder.
Brain imaging performed when the children were between 6 and 10 years old revealed abnormalities in the thickness of the brain cortex of the precuneus and rostral middle frontal region. Despite the relationship between these brain structure alterations and fine particle exposure, the average residential levels of fine particles in the study were well below the current acceptable limit set by the EU - only 0.5 percent of the pregnant women in the study were exposed to levels considered unsafe. The average residential levels of nitrogen dioxide were right at the safe limit.
"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 John Krystal, MD, the editor of the research paper.
The fetal brain is particularly vulnerable during pregnancy, it hasn't yet developed the mechanisms to protect against or remove environmental toxins. The findings of the study suggest that exposure to levels even below those considered safe could cause permanent brain damage.
"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 Dr. Guxens.