DAVIS, Calif. — Air pollution is linked to a number of serious illnesses in humans, such as asthma, lung cancer, and heart disease. New research from scientists at the University of California, Davis suggests that traffic-related air pollution also significantly alters brain growth and development.
Previous research links air pollution to neurodevelopmental disorders such as autism. Yet few studies examine precisely how air pollution affects brain development, and how these changes may lead to abnormal neurodevelopmental outcomes.
Rat model reveals red flags
To determine how traffic-related air pollution impacts brain development, UC Davis researchers set up a rat housing facility next to a busy traffic tunnel in Northern California. They then exposed one group of rat pups to polluted air from the tunnel, and another group of rat pups to filtered air that was free of pollutants.
“This approach was a creative way to get at the question of what impacts air pollution has on the brain in the absence of confounding factors such as socioeconomic influences, diet, etc.,” lead researcher Pamela Lein explains in a media release. “It’s important to know if living close to these roadways poses a significant risk to the developing human brain.”
After exposing the rat pups to either polluted or filtered air, the researchers compared the brains from each group. They found that rat pups exposed to traffic-related air pollution had abnormal brain growth and increased neuroinflammation. In particular, they point to abnormal cell growth in a region of the brain known as the hippocampus, which plays a critical role in learning and memory.
Air pollution and abnormal brain development
These findings are notable for several reasons. First, the majority of previous air pollution studies have looked at the effects of concentrated air pollution particles or diesel exhaust. Both of these are components of air pollution, but do not mimic the complexity of real-world air pollution exposures. By collecting air from a highly trafficked tunnel, the UC Davis researchers created a realistic air pollution exposure scenario.
Second, the researchers found abnormal brain development when air pollution levels were within current regulatory limits. This finding suggests that low levels of air pollution have the potential to negatively impact brain development.
“What we witnessed are subtle changes,” first author Kelley Patten explains. “But we are seeing these effects using air pollution exposures that fall within regulatory limits. With the backdrop of other environmental and genetic risk factors in humans, this may have a more pronounced effect. This exposure also contains very fine particulate matter that isn’t currently regulated.”
In the future, the researchers hope to determine which components of air pollution are responsible for the neurodevelopmental effects they observed.
“We have managed to build a unique and talented team and taken advantage of our built environment to bring us closer than we’ve been before to achieving these objectives,” says co-author Keith Bein. “Increasingly, these types of efforts are required to continue advancing the field, thereby informing policymakers and stakeholders about how best to protect human health.”
The study is published in Translational Psychiatry.