Polluted Freeway Air Causes Brain Damage in Mice

Highway pollution leads to brain damage in mice but more study is needed to see if the results are the same in humans, and if so, how much pollution exposure causes damage.
Highway pollution leads to brain damage in mice but more study is needed to see if the results are the same in humans, and if so, how much pollution exposure causes damage. (Image credit: John Trif | Stock Xchng)

The air around highways — full of tiny particles of burned-up fossil fuel, car parts and pavement — causes damage and inflammation in the brains of mice, a new study finds.

The concentration of freeway air used in the study, which was tested on both mice and human cells in test tubes, represents the same level of freeway air exposure experienced by people whose occupations require extensive driving, especially in open-air vehicles, said study researcher Todd Morgan, research associate professor at the University of Southern California.

However, "more studies are needed to determine how and to what degree the human brain is susceptible to the toxicity of airborne-derived particles," Morgan told MyHealthNewsDaily.

The study will be published today (April 7) in the journal Environmental Health Perspectives.

Signs of damage

Morgan and his colleagues exposed mice in a laboratory to re-created freeway air, which contained collected freewayparticles about one-thousandth of the width of a single human hair (a size too small for most car filtration systems to trap). The mice were exposed to the air three times a week for five hours over a10-week period (a total of 150 hours).

Researchers found that the mice had damage to the neurons associated with learning and memory, and the neurons in developing mice did not grow as well as neurons not exposed to the freeway air, the study found.

They also found that the mouse brains had signs of inflammation, which is associated with premature aging and Alzheimer's disease.

Far-reaching effects

Even though this study looked at the effects of pollution only in mice, past research suggests that freeway air negatively affects human health.

A 2000 study in the journal Archives of Medical Research compared the health of people who live in Mexico City, a highly polluted city, with people who live in Veracruz, a non-polluted city. Compared with Veracruz residents, the people in Mexico City had more than twice the blood level of proteins indicative of epithelial damage. Epithelial damage occurs when the cells that line the hollow organs (like the lungs) are damaged, and it's considered a sign of asthma.

Another study, published last year in the journal PLoS One, showed that particulates from auto exhaust contributed to atherosclerosis, a thickening of the arterial walls that can lead to heart attack, stroke and coronary heart disease.

Therefore, it's important to avoid participating in activities in highly polluted areas, Morgan said.

"I wouldn’t recommend a daily jogalong the freeway," he said.

Pass it on: Freeway air damages neurons and spurs inflammation in the brains of mice.

Follow MyHealthNewsDaily staff writer Amanda Chan on Twitter @AmandaLChanThis story was provided by MyHealthNewsDaily, a sister site to LiveScience.

Amanda Chan
Amanda Chan was a staff writer for Live Science Health. She holds a bachelor's degree in journalism and mass communication from the Walter Cronkite School of Journalism and Mass Communication at Arizona State University, and a master's degree in journalism from Columbia University.