New Freeway Danger: Roadside Air Pollution Causes Brain Damage in Mice
What’s the News: Scientists have for the first time directly linked freeway vehicle emissions with brain damage. Scientists used a new technique that involved trapping airborne toxins along Los Angeles’ 110 Freeway, freezing them in water, and exposing lab mice to the toxins. â€œAs a society, we need to figure out ways to minimize the level of the very, very nasty particulates we are dumping into the air we breathe,â€ University of Southern California gerontology researcher Todd Morgan told the Los Angeles Times. â€œItâ€™s having terrible consequences.â€How the Heck:
- The researchers used a particle sampler to collect “fresh ambient particulate matter” along the CA-110 Freeway near Los Angeles City for 30 days. After gathering grime on filters, they then soaked the filters in water for 30 minutes before freezing the water-toxin cocktail.
- Frozen pollutants only remain chemically stable for around 3 months, so after collecting freeway toxins, the scientists brought the toxic ice cubed back to their lab soon after. They thawed the ice and released the toxins into the air breathed by their lab mice, exposing them to the fumes for a total of 150 hours over the course of 10 weeks.
- The scientists then harvested the brain tissue of the mice, discovering through various cultures and tests that the mice brains resembled the brains of those suffering from memory loss or Alzheimer’s disease. For example, among other changes, specific receptors in the hippocampus had degenerated and parts of the cerebral cortex were inflamed.
What’s the Context:
- The scientists thought of directly testing pollution’s effect on the brain after another group in 2008 discovered significant differences in the brains of accident victims in Mexico City and Veracruz, which have highly polluted and relatively clean air, respectively. The brains from people in Mexico City “showed more extensive inflammation, oxidized DNA and other pathological markers of Alzheimerâ€™s disease,” Morgan told the Los Angeles Times.
- There was previously some indication that air pollution might cause brain damage, but it was epidemiological (rather than direct) evidence, as in the Mexico study and theÂ 2009 study that found lower cognitive function in older women who lived near high-traffic areas.
- Much past research had linked pollution with heart attacks, cancer, respiratory disease, and other health problems.
- Air pollution in particular has been linked to genetic mutations and some think it has even caused cats in China to grow “wings.”
Not So Fast: Since the tests were done on mice, humans wouldn’t necessarily be subject to the same effects. Also, because the mice were killed and examined immediately after the prescribed exposure period, we don’t know how long the negative effects last; it’s possible, for instance, thatÂ some pollution-caused brain damage might heal after exposure to clean air.
The Future Holds: Instead of looking at the short-term effect of airborne toxins on the brain, the scientists now want to look at the more long-term effect on brain development and aging.
Reference: Morgan TE, Davis DA, Iwata N, Tanner JA, Snyder D, Ning Z, et al. 2011. Glutamatergic Neurons in Rodent Models Respond to Nanoscale Particulate Urban Air Pollutants In Vivo and In Vitro. Environ Health Perspect : doi:10.1289/ehp.1002973
Image: flickr / DEMOSH
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