Freeway Air Pollution Linked to Brain Damage in Mice

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It’s no secret that air pollution — besides damaging the pulmonary system and blackening the skies — can also lead to cardiovascular problems and even heart attacks. But a new study in the journal Environmental Health Perspectives by researchers at the University of Southern California (USC) indicates that the kind of pollution we’re exposed to when we sit in gridlock could impact another important body part: the brain.

The researchers, led by USC neurobiologist Caleb Finch, exposed both live mice and mice brain cells in vitro to a sample of air you might end up breathing on the 405 outside Los Angeles — a mix of particles from burning fossil fuels and bits of car parts and weathered pavements. (The innovative method for replicating freeway air in a liquid suspension came from USC engineer Constantinos Sioutas, which made it possible to test both brain cells in a test tube and live mice.) Both the in vitro brain cells and the neurons in the live mice showed similar problems, including signs of inflammation associated with Alzheimer’s disease and damage to cells associated with learning and memory.

The particulates in the experiment are tiny — perhaps one-thousandth the width of a human hair, and far too small to be trapped by car filtration systems. Nor were the mice exposed for very long in the study — just 150 hours over 10 weeks, in three sessions per week lasting at least five hours each. Those numbers should worry frequent commuters, who might be exposed to bad freeway air over an even longer period than the mice were in the study. “How can we protect urban dwellers from this type of toxicity?” lead author Finch said in a statement. “That’s a huge unknown.”

Protection won’t be easy, as study co-author Todd Morgan told the Los Angeles Times in an interview:

Our data would suggest that freeway pollution could have a profound effect on the development of neurons and brain health in children and young kids, especially those who attend schools built alongside freeways.

So limiting one’s exposure — especially children’s exposure — to freeway pollution is essential to control asthma, cardiovascular conditions and cognitive development.

Commuters might be able to switch their modes of transportation, or even work from home — but those unfortunate enough to live near freeways have little defense against air pollution. Indeed, the EHP study was prompted in part by earlier research by a group in Mexico who found evidence of extensive inflammation, oxidized DNA and other markers of Alzheimer’s in accident victims from smoggy Mexico City, compared to relatively clean Veracruz. You can call that environmental injustice.