From the Wall Street Journal (a report about Upstream contributor Dr. Frederica Perera):

Congested cities are fast becoming test tubes for scientists studying the impact of traffic fumes on the brain.

As roadways choke on traffic, researchers suspect that the tailpipe exhaust from cars and trucks—especially tiny carbon particles already implicated in heart disease, cancer and respiratory ailments—may also injure brain cells and synapses key to learning and memory.

New public-health studies and laboratory experiments suggest that, at every stage of life, traffic fumes exact a measurable toll on mental capacity, intelligence and emotional stability. “There are more and more scientists trying to find whether and why exposure to traffic exhaust can damage the human brain,” says medical epidemiologist Jiu-Chiuan Chen at the University of Southern California who is analyzing the effects of traffic pollution on the brain health of 7,500 women in 22 states. “The human data are very new.”

So far, the evidence is largely circumstantial but worrisome, researchers say. And no one is certain yet of the consequences for brain biology or behavior. “There is real cause for concern,” says neurochemist Annette Kirshner at the National Institute of Environmental Health Sciences at Research Triangle Park in North Carolina. “But we ought to proceed with caution.”

To be sure, cars and trucks today generate one-tenth the pollution of a vehicle in 1970. Still, more people are on the road and they are stuck in traffic more often. Drivers traveling the 10-worst U.S. traffic corridors annually spend an average of 140 hours, or about the time spent in the office in a month, idling in traffic, a new analysis reported.

No one knows whether regular commuters breathing heavy traffic fumes suffer any lasting brain effect. Researchers have only studied the potential impact based on where people live and where air-pollution levels are highest. Even if there were any chronic cognitive effect on drivers, it could easily be too small to measure reliably or might be swamped by other health factors such as stress, diet or exercise that affect the brain, experts say.

* * *

Scientists believe that simple steps to speed traffic are a factor in reducing some public-health problems. In New Jersey, premature births, a risk factor for cognitive delays, in areas around highway toll plazas dropped 10.8% after the introduction of E-ZPass, which eased traffic congestion and reduced exhaust fumes, according to reports published in scientific journals this year and in 2009. The researchers, Princeton University economist Janet Currie and her colleagues at Columbia University, analyzed health data for the decade ending 2003.

After New York traffic managers rerouted streets in Times Square recently to lessen congestion, air-pollution levels in the vicinity dropped by 63%.

Scientists are only beginning to understand the basic biology of car exhaust’s toxic neural effects, especially from prenatal or lifetime exposures. “It is hard to disentangle all the things in auto exhaust and sort out the effects of traffic from all the other possibilities,” says Dr. Currie, who studies the relationship between traffic and infant health.

Researchers in Los Angeles, the U.S.’s most congested city, are studying lab mice raised on air piped in from a nearby freeway. They discovered that the particles inhaled by the mice—each particle less than one-thousandth the width of a human hair—somehow affected the brain, causing inflammation and altering neurochemistry among neurons involved in learning and memory.

To study the effect of exhaust on expectant mothers, Frederica Perera at Columbia University’s Center for Children’s Environmental Health began in 1998 to equip hundreds of pregnant women with personal air monitors to measure the chemistry of the air they breathed. As the babies were born, Dr. Perera and colleagues discovered a distinctive biochemical mark in the DNA of about half of the infants, left by prenatal exposure to high levels of polycyclic aromatic hydrocarbons in exhaust.

By age 3, the children who bore the mark of exhaust in their genes were developing mental capacities fractionally more slowly. By age 5, their IQ scores averaged about four points lower on standard intelligence tests than those of less exposed children, the team reported in 2009. The differences, while small, were significant in terms of later educational development, the researchers said.

By age 7, the children were more likely to show symptoms of anxiety, depression and attention problems, the researchers reported this year in Environmental Health Perspectives.

“The mother’s exposure—what she breathed into her lungs—could affect her child’s later behavior,” Dr. Perera says. “The placenta is not the perfect barrier we once thought.”

More.

See the excellent interview of WSJ journalist covering this story (Lee Hotz) below:

View the extended Upstream Interview of Dr. Frederica Perera here.

 

Advertisements