Another type of traffic stress

Inhaling the air pollutants spewed by cars and trucks can stress cells throughout the body by exposing them to an unhealthy oxidative environment. A new study in Beijing — one of the world’s more polluted cities — quantifies those oxidative changes in a pair of young, nonsmoking security officers at Peking University.

For two winter months, scientists measured fine-dust-size particulates in the air at a background site on the campus and at the entrance gate where these human guinea pigs work the noon to 8 p.m. shift. Roughly 8,000 to 10,000 vehicles pass the gate they guard daily. The researchers analyzed the air from these sites for more than 100 organic chemicals and metals.

Urine samples from the men were collected prior to and after shifts at 29 periods throughout the winter and used to quantify concentrations of a marker of oxidation. This marker offers a gauge of the inflammatory environment that may have been triggered, since several oxidative compounds play a major role in the body’s inflammatory attack on foreign materials, such as pollutants.

In this study, the researchers focused on chemical changes to a building block of DNA (deoxyguanosine) that occur when it’s damaged by a highly potent oxidant known as hydroxyl radical. The 8-HOdG (for 8-hydroxy-2’-deoxyguanosine) that forms isn’t used by the body or broken down.

Concentrations of 8-HOdG in urine tripled over the course of a work day, the researchers report in Environmental Science & Technology. A copy of the paper is available online ahead of print. Work-shift elevations in this stress marker correlated with two types of combustion pollutants: polycyclic aromatic hydrocarbons, some of which are carcinogenic, and metals such as vanadium, chromium and manganese.

Being pollution analysts, these researchers don’t (and probably can’t) assess the health implications of the changes they measured — other than to point out that the trend they found has a decidedly unhealthy direction.

Janet Raloff is the Editor, Digital of Science News Explores, a daily online magazine for middle school students. She started at Science News in 1977 as the environment and policy writer, specializing in toxicology. To her never-ending surprise, her daughter became a toxicologist.

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