Air Pollution May Up Lung Cancer Risk

Long-Term Exposure and Serious Pollutants Lead to a Small Risk Increase

Dec. 3, 2003 -- City air can kill you: A new study shows decades of breathing air pollution may increase the risk of lung cancer.

It's more evidence that carcinogens in urban air are toxic to our long-term health, writes researcher Per Nafstad, PhD, with the Norwegian Institute of Public Health. His paper appears in this month's issue of the journal Thorax.

Nafstad and colleagues tracked more than 16,000 men living in Oslo, Norway. All were in their 40s when the study began in the early 1970s. Lung cancer has a long latency period before it is actually diagnosed, Nafstad explains.

Researchers factored in the average levels of air pollution that each man would have been exposed to every year between 1974 and 1995. That included reports on sulfur dioxide from heating and nitrogen oxide from traffic.

They also looked at national data on reported cancer-related deaths during that time period, from 1974 to 1998.

The findings: 18% of the men had been registered in the Norwegian cancer register as having developed cancer; 418 (2.6%) men had developed lung cancer.

Even after age, smoking habits, and occupation were factored in, the men's exposure to high levels of nitrogen oxide from air pollution was a contributing factor to their lung cancer, reports Nafstad.

A similar association was not seen between lung cancer and sulfur dioxide levels.

Exposure to either nitrous oxide or sulfur dioxide alone would not cause lung cancer, Nafstad explains. However, high levels of these compounds likely indicate a cocktail of unknown particles and carcinogens that could indeed cause the lung cancer.

Finally, he ends his study by saying that although urban air pollution may increase the risks of developing lung cancer, when compared with smoking, this association was weak but expected.

SOURCE: Nafstad, P. Thorax, December 2003; vol 58: pp 1071-1076.