New Findings on Smoking Reduction and Smoking Compensation

Heavy smokers who cut down on cigarettes take in more toxins than light smokers, even when the number of cigarettes smoked per day is identical.

The finding comes from the University of Minnesota Transdisciplinary Tobacco Use Research Center (TTURC). TTURC researchers measured the levels of a specific tobacco carcinogen called NNAL in smokers who were part of smoking reduction programs. As TTURC design and study analysis director, SPH professor Chap Le served as the study’s lead biostatistician.

The researchers selected 62 participants in two smoking reduction programs. The light smokers averaged 6 cigarettes a day. The heavy smokers started the study averaging 26 cigarettes a day, and then after six months reduced intake to 5 cigarettes a day.

After the reduction by the heavy smokers, the two groups were matched to form clusters with the same number of cigarettes smoked per day. In each cluster, researchers found that the average level of the NNAL carcinogen in the heavy smokers was more than twice that of the light smokers.

Why the difference?

Researchers point to "smoking compensation"--the act of inhaling longer and deeper, which has been known to increase exposure to carcinogens. Smokers trying to cut back often compensate in this way to satisfy their urge to smoke more.

A breakthrough for Le and the research team was the idea of a "matched design" (matching the reduced heavy smokers to the light smokers) to arrive at more accurate measures of smoking compensation. The study design also revealed that the greater the reduction in smoking, the greater the amount of compensation.

The results suggest that heavy smokers who cut down still face harmful exposures to cancer-causing toxins. Likewise, no research has indicated whether there exists a "safe" level of reduction.

There remains only one known way to lower the risks involved with cigarettes: Stop smoking completely.