Smokers who think they are doing themselves a favor by smoking light cigarettes may be getting more nicotine, tar and other harmful agents than they bargained for.

People who smoke low- and medium-yield cigarettes receive more than twice the amounts of nicotine and tar listed on cigarette packs and in advertisements, according to a study released in the Jan. 19 issue of the Journal of the National Cancer Institute. These findings are particularly important because low- and medium-yield cigarettes make up more than 80 percent of the cigarettes smoked in the United States. They also illustrate, as experts say, that the only safe dose of cigarettes is no dose.

“Our data strongly support the conclusion … that FTC [Federal Trade Commission] listings of tar and nicotine … do not offer the public sound information on which to base critical decisions with regard to health risks,” wrote the study authors.

Since the late 1960s the FTC has published the amounts of tar and nicotine that smokers supposedly derive from cigarettes. These ratings, based on a standardized “machine-smoking” method established in the 1930s, are disclosed in cigarette advertisements and often on the packages themselves.

But some researchers have questioned the accuracy of the FTC’s testing method, in light of findings that smokers of light cigarettes inhale more vigorously or deeply to compensate for the reduced nicotine delivery. Indeed, the FTC itself has proposed changing its protocol for evaluating nicotine and tar yields to make the measurements more realistic.

The latest work underscores the need for such an overhaul. Scientists at the American Health Foundation evaluated whether the FTC’s machine-derived smoke-yields differed significantly from actual measurements taken from smokers. The smoking characteristics of 133 smokers of low- and medium-yield cigarettes (yielding 1.2 milligrams or less of nicotine) were examined, and tests for nicotine, tar, carbon monoxide and two cancer-causing agents were performed on a randomly chosen subset of 72 smokers.

The researchers found that smokers of low- and medium-yield cigarettes took larger puffs, puffed more frequently and inhaled a greater total volume of smoke than the FTC’s model would predict. In addition, 20 percent to 30 percent of these smokers used their fingers or lips to block the cigarettes’ filter vents — a habit, however unconscious, that increases the amount of nicotine and other smoke constituents being inhaled.

Not only were the nicotine and tar doses more than double the FTC values, but the concentrations of carbon monoxide and two known lung carcinogens, BaP and NNK, were also roughly twice as much as the government estimates.

“A smoker who uses the FTC ratings to choose a brand of cigarettes with lower amounts of carcinogenic agents will not achieve the reduction anticipated,” concluded study authors. “It is, therefore, somewhat misleading to use published FTC tar and nicotine ratings as a guide for risk assessment of the potential carcinogenicity of low-yield cigarettes,” they added.

An editorial accompanying the study echoes these remarks, and faults tobacco companies for using the deceptive ratings to their advantage in advertising. The editorial also called for the Food and Drug Administration to assume control over tobacco products.

“It is time for a change,” wrote editorial authors, members of the Committee on Tobacco Product Change. “Not just for a change in the manner of testing and reporting of tobacco constituents but also in the way that tobacco products are regulated and marketed.”

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