Alarmed by documents showing that the tobacco industry manipulated information on tar and nicotine to mislead smokers about the health impact of smoking, antismoking leaders are calling on governments to change the way they measure the toxicity of cigarettes, Reuters reported Feb. 7.

Tar and nicotine in cigarettes are measured on machines, but cigarette companies like British American Tobacco (BAT) designed their products so that filters were blocked by smokers' fingers. Companies also knew that smokers of "low-tar" and "light" cigarettes inhaled more deeply to get more nicotine, thus negating any potential health benefits.

"The current review leaves little doubt that the ISO (International Standards Organization) standards should be discarded in favor of new standards that meet the needs of consumers and regulators, rather than the tobacco industry," Professor David Hammond of the University of Waterloo in Ontario, Canada. Hammond said the tar and nicotine listed on cigarette packages represented only a fraction of these substances received by smokers.

"Overall, the documents seem to reveal a product strategy intended to exploit the limitations of the testing protocols and to intentionally conceal from consumers and regulators the potential toxicity of BAT products revealed by BAT's own research," Hammond said.

The review of industry documents was published online by the journal The Lancet.