Scope for regulation of cigarette smoke toxicity: the case for including charcoal filters

To compare the emissions toxicity of two manufactured cigarette brands, one with and one without a charcoal filter, in the light of manufacturers' laboratory research findings on the properties of charcoal filters.

Emissions of Mild Seven charcoal filter brands, regular (labelled '12 mg tar') and Light (labelled '9 mg tar') purchased in 2004, were compared with those of Holiday Extra-mild brand (9 mg tar, acetate filter), purchased in 2002. All emissions were tested under intensive machine smoking conditions by Labstat International Inc., Kitchener, Ontario.

The Mild Seven brands contained a small amount of charcoal, its black granules visible against the white acetate filter. The charcoal filter in the brands tested did not reduce toxicity to the extent expected, though they gave significantly lower emissions for the respiratory-toxicants acrolein (14%-17% lower, p 'less than and equal to' 0.01) and formaldehyde (26-37% lower, p 'less than and equal to' 0.01). Reductions were not significant for acetaldehyde, and actually higher for hydrogen cyanide. Overall, estimated cardiovascular-respiratory toxicity was not reduced, whether based on toxicant emissions or the toxicant to nicotine ratios. Of the packet labels, neither tar yield (mg) nor the descriptors 'mild', 'light', or 'extra-mild', or 'charcoal filter' for these three brands was associated with any reduction of the combined respiratory--and cardiovascular toxicity of mainstream smoke, as measured by leading toxicants tested by the intensive method. Previously secret documents from cigarette companies, including British American Tobacco, reported reductions of 75%-80% in hydrogen cyanide, acetaldehyde, acrolein, and formaldehyde in mainstream smoke from addition of charcoal to the filter. We estimated that an effective charcoal filter could reduce a brand's overall relative toxicity score for identifiable toxicant by over 40%.

Since 1965, major cigarette firms have known from their chemists that many smoke toxicants, including hydrogen cyanide and acrolein, were removable by manufacturing the cigarette with a charcoal filter. To this day, few brands have charcoal filters. The best known, Mild Seven, contained a token charcoal filter only. In neither Japan nor New Zealand did this brand lower cardiovascular toxicant emissions in smoke. In the Smoke-free Environments Act, Government has the power to lower smoke emissions by regulation, but no regulations are in place. The Act does not give power to add filters to cigarettes, but does give power to lower smoke emissions to the level attainable by using a charcoal filter, which could reduce smoke emission toxicity to a large extent. Regulation to require effective charcoal filters is now long overdue.