Effect of filtration by activated charcoal on the toxicological activity of cigarette mainstream smoke from experimental cigarettes.

Activated charcoal (AC) filtration reportedly decreases the yields of smoke vapor phase constituents including some identified as human carcinogens and respiratory irritants. Non-clinical studies including chemical smoke analysis, in vitro cytotoxicity and mutagenicity (bacterial and mammalian cells), and in vivo subchronic rat inhalation studies were carried out using machine smoking at ISO conditions with lit-end research cigarettes containing AC filters. The objective was to assess whether AC filter technology would alter the established toxicity profile of mainstream smoke by increasing or decreasing any known toxicological properties, or elicit new ones. The reduced yield of vapor phase irritants from AC filter cigarettes correlated with markedly decreased in vitro cytotoxicity and in vivo morphology of the nose and lower respiratory tract. Increased yields of particulate phase constituents (e.g. polycyclic aromatic hydrocarbons) in AC filtered smoke were noted in comparison to controls in some studies. The in vitro bacterial mutagenicity of AC filtered smoke particulate preparations was occasionally increased over control levels. Laryngeal epithelial thickness was increased in some rats inhaling AC filtered smoke in comparison to controls, an effect perhaps related to higher inspiratory flow. When tested under more intense Massachusetts Department of Public Health smoking conditions, AC filter associated reductions in vapor phase constituent yields were smaller than those seen with ISO conditions, but the effect on in vitro cytotoxicity remained.

Smoke chemistry, in vitro and in vivo toxicology evaluations of the electrically heated cigarette smoking system series K.

The Electrically Heated Cigarette Smoking System Series K (EHCSS) produces smoke through the controlled electrical heating of tobacco. Evaluation of the EHCSS was accomplished by comparison with commercial and reference cigarettes, using International Organization for Standardization (ISO) and alternative puffing regimens based on nicotine exposures measured in a short-term clinical study. Using the alternative puffing regimen and compared with conventional cigarettes on a per cigarette basis, the EHCSS had 50-60% reductions in tar and nicotine; at least 90% reductions in carbon monoxide, nitrogen oxides, 1,3-butadiene, isoprene, acrylonitrile, polyaromatic hydrocarbons, hydrogen cyanide, aromatic amines, tobacco specific nitrosamines, and phenol; and least a 40% reduction in 2-nitropropane. Other important smoke constituents in EHCSS smoke were reduced as well. The in vitro studies showed similar large reductions in biological activity. Ames mutagenicity of total particulate matter (TPM) from the EHCSS was reduced by 70-90%; cytotoxicity of the TPM was reduced by approximately 82% and 65% for the gas-vapor phase. In vivo testing under ISO smoking conditions in the mouse skin painting assay demonstrated later dermal tumor onset, lower dermal tumor incidence, reduced dermal tumor multiplicity, and a lower proportion of malignant dermal tumors in EHCSS smoke condensate-exposed mice. Thirty-five day and 90-day nose-only inhalation studies in rats showed reductions in pulmonary inflammation and other biological activity, including histopathological endpoints. We conclude that under the conditions of these in vitro and in vivo studies, the EHCSS demonstrated significantly lower biological activity compared to conventional cigarettes, and may suggest the potential for reductions in human smokers.

Toxicological comparisons of cigarettes containing different amounts of vanillin.

Vanillin is a flavoring agent used in cigarettes. Previous toxicological examinations of the effects on the addition of vanillin to tobacco used mixtures with several other flavoring agents. In the present work, toxicological comparisons were made of experimental cigarettes containing no added vanillin against otherwise similar cigarettes with three different amounts of vanillin added to the tobacco. The main toxicological comparison was a subchronic inhalation study with mainstream smoke in Sprague-Dawley rats (exposures of 150 mg/m3 of total particulate matter, 6 h exposure per day, for 90 consecutive days). Vanillin concentrations in the tobacco of the 4 cigarette types at the end of the study were 0, 67, 1233, and 3109 ppm. Additional studies with mainstream smoke were Salmonella mutagenicity (5 bacterial strains, both with and without metabolic activation, particulate phase only), cytotoxicity of both particulate and gas/vapor phases (using the neutral red uptake assay), and analytical chemistry (49 analytes, including 5 metals). Similar responses were seen across the four cigarette types, and the responses were similar to those previously described in the scientific literature. At the same smoke concentration, the inhalation exposures produced effectively the same responses, in each of the four groups. Most of the changes produced in the 90 days of exposure were resolved in a 42-day postinhalation period. The addition of vanillin to tobacco at inclusion rates up to 3109 ppm did not influence a broad range of toxicological endpoints.