Toxicological evaluation of potassium sorbate added to cigarette tobacco

Potassium sorbate (PS) may be incorporated in blended cigarette tobacco either as a mold growth inhibitor in processed tobacco sheet material, or as a preservative in flavor systems or paper adhesives. To evaluate the effect of PS addition, neat material pyrolysis studies, smoke chemistry and biological activity studies (bacterial mutagenicity, cytotoxicity, in vivo micronucleus, and 90-day nose-only rat inhalation) with mainstream smoke, or mainstream smoke preparations from cigarettes containing various measured levels of PS (0%, 0.15%, 1.6%, and 3.7%) were performed. At simulated tobacco burning temperatures up to 1000 degrees C, neat PS completely pyrolyzed to form aromatic ring materials including benzene, toluene, substituted benzenes, naphthalene, and substituted naphthalenes. Under machine smoking conditions (FTC/ISO), high levels of PS may alter the burning characteristics of the cigarette leading to decreased puff count, total particulate matter, carbon monoxide, hydrogen cyanide, 2-nitropropane, and tobacco specific nitrosamines yields in the smoke, while increasing the yield of nicotine, 1,3-butadiene, isoprene, and some PAHs. Biological studies indicated no relevant differences in the genotoxic or cytotoxic potential of either mainstream smoke from cigarettes with or without added PS. Rats exposed to mainstream cigarette smoke developed respiratory tract changes consistent with those seen in previous smoke inhalation studies, with no relevant histopathological differences between the control and the PS test cigarette groups. These studies demonstrated that high levels of PS could alter the burning rate of the tobacco leading to alteration in the smoke chemistry profile. Yet, based on the panel of biological endpoints monitored here, it appeared that added PS produced little relevant change in the overall toxicity profile of smoke.