Context: A total of 32 essential oils and resins were added individually to experimental cigarettes.
Objective: A battery of tests was used to compare the toxicity of mainstream smoke from these experimental cigarettes. The lowest target inclusion level was 100 ppm and the highest was 100,000 ppm.
Materials and methods: Smoke from each of the experimental cigarette was evaluated using analytical chemistry and in vitro bacterial (Salmonella, five strains) mutagenicity and cytotoxicity (neutral red uptake) assays. For seven of the ingredients (carob bean, carob bean extract, carrageenan, chamomile flower Hungarian oil, guar gum, peppermint oil, and spearmint oil), 90-day smoke inhalation studies with rats were also performed.
Results: In general, inclusion levels resulted in minimal changes in smoke chemistry; the exceptions were PO and SO, where reductions to 40-60% of control values were noted, possibly indicating a tobacco displacement effect. Cytotoxicity and mutagenicity were unaffected by any of the test ingredients, except for a dose-related reduction in cytotoxicity for SO. There were very few statistically significant differences within any of the seven inhalation studies; when present, the differences were sporadic and inconsistent between sexes. The addition of SO appeared to depress body weight gain and increase the atrophy of olfactory epithelia, but only in males.
Conclusion: The essential oils and resins tested here as ingredients in experimental cigarettes show minimal toxicological sequelae, even at high inclusion levels. The highest inclusion level for SO showed some equivocal responses.