An evaluation of the toxicity of 95 ingredients added individually to experimental cigarettes: approach and methods.

CONTEXT: Ingredients have been used in modern cigarette manufacturing to facilitate tobacco processing, provide flavor, and preserve tobacco. Concern has been raised regarding the use of ingredients in cigarette manufacturing due to the possible generation of toxic chemicals resulting from their combustion when added to tobacco.
OBJECTIVE: Investigate the impact of individual ingredients on cigarette smoke toxicity.
MATERIALS AND METHODS: A total of 95 ingredients were tested individually through addition at different concentrations to the tobacco of experimental cigarettes. Mainstream cigarette smoke chemistry analysis, bacterial mutagenicity testing, and cytotoxicity testing were conducted. Additionally, 31 of the ingredients were tested in 90-day nose-only rat inhalation studies using mainstream cigarette smoke. Studies were designed following conventional toxicity testing methods employed for food additives and other consumer products.
RESULTS: The studies reported here demonstrate that high levels of some ingredients can change the quantity of some smoke constituents, altering the smoke chemistry profile. From the panel of biological endpoints monitored, these added ingredients produced minimal changes in the overall toxicity profile of mainstream cigarette smoke. In some cases, the addition of high levels of an ingredient caused a small reduction in toxicity findings, probably due to displacement of burning tobacco.
CONCLUSION: The battery of testing results presented here is a useful addition to the available scientific information for cigarette ingredients and extends the dataset which can be used for evaluating their appropriate use.