A brief review is presented of the scientific literature on the effects of ammonia compounds, when used as tobacco additives, on the smoke chemistry and bioavailablity of nicotine. The review concludes that ammonia compounds used in the manufacture of certain types of tobacco sheet materials:
1) contribute to the flavor properties of cigarette smoke,
2) do not increase the amount, rate or efficiency of nicotine transferred from tobacco to mainstream smoke (MS),
3) do not increase the percentage of nicotine in MS gas phase using the FTC/ISO (Federal Trade Commission/International Organization for Standardization) method,
4) have no influence on the determination of MS nicotine yield as measured by the FTC/ISO method, and
5) do not increase the total rate or amount of nicotine absorbed by the smoker.
The review also examines the use of pH as it relates to tobacco and to smoke and suggests a terminology which more accurately describes the measurement (pH of aqueous extract of tobacco, pH of aqueous extract of smoke, and pH/electrode in smoke). Lastly, a number of research gaps in these areas are identified.