Background: Cold air stimulates upper airway cold receptors causing a reflex depressive effect on respiratory activity. Menthol, in low concentrations can also stimulate these same cold receptors causing a depressive effect on respiratory activity. Menthol cigarettes when smoked, deliver enough menthol to stimulate cold receptors resulting in the smoker experiencing a "cool sensation." The "cool sensation" experienced by the menthol smoker can result in a reflex-depressive effect on respiratory activity.
Method: Literature searches were done for the NLM databases (e.g., MEDLINE from 1966, TOXLINE, OLDMEDLINE (1985-1965), CANCERLIT, plus tobacco industry documents and hardcopy indices. The evidence was evaluated with application to mentholated cigarette smoking.
Results and discussion: A logical progression is presented that develops the framework to prove that menthol found in mentholated cigarettes may cause respiratory depression resulting in greater exposure to the toxic substances found in tobacco smoke.
Conclusion: As a result of breath holding that results from the stimulation of cold receptors there is a greater opportunity for exposure and transfer of the contents of the lungs to the pulmonary circulation. For the menthol smoker this results in a greater exposure to nicotine and the particulate matter (tar) of the smoked cigarette. This exposure can result in increased nicotine dependence and greater chance of tobacco-attributable disease.