The first issue raised by Dr Homburger on our recent article in The Journal is the possible alteration in the proportion of toxic smoke constituents of today's cigarettes compared with pre-1960 cigarettes. The formulation of today's low tar and low nicotine cigarettes is carried out by processes that reduce quantitatively, and largely nonselectively, the amount of smoke produced in both the particulate phase (which contains tar, nicotine, and water) and the gas phase (which contains the other smoke constituents). Table 3 of our article suggests this overall quantitative reduction, in that the six constituents addressed are reduced for each of the cigarette brands listed. The constituents considered were chosen because these have been implicated in human disease incidence.
These and other constituents have been addressed by the National Cancer Institute's Smoking and Health Program, where over 130 types of experimental cigarettes have been tested for potentially lower toxicity.