Carcinogenic Activity of Cigarette Smoke Gas Phase and Its Modulation by Beta-Carotene and N-Acetylcysteine. Toxicol Sci 2004

Male strain A/J mice were exposed for six hours a day, five days a week for sixmonths to either full tobacco smoke or to tobacco smoke drawn through a HEPA filter that removed more than 99 % of par-ticulate matter. After another four months in air, the animals were sacrificed and lung tumors were counted for calculation of multi-plicities and incidences. Analysis of the chamber atmospheres showed that in the filtered smoke the concentrations of polycyclic aromatic hydrocarbons and tobacco smoke specific nitrosamines were reduced to from below 18 % to even nondetectable levels of the original valuesmeasured in the unfiltered smoke.Aldehydes and other volatile organic compounds such as 1,3-butadiene, benzene, or acroleinwere reduced toabout50 to90%of theconcentrations found in unfiltered smoke. Some potentially carcinogenic metals reached levels in filtered smoke ranging from 77 % to less than 1 % found in full smoke. The mice exposed to the filtered smoke atmosphere ha