COMPARATIVE CYTOTOXICITY STUDIES OF SMOKE CONDENSATES FROM DIFFERENT TYPES OF CIGARETTES AND TOBACCOS

The neutral red assay, a rapid and accurate method for estimating the cytotoxicity of chemicals, has been used to assess the cytotoxicity of cigarette smoke condensate (CSC), a complex chemical mixture containi ng over 3000 identified compounds. The first objective was to optimize the neutral red assay for evaluation of CSCs. This study also assesse d and compared the cytotoxicity of smoke condensates from three refere nce cigarettes which differ in 'tar' content; cigarettes of different tobacco type composition; an ultra-low tar cigarette (R1); and an RJR test cigarette which heats but does not burn tobacco. Finally, this st udy investigated the cytotoxicity of a specific CSC component, nicotin e, and its metabolite, cotinine. Exposure Limes of 24 hours or longer using CHO cells provided optimal conditions for evaluation of CSC cyto toxicity. The cytotoxicity of CSCs from reference cigarettes was simil ar. CSC from cigarettes comprised of flue-cured flue-cured tobacco exh ibited greater cytotoxicity than CSC from cigarettes comprised of burl ey tobacco. CSC from the R1 cigarette exhibited similar cytotoxicity c ompared with 1R4F CSC, The CSC from a cigarette that heated but did no t burn tobacco (RJR test cigarette) demonstrated no cytotoxicity in CH O cells. Finally, nicotine and cotinine were not cytotoxic to CHO cell s. The neutral red assay has been proved useful for quantifying differ ences in cytotoxicity of smoke condensates from cigarettes which vary in 'tar' yield and for assessing specific smoke constituents. (C) 1998 Elsevier Science Ltd. All rights reserved.