Tobacco Documents Online

TC126/WG6 N63 RELATIVE HUMAN UPTAKE Laboratory experiments have raised questions as to whether channel ventilated cigarettes are appropriately ranked with other llmg tar cigarettes. A definitive answer can only be obtained by measuring, actual human smoke uptake in normall everyday smoking. No marker has yet been developed for tar uptaike, but relative nicotine uiptakes may be determined from measurements of its metabolite, cotiinine,'ini blood samples. Galieazzi'et al (N64), show that cotinine levels in plasma are indeed linearly related to nicotine intake. Gori and Lynch show that in a large scale, 288 person study (N6'5), cotinine levels iin blood are 1.5 times higher wheni subjects smoke BRAND A(BARCL/#Y - 0.2 mg nicotine)' thani when smoking BRAND B or BRAND, C ('Carlton and Cambridge, at that time both nominal 0.1 mg nicotine cigarettes). Relative human nicotinel uptakes are therefore in the ratio.of 1.5 to 1 for channel ventilated, cigarettes as compared to the other conventionally ventilated' cigaret'tes which is consistent with their machine ranking. Although tar to nicotine ratiios in human smoking are not precisely known, nevertheless the higher nicotine content of the blend, used in BRAND A. (3% nicotine versus 2% for the other two cigarettes)lindicates that the relative tar uptakes will be no greater than 1.5 to 1 and are probably less than this ratio. More detailed analyses of nicotine pharmacodynamics and of the Gori and Lynch paper are given in a review article written by Darby, McNamee and vaniRossum. (N66). A further study by GORI and LYNCH (N67) conductedlwith 800 smokers and a variety of US brands shows that the average range of nicotine uptake in the human is less than indicatedlby standard smoking machine values., Indeed therelis evidence for bothupwaird and downward compensation. They also show, that variability of uptake between smokers of a given bramd is extremely large.