HUMAN URINE MUTAGENICITY STUDY COMPARING CIGARETTES WHICH BURN OR PRIMARILY HEAT TOBACCO

Cigarette smokers have been reported to void urine which is more mutag enic, as measured in the Ames assay, than urine voided by non-smokers. Condensate from the mainstream smoke of a cigarette which primarily h eats tobacco (test cigarette) has shown significantly reduced mutageni city in a battery of in vitro genotoxicity assays compared with tobacc o-burning cigarettes. The objective of this study was to determine whe ther the reduction in mutagenic activity observed in the in vitro assa ys would be reflected in the urine of smokers of the test cigarette. T wenty smokers were enroled in a 4-week crossover study, with each smok er consuming test cigarettes ad libitum for a week and their usual bra nd of tobacco-burning cigarettes the other 3 weeks. Diet was strictly controlled throughout the study, and broiled and pan-fried meat was no t served to minimize ingestion of mutagenic protein pyrolysis products . There was no statistically significant difference (p = 0.06) in cons umption of tobacco-heating and tobacco-burning cigarettes. There were no statistically significant differences (p = 0.22) in salivary cotini ne concentrations for smokers when smoking either tobacco-burning or t obacco-heating cigarettes. Urinary nicotine (ng/mg creatinine) was not different (p = 0.31) for smokers when smoking either tobacco-burning or tobacco-heating cigarettes. Urinary cotinine (ng/mg creatinine) was 32% lower (p = 0.0004) when smoking tobacco-heating cigarettes as com pared with smoking tobacco-burning cigarettes. Twenty-four-hour urine samples were collected twice weekly, concentrated using XAD-2 resin an d tested in Ames strains TA98 and YG1024 with metabolic activation. To bacco-burning cigarette smokers experienced a 79% reduction in urinary mutagenicity as measured in strain YG1024 and a 72% reduction as meas ured in strain TA98 during the week that they smoked the tobacco-heati ng cigarette while maintaining a fixed dietary regimen. The results of this study indicate that smokers of tobacco-heating cigarettes void u rine which is significantly less mutagenic than urine voided by smoker s of tobacco-burning cigarettes.