Urinary mutagenicity is widely recognised as a useful biomarker for assessment of mutagen exposure level in humans. In this study, we optimised several parameters affecting the activity of urinary mutagenicity using a highly sensitive mutation test (microsuspension assay) instead of the conventional Ames test for assessment of exposure to smoke. First of all, we chose YG1024 as a highly sensitive strain from three strains of Salmonella typhimurium (TA98, TA100, YG1024) using representative mutation substances of cigarette smoke, such as Benzo[a]pyrene, 2-Aminonaphthalene, 2-amino-3-methyl-9H-pyrido[2,3-b]indole (MeAaC) and cigarette smoke condensate (CSC). And we established several kinds of test conditions such as number of bacteria, concentration of metabolic activation system and incubation time for the most sensitive reaction. Also, we optimised the preparation condition of urinary extracts and this method showed more than 90% recovery value. When we compared the urinary mutagenicity between the smokers and non-smokers, it showed a significant difference according to level of smoking and these results were significantly correlated with smoke exposure biomarkers such as nicotine metabolites and acrolein.

In conclusion, the optimised highly sensitive mutation test to measure the urinary mutagenicity of smokers may be useful in the clinical evaluation of less harmful tobacco products developed in the future.