Measurement of DNA damage in different groups of passive smokers. A, DNA damage was evaluated in passive smokers who were addicted to snuff. Compared to passive smokers, the level of DNA damage was found higher in those who were addicted to snuff too. B, quantitative analysis of TCS values between passive smokers and those who were addicted to snuff. A significant increase in TCS values was found in snuff-addicted passive smoker compared to those who were not using snuff (**p˂0.005).