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(NNK) and N’-nitroso nornicotine (NNN). 10, 11 Tobacco smoke also contains carcinogens as combustion products, such as arylamines, polycyclic aromatic hydro carbons, and volatile organics. 11 Many studies have investigated possible associ ations between polymorphisms in carcinogen-metab olising genes and tobacco-related cancers; most results are ambiguous, with the possible exception of NAT2 in bladder and breast cancers, and GSTM1 alone or in combination with CYP1A1 in lung cancer. Tobacco smoking, second-hand smoke, and smokeless tobacco were all reaffirmed as carcinogenic to humans (Group 1), along with NNK and NNN. Around 600 million people are estimated to chew betel quid in India and southeast Asia (prevalence of up to 80% in parts of India). Betel quid generally consists of areca nut, betel leaf, catechu, slaked lime, and often tobacco. Carcinogenic nitro samines derived from …