Is pan masala-containing tobacco carcinogenic?

BACKGROUND: Pan masala-containing tobacco (PM-T) was introduced in the Indian market during the 1970s. It is a mixture of areca nut, tobacco, lime, catechu and spices. Despite mounting evidence of health hazards of tobacco, tobacco manufacturers as well as policy-makers often seek evidence regarding the carcinogenicity of newer tobacco mixtures such as PM-T. METHODS: All the studies on pan masala (with or without tobacco) listed on MEDLARS, and the studies known to the expert committee on the subject constituted by the Directorate General of Health Services, were reviewed. The studies on individual components and PM-T like substances were also reviewed. The interpretation of carcinogenicity of PM-T has been made, based on studies on (i) PM-T; (ii) PM-T like mixtures; and (iii) the effect of individual ingredients of PM-T and the likely effect of their combination. RESULTS: Studies on Chinese hamster ovary cells and Ames test indicate that PM-T is mutagenic. There is limited evidence that it may be carcinogenic to animals. The proportion of areca nut and tobacco in PM-T is in between the proportion of these substances in two known tobacco-areca nut mixtures of India (Mainpuri tobacco and mawa). Studies on Mainpuri tobacco indicate that it is carcinogenic, while literature suggests an association between mawa use and oral submucous fibrosis. CONCLUSION: Human studies on PM-T like mixtures and the limited studies on PM-T suggest that PM-T is likely to be carcinogenic.