Mutagenicity and carcinogenicity of masheri, a pyrolysed tobacco product, and its content of tobacco-specific nitrosamines.

Masheri, an indigenous pyrolysed tobacco product in India, was studied for its chemical, mutagenic and carcinogenic profile. Masheri extract was found to be rich in N-nitrosamines and polycyclic aromatic hydrocarbons. It was highly mutagenic in the presence of an exogenous metabolic system in the Ames test and in the micronucleus test, in a dose-dependent manner. It also induced 8-azaguanine-resistant mutants in Chinese hamster V79 cells. On skin painting, it showed a weak carcinogenic effect in Swiss nude mice. The saliva of masheri users showed high levels of N'-nitrosonornicotine (NNN; 14-43 ppb) and N-nitrosopyrrolidine (NPYR; 2.2-8.3 ppb). Thus, this widespread habit, predominant among women, could be an additive risk factor in the high incidence of oropharyngeal cancer prevalent in India.