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Introduction
Nasvai (sometimes referred to as naswar or nass) is a smokeless tobacco product used in central Asian countries such as Uzbekistan, Tajikistan, Kyrgyzstan, Turkmenistan and Kazakhstan. It is prepared by mixing locally grown tobacco with slaked lime or alkaline tree ash, and adding various combinations of flavouring and colouring ingredients. Nasvai can be produced in cottage industry settings or be custom made, and is sold either prepackaged in small containers or in bulk. While data on the prevalence of nasvai use in central Asian countries are scarce, the existing reports indicate that it may exceed that of smoking: 22.3% of adult men in Uzbekistan and 40% of rural adult men in Tajikistan reported using nasvai, while smoking prevalence estimates in the same populations were 19.6% and 8.7%, respectively. 1 2 The largely unregulated production and accessibility of nasvai suggest that actual consumption may be even greater.
Consistent with the evidence that certain types of smokeless tobacco increase risk of oral cancer, including tobacco with lime in South Asia, the few published studies suggest that the use of nasvai may increase the risk of precancerous oral lesions and oral cancer. 3-5 Analysis of toxic and carcinogenic constituents in nasvai products on the market in central Asian countries could provide important information for better understanding of their harmful potential. We report here initial findings of substantial differences in the levels of several important constituents between two versions of nasvai recently purchased in Kyrgyzstan and Uzbekistan.
Methods
Two samples of nasvai-a prepackaged product with the manufacturer's label and a bulk unlabelled product ( figure 1 )-were obtained from Bishkek, Kyrgyzstan, in February 2015, and from Tashkent, Uzbekistan, in August 2015, respectively. We analysed moisture content, pH, nicotine and unprotonated nicotine, carcinogenic nitrosamines N [variant prime]-nitrosonornicotine (NNN), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL). We also analysed 13 polycyclic aromatic hydrocarbons (PAH), which included benzo[a ]pyrene and other carcinogenic...