Nitrate reductase activity and nitrite levels in the saliva of habitual users of various tobacco products.

Nitrite found in human saliva is the product of the microbial reduction of nitrate circulating through the salivary glands. Saliva samples were collected under controlled conditions from volunteers who were habitual users of different types of tobacco products (tobacco chewers, cigarette smokers, bidi smokers and masheri users) and from controls. The saliva samples were analysed for nitrite levels and for nitrate reductase activity spectrophotometrically. Samples were collected from two different areas, Bombay (urban) and Ghodegaon (rural). Salivary nitrite levels in the control groups ranged from 1.6 ppm in Ghodegaon to 11 ppm in Bombay. The nitrite levels of the masheri-using groups from both locations and of the tobacco-chewing group from Bombay were significantly higher than those of the controls. A number of volunteers showed undetectable levels of salivary nitrate reductase. Volunteers who chewed tobacco or used masheri had higher levels of nitrate reductase activity than the controls. However, there did not seem to be any clear correlation between nitrite levels and nitrate reductase activity in the saliva.