Background:
Tobacco use continues to be the single most leading cause of preventable deaths globally causing more than 5 million deaths/ year. The tobacco use status declared by patients must be objectively validated by biochemical tests. Salivary thiocyanate has been shown to be a suitable indicator of habitual smoking. However, data on its levels among tobacco chewers and passive smokers is lacking. The objective of the present study was to estimate and compare the salivary thiocyanate levels among smokers, passive smokers, tobacco chewers, non-tobacco users in Mangalore, Karnataka, India.

Methods:
A self-administered, pre-tested questionnaire was distributed to one hundred hospital outpatients in Mangalore, Karnataka, India. Based on the responses obtained, the participants were categorized into Smokers (25), Smokeless tobacco users (25), Passive smokers (25) and Non-Users (25). Saliva was collected from the subjects in sterile plastic containers and sent for biochemical analysis to estimate thiocyanate levels. The results obtained were tabulated in Microsoft Excel for Windows and subjected to statistical analysis using SPSS statistical package 17.0. Kruskal Wallis test was used to compare the data among the various groups and the difference was considered as statistically significant if P< 0.05. Pairwise comparison between groups was done using the Mann Whitney U test.

Results:
The mean salivary thiocyanate levels were 79.46+7.80 mMol/L, 50.16+13.83 mMol/L, 50.59+6.87 and 36.61+5.84 among the smokers, tobacco chewers, passive smokers and non-users respectively which was statistically significant. Pairwise comparison of the groups showed that there was significant statistical difference among all pairs except between the passive smokers and smokeless tobacco users.

Conclusions:
Salivary thiocyanate can be used as a reliable diagnostic marker for differentiation of tobacco users from non-tobacco users. Salivary thiocyanate levels may also be a valuable indicator in tobacco cessation clinics for assessing the prognosis of tobacco abusers in their attempt to quit the habit.