Cotinine
When nicotine from tobacco smoke is taken into the lungs and enters the bloodstream, the principal metabolite produced in the liver is cotinine. Cotinine diffuses easily from blood into saliva, and salivary and blood levels are highly correlated. (1)
Cotinine in saliva has a longer half-life than nicotine (more than 10 hours), and the literature has documented it to be a specific and sensitive marker for determining exposure to tobacco and nicotine. (2,3,4)
View the Salimetrics Cotinine Assay
References
1. Benowitz, N.L. (1996). Cotinine as a biomarker of environmental tobacco smoke exposure. Epidemiol Rev, 18(2), 188-204.
2. Dhar, P. (2004). Measuring tobacco smoke exposure: Quantifying nicotine/cotinine concentration in biological samples by colorimetry, chromatography and immunoassay methods. J Pharm Biomed Anal, 35(1), 155- 68.
3. Alterman, A.I., Gariti, P., Niedbala, R.S. (2002). Varying results for immunoassay screening kits for cotinine levels. Psychol Addict Behav, 16(3), 256-59.
4. Van Vunakis, H., Tashkin, D.P., Rigas, B., et al. (1989). Relative sensitivity and specificity of salivary and serum cotinine in identifying tobacco-smoking status of self-reported non-smokers and smokers of tobacco and/or marijuana. Arch Environ Health, 44(1), 53-58.
See graphic on the Salimetrics blog post illustrating Participant Second-Hand Smoke Exposure: Interpreting Salivary Cotinine Levels, Cotinine cut-points used to distinguish smokers from non-smokers vary according to secondhand smoke exposure and to racial/ethnic group. This graphic can help you determine these cut-points.
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