Reducing the confounding effects of environment and diet on saliva thiocyanate values in ex-smokers.

This study focuses on the use of saliva thiocyanate to corroborate self-report in 391 adult ex-smokers who claimed abstinence from cigarettes for a minimum of 3 months. Results indicated significant thiocyanate confounders, such as using and inhaling nontobacco organic substances, working in a "smoky" environment (i.e., tobacco smoke), and consuming varieties of Brassica oleracea (e.g., cabbage), that could be identified and adjusted for in order to clarify classification of smoking status. Before adjustment for confounders, 18% of subjects reporting abstinence had saliva thiocyanate values greater than the standard cut-off point of 100 micrograms/ml, which would classify them as current smokers. After adjustment, only 12% of subjects still had values greater than 100 micrograms/ml.