On the measurement of tobacco use by adolescents. Validity of self-reports of smokeless tobacco use and validity of cotinine as an indicator of cigarette smoking.

This study assessed the validity of self-reports of smokeless tobacco use by adolescents and the validity of cotinine as a measure of adolescent cigarette smoking. For a sample of 1,854 persons aged 12-14 years living in the southeastern United States in 1985, a combination of three biochemical measures (salivary cotinine, salivary thiocyanate, and alveolar carbon monoxide) and self-reports of cigarette smoking were used to identify subjects who used only smokeless tobacco and subjects who did not use smokeless tobacco. The sensitivity and specificity of self-reports of smokeless tobacco use were 40.8% and 97.9%, respectively. It was determined that of the 175 subjects who ordinarily would be considered smokers because they had salivary cotinine levels greater than or equal to 10 ng/ml, 43.4% used only smokeless tobacco.