Analysis for nicotine and cotinine in hair to determine cigarette smoker status.

Noninvasive validation of cigarette smoking behavior is necessary for large population studies, especially with adolescents, where peer pressures can compromise self-report. Saliva and urine samples provide biological material for confirmation of recent nicotine intake by analysis for cotinine, the major metabolite of nicotine. However, detection of infrequent use of cigarettes can be missed in a single annual screen when participants have not smoked in the preceding week. We analyzed scalp hair from smokers and controls, to see whether hair could provide reliable samples for determining nicotine uptake. The amounts of nicotine and cotinine we detected in these samples correlated with individual smoking habits and exposures.