Nicotine, and/or its primary metabolite cotinine, is most often tested to evaluate tobacco use. Because the use of tobacco products can greatly affect the health of individuals, companies may use nicotine/cotinine testing to evaluate prospective employees for tobacco use. Many health and life insurance companies test applicants for nicotine or cotinine as well. Nicotine and cotinine can both be measured qualitatively or quantitatively. Qualitative testing detects the presence or absence of the substances, while quantitative testing measures the concentration of the substance. Quantitative testing can help distinguish between active smokers, tobacco users who have recently quit, non-tobacco users who have been exposed to significant environmental tobacco smoke, and non-users who have not been exposed.

Nicotine and/or cotinine results may be reported as positive or negative, or as a level (e.g., nanograms per milliliter or ng/mL). The level of nicotine and/or metabolites in a person's sample depends on a few factors, such as how much the person inhales or ingests. Also, the rate at which nicotine is metabolized and cotinine is cleared from the body varies from person to person. When someone stops using tobacco and nicotine products, it can take more than two weeks for the blood level of cotinine to drop to the level that a non-tobacco user would have and several weeks more for the urine level to decrease to a very low concentration. • In general, a high level of nicotine or cotinine indicates active tobacco or nicotine product use. • A moderate concentration indicates that the person has not had tobacco or nicotine for two to three weeks. • A lower level may be found in a non-tobacco user who has been exposed to environmental smoke. • Very low to non-detectible concentrations may be found in people who have not used tobacco or nicotine and have not been exposed to environmental smoke or in tobacco or nicotine users who have refrained from tobacco and nicotine for several weeks

Whenever someone requires confirmation of tobacco or nicotine usage. And to check how enviromental factors are affecting non-smokers