Detection of cotinine in biological fluids and body tissues is considered a suitable biomarker of both active smokers and non-smokers exposure to tobacco smoke. The interindividual variability in the metabolism of nicotine and elimination of its metabolite cotinine may limit the value of this test of exposure among indivi- duals. This limitation is compensated in studies of large numbers of subjects, as in epidemiological studies. It has been repeatedly confirmed that cotinine levels in non-smokers correlated positively with the risk of some tobacco smoke-related health complications, especially among children. At present cotinine is considered as the best available biomarker of exposure to tobacco smoke.

        Key words: nicotine - cotinine - exposure