Part of the below study examined cotinine levels (primary chemical nicotine breaks down into) in both smokers and those breathing passive or second hand smoke. If I'm reading this correctly the cotinine level in the urine of smokers was 634 times greater than in passive smokers. If worried about passive smoking causing relapse, cotinine levels are a marker of where nicotine has been. Hopefully this finding helps give you peace of mind, at least in regard to relapse.
Urine cotinine underestimates exposure to tobacco-derived
lung carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone
(NNK) in passive compared to active smokers
Cancer Epidemiology, Biomarkers & Prevention
Published OnlineFirst August 30, 2010.
Neal L. Benowitz, Maciej Goniewicz, Mark Eisner, Eduardo Lazcano-Ponce, Wioleta Zielinska-Danch, Bartosz Koszowski, Andrzej Sobczak, Chis Havel and Peyton Jacob III
Objectives: Cotinine and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) are widely used biomarkers for tobacco-derived nicotine and the lung carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), respectively. The discrepancy between cotinine levels in relation to disease risk comparing active vs. passive smoking suggests a non-linear tobacco smoke dose-response and/or that cotinine is not providing an accurate measure of exposure to tobacco smoke toxic constituents from secondhand smoke.
Methods: Cotinine and NNAL were measured in urine of 373 active smokers and 228 passive smokers.
Results: Average cotinine levels were 1,155
(IQR 703-2,715) for active smokers
(0.45-7.33) ng/mg creatinine for passive smokers.
Average NNAL levels were 183 (103-393) and 5.19 (2.04-11.6) pg/mg creatinine, respectively. NNAL/cotinine ratio in urine was significantly higher for passive smokers when compared to active smokers (2.85×103 vs. 0.16×103, p<0.0001).
Conclusions: Cotinine measurement leads to an underestimation of exposure to the carcinogen NNK from second-hand smoke when compared with active smoking.
http://cebp.aacrjournals.org/content/ea ... PI-10-0497