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. Author manuscript; available in PMC: 2012 Jun 1.
Published in final edited form as: Cancer Epidemiol Biomarkers Prev. 2011 Apr 5;20(6):1213–1221. doi: 10.1158/1055-9965.EPI-10-1027

Figure 1.

Figure 1

Summary of existing and proposed tobacco-specific carcinogen biomarkers for secondhand and thirdhand smoke exposure. Total NNAL (NNAL plus its glucuronides) is an established biomarker for uptake of the tobacco-specific lung carcinogen NNK in non-smokers exposed to secondhand smoke (SHS). The NNK comes from the sidestream smoke of a cigarette and the non-smoker is exposed to it by breathing air that contains sidestream smoke. iso-NNAL has been proposed as a biomarker of thirdhand smoke exposure because it is an expected metabolite of NNA, a compound formed on surfaces containing nicotine and exposed to nitrous acid (HONO). NNA is not known to be present in cigarette mainstream or sidestream smoke (11).