“…Evaluating the magnitude of SHS exposure and identifying its sources are fundamental steps needed to reduce exposure and to target prevention strategies. SHS exposure is assessed by diverse methods, including questionnaires (Al-Delaimy et al, 2000;Delfino et al, 1993;Gaffney et al, 2003;Klepeis, 1999), air nicotine monitoring (Hammond and Leaderer, 1987;Leaderer, 1990;Navas-Acien et al, 2006;Repace et al, 2006;Wipfli et al, 2008), and biomonitoring of nicotine or cotinine in such biofluids as serum, urine or saliva (Benowitz, 1999;Coultas et al, 1987;Seccareccia et al, 2003;Pirkle et al, 2006). The most commonly used biomarker for SHS exposure is nicotine or its metabolite, cotinine, in human body fluids such as urine, saliva and serum (Pichini et al, 2000;Simoni et al, 2006;Thaqi et al, 2005).…”