“…In particular, this association occurred for Li, Ti, V, Co, Ga, Sr. Other studies reported a significant positive correlation between the intensity of ETS exposure in general population and increased levels of some tobacco-related elements in different biological matrices (hair, blood, urine) (Richter et al, 2009;Serdar et al, 2012;Viroonudomphol et al, 2016). Each of these studies, however, reported significant increases for different elements; Serdar et al (2012), for example, found that Pb, Cd, Cu, Ni, and Sb levels in children's hair were positively correlated with the number of smokers and the frequency of smoking at home. Richter et al (2009), instead, evidenced that the urinary concentrations of Cd, Pb, Sb, Ba, Be, Cs, Co, Molybdenum (Mo), Pt, Tl, Tungsten (W) of subjects aged from 6 to N65 years old increased in a similar fashion as theoretical tobacco smoke exposure increase, from unexposed to smokers.…”