Serum oxidative stress parameters and paraoxonase-1 in children and adolescents exposed to passive smoking

Background: Exposure to secondhand smoke is too common in many countries. The mechanism of the detrimental effects of passive smoking on childhood health, however, is poorly described. The purpose of this study was therefore to examine the effect of passive smoking on total antioxidant status (TAS), total oxidant status (TOS), and paraoxonase-1 in children compared with healthy non-passive smokers. Methods: This study included 40 children and adolescents passively exposed to cigarette smoke (as verified on urine cotinines) and 40 age-and gender-matched healthy controls not regularly exposed to cigarette smoke. TAS, TOS, and paraoxonase-1 were all measured, and the oxidative stress index (OSI) calculated for each child to determine the degree of oxidative stress. Results: Age and gender distribution were not statistically different between the two groups (P = 0.619 and 0.712, respectively). Urine cotinine/creatinine was significantly higher in the passive smoking group (127.89 +/- 57.14 ng/ mL) compared with the controls (5.05 +/- 16.66 ng/mL; P < 0.001). TAS was not different between the two groups (P = 0.767), but TOS and OSI were significantly higher for the passive smoke-exposed children (P < 0.001), and serum paraoxonase-1 was significantly lower than in the controls (P = 0.047). Conclusions: Secondhand smoke exposure is associated with increased oxidative stress and decreased paraoxonase1 without any change in antioxidant status.