Assessment of Health Hazards of Passive Tobacco Smoking in School-age Children; Role of Oxidative Stress Biomarkers and Nitric Oxide Metabolites

Abstract

Background: Oxidative stress is thought to be produced by cigarette smoking whether by active or passive exposure. For assessment of smoking related health hazards, several oxidative stress biomarkers have been in use. The aim of the present work is to investigate the impact of passive smoking on the health of school age children who had first degree relative smokers at home. Assessment of smoking related health hazards was done by measurement of malondialdehyde (MDA) as a biomarker of oxidative stress, in addition to measurement of the total antioxidant capacity (TAC), nitric oxide (NO) metabolites and cotinine levels in urine. The state of children’ exposure to tobacco smoke was assessed via parents' questionnaire. Methods: The current study involved participation of a total of 183 Egyptian school age children ranged from 6-15 years old in the period from September 2012 to June 2013. They were grouped into two groups group I cases; Second Hand Smoke (SHS) (n=132) were exposed to cigarette smoke at home (one of the first degree relatives was a heavy smoker; smokes 15-25 cigarettes per day. Group II control group (n=51) were not exposed to cigarette smoke at home. A morning urine sample was collected from all participants for colorimetric measurements of MDA, TAC, NO metabolites and cotinine levels. Results: MDA, NO metabolites and urinary cotinine levels were significantly higher in SHS cases compared to the control group (p<0.0001) while total antioxidant were significantly lower in SHS cases compared to control group (p<0.0001). TAC was significantly higher in males than in females (p=0.003). A negative correlation was found between NO metabolites (nitrite) and the TAC (r =-0.34, P<0.0001). Positive correlation was found between NO metabolites (nitrite) and MDA levels (r =0.44, P<0.0001), between MDA and urinary cotinine (r=0.26, P<0.0001) and between MDA levels and the age (r =0.22, P<0.0001). Grouping of the participated children according to their age group and studying its relation to the different studied biomarkers using one way ANOVA test followed by post hoc test the least significant difference (LSD); NO metabolites was statistically significant between the age group 1 (from 6 to 9 years) and age group 3 (from12 to 15years) (p =0.05). Conclusion: passive parental smoking is associated with significant changes in the balance between oxidant / antioxidant leading to oxidative stress and associated with elevated levels of NO but impaired its action.