Introduction: Tobacco smoking is one of the principal epidemics, a major predisposing factor for multiple non-communicable diseases as vascular, cardiac and respiratory diseases and the 2nd major death risk factor. Passive tobacco smoke inhalation, known as secondhand smoke (SHS) or environmental tobacco smoke, is more common in the closed environment (indoor exposure). This type of smoke inhalation causes 15% of smoking-induced deaths and 2% of total deaths. So, smoking in closed public areas is banned in many countries. In low & middle socio-economic countries, children -at their homes- are the most age group at risk of SHS exposure.
Aim of the Work: This study aimed at evaluating and comparing the possible hazardous effects of SHS on the lungs of male albino rats in childhood and adulthood periods with highlighting the consequences on the bronchiolar ciliated & Clara cells and alveolar pneumocytes-I & II.
Materials and Methods: 24 male albino rats were chosen and sorted equally into child group (~21 days, group I) and adult group (~90 days, group II). Each group was subdivided equally into 2 subgroups: sham-exposed (exposed to fresh air, two times daily with 6 hours interval) and smoke-exposed (treated as sham-exposed subgroup but with SHS instead of fresh air). After 2 weeks, just before sacrifice, serum cotinine level was measured for all animals. Biochemical, histological, immunohistochemical [for Clara cells secretory protein (CCSP), surfactant protein-C (SP-C), ß-tubulin, caspase-3 & CD-68] and morphometric studies were done.
Results: Smoke-exposed subgroups (child & adult) showed lung inflammatory signs and degenerative changes in bronchiolar ciliated and Clara cells and in pneumocytes-I & II that were more noticeable in child subgroup.
Conclusion: SHS has severe detrimental effects on structure and function of rats' lungs via oxidative, inflammatory & apoptotic mechanisms. Additionally, children are more vulnerable than adults to these damaging effects.