Introduction: The worldwide COVID-19 pandemic has led to wide usage of disinfectants as Sodium hypochlorite (NaOCL). Some studies declared that exposure to chlorine-based disinfectants is considered as a source of irritation and airway inflammation.
Aim of Work: Determine the histopathological effects of NaOCL inhalation on the tracheal mucosa and the reversibility of these effects upon recovery.
Material and Methods: Forty adult male albino rats were divided into three groups. Group I: was further subdivided into subgroup IA: ten rats were used as negative control, subgroup IB: ten rats exposed to nebulized distilled water 20 minutes/day for three weeks. Group II: ten rats exposed to nebulized 4% NaOCL 20 minutes/day for three weeks. Group III: ten rats exposed to NaOCL same as group II and were left for another three weeks without exposure. At the end of experiment for each group, rats were anesthetized, sacrificed and trachea were excised and processed for light and electron microscopic examination also morphometric and statistical studies were done.
Results: Examination of sections of group II rats revealed marked distortion of tracheal epithelial cells, indistinct cell boundaries, shrunken heterochromatic nuclei, loss of apical cilia and highly significant decrease in epithelial height with highly significant increase in mean of number of goblet cells and area percentage of collagen. Sections of the group III showed that the tracheal lining was almost restored. Yet, it appeared disorganized cells, with restored but almost amalgamated cilia. Goblet cells revealed back to normal number but were still variable shaped. However, mean epithelial height and mean area percentage of collagen did not go back to their control ranges.
Conclusion: Inhalation of NaOCL has been found to cause partially reversible histopathological effects on the tracheal mucosal. Thus, excessive use of household chlorine containing detergents should be limited or better substituted by others.