The inhalation of gaseous hypochlorous acid (HOCl(g)) at low concentrations, typically encountered during indoor disinfection, does not have a significant cytotoxic effect on human respiratory epithelial cells, according to a study using laboratory model systems.
- Inhalation of gaseous hypochlorous acid (HOCl(g)) at low concentrations (less than 500 ppb) has no cytotoxic effect on respiratory epithelial cells. - The concentration of HOCl(g) reaching the lung pseudo-space is close to zero when the chamber concentration is less than 20.5 ppb. - HOCl(g) adsorbs on gas-contact silicone rubber surfaces, leading to its disappearance during inhalation.
This is from J Microorg Control in 2023 at https://pubmed.ncbi.nlm.nih.gov/37394529/ This is from J Microorg Control in 2023 at https://pubmed.ncbi.nlm.nih.gov/38233168/ This is from Zhonghua Jie He He Hu Xi Za Zhi in 2024 at https://pubmed.ncbi.nlm.nih.gov/38309959/ This is from Natl Toxicol Program Tech Rep Ser in 1993 at https://pubmed.ncbi.nlm.nih.gov/12616290/
Top Five Keywords: bronchiolar epithelium, gaseous hypochlorous acid, human respiratory tract model, inhaled concentration, nasal epithelium.
Abstract
During the disinfection of indoor spaces using gaseous hypochlorous acid (HOCl(g)), inhalation is the most common route of exposure for humans. In this study, an artificial human respiratory tract model was exposed to 12-140 ppb HOCl(g) at an aspiration flow rate of 800 mL/s for 15 h in a 1 m3 chamber. The respiratory tract model was equipped with 5th order bronchi and all gas-contact parts were made of silicone rubber with no other chlorine-consuming substances. The concentration of HOCl(g) reaching the lung pseudo-space was approximately 47.4% of the HOCl(g) concentrations in the chamber and was calculated to be very close to zero when the chamber concentration was less than 20.5 ppb. The disappearance of HOCl(g) during inhalation is likely due to the adsorption of HOCl(g) on the gas-contact silicone rubber surfaces. The cytotoxicity of HOCl(g) on respiratory epithelial cells was also examined using human air-liquid-interface airway tissue models. Human nasal epithelium and bronchiolar epithelium were exposed to 100 ppb and 500 ppb HOCl(g) for 8 h and 5 d, respectively. No significant effects of HOCl(g) on cell viability and ciliary activity were observed in any cell type, indicating that low concentrations of HOCl(g）, less than 500 ppb, had no cytotoxic effect.
Keywords: bronchiolar epithelium; gaseous hypochlorous acid; human respiratory tract model; inhaled concentration; nasal epithelium.
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