Pulmonary Toxicity Assessment after a Single Intratracheal Inhalation of Chlorhexidine Aerosol in Mice.

Guanidine disinfectants are important chemical agents with a broad spectrum of activity that are effective against most microorganisms. Chlorhexidine, one of the most used guanidine disinfectants, is added to shampoo and mouthwash and applied in medical device sterilization. During the use of chlorhexidine, aerosols with micron particle size may be formed, which may cause inhalation toxicity. To assess the toxicity of inhaled chlorhexidine aerosol, mice underwent the intratracheal instillation of different concentrations of chlorhexidine (0, 0.125%, 0.25%, 0.5%, and 1%) using a MicroSprayer Aerosolizer. The mice were exposed for eight weeks and then sacrificed to obtain lung tissue for subsequent experiments. Histopathology staining revealed damaged lung tissues and increased collagen exudation. At the same time, pulmonary function tests showed that chlorhexidine exposure could cause restrictive ventilatory dysfunction, consistent with pulmonary fibrosis. The results of transcriptome analyses suggest that chlorhexidine may trigger an inflammatory response and promote the activation of pathways related to extracellular matrix deposition. Further, we identified that chlorhexidine exposure might enhance mucus secretion by up-regulating and genes, thereby inducing fibrosis-like injury. These findings underscore the need for standardized use of disinfectants and the assessment of their inhalation toxicity.