Sensory Irritation by Sulfite Aerosols on the Upper Respiratory Tract in Mice

Alternations in the respiratory rate of mice in response to inspired sulfite aerosols were investigated and compared to those with sulfur dioxide. With exposure to aerosols of sodium bisulfite or potassium bisulfite, the pattern of response was exactly similar to the one with SO2. There was no difference between sodium bisulfite and potassium bisulfite with regard to sensory irritation potency as measured by the magnitude of maximum respiratory depression. On the other hand, aerosols of sodium sulfite or potassium sulfite were not only inactive but also could not influenced the irritant potency of SO2. Mice desensitized by a given concentration of SO2 to its sensory irritation no longer reacted to an equivalent concentration of sodium bisulfite. It can be concluded that the sensory irritant potency of sulfur dioxide and its corresponding salts is due to the reducing property of bisulfite anion formed in the nasal mucosa independently of the added cation.