An evaluation of the inhalation toxicity of one commercial proteolytic enzyme preparation.

The inhalation toxicity of a commercial proteolytic enzyme preparation containing 12% subtilisin Carlsberg was studied in experimental animals. Guinea pigs that had been pretreated by a series of intradermal injections of the enzyme preparation in saline solution died as a result of a single 6-hour exposure to the enzyme preparation at an air concentraion of 41.2 mg/m-3, while normal guinea pigs and pretreated guinea pigs that were dosed with an antihistamine immediately prior to exposure survived. The 6-hour LC50 for pretreated guinea pigs was determined as 24.7 mg/m-3. Normal rats, normal rabbits, and pretreated rabbits survived exposures to the enzyme preparation at concentrations as high as 36.8 mg/m-3. Pathologic examinations revealed changes only in the lungs of the exposed animals. These pulmonary alterations appear to be reversible. A histamine release is suggested as the primary effect of a secondary exposure to this proteolytic enzyme preparation.