Difference in exposure to airborne major rat allergen (Rat n 1) and to endotoxin in rat quarters according to tasks

Endotoxins found in occupational settings constitute a risk factor in the severity of respiratory allergic symptoms. OBJECTIVES: To assess the airborne concentrations of major rat allergen (Rat n 1) and endotoxin under various circumstances. METHODS: We took 483 airborne samples from 12 sites: 114 individual samples for endotoxin measurements and 113 for Rat n 1, from 38 workers (nine animal technicians, nine laboratory technicians, nine scientists and 11 students); and 256 static samples in rat rooms and experimental rooms, with or without disturbance, for simultaneous endotoxin and Rat n 1 measurements. Rat n 1 was measured with a two-site monoclonal ELISA and endotoxins with the Limulus method. RESULTS: Airborne Rat n 1 and endotoxin were significantly higher in rat rooms than in experimental rooms. Animal technicians had the greatest exposure to both Rat n 1 and endotoxin. Cage cleaning and rat feeding induced the highest exposure to Rat n 1 and endotoxin. Furthermore, we observed no significant difference in endotoxin exposure between researchers with or without rat contact during the sample period. There was no correlation between the number of rats present and airborne endotoxin concentrations. CONCLUSIONS: Exposure to airborne Rat n 1 and endotoxin is higher during cleaning and feeding tasks than during any other task, we feel that a major source of both is contaminated bedding that becomes airborne during disturbance.