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

Background Endotoxins found in occupational settings constitute a risk fact or 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 anima l technicians, nine laboratory technicians, nine scientists and 11 students ); and 256 static samples in rat rooms and experimental rooms, with or with out disturbance, for simultaneous endotoxin and Rat n 1 measurements. Rat n 1 was measured with a two-site monoclonal ELISA and endotoxins with the Li mulus method. Results Airborne Rat n I and endotoxin were significantly higher in rat roo ms than in experimental rooms. Animal technicians had the greatest exposure to both Rat n 1 and endotoxin. Cage cleaning and rat feeding induced the h ighest exposure to Rat n 1 and endotoxin. Furthermore, we observed no signi ficant 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 cle aning and feeding tasks than during any other task, we feel that a major so urce of both is contaminated bedding that becomes airborne during disturban ce.