A 15-week experimental exposure of pigs to airborne dust with added endotoxin in a continuous flow exposure chamber

The purpose of this study was to evaluate the effect of longterm exposure t o airborne dust and endotoxin on the respiratory system of pigs, A continuo us flow exposure chamber was built for the purpose of exposing pigs to sele cted airborne contaminants, Pigs (n = 6) were exposed to a combination of a very fine corn/soybean meal (40.6 mg/m(3)) with added lipopolysaccharide ( LPS; 12.4 mu g/m(3)) for 8 h/d over 5 d for 15 wk (75 d of exposure). Contr ol pigs (n = 6) were housed in a room with minimal contamination of these a irborne contaminants, Surprisingly, dust in the exposure chamber and the co ntrol room was highly contaminated with peptidoglycan, Changes in the lung were monitored by collecting bronchoalveolar lavage (BAL) fluid for cytolog y at 5 different time points throughout the exposure period, Blood samples were collected at the same time for hematology, A non-specific respiratory inflammatory response was found in exposed and control pigs, as suggested b y the increased neutrophils in BAL fluid and the small inflammatory areas i n the lung tissue, No macroscopic lung lesions were observed in control or exposed pigs, The findings in the control pigs imply that even low dust con centrations and possibly peptidoglycan contamination can induce cellular ch anges in the BAL fluid and that a true control pig does not exist, In addit ion, the exposed pigs developed a mild eosinophilia, indicating an allergic response to the airborne contaminants.