Submitted to: Aerobiologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 14, 2009
Publication Date: June 1, 2010
Citation: Dungan, R.S., Leytem, A.B., Bjorneberg, D.L. 2010. Year-Long Monitoring of Airborne Endotoxin at a Concentrated Dairy Operation. Aerobiologia. 26:141-148. Interpretive Summary: Endotoxins are derived from Gram-negative bacteria and are a potential respiratory health risk if continuously inhaled at high concentrations. As a result of the high microbial load at concentrated animal feeding operations (CAFOs), we conducted a year-long study to monitor airborne endotoxin at a large dairy to assess potential risks to humans in downwind plumes. Total airborne endotoxin were measured at upwind (background) and two downwind locations each month for a year. At the upwind location, the average airborne concentration was 28.5 endotoxin units (EU)/cubic meter, while at the downwind edge of the pen and 200 m from the pen edge, the average concentrations were 169 and 72 EU/cubic meter, respectively. Since airborne endotoxin concentrations as low as 50 EU/cubic meter are known to cause acute respiratory effects (e.g. cough, chest tightness, shortness of breath), our results do suggest that workers may be susceptible to endotoxin-related health effects if concentrations remain elevated during a typical shift. However, residents in nearby communities have a decreased risk of exposure, as endotoxin concentrations decrease with distance from the facility.
Technical Abstract: With the increasing prevalence of concentrated animal feeding operations (CAFOs), concern over bioaerosols drifting in downwind plumes is gaining attention as they may cause health effects in humans and livestock. In this study, we monitored total airborne endotoxins at upwind and downwind locations at a large open-lot dairy each month for a year. At the upwind location, the average airborne concentration was 28.5 endotoxin units (EU)/cubic meter, while at the downwind edge of the pen and 200 m from the pen edge, the average concentrations were 169 and 72 EU/cubic meter, respectively. At the upwind location and edge of the lot, there was a significant correlation between the endotoxin concentration and wind speed or solar radiation, but not at 200 m from the pen edge. There were no significant correlations between other ambient weather data and endotoxin concentrations during the year-long study. A comparison between total and inhalable airborne endotoxin concentrations, near the end of the study, revealed no significant differences between the two endotoxin collection methods. From a health-based perspective, our data suggest that endotoxin exposure can be reduced as one increases their distance from the facility.