Monitoring total endotoxin and (1→3)-β-d-glucan at the air exhaust of concentrated animal feeding operations

Abstract

Mitigation of bioaerosol emissions from concentrated animal feeding operations (CAFOs) demands knowledge of bioaerosol concentrations feeding into an end-of-pipe air treatment process. The aim of this preliminary study was to measure total endotoxin and (1→3)-β-glucan concentrations at the air exhaust of 18 commercial CAFOs and to examine their variability with animal operation type (swine farrowing, swine gestation, swine weaning, swine finishing, manure belt laying hen, and tom turkey) and season (cold, mild, and hot). The measured airborne concentrations of total endotoxin ranged from 98 to 23,157 endotoxin units (EU)/m³, and the airborne concentrations of total (1→3)-β-d-glucan ranged from 2.4 to 537.9 ng/m³. Animal operation type in this study had a significant effect on airborne concentrations of total endotoxin and (1→3)-β-d-glucan but no significant effect on their concentrations in total suspended particulate (TSP). Both endotoxin and (1→3)-β-d-glucan attained their highest airborne concentrations in visited tom turkey buildings. Comparatively, season had no significant effect on airborne concentrations of total endotoxin or (1→3)-β-d-glucan. Endotoxin and (1→3)-β-glucan concentrations in TSP dust appeared to increase as the weather became warmer, and this seasonal effect was significant in swine buildings. Elevated indoor temperatures in the hot season were considered to facilitate the growth and propagation of bacteria and fungi, thus leading to higher biocomponent concentrations in TSP.

Implications:

This study monitored total endotoxin and (1→3)-β-d-glucan concentrations at the air exhaust of 18 commercial animal buildings during multiple seasons. The airborne concentrations of total endotoxin and (1→3)-β-d-glucan differed significantly with animal operation type but showed no significant effect by season. Given that animal buildings in general have the highest ventilation rates in summer, these findings suggest that endotoxin and (1→3)-β-d-glucan may attain their maximum emission rates in summer. It is therefore recommended that particular attention should be paid to further investigating summertime bioaerosol emissions from animal feeding operations and the emissions’ impact on neighboring communities.

Acknowledgment

This study was supported by a USDA NRI competitive grant (award no. 2007-55112-17851). The authors are grateful to Steven E. Ford, Matthew J. Robert, and Dr. Ted L. Funk of the University of Illinois at Urbana–Champaign, and all farm workers, technicians, and managers for their consistent and kind assistance during field sampling. The authors also wish to thank Dr. Robert S. Dungan of the USDA-ARS, Northwest Irrigation and Soils Research Laboratory, for his critical review of the manuscript.