A preliminary evaluation of veterinary antibiotics, estrogens, in vitro estrogenic activity and microbial communities in airborne particulate matter collected near dairy production facilities

Particulate matter (PM) emitted from beef cattle feedyards transports manure-affiliated compounds including antibiotics and steroids from feedyards into the surrounding environment. Similarly, commercial dairy operations have the potential to release PM, comprised largely of aerosolized manure, into the surrounding environment along with associated veterinary antibiotics and steroids. The goal of this study was to quantify and compare total suspended particulates, antibiotics and estrogens collected upwind and downwind of dairies in the Southern High Plains, and to characterize microbial community structure and in vitro estrogenic activity of collected PM. PM collected downwind of dairies had greater microbial diversity (as measured by number of operational taxonomic units) and had greater frequencies of detection for antibiotics and estrogens than associated upwind PM. Dominant bacterial phyla and overall microbial community composition were similar among upwind and downwind PM, and extracts of upwind and downwind PM produced no in vitro estrogenic activity. Although this study surveyed a limited number of dairies in the region, these results suggest that dairy operations in the Southern High Plains, in contrast to feedyards, appear to be minor contributors of total aerial PM and associated antibiotics and steroids to the terrestrial environment.