Exposure to dust-borne bacteria in agriculture. I. Environmental studies.

In order to evaluate the exposure of agricultural workers to dust-borne bacteria, microbiological examinations of the air were performed in grain storing and processing plants and in animal houses. Large concentrations of viable microorganisms, ranging from 129.2 to 1289.9 thousands/m3 of air, were found in the rooms contaminated with grain dust and much lower in those contaminated with flour dust (22.6 thousands/m3). Bacteria predominated in the air of grain plants, whereas actinomycetes and fungi were less numerous. The most abundant bacteria were Gram negative rods of the species Erwinia herbicola. Large concentrations of air-borne microorganisms were also found in different animal farms, reaching 225.5 to 595.4 thousands/m3 in hatcheries and 7751.5 thousands/m3 in a broiler house. Staphylococci were most frequently isolated and other common organisms were Corynebacteria and Streptococci. It was concluded that high exposure to dust-borne bacteria creates a hazard to agricultural workers.