Preliminary study of mycoflora and mycotoxins in grain dust from New Orleans area grain elevators.

Dust particles arising from disintegration of grain during handling and shipping may be inhaled by exposed barge and elevator workers. Since the normal grain mycoflora usually contain mycotoxin-producing fungi, these toxins could be natural contaminants of grain dust. Known mycoflora of commercial grain include species of Penicillium, Aspergillus, and Fusarium-fungi that may produce ochratoxins, aflatoxins and zearalenone. A procedure was developed to extract simultaneously these toxins from grain dust. Initial extraction with methylene chloride and water was followed by specific cleanup procedures for each toxin and then by thin layer chromatographic quantitation. In 50-g samples the lowest level of detection for zearalenone was 50 ng of zearalenone/g of dust, for ochratoxin, 10 ng/g and for aflatoxin, 5 ng/g. Dust samples were collected at various locations in two grain elevators and their associated transfer facilities in the New Orleans area. Large amounts of dust that had settled upon floors, machinery and ledges were tested, as well as that which had been collected by dust control systems. Samples were analyzed for aflatoxins, ochratoxin A, and zearalenone. None of the 15 samples contained any detectable amount of aflatoxins or ochratoxin A, but 10 of the 15 samples contained zearalenone at levels from 25 to 100 ng/g.