Levels of fungi and mycotoxins in samples of grain and grain dust collected on farms in Eastern Poland

Abstract

Ten samples of stored wheat grain and 10 samples of settled grain dust released during machine threshing of wheat grain were collected on 10 farms located in Lublin province (eastern Poland). The samples were examined for the concentration of total microfungi, Fusarium species, fusariotoxins (moniliformin, deoxynivalenol, nivalenol), and ochratoxin. Microfungi able to grow on malt agar were present in 30% of grain samples (median for all examined samples = 0, range 0-227.5 x 10(3) cfu/g) and in all samples of grain dust (median = 977.5 x 10(3) cfu/g, range 115.0-16,700.0 x 10(3) cfu/g). Fusarium species (F. avenaceum) were found only in 10% of grain samples (median = 0, range 0-800.0 x 10(3) cfu/g), but in 90% of grain dust samples (median = 1,150 x 10(3) cfu/g, range 5.5-10,060.0 x 10(3) cfu/g). The species F. avenaceum, F. culmorum, F. graminearum, F. poae and F. sporotrichioides were isolated respectively from 50%, 10%, 20%, 40% and 20% of examined grain dust samples. The presence of the mycotoxins produced by Fusarium (moniliformin, deoxynivalenol, and nivalenol) was found altogether in 70% of wheat grain samples (median = 0.1275 microg/g, range 0-1.480 microg/g) and in 90% of grain dust samples (median = 0.350 microg/g, range 0-1.090 microg/g). Moniliformin (MON), deoxynivalenol (DON), and nivalenol (NIV) were each detected in 40% of grain samples, and respectively in 80%, 40%, and 40% of grain dust samples. Ochratoxin A (OTA) was detected in 60% of grain samples and in 60% of grain dust samples (median in both cases was 0.0005 microg/g). The concentrations of F. poae (p<0.05) and of total Fusarium species (p<0.01) in grain samples, and the concentrations of F. culmorum and F. graminearum (p<0.05) in grain dust samples were significantly correlated with the concentration of deoxynivalenol. The concentrations of F. poae (p<0.05) and of total Fusarium species (p<0.01) in grain dust samples were significantly correlated with the concentration of total fusariotoxins. Moreover, the concentration of total Fusarium species in grain dust samples was significantly correlated with the concentration of nivalenol (p<0.05). In conclusion, the majority of samples of wheat grain and grain threshing dust collected on farms in eastern Poland contained notable quantities of fusaria and/or fusariotoxins. This fact poses a potential risk of mycotoxicoses to agricultural workers exposed to grain dust when handling wheat during threshing, unloading, shuffling, and other farm occupations.