Mycotoxins in soil and environment

Mycotoxins are secondary metabolites produced by specific fungi that have harmful effects on animals and humans. Worldwide more than 300 different mycotoxins are already known, frequently with concentrations in harvest products exceeding acceptable limits. Nevertheless, although these compounds have extensively been studied in food and feed, only little is known about their occurrence and fate in soil and agro-environmental matrices, such as manure, sewage sludge, drainage water and sediments. Therefore, the aim of this review was to (i) resume available methods for quantifying mycotoxins in soil, (ii) describe the occurrence and quantities of mycotoxins in soil and related agroenvironmental matrices, and (iii) discuss the environmental fate of these target compounds with specific focus on their leaching potential into groundwater. The safest and most reliable method for mycotoxin quantification relies on mass spectrometry, while the extraction method and solvent composition differ depending on the compound under investigation. Mycotoxin levels detected in soils to date were in the mu g range, reaching maximum amounts of 72.1 mu g kg-1 for zearalenone, 32.1 mu g kg-1 for deoxynivalenol, 23.7 mu g kg-1 for ochratoxin A, 6.7 mu g kg-1 for nivalenol, and 5.5 mu g kg-1 for aflatoxin. Different compartments in the agroecosystem (cereals, corn, rice, water, manure, sewage sludge) each contained at least one mycotoxin. Mycotoxin retention in soils is controlled by texture, with significant adsorption of the compounds to clays but leaching potentials in sandy soils. We did not find any reports detecting mycotoxins in sediments, although there are increasing reports of mycotoxins in freshwater samples. Overall, it appears that soils and sediments are still underrepresented in research on potential environmental contamination with mycotoxins.

Automated summary

Mycotoxins are harmful substances produced by fungi, and their occurrence and fate in soil and agro-environmental matrices are still poorly understood. Mass spectrometry is the safest and most reliable method for quantifying mycotoxins, and their levels in soils are in the microgram range. The retention of mycotoxins in soils is controlled by texture, with significant adsorption in clays and leaching potential in sandy soils.