Deoxynivalenol and zearalenone are among the most prevalent toxins produced by Fusarium spp. They have been investigated in food and feed products for decades but rarely in the environment. We therefore established solid-phase extraction and liquid chromatography-mass spectrometry (LC-MS) methods to quantify these mycotoxins at trace concentrations in aqueous natural samples. In a model emission study, we inoculated a winter wheat field with Fusarium graminearum and subsequently monitored deoxynivalenol and zearalenone in its drainage water. Before during and after harvest in June and July 2007, these toxins were emitted in concentrations from 23 ng/L to 4.9 µg/L for deoxynivalenol and from not detected to 35 ng/L for zearalenone. Simultaneously, in July and August 2007, deoxynivalenol was also detected in a number of Swiss rivers in concentrations up to 22 ng/L and zearalenone was present in several river samples below the method quantification limit. Other mycotoxins might be emitted from Fusarium-infected fields as well, because some of them are produced in similar amounts as deoxynivalenol and zearalenone and exhibit similar or even higher water solubility than deoxynivalenol. The ecotoxicological consequences of the presence of mycotoxins in surface waters remain to be elucidated.

The mycotoxin zearalenone (ZON) is a very potent natural endocrine disrupting chemical, produced by Fusarium graminearum fungi growing on crops such as wheat and maize. Although it is well-investigated in food and feed, very little is known about its environmental fate and behavior. Here, we report the occurrence of ZON on F. graminearum infected wheat and maize fields in crop organs and soil and its emission via drainage water. ZON amounts in the investigated crops and topsoil were between 6.1 and 25.0 and up to 5.6 g/ha, respectively. ZON concentrations in drainage water were in the low nanogram per liter range with a maximum of 35 ng/ L. Cumulated ZON amounts emitted via drainage water ranged from 0.1 to 4.3 mg/ha, depending on the crop cultivated in the respective period. This corresponds to fractions between 0.001 and 0.070% of the initially present ZON amount in the plants. Because of the low concentrations emitted via drainage water, it can be assumed that ZON contributes little if at all to the overall estrogenicity of major surface water bodies. However, in small creeks, mainly fed by agricultural runoff, ZON might be present in environmentally critical concentrations at times of F. graminearum infections.

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