Occurrence of type A, B and D trichothecenes, zearalenone and stachybotrylactam in straw

Straw is the main by-product of grain production, used as bedding material and animal feed. If produced or stored under adverse hygienic conditions, straw is prone to the growth of filamentous fungi. Some of them, e.g. Aspergillus, Fusarium and Stachybotrys spp. are well-known mycotoxin producers. Since studies on mycotoxins in straw are scarce, 192 straw samples (wheat n = 80; barley n = 79; triticale n = 12; oat n = 11; rye n = 12) were collected across Germany within the German official feed surveillance and screened for the presence of 21 mycotoxins. The following mycotoxins (positive samples for at least one mycotoxin n = 184) were detected: zearalenone (n = 86, 6.0-785 μg/kg), nivalenol (n = 51, 30-2,600 μg/kg), deoxynivalenol (n = 156, 20-24,000 μg/kg), 15-acetyl-deoxynivalenol (n = 34, 20-2,400 μg/kg), 3-acetyl-deoxynivalenol (n = 16, 40-340 μg/kg), scirpentriol (n = 14, 40-680 μg/kg), T-2 toxin (n = 67, 10-250 μg/kg), HT-2 toxin (n = 92, 20-800 μg/kg), T-2 tetraol (n = 13, 70-480 μg/kg). 15-monoacetoxyscirpenol (30 μg/kg) and T-2 triol (60 μg/kg) were only detected in one barley sample. Macrocyclic trichothecenes (satratoxin G, F, roridin E, and verrucarin J) were also found in only one barley sample (quantified as roridin A equivalent: total 183 μg/kg). The occurrence of stachybotrylactam was monitored for the first time in four samples (n = 4, 0.96-7.4 μg/kg). Fusarenon-X, 4,15-diacetoxyscirpenol, neosolaniol, satratoxin H and roridin-L2 were not detectable in the samples. The results indicate a non-negligible contribution of straw to oral and possibly inhalation exposure to mycotoxins of animals or humans handling contaminated straw.