Global occurrence of mycotoxins in the food and feed chain: facts and figures

World Mycotoxin Journal, August 2013; 6 (3): 213-222 Wageningen Academic P u b l i s h e r s Global occurrence of mycotoxins in the food and feed chain: facts and figures G. Schatzmayr and E. Streit BIOMIN Research Center, Technopark 1, 3430 Tulln, Austria; gerd.schatzmayr@biomin.net Abstract 1. Introduction Mycotoxins are a chemically diverse group of secondary fungal metabolites. They can contaminate a wide array of food and feed materials and cause toxic responses in humans and animals alike if they are ingested in sufficiently high concentrations (Binder, 2007; Bryden, 2009, 2012). Although there are 300-400 mycotoxins known today (depending on classification; reviewed by Hussein and Brasel, 2001, or Bennet and Klich, 2003 for example), only a handful have received widespread attention. The most important mycotoxins or mycotoxin groups are aflatoxins, zearalenone (ZEA), deoxynivalenol (DON), fumonisins and ochratoxin A (OTA) (Binder, 2007) and numerous countries Received: 18 March 2013 / Accepted: 15 June 2013 2013 Wageningen Academic Publishers RESEARCH PAPER Mycotoxins are ubiquitously present in agricultural commodities, such as cereals and oil seeds. If ingested in sufficiently high concentrations, they exert severe toxic effects in humans and animals. In 2004, a survey programme was launched to assess the extent of mycotoxin contamination in feed and feed raw materials. Since then, over 19,000 samples have been analysed and more than 70,000 individual analyses have been conducted. While it is difficult to infer any long-term trends on a global level, the data confirm that high mycotoxin contamination is often linked to unusual weather. Overall, 72% of the samples contained detectable amounts of aflatoxins, fumonisins, deoxynivalenol, zearalenone or ochratoxin A. Co-contamination with two or more mycotoxins was detected in 38% of the samples. In most cases the concentrations were low enough to ensure compliance with EU guidance values or maximum levels. However, co-contaminated samples with concentrations below guidance and maximum values might still exert adverse effects due to synergistic interactions of the mycotoxins. Emerging mycotoxins and masked mycotoxins may also contribute to the overall toxicity of the feed and their presence is frequently detected with multi-mycotoxin LC-MS/MS. Since by-product feeds, such as distillers dried grain with solubles, often concentrate the mycotoxins of the original substrate, they contribute excessively to the overall contamination of feed rations and therefore need special attention. Regarding food the situation is quite similar: low level contamination is frequently observed in official controls but maximum levels are rarely exceeded in developed countries. As it is very difficult to remove mycotoxins from contaminated commodities, preventing them from accumulation in agricultural commodities is the most effective strategy to combat the problem. Preventive measures range from crop rotation and resistance breeding to inoculation with microbial antagonists. Nevertheless, excessive mycotoxin levels may occur despite all preventive measures. Therefore, continuous monitoring is essential and efficient detoxification strategies are needed to deal with such outbreaks. Keywords: mycotoxin co-occurrence, trade, interaction, prevention, detoxification have established maximum levels and/or guidance values regulating their presence in food and feed (e.g. the European Union; EC, 2002, 2006, 2010). 2. Global occurrence of mycotoxins in feed In 2004, we have established a survey program, monitoring the presence of the five above mentioned mycotoxins/ mycotoxin groups in feed and feed raw materials worldwide. Since then 19,757 samples have been analysed and 64,166 individual analyses have been conducted. The samples were analysed with either HPLC (about 80%) or ELISA (about 20%). ISSN 1875-0710 print, ISSN 1875-0796 online, DOI 10.3920/WMJ2013.1572 213

G. Schatzmayr and E. Streit Finished feed and maize accounted for 27% of the samples each. The pool of samples further comprised wheat and wheat bran (9%), barley (8%), silage (8%), soybean meal (4%), distillers dried grain with solubles (DDGS; 2%), corn gluten meal (1%), rice and rice bran (1%), straw (1%) and other feed ingredients (e.g. cotton seed, sorghum, cassava, peanut, copra, etc.; 12%). The samples originated primarily from Asia (45%) and Europe (37%), with 15% having been sourced in the Americas, 2% in Africa and 1% in the Middle East. Table 1 shows a summary of the overall results and Figure 1 provides an overview of the results on a regional level. As expected, considerable differences can be observed regarding the prevalence of the five mycotoxins/mycotoxin groups in different regions of the world. Aflatoxins were most often detected in South Asia (78% positives; average contamination: 128 µg/kg), followed by South-East Asia (55%; 61 µg/kg). ZEA was most prevalent in North Asia with 56% positive samples containing an average of 386 µg/kg of the mycotoxin. North Asia is also the region where the occurrence of DON was highest (78%; 1,060 µg/kg). The highest average DON contamination however has been observed in North America, where positive samples (68%) contained an average of 1,418 µg/kg DON. Fumonisins were most frequently detected in South American samples (77%; 2,691 µg/kg). OTA prevalence and average contamination were highest in South Asia (55%; 20 µg/kg). Eastern European samples frequently tested positive for OTA as well (49%), but the average contamination was much lower (4 µg/kg). Inferring global trends from the results proved difficult as mycotoxin occurrence and contamination is strongly Table 1. Summary of the global survey results. 1 dependent on regional climatic conditions. Figure 2 shows that the percentage of samples testing positive for each of the analytes has been rather stable over the years. Regarding the average mycotoxin levels in contaminated samples, great differences could sometimes be observed from one year to another (data not shown). Peaks in average contamination are generally due to a very small number of samples containing mycotoxin concentrations that are several orders of magnitude above the levels detected in the other samples. Typically, these samples originate from the same geographical region and the high contamination levels can often be linked to unusual weather events. Detailed examples of the weather s impact on mycotoxin levels will be given in the following section. Even though mycotoxins were ubiquitously present in the analysed feed and feed materials, the detected concentrations were generally low. Only 17% of the aflatoxin-tested samples did not comply with the most stringent EU maximum level of 5 µg/kg aflatoxin B 1 applicable to feed for dairy animals (European Commission, 2002). Concentrations above the lowest guidance levels for ZEA, DON, fumonisins and OTA were detected in 17, 15, 3.2 and 0.9% of the samples, respectively. Assuming that all feed can be redirected to less sensitive species (thus requiring compliance to less stringent maximum levels or guidance values), only 9, 0.3, 0.5, 0.02 and 0.2% of the samples would have to be rejected due to excessive contamination with aflatoxins, ZEA, DON, fumonisins and OTA, respectively. Considering the fact that the EU regulations for mycotoxin contamination in feed are among the strictest worldwide, these rates seem little unsettling. Aflatoxin 2 Zearalenone Deoxynivalenol Fumonisin 2 Ochratoxin A Tested samples 11,967 15,533 17,732 11,439 7,495 Positive samples 3,142 5,797 9,960 6,204 1,902 Percentage of positives 26% 37% 56% 54% 25% Average positives (µg/kg) 57 286 1,009 1,647 14 Median positives (µg/kg) 11 85 453 750 2.6 1 st quartile positives (µg/kg) 3 43 234 332 1.1 3 rd quartile positives (µg/kg) 40 225 972 1,780 6.2 Maximum (µg/kg) 6,323 26,728 50,289 77,502 1,589 Sample origin Myanmar Australia Central Europe China China Sample type (analysis year) other feed (2012) silage (2007) wheat (2007) finished feed (2011) finished feed (2011) 1 Results of the analysis of 19,757 samples of feed and feed raw materials sourced globally, specifying the number of samples analysed for each of the mycotoxins/mycotoxin groups, the number and percentage of samples testing positive (LODs specified in Streit et al., 2013) for the respective mycotoxin as well as the average, median, maximum, first quartile and third quartile of the concentrations detected in positive samples (in µg/kg); regarding maximum values, the type and origin of the sample and the year of analysis are given. 2 Aflatoxin: sum of aflatoxin B 1, aflatoxin B 2, aflatoxin G 1 and aflatoxin G 2 ; Fumonisin: sum of fumonisin B 1, fumonisin B 2 and fumonisin B 3. 214 World Mycotoxin Journal 6 (3)

Global occurrence of mycotoxins in the food and feed chain North America AF: 19 %; ZEA: 37%; DON: 68 %; FB: 48%; OTA: 20% Figure 1. Mycotoxin prevalence in the surveyed regions. 1 1 Number of samples analysed for aflatoxins (AF), zearalenone (ZEA), deoxynivalenol (DON), fumonisins (FB), ochratoxin A (OTA), respectively: North America: 812; 832; 844; 820; 265; South America: 1,521; 784; 768; 1544; 360; Northern Europe (ZEA; DON): 596; 789; others not analysed (NA); Central Europe: 241; 3,632; 5,521; 206; 235; Southern Europe: 299; 381; 463; 233; 242; Africa: 302; 227; 286; 271; 47; Eastern Europe: 59; 106; 111; 70; 86; Middle East: 167; 172; 170; 156; 69; South Asia: 495; 489; 478; 486; 433; South-East Asia: 2,383; 2,350; 2,237; 2,357; 1,623; Oceania: 859; 873; 873; 842; 681; North Asia: 4,723; 4,799; 4,855; 4,365; 3,352. Percentage of positive samples 100 90 80 70 60 50 40 30 20 10 0 South America AF: 20%; ZEA: 38%; DON: 16%; FB: 77%; OTA: 10% Central Europe AF: 19 %; ZEA: 26 %; DON: 58 %; FB: 51 %; OTA: 29 % Northern Europe ZEA: 22 %; DON: 64 %; AF, FB, OTA: NA Southern Europe AF: 34 %; ZEA: 21 %; DON: 51 %; FB: 70%; OTA: 46% Africa AF: 40 %; ZEA: 28 %; DON: 66 %; FB: 72 %; OTA: 36 % Eastern Europe AF: 8 %; ZEA: 13 %; DON: 33 %; FB: 33 %; OTA: 49 % Middle East AF: 14 %; ZEA: 15 %; DON: 34 %; FB: 51 %; OTA: 35 % South Asia AF: 78 %; ZEA: 25 %; DON: 21 %; FB: 52 %; OTA: 55 % South-East Asia AF: 55 %; ZEA: 37 %; DON: 29 %; FB: 56 %; OTA: 27 % sample number AF OTA ZEA DON FB 2005 2006 2007 2008 2009 2010 2011 2012 North Asia AF: 13 %; ZEA: 56 %; DON: 78 %; FB: 54 %; OTA: 23 % Oceania AF: 7 %; ZEA: 20 %; DON: 34 %; FB: 10 %; OTA: 12 % Figure 2. Total sample number and percentage of positive samples for aflatoxins (AF), ochratoxin A (OTA), zearalenone (ZEA), deoxynivalenol (DON) and fumonisins (FB). 4,500 4,000 3,500 3,000 2,500 2,000 1,500 1000 500 0 Number of samples However, even feed that is perfectly compliant with the existing regulations may exert an adverse effect on the animals health. For example, chicken fed diets containing different levels of fumonisins for three weeks showed a considerably higher sphinganine/sphingosine (Sa/So) ratio than the control group, even at fumonisin levels of 10 mg/kg (Schwartz et al., unpublished data) which is half the concentration of the European Union s 20 mg/kg guidance value for fumonisin B 1 + B 2 in compound feed for chicken (EC, 2006). The Sa/So ratio is used as a biomarker World Mycotoxin Journal 6 (3) 215

G. Schatzmayr and E. Streit for fumonisin exposure, because fumonisins disrupt the sphingolipid metabolism by inhibiting a key enzyme, ceramide synthase, which leads to a rapid increase of free sphinganine (Riley et al., 1994). Free sphinganine was found to be growth inhibitory and cytotoxic (Riley et al., 1996). Synergistic interactions of co-occurring mycotoxins might also increase the toxicity of the feed. Grenier and Oswald (2011) reviewed more than 100 studies on mycotoxin interactions and concluded that regarding adverse effects on animal performance, most of these studies reported additive or synergistic interactions of co-occurring mycotoxins. In our survey, 39% of all the samples contained two or more mycotoxins. Within the group of finished feed samples, as much as 59% were co-contaminated with at least two mycotoxins. The influence of weather Weather is deemed one of the most influential factors for fungal proliferation and mycotoxin contamination. Linking the results of this survey to archive precipitation and temperature data has provided some interesting examples for this relationship. US maize analysed in 2010, for instance, exhibited a high prevalence of ZEA (43% positives) and DON (92% positives) in combination with a high mean contamination of 165 µg/kg ZEA and 1,366 µg/kg DON in positive samples. Since maize is harvested rather late in the year (September-October), most of these samples belong to the 2009 crop. The precipitation and temperature maps for the period of August October 2009 retrieved at the US National Climatic Data Center (NCDC, 2012) show that these months had been unusually cool and wet in the corn belt. In 2010, on the other hand, these three months were warmer than normal with normal to slightly below average rainfall. In consequence, ZEA and DON were detected much less frequently in the samples analysed in 2011. ZEA was detected in 16% of the samples and 62% were positive for DON. Aflatoxins, however, were more prevalent with 32% positives compared to 11% in 2010. A similar phenomenon was observed in Australian wheat samples. From 2008 to 2010, the average ZEA concentration detected in positive samples was between 202 µg/kg (2010) and 474 µg/kg (2009), and the average DON contamination ranged between 400 µg/kg (2010) and 586 µg/kg (2008). In 2011, the mycotoxins were present at an average of 1,045 µg/kg (ZEA) and 2,747 µg/kg (DON) in contaminated samples. From July to December 2010, the amount of precipitation recorded in many parts of Australia was very much above average, especially in the eastern half of the continent where many areas reported the highest rainfall amounts ever recorded (BOM, 2011a). The Murray-Darling basin, Australia s main agricultural region, is located in the south of eastern Australia. In combination with the lower than average temperatures measured in this region in the second half of 2010 (BOM, 2011b), the ample rainfall has likely favoured Fusarium infections leading to the high amounts of ZEA and DON in the 2010 harvest. Other fungal metabolites: what else is there in the feed? Striving to further extend the knowledge on mycotoxin occurrence in feed, 35 of the samples sourced in Europe were furthermore subjected to multi-mycotoxin HPLC-MS/ MS analysis. The majority of the samples were feed samples (n=23), but 10 samples of maize and 2 silage samples were analysed as well. The analyses were conducted at BOKU Vienna, department IFA-Tulln (Austria) using the method developed and extended by Sulyok et al. (2006, 2007, 2010). This method is continuously extended and now covers 340 metabolites (M. Sulyok, personal communication). All the samples were co-contaminated with 7 to 34 mycotoxins, and 70 different fungal metabolites were detected in total. The majority of the most commonly detected metabolites were Fusarium metabolites. DON was detected most often (97% positives), followed by beauvericin and enniatins. The latter two always occurred together and were found in 94% of the samples. Other frequently detected metabolites included ZEA (91% positives), DON-3-glucoside, a masked mycotoxin (86%), culmorin (86%), tentoxin (86%), 15-hydroxyculmorin (77%), moniliformin (74%) and aurofusarin (71%). Toxicity data on the less known emerging mycotoxins and fungal metabolites are scarce. Available in vivo studies suggest that beauvericin and enniatins exert low acute toxicity and possess positive pharmacological properties. Beauvericin, for example, was reported to inhibit active efflux of antibiotics, as well as multidrug transport proteins in cancer cells (Jestoi, 2008). Moniliformin has been studied more extensively. Poultry seems to be the most sensitive species (Jestoi, 2008) and a tolerance level of 50 mg/kg for poultry feed has been proposed (Ledoux et al., 1995). On the other hand, moniliformin has been reported to mitigate the egg-weight increase caused by fumonisin B 1 (FB 1 ), thus leading to a lower mortality in the group of chicken fed a co-contaminated diet compared to the FB 1 group (Kubena et al., 1999). In contrast, masked mycotoxins are conjugates of well-known mycotoxins, such as DON or ZEA, that go undetected when testing for the parent toxin. DON-3-glucoside, which was frequently detected in our samples, is formed by Fusarium-infected plants as part of their defence mechanism (Berthiller et al., 2009). Recently, several lactic acid bacteria commonly found in the mammalian digestive tract were reported capable of cleaving a significant amount of DON-3-glucoside (Berthiller et al., 2011). This indicates that DON is released from DON-3-glucoside during digestion increasing the total amount of bioavailable DON in contaminated diets. 216 World Mycotoxin Journal 6 (3)

Global occurrence of mycotoxins in the food and feed chain Masked mycotoxins or co-occurring mycotoxins, that have not been tested for, might be the reason why naturally DON-contaminated feed typically exerts a stronger toxic effect than feed artificially contaminated with pure DON (Dersjant-Li et al., 2003; Trenholm et al., 1994). A literature review by Dänicke et al. (2008) showed that, while there is a clear correlation between feed intake depression in pigs and DON levels in the respective feed at higher DON concentrations, the results are ambiguous in the concentration range below the EC guidance value of 900 µg/kg. In this range, the reported feed intake of pigs consuming a DON-contaminated diet varied between 85 and 105% of the control group s feed intake. This indicates that other factors, such as co-occurring mycotoxins or poor animal husbandry, influence the critical DON concentration in feed (Dänicke et al., 2008; Döll and Dänicke, 2011). Global trade Given that mycotoxin contamination is strongly dependent on climatic factors, distinct regional differences in mycotoxin occurrence are to be anticipated. European cereals, for example, are said to be largely free of aflatoxins, since the formation of these toxins is favoured by a tropical or subtropical climate (EFSA, 2004). On rare occasions, exceptionally hot and dry growing seasons lead to aflatoxin contamination in Southern European cereals. In 2003, for example, a considerable proportion of the maize harvested in northern Italy was unfit for dairy animal consumption due to elevated aflatoxin levels (Piva et al., 2006) and in early 2013 several RASFF alerts concerning excessive aflatoxin levels in maize from Bulgaria, Romania and Serbia were issued (RASFF, 2013). Yet, 26% of the samples sourced in Europe and tested for aflatoxins were contaminated. Most of these samples were imported feed raw materials, such as Percentage of positive samples 100 90 80 70 60 50 40 30 20 10 0 DDGS 20 26 Maize DDGS 314 165 Maize DDGS 3,448 cotton seed meal or peanuts or finished feed presumably containing such raw materials. This suggests that aflatoxin contamination in European feed is mainly an imported problem and points to the importance of international trade in the global distribution of mycotoxins. Several million tons of wheat, maize (global trade volume 2011/2012: 152.8 and 102.6 million metric tons, respectively) and other cereals and feed raw materials are shipped around the globe each year (USDA-ERS, 2012; USDA-FAS, 2012). Inevitably, the mycotoxins specific to the regions of origin of these goods are also distributed around the world. By-product feeds such as DDGS are particularly delicate in this respect, as they often concentrate the mycotoxins present in the starting material. In bioethanol production from maize, for example, the mycotoxins are concentrated by a factor three. Most studies on the fate of mycotoxins during ethanol production established that there is little degradation of mycotoxins during the process and that they are not found in the distilled ethanol fraction. Consequently, the mycotoxins remain in the DDGS fraction that makes up one third of the mass of the original grain (Wu and Munkvold, 2008). Comparing our US maize and DDGS samples from 2010 (Figure 3), this concentration effect is clearly visible for ZEA and DON. As mentioned above, contamination with these two mycotoxins was particularly high in the 2009 harvest. ZEA was detected in 43% of the maize samples and 87% of the DDGS samples with average levels of 165 and 314 µg/kg, respectively. DON was detected in 92% of the maize samples at an average level of 1,366 µg/kg. Of the DDGS samples, 91% tested positive but the contamination average was 3,488 µg/kg. No such concentration effect was observed for the other mycotoxins, although the percentage of samples testing positive for fumonisins and OTA was considerably higher in DDGS than in maize (77 vs. 47% for fumonisins; 35 vs. 2.7% for OTA). Maize 1,366 DDGS 1,072 Maize 1,552 DDGS AF ZEA DON FB OTA 4 14 Maize 4,000 3,500 3,000 2,500 2,000 1,500 1000 500 0 Average contamination of positives (µg/kg) Figure 3. Comparison of the prevalence of and average contamination with aflatoxins (AF), zearalenone (ZEA), deoxynivalenol (DON), fumonisins (FB) and ochratoxin A (OTA) in dried distillers grains and solubles (DDGS) and US maize in 2010. World Mycotoxin Journal 6 (3) 217

G. Schatzmayr and E. Streit 3. Mycotoxin prevalence in food The prevalence of mycotoxins in food is equal to that observed in feed, although the detected concentrations are generally lower in food. Table 2 summarises a number of studies on this subject. The Canadian Food Inspection Agency (CFIA) found detectable levels of aflatoxins in 8% of the surveyed samples of maize, maize products, nuts and nut products. Aflatoxin contamination was more frequent in nut butters than in nuts. One sample of peanuts and one nut butter sample were found to exceed Canadian regulations (CFIA, 2012a). None of the dried fruit (figs and dates) samples contained detectable levels of aflatoxins. OTA was detected in 49% of the samples included in the SCOOP report assessing the OTA exposure of EU population. It was most prevalent in cocoa and cocoa products (81%), dried fruit (73%) and wine (59%) with red or Table 2. Mycotoxin occurrence in food. 1 sweet wine containing higher OTA levels than other wines (SCOOP, 2002). Of the European feed and feed ingredient samples included in our survey, 38% contained detectable levels of OTA. In Canada, the overall occurrence of OTA in food was lower (33%). In wheat products, however, a very high prevalence of OTA was observed (94%) (CFIA, 2012b). DON was found to be equally prevalent in European and Canadian food with 57% of the European (SCOOP, 2003) and 59% of the Canadian (CFIA, 2012b) samples testing positive for this mycotoxin. In our survey, DON was detected in 58% of the European feed and feed raw material samples. As for ZEA, the rate of 32% positive food samples given in the SCOOP report (SCOOP, 2003) again agrees well with our survey results (24% ZEA positives in Europe). FB 1 was detected in 66% of the maize and 46% of the cornflakes samples in Europe (SCOOP, 2003). Even though fumonisins are often regarded as a maize specific problem, 16% of Mycotoxin Country/foodstuff n Positives Average/range (µg/kg) Reference Aflatoxins Canada CFIA, 2012a maize products 285 8% 0.5 nuts/products 252 8% 4.1 dried fruit 90 0% Ochratoxin A Europe SCOOP, 2002 cereals 5,180 55% 0.48 coffee, green 1,704 36% 3.64 coffee, processed 1,184 46% 1.09 beer 496 39% 0.032 wine 1,470 59% 0.59 cocoa/derived products 547 81% 0.28 dried fruits 800 73% 3.08 meat products 1,860 18% 0.83 spices 361 52% 5.06 Canada 943 33% 0.4-6,773 CFIA, 2012b most prevalent: wheat products 94% 0.91 breakfast cereals 62% 0.47 Deoxynivalenol Europe 11,022 57% 2-50,000 SCOOP, 2003 most prevalent: maize 89% 660 Canada 943 59% 1-2,060 CFIA, 2012b most prevalent: wheat products 100% 165 breakfast cereals 96% 156 Zearalenone Europe 5,018 32% max. 6,492 SCOOP, 2003 Fumonisin B 1 Europe SCOOP, 2003 maize 801 66% 730 cornflakes 274 46% 74 wheat flour 256 16% max. 4,343 Brazil Martins et al., 2012 maize-based products 100 82% 398 1 Summary of selected studies on the occurrence of aflatoxins, ochratoxin A, deoxynivalenol, zearalenone and fumonisin B 1 in food. The studied region and foodstuffs are given along with the number of tested samples (n), the percentage of samples testing positive and available information regarding mycotoxin concentrations (in µg/kg). 218 World Mycotoxin Journal 6 (3)

Global occurrence of mycotoxins in the food and feed chain the wheat flour samples also tested positive for FB 1. In Brazil, FB 1 was detected in 82% of the maize-based products investigated by Martins et al. (2012). In South American feed, fumonisin prevalence was 77% (Figure 1). 4. Mycotoxin prevention Fungal infection and mycotoxin formation may occur in the field as well as during storage. Therefore, mycotoxin prevention starts with good agricultural practice. Crop rotation and tillage are two very important factors, especially where maize has been the pre-crop. Maize is very susceptible to Fusarium infection and should be avoided as pre-crop for other Fusarium sensitive crops. Ploughing after wheat and maize was shown to result in lower DON levels in the following wheat crop than minimum tillage approaches (Jouany, 2007). Also, the presence of maize residues was proposed as an important factor contributing to DON contamination in wheat (Jouany, 2007; Munkvold, 2003). An early planting date, reduced plant density and adequate irrigation were also reported to reduce mycotoxin levels in maize (Munkvold, 2003). At harvest, appropriate settings of the cutting height and the fan speed of the combine harvester contribute to limiting fungal counts and mycotoxin contamination. The cutting height should be chosen so as to minimise the contact of healthy grains and soil. The fan acts as a first cleaning step by eliminating damaged kernels (Jouany, 2007). Before storage, grains should be dried to a moisture level of 12%. Aside from these agricultural practice-related factors, the resistance of the planted crop variety is a crucial factor. In wheat, for example, Fusarium resistance is controlled by a small number of genes that often coincide with morphological characteristics such as taller plants (Anderson, 2007; Snijders, 2004). However, other varietal characteristics that do not seem to relate to fungal resistance at first glance may also have an impact on mycotoxin levels. A prominent example is Bt-corn, made insect resistant by genetic engineering. It was found that this maize has lower fumonisin and aflatoxin levels as less insect damage results in fewer wounds that facilitate fungal infection (Munkvold, 2003). The annual benefit of the Bt-corn related fumonisin and aflatoxin reduction in US maize was estimated to be 23 million USD (Wu, 2006). In areas with high European corn borer pressure, Bt-corn also has lower DON levels than other hybrids (Kendra and Dyer, 2007). Regarding plant protection, microbial antagonists are a promising alternative to conventional fungicides. Bacillus subtilis strains, for example, have been reported to inhibit the growth of fusaria (Jouany, 2007) and atoxigenic Aspergillus flavus strains successfully reduce aflatoxin contamination in treated crops (Cole and Cotty, 1990). They occupy the same ecological niche as the mycotoxinproducing fungi and thus displace toxigenic strains. Spores of atoxigenic A. flavus strains on carriers (sorghum or barley grains) are marketed as a means of preventing excessive aflatoxin levels. Applying atoxigenic strains changes the composition of the A. flavus community associated with the crop and these changes are shown to persist for several years following the treatment. The extent of A. flavus infections in crops remained unchanged by the treatment (Cotty, 2006). While preventive measures are valuable tools for reducing the mycotoxin load in agricultural commodities, they are unable to reliably preclude excessively high contamination levels owing to the fact that climatic conditions are of pivotal importance to fungal infection and mycotoxin formation. Hence, continuous monitoring is essential in order to prevent negative impacts on human and animal health and has become an integral part of quality control systems in the food and feed industry. Predictive models such as DONcast (Hooker and Schaafsma, 2003) are valuable complements, as they provide an estimate of the regional risk of mycotoxin contamination based on weather data and other variables and help to adopt a more directed, risk-based monitoring approach. 5. Gastrointestinal detoxification Despite all preventive efforts, elevated or excessively high mycotoxin concentrations are likely to occur in agricultural commodities, especially as a result of growing seasons characterised by unusual or extreme weather conditions. For this reason, effective detoxification methods are needed. In recent years, adsorption and biotransformation have received much attention. Certain bentonite clays, such as montmorillonite, were shown to mitigate the adverse effects of aflatoxins in contaminated diets and diminish aflatoxin carry-over to milk of lactating animals. The planar structure of aflatoxin B 1 is important for adsorption to the clay surface (Phillips et al., 2006). Aflatoxin-sequestering clays must not interfere with the nutritive value of the feed by binding nutrients along with the mycotoxin. While non-nutritive adsorbents are a suitable approach for dealing with aflatoxin-contaminated diets, these binding agents have little to no effect on other relevant mycotoxins (Phillips et al., 2006; Schatzmayr et al., 2006a). Detoxification by biotransformation is an alternative strategy to combat these mycotoxins. Biotransformation is based on microbial degradation of a mycotoxin into less toxic or non-toxic metabolites, using either the microorganism itself or enzyme preparations. As the time frame for gastrointestinal detoxification is short, the degradation has to take place rapidly (Schatzmayr et al., 2006a). In 1998, Binder et al. described a Eubacterium strain, BBSH 797 capable of transforming DON to de-epoxy-deoxynivalenol, a nontoxic metabolite. Likewise, Molnar et al. (2004) described a yeast strain, Trichosporon mycotoxinivorans capable of detoxifying both OTA and ZEA. T. mycotoxinivorans World Mycotoxin Journal 6 (3) 219

G. Schatzmayr and E. Streit cleaves OTA into phenylalanine and OTα, a metabolite that has been described as much less toxic to non-toxic (Schatzmayr et al., 2006b). ZEA is detoxified by opening its macrocyclic ring at the ketone group of C6. The resulting ZOM-1 no longer shows estrogenic activity (Vekiru et al., 2010). In feeding trials, both Eubacterium BBSH 797 and T. mycotoxinivorans have been shown to successfully detoxify mycotoxins in vivo (Binder et al., 2001; Politis et al., 2005). The gene coding for a carboxylesterase (fumd) was isolated from a soil bacterium and cloned into Pichia pastoris. The expressed enzyme detoxifies fumonisins in the gastrointestinal tract of pigs by cleavage of the tricarballylic side chains resulting in non-toxic metabolites (Hartinger and Moll, 2011). 6. Conclusions The mycotoxin survey programme shows that mycotoxins are ubiquitously present in feed and that mycotoxin cooccurrence is common. The percentage of contaminated samples has been rather stable over the 8-year survey period. The average contamination, however, varies from year to year. Contamination peaks are often traceable to a certain region and usually linked to extreme weather events or at least uncommon weather conditions. The prevalence of mycotoxins in food is comparable to that in feed, although at a lower level. Preventive methods can help to reduce the mycotoxin level in a given crop. However, concentrations exceeding the legal limits may still occur in spite of all efforts. Therefore, continuous monitoring of the extent of mycotoxin contamination is indispensable, necessitating the development of fast and reliable screening methods. Predictive models facilitate this task, as they are a valuable tool for estimating the risk of mycotoxin contamination in crops of a given growing season. Such models are inherently regional. DONcast (Hooker and Schaafsma, 2003), for example, predicts DON contamination in wheat in Ontario, Canada, yet an adaptation for Europe is under validation (www.doncast.eu). The development of similar models for other regions and/or mycotoxins is desirable. When it comes to predicting mycotoxin contamination, global trade of feed commodities has to be considered as a confounding factor. Feed grain trade flows distribute mycotoxins outside their natural occurrence areas around the globe, thereby complicating the accurate estimation of final mycotoxin loads in finished feed. The frequent detection of co-occurrence of aflatoxins, ZEA, DON, fumonisins and OTA with each other and/or other emerging mycotoxins raises concern regarding possible synergistic or additive interactions of co-contaminants. Therefore, more research on the effects of co-occurring mycotoxins is needed and also on the toxicological implications of the frequent occurrence of emerging and masked mycotoxins. In view of the current premium prices for major feed commodities, such as maize and soybean meal resulting from the meagre US maize harvest in 2012, it is obvious that feed ingredients are not as abundant as we might wish. The present situation is aggravated by the fact that the 2012 US maize crop contains high levels of aflatoxin B 1, rendering a considerable proportion unfit for animal feed. This emphasises the fact that mycotoxin deactivation is important so as to enable the use of a larger proportion of the available grain for feeding purposes. Further research is needed in this area. References Anderson, J.A., 2007. Marker-assisted selection for Fusarium head blight resistance in wheat. International Journal of Food Microbiology 119: 51-53. Bennet, J.W. and Klich, M., 2003. Mycotoxins. Clinical Microbiology Reviews 16: 497-516. Berthiller, F., Krska, R., Domig, K.J., Kneifel, W., Juge, N., Schuhmacher, R. and Adam, G., 2011. 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