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DON Occurrence in Grains: A North American Perspective Introduction ABSTRACT Fungi associated with production and In agricultural commodities, the occurrence of deoxynivalenol (DON) has been reported all storage of grains in North America in- over the world, with levels varying among grain types and years of production. The grain supply clude the genera Fusarium, Penicillium, chain, including growers, buyers, and end users, have effectively managed DON with strategies and Aspergillus. Mycotoxins are second- to control this issue systematically. The safety of consumers is ensured through use of these man- ary metabolites of these filamentous fun- agement strategies. This is observed in this review of the North American systems. This article gi that can cause illness in humans and describes the occurrence and management of DON in North America, which is accomplished animals through absorption, ingestion, by 1) a review of the toxicological effects of DON; 2) a review of publically available data and or inhalation (2). Since grains, in general, introduction of new information regarding the occurrence of DON in wheat, maize, and barley in North America, including variability due to growing regions, grain varieties, and year of provide an ideal substratum (medium) production; 3) an overview of industry practices to reduce DON contamination from field for mold growth and mycotoxin pro- through milling when necessary; 4) a review of how all in the value chain, including growers, duction, close attention must be paid to buyers, and end users, have effectively managed DON for more than 20 years; 5) a description their food and feed safety. Additionally, of current maximum limits associated with DON; and 6) the economic impact of any potential grains and grain-based products repre- changes in international regulations. This article focuses on wheat, maize, and barley grown in sent one of the major sources of carbo- Canada and the USA, as these two countries are the major exporters of these grains in North hydrates for humans and livestock (3); America (1). therefore, their safety is of primary con- cern. The prevalence of mycotoxins in grains AUTHORS J. David Miller, Department of is usually associated with the occurrence Andreia Bianchini, The Food Chemistry, Carleton University, of the causal organisms and related causal Processing Center, Food Science and Ottawa, ON, Canada factors, such as temperature and moisture, Technology Department, University of W. Thomas Shier, Department of in both the field and in storage (2,3). De- Nebraska – Lincoln, NE, USA Medicinal Chemistry, University of oxynivalenol, also referred to as DON or vomitoxin, is one of a broad category of Richard Horsley, Department of Plant Minnesota, MN, USA mycotoxins known as trichothecenes. Sciences, North Dakota State Glen Weaver, Ardent Mills, Omaha, DON is produced mainly by F. grami- University, ND, USA NE, USA nearum and F. culmorum, especially in Maia M. Jack, CPGglobal, LLC, USA grains. Production of DON by F. pseudo- PUBLIC REVIEWERS Brent Kobielush, General Mills, MN, graminearum has also been reported in USA Dave Katzke, General Mills, MN, USA warmer climates, although with less fre- Dirk E. Maier, Kansas State University, quency than the major producers (2). Dojin Ryu, Bi-State School of Food F. graminearum is an important plant Science, University of Idaho/Washington Grain Science & Industry, Manhattan, KS, USA pathogen that causes Fusarium head State University, ID, USA blight (FHB) in wheat and barley and ear Sheryl Tittlemier, Grain Research Jim Pestka, Food Science and Human rot in maize. This leads to DON contami- Laboratory, Canadian Grain Nutrition/Microbiology & Molecular nation of these crops during crop growth, Commission, Winnipeg, MB, Canada Genetics, Michigan State University, prior to harvest. DON is found globally in East Lansing MI, USA these crops, as well as in rye, oats, and William W. Wilson, Department of rice (4–6). Agribusiness and Applied Economics, LIAISONS To minimize human exposure to DON North Dakota State University, ND, USA Benjamin Boroughs, NAMA Liaison, via the consumption of contaminated Hamed K. Abbas, USDA-ARS, NBCL, Director of Regulatory and Technical grain-based foods, regulatory organiza- Stoneville, MS, USA Affairs tions have established advisory levels, Susan Abel, Food & Consumer guidelines, and regulations for various Anne R. Bridges, AACCI Liaison, commodities and foods. In North Ameri- Products of Canada, Toronto, ON, Director of Technical Resources Canada ca, the US-FDA has imposed a restric- tion of 1 mg/kg on processed grains (7). Gordon Harrison, Canadian National Health Canada has set regulations of Millers’ Association, Ottawa, ON, 2 mg/kg in uncleaned soft wheat for use Canada in nonstaple foods and 1 mg/kg in un- cleaned soft wheat for use in baby foods; http://dx.doi.org/10.1094/CFW-60-1-0032 however, these regulations are currently ©2015 AACC International, Inc. under review. 32 / JANUARY–FEBRUARY 2015, VOL. 60, NO. 1 Toxicity and Deoxynivalenol (DON) when exposure occurs in single or mul- Although DON has been associated with DON was isolated from moldy barley tiple bolus doses (9). The latter does not a number of acute (8,9,13,25) and chronic by Japanese scientists in 1973 and rede- represent a likely scenario for the vast (8,9) health events, the likelihood of such scribed as “vomitoxin” by USDA research- majority of the global population today occasions remains relatively rare. In the ers in the same year (8–12). Since then, who can readily access minimally con- USA, for instance, advisory levels for grain toxicologists have sought to understand taminated sorted and cleaned grains that containing DON have been in place since the acute and chronic effects that may be very rarely result in acute incidences. 1982 (7). In fact, in 1993, an outbreak of associated with the ingestion of DON. In contrast, as previously mentioned, DON in wheat led to the elimination of a The principal health risks of DON are high chronic exposure has been shown to previously held limit of 2 mg/kg on un- associated with acute dietary exposure, cause growth retardation, alter immune processed raw wheat and wheat by-prod- which is caused by intake of large amounts function, and interfere with reproduc- ucts. After this incident the US-FDA de- of DON within a short time frame. Short- tion and development (8,9). In 2001, the cided to rely on purchasing and cleaning ly after ingestion of heavily contaminated Joint Food and Agriculture Organization/ practices to significantly reduce DON grains, DON causes vomiting and feed World Health Organization (FAO/WHO) levels to the 1 mg/kg maximum for fin- refusal in animals, especially swine, and Expert Committee on Food Additives ished wheat products, including the fol- causes gastroenteritis with vomiting in (JECFA) proposed a provisional maxi- lowing: flour, germ, and bran (7). Since humans (13–15). To date there is no evi- mum tolerable daily intake (PMTDI) for then, the US-FDA continues to recognize dence of occurrence of adverse human DON of 1 µg/kg body weight (bw) based an advisory limit of 1 mg/kg on finished health outcomes in North America as- on the growth effects associated with DON food products containing wheat and wheat sociated with acute dietary intake of DON. exposure (8,27,28). In the following de- by-products. A level that remains protec- The chronic effects of dietary intake of cade, investigations into the mechanisms tive for the USA population and USA ex- DON include weight gain suppression, of the effect of DON on weight gain were port markets. The same is true for advi- anorexia, and altered nutritional efficiency pursued and understood (8,9,29–32). In sory levels on finished grain established (16). It has also been shown to adversely 2010, JECFA extended the PMTDI to ap- by regulatory agencies elsewhere. affect immune systems (17). With any ply to both DON and its acetylated de- toxicological risk assessment, it is impor- rivatives and concluded that mean esti- DON Occurrence in North America tant to understand the absorption, distri- mates of national exposure to DON were The body of available research indicates bution, metabolism, and elimination of a below the PMTDI of 1 µg/kg bw (8,27,28). that acceptably low DON levels in unpro- given toxin or toxicant (18). Unlike other Likewise, recent national assessments de- cessed grain products can be achieved in toxins, such as dioxin and other fat-soluble termined that exposures to DON were exports and shipments for domestic use in compounds, DON is water soluble, which below levels of concern. Based on these most crop years. These levels are achieved allows it to be rapidly cleared in vivo. In collective assessments, the current global through the aggregation of grain stocks rodents and swine, which are frequently limits on DON are not only protective and blending that occurs along the supply used to study the adverse effects of DON from a chronic ingestion standpoint, but chain, monitoring of DON levels in deliv- (9), this toxin and its metabolites are ab- affirm that a level of 1 mg/kg on semipro- eries of grain shipments to processors, and sorbed and excreted quite rapidly (8). Spe- cessed grains is safe, and levels proposed a variety of grain sorting and cleaning cifically, studies have shown that 25% and for unprocessed raw grain would have no technologies available to processors. The 64% of radiolabeled, orally administered benefit from a public health safety per- North American grain industry’s experi- doses of DON and known metabolites in spective, as described further below. ence suggests that adoption of unduly rats were detected within 96 hr in urine and feces, respectively (8,19). Subsequent analyses of the tissues in these rats showed that no radioactivity was retained in the tissues after 96 hr (8,19).