Effects of deoxynivalenol in naturally contaminated wheat on feed intake and health status of horses

Assessment of information as regards the toxicity of deoxynivalenol for horses and poultry

In 2017, the EFSA Panel on Contaminants in the Food Chain (CONTAM) adopted a Scientific Opinion on the risks for animal health related to the presence of deoxynivalenol (DON) and its acetylated and modified forms in food and feed. No observed adverse effect levels (NOAELs) and lowest observed adverse effect levels (LOAELs) were derived for different animal species. For horses, an NOAEL of 36 mg DON/kg feed was established, the highest concentration tested and not showing adverse effects. For poultry, an NOAEL of 5 mg DON/kg feed for broiler chickens and laying hens, and an NOAEL of 7 mg DON/kg feed for ducks and turkeys was derived. The European Commission requested EFSA to review the information regarding the toxicity of DON for horses and poultry and to revise, if necessary, the established reference points (RPs). Adverse effect levels of 1.9 and 1.7 mg DON/kg feed for, respectively, broiler chickens and turkeys were derived from reassessment of existing studies and newly available literature, showing that DON causes effects on the intestines, in particular the jejunum, with a decreased villus height but also histological damage. An RP for adverse animal health effects of 0.6 mg/kg feed for broiler chickens and turkeys, respectively, was established. For horses, an adverse effect level of 5.6 mg DON/kg feed was established from studies showing reduced feed intake, with an RP for adverse animal health effects of 3.5 mg/kg feed. For ducks and laying hens, RPs remain unchanged. Based on mean and P95 (UB) exposure estimates performed in the previous Opinion, the risk of adverse health effects of feeds containing DON was considered a potential concern for broiler chickens and turkeys. For horses, the risk for adverse health effects from feed containing DON is low.

Evaluation of Inner Exposure of Horses to Zearalenone (ZEN), Deoxynivalenol (DON) and Their Metabolites in Relation to Colic and Health-Related Clinical-Chemical Traits

Mycotoxin contaminated feed has been associated with colic of horses caused by intestinal disorders. Whether such disease conditions alter the intestinal toxin metabolism and transfer across a compromised mucosal barrier is unknown. A screening approach was used to relate blood residue levels of DON, ZEN and their metabolites to the status of the horses (sick vs. healthy). A total of 55 clinically healthy horses from 6 different farms with varying feeding background served as control for sick horses (N = 102) hospitalized due to colic. ZEN, alpha-zearalenol (ZEL), beta-ZEL and DON were detectable in peripheral blood as indicators for the inner exposure with significant farm effects for alpha- and beta-ZEL. However, the levels in sick horses were similar to all farms. Moreover, the proportion of beta-ZEL of all detected ZEN metabolites as an indicator for the degree of metabolism of ZEN was not different for sick horses but differed amongst the control farms. Although the incidence of DON in blood was generally low and not significantly different amongst healthy and sick horses, the positive samples were nearly exclusively found in sick horses suggesting either a higher toxin transfer, an association of DON with the development of colic or a different feeding background.

Risks to human and animal health related to the presence of deoxynivalenol and its acetylated and modified forms in food and feed

Deoxynivalenol (DON) is a mycotoxin primarily produced by Fusarium fungi, occurring predominantly in cereal grains. Following the request of the European Commission, the CONTAM Panel assessed the risk to animal and human health related to DON, 3-acetyl-DON (3-Ac-DON), 15-acetyl-DON (15-Ac-DON) and DON-3-glucoside in food and feed. A total of 27,537, 13,892, 7,270 and 2,266 analytical data for DON, 3-Ac-DON, 15-Ac-DON and DON-3-glucoside, respectively, in food, feed and unprocessed grains collected from 2007 to 2014 were used. For human exposure, grains and grain-based products were main sources, whereas in farm and companion animals, cereal grains, cereal by-products and forage maize contributed most. DON is rapidly absorbed, distributed, and excreted. Since 3-Ac-DON and 15-Ac-DON are largely deacetylated and DON-3-glucoside cleaved in the intestines the same toxic effects as DON can be expected. The TDI of 1 μg/kg bw per day, that was established for DON based on reduced body weight gain in mice, was therefore used as a group-TDI for the sum of DON, 3-Ac-DON, 15-Ac-DON and DON-3-glucoside. In order to assess acute human health risk, epidemiological data from mycotoxicoses were assessed and a group-ARfD of 8 μg/kg bw per eating occasion was calculated. Estimates of acute dietary exposures were below this dose and did not raise a health concern in humans. The estimated mean chronic dietary exposure was above the group-TDI in infants, toddlers and other children, and at high exposure also in adolescents and adults, indicating a potential health concern. Based on estimated mean dietary concentrations in ruminants, poultry, rabbits, dogs and cats, most farmed fish species and horses, adverse effects are not expected. At the high dietary concentrations, there is a potential risk for chronic adverse effects in pigs and fish and for acute adverse effects in cats and farmed mink.

Fate of deoxynivalenol and deoxynivalenol-3-glucoside during cereal-based thermal food processing: a review study

Deoxynivalenol (DON), the most commonly occurring trichothecene in nature, may affect animal and human health through causing diarrhea, vomiting, gastrointestinal inflammation, and immunomodulation. DON-3-glucoside (DON-3G) as a major plant metabolite of the mycotoxin is another "emerging" food safety issue in recent years. Humans may experience potential health risks by consuming DON-contaminated food products. Thus, it is crucial for human and animal health to study also the degradation of DON and DON-3G during thermal food processing. Baking, boiling, steaming, frying, and extrusion cooking are commonly used during thermal food processing and have promising effects on the reduction of mycotoxins in food. For DON, however, the observed effects of these methods, as reported in numerous studies, are ambiguous and do not present a clear picture with regard to reduction or transformation. This review summarized the influence of thermal processing on the stability of DON and the formation of degradation/conversion products. Besides this, also a release of DON and DON-3G from food matrix as well as the release of DON from DON-3G during processing is discussed. In addition, some conflicting findings as reported from the studies on thermal processing as well as cause-effect relationships of the different thermal procedures are explored. Finally, the potential toxic profiles of DON degradation products are discussed as well when data are available.

Effects of deoxynivalenol (DON), zearalenone (ZEN), and related metabolites on equine peripheral blood mononuclear cells (PBMC) in vitro and background occurrence of these toxins in horses

Both deoxynivalenol (DON), zearalenone (ZEN), and their metabolites are known to modulate immune cells in various species whereby viability and proliferation are influenced. Such effects were rarely examined in horses. Therefore, one aim of the present study was to titrate the inhibitory concentrations of DON, 3-acetyl-DON (3AcDON), de-epoxy-DON (DOM-1), ZEN, and α- and β-zearalenol (ZEL) at which viability and proliferation of equine PBMC were reduced by 50 % (IC50) and 10 % (IC10) in vitro. For evaluation of practical relevance of the in vitro findings, a further aim was to screen horses for the background occurrence of DON, ZEN, and their metabolites in systemic circulation and to relate toxin residues both to the inhibitory toxin concentrations and to hematological and clinical-chemical characteristics.The IC50 (μM) for DON, 3AcDON, β-ZEL, α-ZEL, and ZEN were determined at 3.09, 25.90, 75.44, 97.44, and 98.15 in unstimulated cells, respectively, while in proliferating cells, the corresponding IC50 values were 0.73, 6.89, 45.16, 75.96, and 82.51. Neither viability nor proliferation was influenced by DOM-1 up to a concentration of 100 μM.The in vivo screening (N = 49) revealed the occurrence of ZEN (N = 24), α-ZEL (N = 3), β-ZEL (N = 37), DON, and DOM-1 (N = 2). The detected concentrations were much lower than the corresponding IC50 while the IC10 of DON and β-ZEL for proliferating PBMC corresponded to approximately 26 and 35 ng/mL which might be relevant when contaminated diets are fed.Clinical-chemical and hematological traits were not related to mycotoxin residue levels excepting blood urea nitrogen which was positively correlated to the sum of β-ZEL, α-ZEL, and ZEN concentration. Whether this reflects simply the feeding history of the horses or renal failures giving rise to a prolonged half-life of the toxins needs to be clarified further.