EFSA JournalVolume 15, Issue 7 e04851 Scientific OpinionOpen Access Risks for animal health related to the presence of zearalenone and its modified forms in feed EFSA Panel on Contaminants in the Food Chain (CONTAM), EFSA Panel on Contaminants in the Food Chain (CONTAM)Search for more papers by this authorHelle-Katrine Knutsen, Helle-Katrine KnutsenSearch for more papers by this authorJan Alexander, Jan AlexanderSearch for more papers by this authorLars Barregård, Lars BarregårdSearch for more papers by this authorMargherita Bignami, Margherita BignamiSearch for more papers by this authorBeat Brüschweiler, Beat BrüschweilerSearch for more papers by this authorSandra Ceccatelli, Sandra CeccatelliSearch for more papers by this authorBruce Cottrill, Bruce CottrillSearch for more papers by this authorMichael Dinovi, Michael DinoviSearch for more papers by this authorLutz Edler, Lutz EdlerSearch for more papers by this authorBettina Grasl-Kraupp, Bettina Grasl-KrauppSearch for more papers by this authorChrister Hogstrand, Christer HogstrandSearch for more papers by this authorLaurentius (Ron) Hoogenboom, Laurentius (Ron) HoogenboomSearch for more papers by this authorCarlo Stefano Nebbia, Carlo Stefano NebbiaSearch for more papers by this authorAnnette Petersen, Annette PetersenSearch for more papers by this authorMartin Rose, Martin RoseSearch for more papers by this authorAlain-Claude Roudot, Alain-Claude RoudotSearch for more papers by this authorTanja Schwerdtle, Tanja SchwerdtleSearch for more papers by this authorChristiane Vleminckx, Christiane VleminckxSearch for more papers by this authorGünter Vollmer, Günter VollmerSearch for more papers by this authorHeather Wallace, Heather WallaceSearch for more papers by this authorChiara Dall'Asta, Chiara Dall'AstaSearch for more papers by this authorSven Dänicke, Sven DänickeSearch for more papers by this authorGunnar-Sundstøl Eriksen, Gunnar-Sundstøl EriksenSearch for more papers by this authorAndrea Altieri, Andrea AltieriSearch for more papers by this authorRuth Roldán-Torres, Ruth Roldán-TorresSearch for more papers by this authorIsabelle P Oswald, Isabelle P OswaldSearch for more papers by this author EFSA Panel on Contaminants in the Food Chain (CONTAM), EFSA Panel on Contaminants in the Food Chain (CONTAM)Search for more papers by this authorHelle-Katrine Knutsen, Helle-Katrine KnutsenSearch for more papers by this authorJan Alexander, Jan AlexanderSearch for more papers by this authorLars Barregård, Lars BarregårdSearch for more papers by this authorMargherita Bignami, Margherita BignamiSearch for more papers by this authorBeat Brüschweiler, Beat BrüschweilerSearch for more papers by this authorSandra Ceccatelli, Sandra CeccatelliSearch for more papers by this authorBruce Cottrill, Bruce CottrillSearch for more papers by this authorMichael Dinovi, Michael DinoviSearch for more papers by this authorLutz Edler, Lutz EdlerSearch for more papers by this authorBettina Grasl-Kraupp, Bettina Grasl-KrauppSearch for more papers by this authorChrister Hogstrand, Christer HogstrandSearch for more papers by this authorLaurentius (Ron) Hoogenboom, Laurentius (Ron) HoogenboomSearch for more papers by this authorCarlo Stefano Nebbia, Carlo Stefano NebbiaSearch for more papers by this authorAnnette Petersen, Annette PetersenSearch for more papers by this authorMartin Rose, Martin RoseSearch for more papers by this authorAlain-Claude Roudot, Alain-Claude RoudotSearch for more papers by this authorTanja Schwerdtle, Tanja SchwerdtleSearch for more papers by this authorChristiane Vleminckx, Christiane VleminckxSearch for more papers by this authorGünter Vollmer, Günter VollmerSearch for more papers by this authorHeather Wallace, Heather WallaceSearch for more papers by this authorChiara Dall'Asta, Chiara Dall'AstaSearch for more papers by this authorSven Dänicke, Sven DänickeSearch for more papers by this authorGunnar-Sundstøl Eriksen, Gunnar-Sundstøl EriksenSearch for more papers by this authorAndrea Altieri, Andrea AltieriSearch for more papers by this authorRuth Roldán-Torres, Ruth Roldán-TorresSearch for more papers by this authorIsabelle P Oswald, Isabelle P OswaldSearch for more papers by this author First published: 31 July 2017 https://doi.org/10.2903/j.efsa.2017.4851Citations: 59 Correspondence: contam@efsa.europa.eu Requestor: European Commission Question number: EFSA-Q-2015-00247 Panel members: Jan Alexander, Lars Barregard, Margherita Bignami, Beat Brüschweiler (from 23 June 2016), Sandra Ceccatelli, Bruce Cottrill, Michael Dinovi, Lutz Edler, Bettina Grasl-Kraupp, Christer Hogstrand, Laurentius (Ron) Hoogenboom, Helle Katrine Knutsen, Carlo Stefano Nebbia, Isabelle P. Oswald, Annette Petersen, Martin Rose, Alain-Claude Roudot, Tanja Schwerdtle, Christiane Vleminckx, Günter Vollmer, and Heather Wallace. Amendment: An editorial amendment was carried out that does not materially affect the contents or outcome of this scientific output. On p. 84 the reference Jiang et al. (2012) has been corrected so as to match the main text and conclusions on adverse effects on pigs. To avoid confusion, the older version has been removed from the EFSA Journal, but is available on request, as is a version showing all the changes made. Acknowledgements: The EFSA CONTAM Panel thanks the hearing expert Andrew David Hart, member of the EFSA WG on Uncertainty in Risk Assessment for the support provided to this scientific output. The Panel acknowledges all European countries and European stakeholder organisations that provided feed consumption data and occurrence data on zearalenone and its modified forms in feed. Adopted: 10 May 2017 Reproduction of the image listed below is prohibited and permission must be sought directly from the copyright holder: Figure 4: © Elsevier Ltd. Amended: 18 July 2018 AboutSectionsPDF ToolsExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Abstract Zearalenone (ZEN), a mycotoxin primarily produced by Fusarium fungi, occurs predominantly in cereal grains. The European Commission asked EFSA for a scientific opinion on the risk to animal health related to ZEN and its modified forms in feed. Modified forms of ZEN occurring in feed include phase I metabolites α-zearalenol (α-ZEL), β-zearalenol (β-ZEL), α-zearalanol (α-ZAL), β-zearalanol (β-ZAL), zearalanone (ZAN) and phase II conjugates. ZEN has oestrogenic activity and the oestrogenic activity of the modified forms of ZEN differs considerably. For ZEN, the EFSA Panel on Contaminants in the Food Chain (CONTAM) established no observed adverse effect levels (NOAELs) for pig (piglets and gilts), poultry (chicken and fattening turkeys), sheep and fish (extrapolated from carp) and lowest observed effect level (LOAEL) for dogs. No reference points could be established for cattle, ducks, goats, horses, rabbits, mink and cats. For modified forms, no reference points could be established for any animal species and relative potency factors previously established from rodents by the CONTAM Panel in 2016 were used. The dietary exposure was estimated on 17,706 analytical results with high proportions of left-censored data (ZEN about 60%, ZAN about 70%, others close to 100%). Samples for ZEN were collected between 2001 and 2015 in 25 different European countries, whereas samples for the modified forms were collected mostly between 2013 and 2015 from three Member States. Based on exposure estimates, the risk of adverse health effects of feed containing ZEN was considered extremely low for poultry and low for sheep, dog, pig and fish. The same conclusions also apply to the sum of ZEN and its modified forms. Summary Following a request from the European Commission, the EFSA Panel on Contaminants in the Food Chain (CONTAM) assessed the risk to animal health related to the presence of zearalenone (ZEN) and its modified forms in feed. The CONTAM Panel was asked to consider all relevant adverse health effects, and in particular to address the co-occurrence of ZEN and its modified forms, and to estimate the dietary exposure of different animal species. Previous risk assessments from the European Food Safety Authority (EFSA) on ZEN in feed (2004), ZEN in food (2011), modified forms of certain mycotoxins in food and feed (2014) and on the appropriateness to set a group health-based guidance value for ZEN and its modified forms (2016) have been used as a starting point for the present assessment. ZEN is a phenolic resorcylic acid lactone mycotoxin produced by several Fusarium species, particularly Fusarium graminearum. ZEN can be modified in plants, fungi and animals by phase I and phase II metabolism. Modified forms of ZEN occurring in feed include its reduced phase I metabolites, i.e. α-zearalenol and β-zearalenol (α-ZEL and β-ZEL), α-zearalanol and β-zearalanol (α-ZAL and β-ZAL), zearalanone (ZAN) and its phase II derivatives, such as those conjugated with glucose, sulfate and glucuronic acid. α-ZAL, one of the phase I metabolites of ZEN, is used as a growth promoter in non-European Union (EU) countries under the name of Zeranol. It is banned in Europe, and therefore, it is included in official control plans. Analytical methods for ZEN and its modified forms in feed are well-established. However, while methods reported in the scientific literature are widely based on the more sensitive liquid chromatography–tandem mass spectrometry (LC–MS/MS), most of the routine analyses are still performed by liquid chromatography-fluorescence detector (LC-FLD) or liquid chromatography-ultraviolet detector (LC-UV). Of note, calibrants for ZEN conjugates and reference materials for phase I and phase II modified forms are not commercially available. Wide interspecies differences in ZEN absorption, distribution, metabolism and excretion (ADME) have been documented. Prehepatic, hepatic end extrahepatic ZEN metabolism has been reported; the nature and the amount of the generated metabolites may affect the species-sensitivity to the toxin. In farm and companion animals, reductive biotransformations largely prevail; the main ZEN metabolites are α-ZAL, β-ZAL, with only very limited amounts of α-ZEL, β-ZEL, and other reductive metabolites being produced; reduced metabolites retain or increase the oestrogenic potency of the parent compound. Based on the levels measured in biological fluids (plasma, urine or bile) of ZEN-treated animals, the α-derivatives seem to prevail in pigs, dogs, and turkeys while the β-derivatives appear to be more abundant in cattle, goats, horses, broiler chickens, and laying hens. Cytochrome P450 (CYP)-mediated aromatic or aliphatic hydroxylation also occurs, but information in farm and companion animals is limited. In orally exposed animals, ZEN and its metabolites are rapidly absorbed, distributed to several organs and quickly excreted mainly via the biliary route as glucuronides; an active enterohepatic circulation has been demonstrated. Excretion in milk and eggs has been documented for ZEN and its metabolites. There is scant information on the toxicokinetics of ZEN in cattle; rumen microbes extensively metabolise ZEN to α-ZAL and β-ZAL, the latter being predominant also in biological fluids. Little is known on the toxicokinetics of ZEN in sheep; ZEN is almost completely biotransformed by ovine rumen fluid to α-ZAL, β-ZAL at similar proportions and both metabolites are present in urine of dosed animals as both free and conjugated forms. No studies have been identified on ZEN administration to goats by the oral route. There is a large data set for ZEN toxicokinetics in pigs, including piglets, gilts, and sows. In all porcine categories, the production of α-ZEL largely outweighed that of β-ZEL and other reductive metabolites which were recovered, along with ZEN in blood, urine, and bile mostly in their glucuronidated form. The modified forms ZEN-14-O-β-glucoside (ZEN14Glc), ZEN-16-O-β-glucoside (ZEN16Glc) and ZEN-14-sulfate (ZEN14Sulf) were not detected in urine and faeces when administered orally, suggesting a complete hydrolysis and thereby contribution to ZEN overall toxicity. In poultry, ZEN is characterised by a low oral bioavailability and a rapid elimination. β-ZEL was largely predominant over α-ZEL in broiler chickens and laying hens, while turkey poults tended to biotransform ZEN more extensively and synthesise a relatively high amount of α-ZEL; in all cases, glucuronidation was the main conjugation reaction. In horses, α-ZEL and β-ZEL are the main ZEN metabolites, the latter being predominantly formed over α-ZEL under in vivo conditions. Little is known about the toxicokinetics of ZEN in rabbits; ZEN, α-ZEL and β-ZEL were detected in colonic chyme, faeces, bile and urine of rabbits orally dosed with ZEN. There is scant information concerning ZEN toxicokinetics in fish. In rainbow trout, there is evidence of a prevalent production of β-ZEL vs α-ZEL, while the reverse seems to occur in carp. No information could be identified for toxicokinetics of cats and farmed mink. In orally exposed dogs, measurable blood levels of ZEN, α- and β-ZEL were detected throughout the experiment, with a clear prevalence of the α- over the β-derivative (up to 100%). Little is known about the metabolic fate of modified forms, except for α-ZAL. In all species, α-ZAL is oxidised to ZAN and isomerised to β-ZAL; the parent compound and the metabolites are mainly glucuronidated. The main biological activity of ZEN is its oestrogenicity, i.e. the ability to act like the endogenous steroidal sex hormone 17-β-oestradiol. ZEN binds to oestrogenic receptors (ERs) and has a stronger affinity to ER-α than to ER-β. ZEN and its modified forms differ considerably in their oestrogenic activity. Based on their ‘uterotrophic activity’ assessed in rodents, ZEN and its modified forms are ranked as follows: α-ZEL > α-ZAL > ZEN ≈ ZAN ≈ β-ZAL > β-ZEL. ZEN can activate the pregnane X receptor (PXR) and increase the transcription of a number of genes, including several CYPs. Cattle appear to be more resistant to the adverse effects of ZEN than other farm animals because they biotransform ZEN more into β-ZEL than α-ZEL. The only one available dose–response experiment in dairy cows orally exposed to pure ZEN for which a reduction in the size of corpora lutea was claimed but no effects level could be identified, was too limited to identify adverse effects. Similar limitations were identified in a study on heifers at relatively high exposure level where the conception rate tended to be decreased. No reference point for risk characterisation could be derived in cattle. Based on ovulation rates and lambing percentages, a lowest observed adverse effect level (LOAEL) of 56 μg ZEN/kg body weight (bw) per day and a no observed adverse effect level (NOAEL) 28 μg ZEN/kg bw per day was established for sheep. No data were available for deriving reference points for risk characterisation for goats. Pigs are generally regarded as being a very sensitive species to ZEN, the most sensitive being prepubertal female piglets. Based on the appearance of the vulva and the uterus weight, a no observed effect level (NOEL) of 10.4 μg ZEN/kg bw per day was established for piglets by the CONTAM Panel in 2011 and retained in 2016. For sexually mature female pigs, a NOAEL of 40 μg/kg bw per day was identified based on prolonged cycling. Poultry responds to the presence of ZEN in feed only at rather high dietary concentrations and can generally be regarded as resistant. Based on decreased number of lymphocytes and the vent swelling, NOAELs of 7,500 and 9,100 μg/kg bw per day were identified for chickens and turkeys, respectively. For other poultry species and categories data are scarce. Therefore, LOAELs/NOAELs could not be derived. The only available study performed in horses with the purified mycotoxin did not allow the derivation of NOAEL or a LOAEL due to poor experimental design and the lack of a control group. In rabbits, no oestrogenic effects at 100 μg/kg bw per day were observed. However, at 10 μg ZEN/kg bw per day, a transient increase of catecholamine was observed. No NOAEL or LOAEL could be established. Very limited toxicity data for ZEN are available for fish. The CONTAM Panel estimated a NOAEL for carp of 0.3 mg ZEN/kg feed to correspond to 9 μg ZEN/kg bw per day based on decreased number of monocytes, increased number of granulocytes and increased lipid peroxidation in liver and gill and altered the carbohydrate metabolism. No effect level to characterise the hazard of ZEN could be established for other fish species. Dogs are considered a sensitive species to ZEN. No NOAEL could be established. Based on myometrium and endometrium lesions, aspect of uterine glands, blood haematology and biochemistry a LOAEL of 25 μg ZEN/kg bw per day has been estimated for dogs (mature bitches). No data could be identified concerning the effects of ZEN in cats. For farmed mink, the available studies were not suitable for deriving reference point of hazard characterisation since they were performed at doses hardly occurring in practice and the lowest tested dose (1,000 μg/kg bw per day) already caused overt oestrogenic effects. Very few experiments investigated the adverse effect of the modified forms of ZEN on livestock species, horses, fish and dogs and none of them were suitable to derive a NOAEL or LOAEL. The dietary exposure was estimated using a final data set of 17,706 analytical results of ZEN and modified forms occurrence in feed. Data were representing most of the feed commodities but for many commodities only a limited number of samples were analysed. Samples for ZEN were collected between 2001 and 2015 in 25 different European countries, whereas samples on the modified forms were collected mostly between 2013 and 2015 from three Member States. The percentage of left-censored data (results below limit of detection and/or limit of quantification) was high (ZEN about 60%; ZAN about 70%; α-ZEL, β-ZEL, α- ZAL and β-ZAL about 100%). The CONTAM Panel considered it important to estimate the occurrence and the animal exposure to the total concentration of ZEN, α-ZAL, β-ZAL, ZAN, α-ZEL, β-ZEL through feed. Apart from ‘Cereal grains, their products and by-products’ and ‘Compound feed’, only a limited number of quantified data were available for other feed groups, i.e. forages, land animal products, legume seeds, minerals, oil and other seeds and tubers. The highest number of reported samples for ZEN corresponded to the feed group ‘Cereal grains, their products and by-products’ (~ 67%) and particularly for ‘Wheat’ (n = 6,499). Other food groups that were well represented were ‘Complementary/Complete feed’ (n = 2,625), ‘Maize and corn’ (n = 2,048) and ‘Barley’ (n = 1,596). Although an important ingredient in commercial rabbit diets, no data were reported for lucerne meal. The occurrence assessment for ZEN reported in the literature is consistent with data in the EFSA database. Concerning the occurrence of modified forms, phase II conjugated forms have been often reported in the recent literature, whereas no data have been received by EFSA. The co-occurrence of ZEN and its phase I and phase II modified forms is mainly described in cereals and products thereof. While milling may lead to a redistribution of ZEN and its modified forms in the final fractions, with a possible enrichment in middlings, there is no evidence of significant degradation by processing. Molar relative potency factors (RPFs) of the modified forms relative to ZEN were applied to occurrence levels of the respective ZEN metabolites according to the Opinion of the EFSA CONTAM Panel delivered in 2016. Exposure to ZEN and its modified forms is primarily from consumption of contaminated cereal grains and cereal by-products. Except for forage maize (and maize silage produced from it) and cereal straw, levels in forages are generally low. The mean lowest lower bound (LB) to highest upper bound (UB) exposures of dairy cows and beef cattle to ZEN ranged from 0.06 to 5.1 μg/kg bw per day, and the P95 exposures ranged from 0.30 to 32.9 μg/kg bw per day. For sheep and goats, the calculated lowest LB to highest UB mean exposures to ZEN were 0.18 and 1.78 μg/kg bw per day, respectively, while at the 95th percentile the range was from 0.27 (LB) to 10.8 (UB) μg/kg bw per day. The calculated mean LB and UB exposures for pigs were 0.81 and 1.35 μg/kg bw per day, respectively, while the 95th percentile exposures ranged from 2.50 (LB) to 7.88 (UB) μg/kg bw per day, respectively. For poultry, estimates of the mean exposure ranged from 0.74 (LB) to 3.64 (UB) μg/kg bw per day. The equivalent range for the 95th percentile estimates of exposure was 3.46 and 12.7 μg/kg bw per day, respectively. For horses, the LB and UB mean exposure estimates to ZEN were 0.18 and 0.89 μg/kg bw per day, respectively, while for the 95th percentile the range LB to UB was 0.35 to 3.69 μg/kg bw per day. Based on assumed diet compositions, the estimated mean LB and UB exposures for farmed salmonids and carp ranged from 0.08 to 0.50 μg/kg bw per day, respectively. At the 95th percentile, LB and UB estimates of exposure were 0.49 and 1.78 μg/kg bw per day, respectively. The estimated mean exposure for farmed rabbits and mink ranged from 0.31 (LB) to 1.11 (UB) μg/kg bw per day, while the equivalent range for the 95th percentile was from 0.85 to 1.41 μg/kg bw per day. For companion animals (cats and dogs), LB and UB mean exposure to ZEN ranged from 0.22 to 0.33 μg/kg bw per day, respectively, while at the 95th percentile the range was from 0.75 (LB) to 0.80 (UB) μg/kg bw per day. There was considerable variation between livestock groups in the percentage of the total exposure (ZEN + α-ZAL + β-ZAL + ZAN + α-ZEL + β-ZEL) that was accounted for by the sum of the modified forms (α-ZAL + β-ZAL + ZAN + α-ZEL + β-ZEL). For many species, notably poultry, ZEN accounted for the total exposure (100%) because of lack of data of ZEN modified forms. At the LB exposure, the modified forms accounted for 0–39% of the total exposure at both the mean and 95th percentile for cattle, goat, sheep, horses, pigs, fish, rabbits, cats, dogs and mink. At the UB exposure, the modified forms accounted for 50% or more of the total exposure, both at the mean and 95th percentile for dairy cows, beef cattle, lactating sheep, horses, weaned pigs and rabbits. More than half of the UB mean exposure for fattening pigs, lactating sows, cats and dogs was from the modified forms, but was < 50% at the 95th percentile. The Panel noted that estimating the occurrence and exposure with such a high number of left censored data leads to a very high uncertainty. Risk characterisation for ZEN, was performed comparing the chronic exposure values in diets at the UB mean and UB 95th percentile concentrations for ZEN with identified reference points. For cattle, horses, rabbit, goat, duck, mink and cats the health risk from the exposure to ZEN could not be assessed as no NOAEL or LOAEL have been identified. For poultry (chicken and fattening turkeys), the highest estimated chronic exposure of ZEN was less than 0.06% of the NOAEL. The Panel concluded that the estimated risk for chronic adverse health effects from feed containing ZEN was extremely low for poultry. For sheep, the highest estimated chronic exposure of ZEN was less than 16% of the NOAEL. The Panel concluded that the risk of adverse health effects of feed containing ZEN was low for sheep. For dogs, only a LOAEL was available. The highest estimated chronic exposure of ZEN was less than 3% of the LOAEL. The Panel concluded that the estimated risk for chronic adverse health effects from feed containing ZEN was low for dog. For fish, a NOAEL was only available for carp and was extrapolated to all fish species. The highest estimated chronic exposure of ZEN was 24% of the NOAEL. The Panel concluded that the estimated risk for chronic adverse health effects from feed containing ZEN was low for fish. For piglets and gilts, the highest estimated chronic exposure (P95) of ZEN was 21% and 9% of the NOAEL, respectively. The Panel concluded that the estimated risk for chronic adverse health effects from feed containing ZEN was low for piglets and gilts. Risk characterisation for the sum of ZEN and its modified forms, was performed comparing the chronic exposure of the sum of ZEN and its modified forms corrected for molar RPFs with identified reference points obtained for ZEN. For cattle, horses, rabbit, goat, duck, mink and cats the health risk from the exposure to ZEN and its modified forms could not be assessed as no NOAEL or LOAEL have been identified. The Panel noted that no data on levels of α-ZAL, β-ZAL, ZAN, α-ZEL or β-ZEL were provided in species-specific compound feeds for poultry. However, considering the very high NOAELs for these species, and the composition of their feed, the Panel considered the risk of health effects from ZEN and its modified forms was extremely low for these species. For sheep, the highest estimated chronic exposure of ZEN and modified forms was less than 25% of the NOAEL. The Panel concluded that the risk of adverse health effects of feed containing ZEN and its modified forms was low for sheep. For dogs, only a LOAEL was available. For this species, the highest estimated chronic exposure of ZEN and its modified forms were less than 5% of the LOAEL. The Panel concluded that the estimated risk for chronic adverse health effect from consuming feed containing ZEN and its modified forms was low for dog. For fish, a NOAEL was only available for carp and was extrapolated to all fish species. The highest estimated chronic exposure of ZEN and its modified forms was less than 30% of the NOAEL. The Panel concluded that the estimated risk for chronic adverse health effect from feed containing ZEN and its modified forms was low for fish. For piglets and gilts, the highest estimated chronic exposure of ZEN and its modified forms were 59% and 12% of the NOAEL, respectively. The Panel concluded that the estimated risk for chronic adverse health effects from feed containing ZEN and its modified forms was low for piglets and gilts. The CONTAM Panel noted that there is a need for more data on the occurrence of modified forms of ZEN in feed. In addition, there is a need of calibrants and reference materials for the development of properly validated and sensitive routine analytical methods for ZEN modified forms in the feed commodities and especially highly sensitive methods to identify the most potent form α-ZEL. There is also a need for toxicological and toxicokinetic data on ZEN modified forms, particularly for cattle, horses, rabbit, poultry, for companion animals and mink to ZEN, to reduce the uncertainties in the animal risk assessment. 1 Introduction 1.1 Background and Terms of Reference as provided by the European Commission BACKGROUND Following a request from the European Commission, the risks to human and animal health related to modified forms of the Fusarium toxins zearalenone, nivalenol, T-2 and HT-2 toxins and fumonisins were evaluated in the scientific opinion on the risks for human health related to the presence of modified forms of certain mycotoxins in food and feed,1 adopted by the EFSA Panel on Contaminants in the Food Chain (CONTAM) on 25 November 2014. The CONTAM Panel indicated in the recommendations that the animal health effects of zearalenone need to be re-assessed in order to possibly set No observed adverse effect levels/lowest observed effect levels (NOAELs/LOAELs) for zearalenone in order to be able to assess the risk for animal health related to the presence of zearalenone and its modified forms in feed. TERMS OF REFERENCE In accordance with Art. 29 (1) (a) of Regulation (EC) No 178/2002, the Commission asks the European Food Safety Authority (EFSA) for a scientific opinion on the risks for animal health related to the presence of zearalenone and its modified forms in feed. 1.2 Interpretation of the Terms of Reference The CONTAM Panel concluded that the terms of reference provided by the Commission were clear. 1.3 Additional information 1.3.1 Previous risk assessments The Scientific Opinion related to zearalenone (ZEN) as an undesirable substance in animal feed (EFSA, 2004) concluded that zearalenone exerts its toxic action by interacting with oestrogen receptors (ERs) and causing an oestrogenic response in animals. Pigs were considered the most sensitive animal species to zearalenone, with female pigs more sensitive than male pigs, followed by sheep, cattle and poultry. The CONTAM Panel concluded that the calculation of animal exposure levels based on the individual occurrence data of zearalenone in feed materials could not be carried out due to the variability within the European Union (EU) member states feeding regimes for farm animals. No NOAELs/LOAELs for zearalenone in animals were derived since the available data were considered inadequate. In the human ZEN risk assessment from EFSA in 2011, (EFSA CONTAM Panel, 2011), a tolerable daily intake (TDI) of 0.25 μg/kg body weight (bw) per day was derived from a no observed effect level (NOAEL) of 10 μg/kg bw for oestrogenic effects observed in immature gilts and applying an uncertainty factor of 40 (4 for interspecies differences in toxicokinetics and 10 for inter-human variability). Lowest-observed-effect-levels (LOELs) for ovary, uterus and vulva in female pigs ranged from 17 to 200