Appropriateness to set a group health-based guidance value for zearalenone and its modified forms

Heather Wallace, Alexander Jan, Lars Barregård, Margherita Bignami, Sandra Ceccatelli, Bruce Cottrill, Michael Dinovi, Lutz Edler, Bettina Grasl-Kraupp, Christer Hogstrand, Laurentius (Ron) Hoogenboom, Helle Katrine Knutsen, Carlo Stefano Nebbia, Isabelle Oswald, Annette Petersen, Vera Maria Rogiers, Martin Rose, Alain-Claude Roudot, Tanja Schwerdtle, Christiane VleminckxGünter Vollmer, EFSA Panel on Contaminants in the Food Chain (CONTAM)

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The current tolerable daily intake (TDI) for zearalenone (ZEN) of 0.25 μg/kg body weight (bw) per day established by the EFSA Panel for Contaminants in the Food Chain (CONTAM Panel) in 2011 is based on oestrogenicity in pigs. No new studies were identified to change this TDI. The modified forms of ZEN identified are phase I and phase II metabolites. Phase I metabolites are mainly formed through reduction. Phase II metabolites are formed by conjugation of ZEN and its phase I metabolites with glucose or sulfate, and in animals glucuronic acid. The few data on the occurrence of modified forms of ZEN indicated that cereal-based foods are the main source, containing amounts varying from a few up to 100% of ZEN. Most of the phase I metabolites have oestrogenic activity and it is assumed that their combined action will be additive. The CONTAM Panel found it appropriate to set a group TDI of 0.25 μg/kg bw per day expressed as ZEN equivalents for ZEN and its modified forms (phase I and phase II metabolites). To account for differences in in vivo oestrogenic potency, each phase I metabolite was assigned a potency factor relative to ZEN to be applied to exposure estimates of the respective ZEN metabolites. It was assumed that conjugates (phase II metabolites) of ZEN and its phase I metabolites, which per se have no oestrogenic activity, will be cleaved releasing ZEN and its phase I metabolites. These conjugates were assigned the same relative potency factors as their aglycones. The overall uncertainty associated with the present assessment is considered as high. It would rather overestimate than underestimate any risk of modified ZEN. Several aspects of the uncertainty could be reduced provided more data are made available on oestrogenicity of modified ZEN, in particular α-zearalenol, in pigs.
Original languageEnglish
Article number4425
Pages (from-to)1-46
Number of pages46
JournalEFSA Journal
Issue number4
Early online date9 Apr 2016
Publication statusPublished - Apr 2016

Bibliographical note

The Panel wishes to thank the members of the Working Group on group HBGVs for mycotoxins and their modified forms: Jan Alexander, Chiara Dall’Asta, Arno Gutleb, Manfred Metzler, Isabelle Oswald and Dominique Parent-Massin for the preparatory work on this scientific opinion, and the EFSA staff member Hans Steinkellner for the support provided to this scientific opinion.


  • zearalenone
  • modified forms
  • metabolites
  • group tolerable daily intake
  • oestrogenicity
  • relative potency factors


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