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In the context of the ongoing debate on the risk assessment of GM food/feed in Europe, it is crucial to put the findings of the 2-year feeding study in a perspective that covers:

  1. The scientific quality of chronic toxicity and carcinogenicity testing in rats to whole foods/feeds.
  2. The scientific value of long-term feeding trials for GM food/feed risk assessment.


The evaluation of the scientific value will be conducted in a carefully designed and transparent step-by-step approach.


Criteria to evaluate the scientific quality of 2-year feeding trials will be developed and applied prior to the actual feeding trials. The scientific value will mainly be evaluated by clarifying what toxicity relevant information from risk assessment would trigger a long-term feeding study. In both cases G-TwYST will draw on the experience and standards in other toxicity assessment contexts.

Evaluation of the scientific quality of long-term GM food/feed feeding trials

In order to identify criteria to evaluate the scientific quality of long-term feeding studies, guidance documents for aspects of toxicity assessment relevant to the scope of the WP have been identified and analyzed. The criteria cover all aspects of the feeding trials.

Based on these documents a draft set of suitable criteria has been established by the project team and will be applied to the feeding trials being performed by the G-TwYST project and by the GRACE project as well as to the feeding trials having been performed by other research groups/consortia in the past.
The criteria as well as the experience and insights gained from their application for GM food/feed testing have been discussed in a mini-workshop to which external experts were invited. Subsequently, the draft list of criteria has been revised according to the recommendations resulting from the workshop and a final set of quality criteria has been published at the reports pages of the project website.


Justification of long-term feeding trials for GM food/feed risk assessment

In order to define the triggers that would justify performing a chronic toxicity/carcinogenicity feeding trial, the scientific literature and guidance documents on 90-day feeding trials from a broad range of toxicity assessment contexts will be searched and collected from publicly accessible databases (scientific literature, research projects, data collections, and bibliographies) and further accessible sources such as the GRACE central access database.
Previously applied or suggested trigger items will be subjected to a review by the project team and candidate trigger items will be identified. In a subsequent step the usefulness of the candidate triggers will be evaluated by analyzing the data obtained by the Project with GM maize NK603 and GM maize MON8 10 in 90-day, the 12-month feeding trials, and the preliminary results of the 2-year feeding trials as well as the results of feeding trials having been performed by other research groups/consortia in the past, thereby allowing to determine the added value of long-term feeding trials for GM food/feed risk assessment.
The candidate trigger items and the experience in applying them in practice will be discussed and recommendations will be compiled in a second mini-workshop, to which external experts will be invited (M26, month 43). Based on the results of this workshop a report characterizing the proposed trigger items and describing the underlying rationale will be prepared and published at the project website.

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1-year feeding study with MON810 on ARTE

In October 2016 ARTE broadcasted "OGM - Mensonges et vérités" (GMOs - Lies and truths) on French and German Television. In this 100 minutes long documentary Frédéric Castaignède sheds light on genetically modified crops, the impact on farmers, biodiversity and human health. We have selected and translated a fragment in which G-TwYST project leader Prof Pablo Steinberg presents the results of the 1-year feeding study with MON810 maize in the GRACE project.


The documentary provides a ‘snapshot’ of the GRACE final Conference which took place on November 9-10 2015 in Potsdam, Germany. We refer to videos on the GRACE Youtube channel  for a full account.


Paper published describing the statistical approach for equivalence testing in G-TwYST

An open access paper describing the statistical approach for equivalence testing in G-TwYST has now been published in Food and Chemical Toxicology. The method was tested on data from the GRACE project, as described in this paper. We will now progress by applying the method in the statistical analyses of the G-TwYST feeding trials, to be reported first in the statistical reports as project deliverables.


  • An equivalence testing method is proposed to assess the safety of regulated products
  • We combine data from a current study with test and control, and historical studies with assumedly safe reference products
  • The method is illustrated with animal feeding studies using genetically modified and reference maize varieties
  • A high statistical power of the equivalence test is the basis for the equivalence criterion
  • Generalized fiducial inference is used to integrate uncertainties from the historical and the current data


van der Voet H, Goedhart PW, Schmidt K (2017). Equivalence testing using existing reference data:  an example with genetically modified and conventional crops in animal feeding studies. Food and Chemical Toxicology, 109: 472-485. https://doi.org/10.1016/j.fct.2017.09.044

G-TwYST Interim Report available

15 February 2017


The G-TwSYT team completed a publicly available Interim report with information about the progress that has been made in the first 1.5 years of the project. The report can be downloaded here.