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Considerations

In a first consideration, the G-TwYST consortium intended to perform rat feeding trials with GM maize NK 603 and MON810 based on OECD Test Guidelines and according to EFSA recommendations. In autumn 2014, EFSA published an explanatory statement regarding the applicability of the Guidance of the EFSA Scientific Committee on conducting repeated-dose 90-day oral toxicity study in rodents on whole food/feed for GMO risk assessment and proposed to consider an increased inclusion rate for maize (e.g. up to 50%) rather than a standard inclusion rate of 33%. In addition, the G-TwYST Advisory Board and several stakeholders criticized the suggested chronic toxicity feeding trial with MON810, which only included one instead of typically two dosage groups because of animal housing capacity limitations and financial constraints. Moreover, several stakeholders criticized that potential toxic effects such as immunotoxicity and endocrine disruption were not taken into consideration.

 

Major changes

By taking into account all the above-mentioned considerations, the G-TwYST consortium took the following decisions:

  1. to perform the original 90-day feeding trial with GM maize NK603 at an inclusion rate of 11 and 33%;
  2. not to perform the 2-year feeding trial with the GM maize MON810*;
  3. to perform a further 90-day feeding trial with GM maize NK603 at an inclusion rate of 50%;
  4. to perform the original combined chronic toxicity/carcinogenicity feeding trial with GM maize NK603 at an inclusion rate of 11 and 33%;
  5. to analyze potential immunotoxic and endocrine effects in the 90-day feeding trial with GM maize NK603 at an inclusion rate of 11 and 33%.

 

Written comments

Seven stakeholders representing industry, civil society, science and competent authorities filed more than 100 written comments to the G-TwYST draft study plan. Comments and responses were split in 8 categories:

  1. General comments
  2. Cultivation
  3. Feed production and plant analysis
  4. Feed quality
  5. Design of the feeding trials
  6. Data collection
  7. Statistical analysis
  8. Other issues

The full report (PDF) is available here.

 

Final study plans

 

Final study plans with track changes

 

Draft study plans

The draft study plans consist of 6 documents:

 

  1. The G-TwYST 90-day subchronic toxicity study in rats fed GM maize NK 603;
  2. The G-TwYST 90-day NK603 Feeding Trial Study Plan - Supplementary Information: Maize and diet production as well as maize and diet analyses;
  3. The G-TwYST combined chronic toxicity and carcinogenicity study in rats fed GM maize NK603;
  4. The G-TwYST combined chronic toxicity/carcinogenicity NK603 Feeding Trial Study Plan - Supplementary Information: Maize and diet production as well as maize and diet analyses;
  5. The G-TwYST 2-year carcinogenicity study of rats with GM maize MON810;
  6. The G-TwYST  2-Year MON810 Feeding Trial Study Plan - Supplementary Information: Maize and diet production as well as maize and diet analyses.

 

 

*In the frame of G-TwYST it was originally planned to perform a 2-year carcinogenicity feeding trial with the GM maize MON810 at an inclusion rate of 33% on top of the 2-year study with maize NK603. Due to financial and animal housing constraints, it was not possible to include a further experimental group with an inclusion rate of e.g. 11% for the maize MON810 study. Hence, it would not have been possible to analyse a dose-effect relationship with this trial data.
Moreover, in the stakeholder consultation it was strongly recommended to include a 50% maize NK603 diet in the 90-day study with maize NK603, pushing the maize content of the diet to the limit of what is considered acceptable in terms of nutritional balance.


Given the constraints in time, lab space (the number of animals we can house at the same time) and funding we are not able to follow all recommendations, i.e. both including a 50% diet in the 90-day study and largely increasing the number of animals in a maize MON810 combined 2-year study, so we chose to focus on an approach that will ensure most robust outcomes in terms of science and statistics. The best way to achieve that is dropping the 2-year maize MON810 study and include an additional 90-day study with maize NK603 (study plan 2) with a 50% diet.

 

It should be mentioned that in the frame of GRACE 90-day feeding trials as well as a 1-year chronic toxicity feeding trial have been performed with maize MON810.
 

Latest news

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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.

Highlights

  • 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.