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The Biostatistics work package performs statistical analyses of the results from the rodent feeding studies, reports on the results, and provides recommendations on the statistical methodology for long-term feeding trials.

 

The statistical power attainable for the primary parameters of toxicological interest when using sample sizes as specified in the standard OECD protocols is evaluated in a prospective power analysis.

 

The purpose of the statistical analysis is to derive point and interval estimates of the difference in parameters between the NK603-fed groups and the control group. These estimates are compared to a null hypothesis of equality (classical approach, differences tests) and to null hypotheses specifying a difference equal to external equivalence limits (G-TwYST approach, equivalence tests). Equivalence limits indicate minimum differences of potential toxicological relevance. For setting the equivalence limits use is made of data from non-GM groups in the feeding studies of the GRACE project.

 

 

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

 

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G-TwYST Conclusions & Recommendations

29 April 2018

 

At a Conference held in Bratislava, Slovakia, on 16 April 2018, G-TwYST presented draft conclusions and recommendations regarding guidance on the design, conduct, interpretation, and analysis of animal feeding studies and their value for GMO risk assessment. A final version of G-TwYST Conclusions and Recommendations can be downloaded here.

Final programme 28/29 March available

18 March 2018

The final programma for the G-TwYST stakeholder consultation workshop on March 28 and 29 in Antwerp is available now and can be downloaded here.

 

This workshop, which is open for interested stakeholders, will focus on the draft results of a 90-day feeding study with 50% inclusion rate of GM maize NK603, as well as a combined chronic toxicity and carcinogenicity feeding study and the overall draft conclusions. Also included in the scope would be proposed quality criteria for whole-food animal feeding studies, and preliminary conclusions on the scientific value of such studies for GMO risk assessment. An additional agenda item will be insights from an analysis of scientific controversies around animal feeding studies including the GMO case.

 

 

Written comments, including from interested parties not able to attend, are welcome, and should be submitted before 6 April. Please, note, due to the tight schedule of the final phase of the project, this will be a firm deadline.