G-TwYST study C a 90-day toxicity study in rats fed GM maize NK603 : statistical report

Abstract

The purpose of oral toxicity study C in the EU project G-TwYST was to assess the effects of genetically modified (GM) maize NK 603, grown both with and without the use of RoundUp, when fed to rats for a period of 90 days at GM incorporation rates of 11%, 33% and 50% in the feed, if needed supplemented with near-isogenic non-GM maize to total maize inclusion rates of 33% or 50%. Differences between feeding groups were compared, using a recently developed method for equivalence testing, to differences between non-GM feeds obtained in previous studies performed in the EU project GRACE. Given tentative settings for regulatory parameters, for a set of 648 comparisons involving body and organ weights, haematology and clinical chemistry, equivalence was established in 99% of cases, higher than the minimal nominal confidence level of the test which was 95%. Equivalence was found to be more likely than lack of equivalence in 100% of cases. In addition to this primary analysis, the report also contains results for equivalence testing using external target effect sizes for a limited set of variables, results for classical statistical analysis of differences, graphs of standardised effect sizes such as performed in the GRACE study, results of factorial analysis, graphs showing correlations between variables associated with liver or kidney damage, and a post-hoc power analysis comparing trials with 33% and 50% maize inclusion rates.

Lack of adverse effects in subchronic and chronic toxicity/carcinogenicity studies on the glyphosate-resistant genetically modified maize NK603 in Wistar Han RCC rats

“…The urinalysis data are summarized in the statistical report by Goedhart and van der Voet (2018f). The urine pH was significantly lower in male rats fed the 50% NK603 + Roundup diet than in the group fed the 33% NK603 + Roundup diet.…”