90-day rodent feeding studies on whole GM food/feed: Is the mandatory EU requirement for 90-day rodent feeding studies on whole GM food/feed fit for purpose and consistent with animal welfare ethics?

Investigation of the toxicity and safety concerns of transgenic maize seeds expressing immunogenic F and HN protein genes against Newcastle disease virus

Introduction

The presented study investigated the potential toxicity and safety concerns associated with transgenic maize seeds expressing immunogenic F and HN protein genes against Newcastle disease virus (NDV).

Methodology

The experiment involved feeding Sprague-Dawley rats with transgenic maize seeds formulated into standard diets at levels of 30% (w/w) for a duration of 90 days. The rats were divided into three groups, with 10 rats per group. We assessed various parameters including overall appearance, feed consumption, body weight, organ weight, hematological parameters, serum chemistry, and histopathology.

Results

The results of these assessments were compared between the control group and the treatment groups. The study findings revealed that there were no significant differences between the control and treatment groups in terms of overall appearance, feed consumption, body weight, organ weight, hematological parameters, serum chemistry, microscopic histopathology, and gross appearance of tissues. These observations suggest that the consumption of transgenic maize seeds did not lead to any treatment-related adverse effects or toxicological issues. Furthermore, the transgenic maize seeds were found to be nutritionally equivalent to their non-transgenic counterpart.

Conclusion

Overall, no physiological, pathological, or molecular toxicity was observed in the Rats fed with transgenic feed.However, it is important to note that this study focused specifically on the parameters measured and the outcomes observed in Sprague-Dawley rats, and further research and studies are necessary to fully evaluate the safety and potential applications of transgenic edible vaccines in humans or other animals.

Subchronic feeding study of glyphosate-tolerant maize GG2 with the gr79-epsps and gat genes in Wistar Han RCC rats

The genetically modified (GM) maize GG2 contains gr79-epsps and gat genes, conferring glyphosate tolerance. The present study aimed to investigate potential effects of maize GG2 in a 90-day subchronic feeding study on Wistar Han RCC rats. Maize grains from GG2 or non-GM maize were incorporated into diets at concentrations of 25% and 50% and administered to Wistar Han RCC rats (n = 10/sex/group) for 90 days. The basal-diet group of rats (n = 10/sex/group) were fed with common commercialized rodent diet. Compared with rats fed with the corresponding non-GM maize and the basal-diet, no biologically relevant differences were observed in rats fed with the maize GG2, according to the results of body weight/gain, feed consumption/utilization, clinical signs, mortality, ophthalmology, clinical pathology (hematology, prothrombin time, urinalysis, serum chemistry), organ weights, and gross and microscopic pathology. Under the conditions of this study, these results indicated that maize GG2 is as safe as the non-GM maize in this 90-day feeding study.

A 90-day feeding study of genetically modified maize LP007-1 in wistar han RCC rats

LP007-1 is a variety of insect-resistant and herbicide-tolerant maize containing the modified cry1Ab, cry2Ab, vip3Aa and cp4-epsps genes. The food safety assessment of the maize LP007-1 was conducted in Wistar Han RCC rats by a 90-days feeding study. Maize grains from both LP007-1 or its corresponding non-genetically modified control maize AX808 were incorporated into rodent diets at 25% and 50% concentrations by mass and administered to rats (n = 10/sex/group) for 90 days. A commercialized rodent diet was fed to an additional group as the basal-diet group. The diets of all groups were nutritionally balanced. No biologically relevant differences were observed in rats fed with maize LP007-1 compared to rats fed with AX808 and the basal-diet with respect to body weight/gain, food consumption/utilization, clinical signs, mortality, ophthalmology, clinical pathology (hematology, prothrombin time, activation of partial thrombin time, serum chemistry, urinalysis), organ weights, and gross and microscopic pathology. Considering the circumstances of this study, the results provided evidence that LP007-1 maize did not exhibit toxicity in the 90-day feeding study.

The EU's GM crop conundrum: Did the EU policy strategy to convert EFSA GMO guidance into legislation deliver on its promises?: Did the EU policy strategy to convert EFSA GMO guidance into legislation deliver on its promises?

Efforts by the EU to improve its regulatory framework for importing GM food and feed have done nothing to make the process easier and more predictable for applicants.

Safety assessment of phytase transgenic maize 11TPY001 by 90-day feeding study in rats

11TPY001 is a transgenic maize that expresses the Aspergillus niger phyA2 gene which could significantly improve phosphorus bioavailability in monogastric animals. The present study was conducted to investigate the potential health effects of phytase transgenic maize 11TPY001 through a 90-day subchronic rodent feeding study. Maize grains from 11TPY001 or its parental counterpart maize OSL963 were incorporated into rodent diets at 12.5%, 25% and 50% concentrations by mass and administered to Sprague-Dawley rats (n = 10/sex/group) for 90 days. An additional control group of rats (n = 10/sex/group) were fed with common maize Zhengdan958 diets at 50% by mass. All formulated diets were nutritionally balanced. Body weights, food intake, hematology, serum chemistry, absolute and relative organ weights were measured, and gross as well as microscopic pathology were examined. Compared with rats fed OSL963 maize and the common maize diet groups, no adverse diet-related differences were observed in rats fed 11TPY001 maize diets with respect to clinical signs of toxicity, body weight/gain, food consumption/efficiency, hematology, clinical chemistry, organ weights, and gross and microscopic pathology. Under the conditions of this study, the results indicated that 11TPY001 did not cause any treatment related adverse effects in rats compared with its non-transgenic parental maize OSL963.

A 90-day subchronic toxicity study of transgenic cotton expressing Cry1Ac, Cry2A and CP4-EPSPS proteins in Sprague-Dawley rats

Genetically engineered crops expressing insecticidal and herbicide-tolerant traits offer a new strategy for crop protection and enhanced production; however, at the same time present a challenge in terms of toxicology and safety. The current experiment presents the findings of a 90-day feeding study in Sprague-Dawley rats with transgenic cottonseed which is expressing insecticidal Cry proteins (Cry1Ac and Cry2A), and tolerant to the herbicide glyphosate. There were 100 rats in this experiment divided into 5 groups of 10 rats/sex/group. Cottonseed from transgenic and control (near-isogenic) lines was formulated into standard diets at levels of 10% and 30% (w/w). All formulated diets were nutritionally balanced. Overall appearance, feed consumption, body weight, organ weight, haematology, serum chemistry and urinalysis were comparable between control and treatment groups. In addition, there was no treatment-related difference in findings of microscopic histopathology and gross appearance of tissues. In conclusion, following the 13-week of feeding transgenic cottonseed, no treatment-related adverse effects were observed in any of the parameters measured in this experiment. Thus, this study demonstrated that transgenic cottonseeds do not cause toxicity and are nutritionally equivalent to its conventional counterpart.

DP-2Ø2216-6 maize does not adversely affect rats in a 90-day feeding study

Maize plants containing event DP-2Ø2216-6 (DP202216), which confers herbicide tolerance through expression of phosphinothricin acetyltransferase and enhanced grain yield potential via temporal modulation of the native ZMM28 protein, were developed for commercialization. To address current regulatory expectations, a mandatory 90-day rodent feeding study was conducted to support the safety assessment. Diets containing 50% by weight of ground maize grain from DP202216, non-transgenic control, and 3 non-transgenic reference varieties, were fully characterized, along with the grain, and diets were fed to Crl:CD®(SD) rats for at least 90 days. As anticipated, no biologically-relevant effects or toxicologically-significant differences were observed on survival, body weight/gain, food consumption/efficiency, clinical and neurobehavioral evaluations, ophthalmology, clinical pathology (hematology, coagulation, clinical chemistry, urinalysis), organ weights, or gross and microscopic pathology parameters in rats fed a diet containing up to 50% DP202216 maize grain when compared with rats fed diets containing control or reference maize grains. The results of this study support the conclusion that maize grain from plants containing event DP-2Ø2216-6 is as safe and nutritious as maize grain not containing the event and add to the significant existing database of rodent subchronic studies demonstrating the absence of hazards from consumption of edible fractions of genetically modified plants.

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

In 2012, a controversial study on the long-term toxicity of a Roundup herbicide and the glyphosate-tolerant genetically modified (GM) maize NK603 was published. The EC-funded G-TwYST research consortium tested the potential subchronic and chronic toxicity as well as the carcinogenicity of the glyphosate-resistant genetically modified maize NK603 by performing two 90-day feeding trials, one with GM maize inclusion rates of 11 and 33% and one with inclusion rates of up to 50%, as well as a 2-year feeding trial with inclusion rates of 11 and 33% in male and female Wistar Han RCC rats by taking into account OECD Guidelines for the testing of chemicals and EFSA recommendations on the safety testing of whole-food/feed in laboratory animals. In all three trials, the NK603 maize, untreated and treated once with Roundup during its cultivation, and the conventional counterpart were tested. Differences between each test group and the control group were evaluated. Equivalence was assessed by comparing the observed difference to differences between non-GM reference groups in previous studies. In case of significant differences, whether the effects were dose-related and/or accompanied by changes in related parameters including histopathological findings was evaluated. It is concluded that no adverse effects related to the feeding of the NK603 maize cultivated with or without Roundup for up to 2 years were observed. Based on the outcome of the subchronic and combined chronic toxicity/carcinogenicity studies, recommendations on the scientific justification and added value of long-term feeding trials in the GM plant risk assessment process are presented.

Optimizing the Use of Zebrafish Feeding Trials for the Safety Evaluation of Genetically Modified Crops

In Europe, the toxicological safety of genetically modified (GM) crops is routinely evaluated using rodent feeding trials, originally designed for testing oral toxicity of chemical compounds. We aimed to develop and optimize methods for advancing the use of zebrafish feeding trials for the safety evaluation of GM crops, using maize as a case study. In a first step, we evaluated the effect of different maize substitution levels. Our results demonstrate the need for preliminary testing to assess potential feed component-related effects on the overall nutritional balance. Next, since a potential effect of a GM crop should ideally be interpreted relative to the natural response variation (i.e., the range of biological values that is considered normal for a particular endpoint) in order to assess the toxicological relevance, we established natural response variation datasets for various zebrafish endpoints. We applied equivalence testing to calculate threshold equivalence limits (ELs) based on the natural response variation as a method for quantifying the range within which a GM crop and its control are considered equivalent. Finally, our results illustrate that the use of commercial control diets (CCDs) and null segregant (NS) controls (helpful for assessing potential effects of the transformation process) would be valuable additions to GM safety assessment strategies.

A 90-day subchronic toxicology screen of genetically modified rice Lac-3 and its effects on the gut microbiota in Sprague-Dawley rats

A 90-day subchronic toxicology screen of genetically modified (GM) rice Lac-3 expressing human lactoferrin (hLF) and its effects on the gut microbiota were studied in comparison to non-GM rice fed to Sprague-Dawley (SD) rats. Three different dietary concentrations (17.5%, 35% and 70%, w/w) of the GM rice or its corresponding non-GM rice were used. Additionally, the phylotypes of gut microbiota in the control group, the 70% GM rice diet group and the 70% non-GM rice diet group on day 90 were determined by 16S rRNA sequencing. The results of the 90-day subchronic feeding study demonstrated that the GM rice Lac-3 containing human lactoferrin (LF) gene is considered as safe as the non-GM rice. The results of bacterial 16S rRNA sequencing showed that the structure of gut microbiota in the 70% GM group slightly changed when compared with the control group and the 70% non-GM group. There were no significant differences in the microbiota diversity among the three groups.

Safety evaluation of DAS-44406-6 soybeans in Wistar rats

A 90-day in-country feeding trial in Wistar rats was conducted at Tianjin Laboratory in China to assess toxicity of diets containing DAS-44406-6 soybean meal. There were no treatment-related changes observed when compared with the non-GM isoline control groups but histopathologically, 2 of 10 high-dose females were reported to show kidney lesions. However, these findings contrasted with the absence of any treatment-related kidney lesions in 3 separate 90-day toxicity studies previously conducted in Sprague Dawley rats. Strain difference is not expected in the kidney response, and based on the low incidence and contrary evidence from previous studies, it is likely that these lesions were of spontaneous origin, or artefactual. To determine that the lesions observed were not treatment-related in Wistar rats, a specific follow-up confirmatory study was conducted under Good Laboratory Practices (GLP) in the Wistar strain of rats following an identical study design to the Tianjin study. To increase the power of detecting effects, twice the number of animals per group (20/sex/group) were used, and no treatment-related kidney histopathological changes were observed. Based on these results and entire weight of evidence evaluation, it is concluded that the histopathological changes previously noted in the 2 female Wistar rats of Tianjin study were not treatment-related and that DAS-44406-6 soybeans are as safe as conventional non-GM soybeans.

Safety Assessment of Food and Feed from GM Crops in Europe: Evaluating EFSA's Alternative Framework for the Rat 90-day Feeding Study

Regulatory-compliant rodent subchronic feeding studies are compulsory regardless of a hypothesis to test, according to recent EU legislation for the safety assessment of whole food/feed produced from genetically modified (GM) crops containing a single genetic transformation event (European Union Commission Implementing Regulation No. 503/2013). The Implementing Regulation refers to guidelines set forth by the European Food Safety Authority (EFSA) for the design, conduct, and analysis of rodent subchronic feeding studies. The set of EFSA recommendations was rigorously applied to a 90-day feeding study in Sprague-Dawley rats. After study completion, the appropriateness and applicability of these recommendations were assessed using a battery of statistical analysis approaches including both retrospective and prospective statistical power analyses as well as variance-covariance decomposition. In the interest of animal welfare considerations, alternative experimental designs were investigated and evaluated in the context of informing the health risk assessment of food/feed from GM crops.