Correction to: 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 the original publication, the starting point in time for the three feeding trials.

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.

Transcriptomic Analysis of Intestinal Tissues from Two 90-Day Feeding Studies in Rats Using Genetically Modified MON810 Maize Varieties

Background: Global as well as specific expression profiles of selected rat tissues were characterized to assess the safety of genetically modified (GM) maize MON810 containing the insecticidal protein Cry1Ab. Gene expression was evaluated by use of Next Generation Sequencing (NGS) as well as RT-qPCR within rat intestinal tissues based on mandatory 90-day rodent feeding studies. In parallel to two 90-day feeding studies, the transcriptional response of rat tissues was assessed as another endpoint to enhance the mechanistic interpretation of GM feeding studies and/or to facilitate the generation of a targeted hypothesis. Rats received diets containing 33% GM maize (MON810) or near-isogenic control maize. As a site of massive exposure to ingested feed the transcriptomic response of ileal and colonic tissue was profiled via RT-qPCR arrays targeting apoptosis, DNA-damage/repair, unfolded protein response (UPR). For global RNA profiling of rat ileal tissue, we applied NGS.

Results: No biological response to the GM-diet was observed in male and in female rat tissues. Transcriptome wide analysis of gene expression by RNA-seq confirmed these findings. Nevertheless, gene ontology (GO) analysis clearly associated a set of distinctly regulated transcripts with circadian rhythms. We confirmed differential expression of circadian clock genes using RT-qPCR and immunoassays for selected factors, thereby indicating physiological effects caused by the time point of sampling.

Conclusion: Prediction of potential unintended effects of GM-food/feed by transcriptome based profiling of intestinal tissue presents a novel approach to complement classical toxicological testing procedures. Including the detection of alterations in signaling pathways in toxicity testing procedures may enhance the confidence in outcomes of toxicological trials. In this study, no significant GM-related changes in intestinal expression profiles were found in rats fed GM-maize MON810. Relevant alterations of selected cellular pathways (apoptosis, DNA damage and repair, UPR) pointing toward intestinal toxicity of the diets were not observed. Transcriptomic profiles did not reveal perturbations of pathways associated with toxicity, underlining the study results revealed by classical OECD endpoints.

One-year oral toxicity study on a genetically modified maize MON810 variety in Wistar Han RCC rats (EU 7th Framework Programme project GRACE)

The GRACE (GMO Risk Assessment and Communication of Evidence; www.grace-fp7.eu ) project was funded by the European Commission within the 7th Framework Programme. A key objective of GRACE was to conduct 90-day animal feeding trials, animal studies with an extended time frame as well as analytical, in vitro and in silico studies on genetically modified (GM) maize in order to comparatively evaluate their use in GM plant risk assessment. In the present study, the results of a 1-year feeding trial with a GM maize MON810 variety, its near-isogenic non-GM comparator and an additional conventional maize variety are presented. The feeding trials were performed by taking into account the guidance for such studies published by the EFSA Scientific Committee in 2011 and the OECD Test Guideline 452. The results obtained show that the MON810 maize at a level of up to 33 % in the diet did not induce adverse effects in male and female Wistar Han RCC rats after a chronic exposure.

Ninety-day oral toxicity studies on two genetically modified maize MON810 varieties in Wistar Han RCC rats (EU 7th Framework Programme project GRACE)

The GMO Risk Assessment and Communication of Evidence (GRACE; www.grace-fp7.eu ) project is funded by the European Commission within the 7th Framework Programme. A key objective of GRACE is to conduct 90-day animal feeding trials, animal studies with an extended time frame as well as analytical, in vitro and in silico studies on genetically modified (GM) maize in order to comparatively evaluate their use in GM plant risk assessment. In the present study, the results of two 90-day feeding trials with two different GM maize MON810 varieties, their near-isogenic non-GM varieties and four additional conventional maize varieties are presented. The feeding trials were performed by taking into account the guidance for such studies published by the EFSA Scientific Committee in 2011 and the OECD Test Guideline 408. The results obtained show that the MON810 maize at a level of up to 33 % in the diet did not induce adverse effects in male and female Wistar Han RCC rats after subchronic exposure, independently of the two different genetic backgrounds of the event.

Teratological assessment of stobadine after single and repeated administration in mice

Teratological studies were performed with stobadine, a compound with antiarrhythmic and antihypoxic activity. Single i.v. injections of stobadine in the form of dihydrochloride (DH 1011) to ICR mice on days 3, 6, 9 or 12 of gestation at doses of 1 and 3 mg kg-1 had no teratogenic effect. Slight fetal toxicity was manifested by decreased fetal weight after treatment on days 3 and 6, increased incidence of rudimentary ribs after treatment on days 9 and 12 of gestation and non-significantly increased postimplantation loss after injection on day 6 of gestation. The effect of repeated oral administration in the form of dipalmitate salt (DP 1031) was studied in doses of 12.2, 61.0 and 122.0 mg kg-1 on days 4-16 of gestation. Oral exposure to 61.0 mg kg-1 DP 1031 resulted in significant reduction of implantations, live fetuses and litter weight, and after 122.0 mg kg-1 DP 1031 the fetal weight was significantly decreased. External and skeletal examinations of the fetuses revealed no evidence of teratogenesis. The relevance of the two routes of stobadine administration for risk involvement is discussed.

Reproductive toxicity studies with cis-(-)-2,3,4,4a,5,9b-hexahydro-2,8-dimethyl-1H-pyrido-[4,3-b]indole dipalmitate in rats

cis-(-)-2,3,4,4a,5,9b-Hexahydro-2,8-dimethyl-1H-pyrido-[4,3-b]indole dipalmitate (stobadin dipalmitate; in the following briefly called STB) a new prospective cardioprotective drug, was evaluated for effects on fertility, general reproductive performance, prenatal and peri-postnatal development in the rat. Doses of 5, 15 and 50 mg/kg/d were administered orally in aqueous suspension to rats in all studies. Daily treatment of male rats for 70 days before mating and female rats for 14 days before mating and during gestation and lactation had no adverse effects on fertility, survival rate and weight gains of parental animals or on prenatal and postnatal development of pups. There was only evidence of slight adult toxicity late in the experiment, significant increase of anomalous foetuses in both the 15 and 50 mg/kg/d doses and decreased body weight of the young at 50 mg/kg/d on day 21 post partum. Daily oral treatment of pregnant rats with STB throughout organogenesis (day 4 to 16) had no overt effects on dams or on embryo-foetal development, except of increased incidence of some skeletal variations in all treated groups. In the peri-postnatal toxicity study treatment of pregnant dams with STB continuously from day 15 of gestation through parturition and lactation had no adverse effects on reproductive parameters of dams or on survival and development of F1 offspring at any dose used. There were only signs of slight maternal toxicity at 50 mg/kg/d, which consisted of sedated behaviour, reduced liver weight and reversible histopathological changes in kidney tissue. The results of these studies did not reveal serious developmental hazard potentials of STB administered to rats in doses up to 50 mg/kg/d.

[Characteristics of new approaches for evaluation of embryotoxic effects of chemical substances]

New approaches to the evaluation of embryotoxic effects of xenobiotics are characterized in the light of mother--fetus interrelationship. The first part of the paper analyzes problems of evaluating maternal and embryofetal toxicity and substantiates the necessity of sensitive selection and precise evaluation of individual parameters of toxicity. The second part presents a survey of classical testing procedures and of alternative methods used in assessing the safety of new drugs. The third part characterizes methods of quantitative determination of risks inherent to chemical substances. A detailed description of the principles of the new method is presented which is based on the interrelationship of maternal and embryofetal toxicity (adult/developmental--A/D). The acceptability of the new method has been verified experimentally on evaluating some new prospective drugs according to standard teratological studies.

Teratological study of the hypolipidaemic drugs etofylline clofibrate (VULM) and fenofibrate in Swiss mice

Teratological studies of the hypolipidaemic drugs etofylline clofibrate (VULM) and fenofibrate were carried out in mice. Pregnant mice were given etofylline clofibrate and fenofibrate in doses 11.7, 117.1, and 585.5 mg/kg orally from day 7 to 16 of gestation. Terminal maternal body weight was significantly decreased after all doses of etofylline clofibrate in a non-dose-related fashion compared to the control group. The foetuses were examined on day 19 of gestation. They were weighed and inspected for external, skeletal and visceral abnormalities. The low and middle doses of etofylline clofibrate and fenofibrate had no adverse effects on embryofoetal development. The highest etofylline clofibrate dose induced a significant decrease of foetal weight at term, likewise postimplantation loss was significantly increased after the highest dose of fenofibrate. The incidence of external, skeletal and visceral anomalies was not dose-dependent. In this study no teratogenic effects were detected, yet with the highest etofylline clofibrate and fenofibrate doses some foetotoxic effects were observed.

Teratological and cytogenetical evaluation of two antihistamines (pipethiadene and pizotifen maleate) in mice

The teratogenic and cytogenetic effects of two drugs with antihistamine properties, Pipethiadene and Pizotifen maleate, were investigated. Three groups of pregnant mice were treated daily with oral doses (0.24, 0.6 and 1.2 mg/kg) of these drugs from day 4 to day 16 of gestation. The following parameters were investigated: reproductive health of the dams, external, skeletal and visceral malformations of fetuses and frequencies of micronuclei and chromosome aberrations in bone marrow cells of dams. Oral administration of Pipethiadene or Pizotifen maleate produced no teratogenic effects. No elevation was observed in the frequencies of micronuclei and chromosome aberrations. However, the significant reduction of fetal weight after all doses of Pipethiadene or Pizotifen maleate was found to correlate well with the decreased values of the mitotic indices of bone marrow cells of mice, suggesting a potential embryotoxic effect of the tested substances.