Safety assessment of transgenic canola RF3 with bar and barstar gene on Sprague-Dawley (SD) rats by 90-day feeding test

Rodent and broiler feeding studies with maize containing genetically modified event DP-915635-4 show no adverse effects on health or performance

Several regulatory agencies continue to require animal feeding studies to approve new genetically modified crops despite such studies providing little value in the safety assessment. Feeding studies with maize grain containing event DP-915635-4 (DP915635), a new corn rootworm management trait, were conducted to fulfill that requirement. Diets fed to Crl:CD®(SD) rats for 90 days contained up to 50% ground maize grain from DP915635, non-transgenic control, or non-transgenic reference hybrids (P1197, 6158, and 6365). Ross 708 broilers received phase diets containing up to 67% maize grain from each source for 42 days. Growth performance was compared between animals fed DP915635 and control diets; rats were further evaluated for clinical and neurobehavioral measures, ophthalmology, clinical pathology, organ weights, and gross and microscopic pathology, whereas carcass parts and select organ yields were determined for broilers. Reference group inclusion assisted in determining natural variation influence on observed significant differences between DP915635 and control groups. DP915635 maize grain diet consumption did not affect any measure evaluated in either feeding study. Results demonstrated DP-915635-4 maize grain safety and nutritional equivalency when fed in nutritionally adequate diets, adding to the existing literature confirming the lack of significant effects of feeding grain from genetically modified plants.

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.

Evaluation of the effects of feeding glyphosate-tolerant soybeans (CP4 EPSPS) on the testis of male Sprague-Dawley rats

Glyphosate tolerant soybeans represent a large portion of soybeans grown and fed to farm animals around the world. Despite their widespread use for many years, some have raised questions regarding their safety because the soybeans were genetically modified. The CP4 EPSPS gene which imparts resistance to topical application of the herbicide glyphosate was introduced into soybeans. Application of glyphosate to soybean fields will reduce weed pressure and increase soybean yield. To assess their safety on the rat reproduction system, male Sprague Dawley rats were fed either glyphosate-tolerant (GM) soybean (40-3-2) or near-isogenic, non-GM (A5403) (control) soybean meal. The processed soybean meal was added to formulated rodent diets at 20% (w/w) and fed to rats for 90 days. Some rats from the control group were separately administered mitomycin C for 40 days and served as positive controls in the sperm abnormality test. Body weights and behavior were monitored daily, serum enzymes and histologic and EM appearance of the testis, and sperm morphology were also examined. After 90 days of feeding, no adverse effects were observed in rats fed glyphosate-tolerant soybeans.