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General Information

Document type
  • Peer-reviewed journal article
GE organism
  • maize
GE trait
  • herbicide tolerance
  • USA


  • no effect
Safety for consumption
  • no effect

Results of a 13 week safety assurance study with rats fed grain from glyphosate tolerant corn

Hammond, B; Dudek, R; Lemen, J; Nemeth, M
Food and Chemical Toxicology. 2004 June. 42(6):1003–1014

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PMID: 15110110 DOI: 10.1016/j.fct.2004.02.013 ISSN: 0278-6915


The current study presents the results of a 13 week feeding study in rats with grain from Roundup Ready corn which is tolerant to the herbicide glyphosate. Herbicide tolerance was accomplished through the introduction of cp4 epsps coding sequences into the corn genome for in planta production of CP4 EPSPS enzymes. Unlike related corn EPSPS enzymes, CP4 EPSPS enzymes are not inhibited by the herbicide glyphosate. Purina TestDiets formulated Roundup Ready corn grain into rodent diets at levels of 11 and 33% (w/w). The responses of rats fed diets containing Roundup Ready corn grain were compared to that of rats fed diets containing non-transgenic grain (controls). All diets were nutritionally balanced and conformed to Purina Mills, Inc. specifications for Certified LabDiet 5002. There were 400 rats in the study divided into 10 groups of 20 rats/sex/group. Overall health, body weight, food consumption, clinical pathology parameters (hematology, blood chemistry, urinalysis), organ weights, gross and microscopic appearance of tissues were comparable between groups fed diets containing Roundup Ready and control corn grain. This study complements extensive agronomic, compositional and farm animal feeding studies with Roundup Ready corn grain, confirming it is as safe and nutritious as existing commercial corn hybrids.


Corn; Genetically modified; Herbicide tolerant; Roundup herbicide; Rat feeding study


Funding source
  • Monsanto
Funding country
  • United States
Funding type
  • industry: same

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Cite this study


Hammond, B, R Dudek, J Lemen, M Nemeth. "Results of a 13 week safety assurance study with rats fed grain from glyphosate tolerant corn." Food and Chemical Toxicology 42.6 (2004): 1003–1014. Web. 11 Dec. 2023.


Hammond, B., Dudek, R., Lemen, J., & Nemeth, M. (2004). Results of a 13 week safety assurance study with rats fed grain from glyphosate tolerant corn. Food and Chemical Toxicology, 42(6), 1003–1014. doi:10.1016/j.fct.2004.02.013

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