QHow long was Monsanto's study of GMOs, before they were "deemed" safe? How long was the longest study?

How long was Monsanto's study of GMOs, before they were "deemed" safe? How long was the longest study?

AExpert Answer

It appears the first question is referring to how long it takes to demonstrate the safety of GM crops. It is important to emphasize for clarity that GM crop developers like Monsanto do not “deem” GMOs to be as safe as conventional crops, this determination is made by the hundreds of scientists in the regulatory agencies around the world that review the safety data generated. However, it is a requirement for GM crop developers to demonstrate, or evaluate, the safety of these products; a responsibility that is taken very seriously in order to adhere to the laws and regulations of each country before a product can be approved for use and made available to farmers.


For each potential GM product, in order to demonstrate safety, research teams conduct years of field trials and comprehensive testing to be scientifically certain the new trait and genetic modification have not changed the safety of the crop. These research teams focus on product safety and discontinue the development of any product that does not successfully pass each internal, rigorous scientific review and approval. For example, tests are conducted on the genetics, efficacy, nutritional characteristics, agronomic performance and environmental safety of each potential product, following the requirements of scientific regulatory agencies and the guidelines of international agencies such as the World Health Organization (WHO), the Food and Agriculture Organization (FAO) the Organization for Economic Cooperation and Development (OECD) and Codex Alimentarius International Food Standards. On average, it takes 13 years for discovery, development and global approvals of a new plant biotechnology trait at the cost of $136 million (Phillips-McDougall Study: Cost of Bringing a Biotech Crop to Market). Additionally, safety data is subjected to review by hundreds of regulators in the regulatory agencies worldwide before the product is approved for use and made available to farmers.
Currently, research and assessments of GM crops have been on-going for 30 years strongly supported by the weight of scientific evidence, as well as the conclusions of the global scientific community. In fact, GM crops have been reviewed and tested more than any other crops in the history of agriculture and have been shown to be as safe as conventional crops.

To address the second question, the longest safety studies are the feeding studies, in particular 90-day toxicology study with the whole food (i.e., grain from corn or meal from soybean) is typically the longest feeding study conducted, but not the only safety study conducted, before Monsanto considers its products are safe. Monsanto utilizes a Weight of the Evidence (WOE) approach when evaluating GM crop safety. This WOE approach was independently developed by the Codex Alimentarius Commission (Codex) of the World Health Organization and Food and Agriculture Organization of the United Nations. Codex’s standards and guidelines relating to food safety for conventional and GM crops are internationally recognized. Specifically, Monsanto utilizes guidance in the current version of Foods Derived from Modern Biotechnology (Codex, 2009) for the conduct of its safety assessments. These assessments include: 1) molecular characterization of the gene insert and safety assessment of introduced protein; 2) comparison of the agronomic performance of the GM crop and a conventional comparator grown at the same time and location; 3) compositional equivalence between the GM crop and its conventional comparator (macro- and micronutrients, anti-nutrients); and 4) animal testing conducted on a “case-by-case” basis. Regarding animal testing, the European Food Safety Authority (EFSA) recently has stated, “If the GM plant and derived food and feed have been assessed as compositionally not different from its comparator except for the introduced trait(s), no further studies to demonstrate nutritional equivalence are required.” (EFSA, 2011). However, in practice, animal testing has been conducted more routinely than “case-by-case” as an additional assurance of safety to expedite the regulatory review process. Each of the four classes of assessment mentioned above include multiple endpoints that have the ability to detect adverse effects. Altogether the results are considered the Weight of the Evidence, and adverse findings in any of the analyses would trigger additional, targeted analyses to determine the safety of the product. All commercially available Monsanto GM crops have a WOE that indicates they are as safe and nutritious as their conventional comparator. Furthermore, almost 20 years of cultivating GM crops has verified the finding of these safety studies that demonstrate food derived from GM crops is as safe as conventional food.


Despite a substantial WOE for commercially available GM crops, critics of the technology have called for longer feeding studies. Presumably, their theory is that if the animals are dosed long enough some evidence of toxicity will become apparent. However, this theory is not consistent with what is known about the ability of 90-day studies to predict toxicities that may be observed on longer term studies. Regarding the 90-day study, EFSA is on record as stating, “Laboratory animal feeding studies of 90-days duration appear to be sufficient to pick up adverse effects of compounds that would also give adverse effects after chronic exposure, and therefore in general, chronic toxicity testing of GM food and feed does not seem to generate additional valuable information to the safety assessment” (EFSA, 2008). A review of the scientific literature on GM crop feeding studies provides a prominent example of the predictive power of the 90-day study; studies published in peer-reviewed journals found no safety concerns for GM soybeans whether the feeding period was 90 days, 1 year, or 2 years.


In 1996, Monsanto published a study detailing the results of feeding studies with RoundUp Ready soybeans in several animal species. RoundUp Ready soybeans contain the cp4 epsps gene, which encodes the CP4 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) protein, and confers glyphosate resistance to plants expressing it. One of those feeding studies was a 90-day rat study which demonstrated that the RoundUp Ready soybeans were as safe and nutritious as their conventional comparator (Hammond et al., 1996). Several years later, 52- and 104-week feeding studies were published by a group of researchers at the Department of Environmental Health and Toxicology, Tokyo Metropolitan Institute of Public. The authors of these studies concluded that long term consumption of the GM soybeans had no adverse effects on the rats (Sakamoto et al., 2007; Sakamoto et al., 2008). Based on EFSA’s assessment of the predictive power of 90-day studies, and the existing WOE for RoundUp Ready soybeans, these results were anticipated. Thus, when a 90-day study is conducted, and the results are in-line with the rest of the WOE for that crop, we consider that a confirmatory result and one part of a rigorous evaluation of safety. Additional, longer-term studies that do nothing more than confirm the results of 90-day feeding studies are of limited scientific value, and therefore should be very carefully considered from an animal welfare perspective – the scientific community has an ethical obligation to reduce, refine, and replace animal testing when feasible.


Codex Alimentarius (2009). Foods derived from modern biotechnology. Rome, Italy, Codex Alimentarius Commission, Joint FAO/WHO Food Standards Programme, Food and Agriculture Organization of the United Nations. Second Edition.


EFSA (2008). "Safety and nutritional assessment of GM plants and derived food and feed: The role of animal feeding trials." Food and Chemical Toxicology 46: S2-S70.


EFSA (2011). "Guidance for risk assessment of food and feed from genetically modified plants." EFSA Journal 9: 2150.


Hammond, B. G., et al. (1996). "The feeding value of soybeans fed to rats, chicken, catfish and dairy cattle is not altered by genetic incorporation of glyphosate tolerance." Journal of Nutrition 126: 717-727.


Sakamoto, Y., et al. (2007). "A 52-week feeding study of genetically modified soybeans in F344 rats." Shokuhin Eiseigaku Zasshi 48: 41-50.


Sakamoto, Y., et al. (2008). "A 104-week feeding study of genetically modified soybeans in F344 rats." Shokuhin Eiseigaku Zasshi 49: 272-282.

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