A review of the science of Roundup Ready soya safety in 2008

March 2011

More than 10 years after RR soya was put into our food chain, the question was being asked where's the scientific evidence that it's safe?

'Roundup Ready' crops have been one of the biggest success stories in the short history of GM agriculture. Any crop all, it seems, can be given the gene to make it resistant to Monsanto's Roundup weedkiller, with the added attraction that the seed can be lucratively linked to the marketing of the herbicide.

The sales-pitch for Roundup Ready (RR) seed is simple. The active ingredient is the least unfriendly to the environment of all the weedkillers, it degrades to harmless end-products, and it rapidly becomes inactivated in the soil. Roundup technology benefits the farmer and his yields through cheap and easy weed control. It allows no-till agriculture to the benefit of the soil, and the transgenic protein produced by the GM plant is non-toxic and non-allergenic.

The prototype herbicide-tolerant crop was GM soya. Any initial questions about safety were easily dismissed by three published studies, commissioned by Monsanto. These demonstrated that the compositional and feeding value are equivalent to conventional soya and that the novel protein was easily digested.

In summary, Roundup ready crops hit the market with all benefit to the farmer, no problem for environment, and human health problems just weren't in the picture at all.

The reality, twelve years down the line, is beginning to look a little different.

Five years after Roundup Ready soya entered our food chain, Arpad Pusztai asked:
“How can the public make informed decisions about GM food when there's so little evidence about its safety?” 
An attempt to review the citations in the scientific literature on human and animal toxicological risks from GM food six years later drew the comment that “... it is quite amazing to note ... the number (of articles) was particularly small ... and) surprisingly limited”. This review concluded with the question “where is the scientific evidence showing that GM foods are toxicologically safe?”

How and where? Indeed. Let's look at the evidence.

The study commissioned by Monsanto for publication way back in 1996 focused on feeding value for commercial livestock, but also included a very short (28 day) trial on young rats. This assessed gross symptoms of disease on the basis of organ weights and general appearance. Beyond this, only the pancreas received some extra attention because soya produces a number of known anti-nutrients which can adversely affect this organ. Observed organ differences were declared not “meaningful”.

In 1999, a short (140 day) Russian study was published which looked at liver function in rats fed Roundup Ready soya protein concentrate. Since this organ deals with toxins entering, or produced by, the body, it is an obvious place to look for signs of unusual activity. The authors noted modifications to the liver cell membrane function and enzyme activity, but these were considered to be “within physiological standards”.

COMMENT This paper was a translation from the Russian, and slightly difficult to follow, but it sounds like another version of Monsanto's not “meaningful”.

In 2000, a short (105 day) study on rats and mice fed Roundup Ready soya looked at the immune-system because harmful qualities in the food will tend to provoke protective mechanisms in the physiology. No adverse effects on immune-related organs were found.

In summary, by 2001, when people had already been eating Roundup Ready soya for 5 years, the 'proof' of safety seems to have amounted to three brief feeding studies. A single belated experiment had been performed on each of three key areas of the physiology which might reasonably be affected by untoward qualities in the food: pancreatic-based digestion, the liver-based detoxification, and the immune system.

Since then, two other approaches using more detailed research have been pursued.

On the basis that the high rate of proliferation and unique cell differentiation in a normal testis make this organ very sensitive to toxins, two experiments were published in 2004 which looked at mice whose mothers were fed Roundup Ready soya chow during gestations and lactation, and who were then fed the GM chow after weaning.

Using testicular cell development as a bioindicator of exposure to toxins, an American team measured the proportions of different cell types present in the testis as the testis matured. Their measurements were repeated on the fourth generation of mice fed GM chow. No differences were detected in cell growth or differentiation in any of the animals.

The second study, by an Italian team, used immuno-electron microscopy to identify subtle alterations in the ultrastructure of the different cell types found in the testes. Signs of reduced nuclear activity similar to those caused by stress factors or drugs were evident, some of which normalised with age.

The second line of research has emerged from various Italian teams who took a much closer look at organ changes at the sub-cellular level in response to Roundup Ready soya.

In the pancreas of mice up to 8 months old, paradoxical reductions were seen in the enzyme-production mechanism a of a kind previously associated with starvation, diabetes, or dietary anti-nutrients (none of which were present). A follow-up study on pancreatic-cell nuclear activity gave supporting evidence of reduced protein-synthesis.

Two studies revealed signs of increased metabolic activity in the livers of young male mice fed Roundup Ready soya. In one long-term study this early increase was ominously followed by a slowing of metabolic activity indicative of premature aging in old mice. A supporting study which had appeared in 2006 also reported increased cell metabolism in the kidneys and hearts of rabbits fed RR soya.

soya levels as high as 90% of the diet. This was surprising because previous work had indicated that maximum levels of soya compatible with health in the rodent diet were much lower: Monsanto's study in 1996 used 24% processed soya, the American mouse testis study used 21%, the Italian mouse testis and rat studies used 14%.

One possible explanation for this contradiction tends to jump uncomfortably out of the literature. The experiments which failed to identify any problems, including the one which tried 90% soya chow, were short-term and used young animals. The experiments which suggested problems involved longer-term feeding. For example, the American four-generation mouse-testis study used young animals of 63-87 days-old, while in the Italian experiments which revealed evidence of harm, extended to 140 and 224 days.

You might be getting the impression by now that half the published toxicological studies on RR soya have been designed to be too short, too superficial in the parameters measured, and have used too healthy animals to pick up on problems.

To go back to the original questions of 'how to make an informed decision' and 'where's the evidence' of toxicological safety to base any decision on, the sum total of evidence seems to be: eleven published studies. Two concluded no adverse findings, three concluded no meaningful differences and six concluded something odd, inexplicable and potentially harmful to health was apparent. This looks like six-to-five against (or, six against, two for, and three inconclusive maybe/ maybe-nots). Is this sufficient evidence for you to make an informed decision on whether RR soya is safe to eat? Or, is it a reason to urgently require more detailed, systematic and comprehensive study?

The question, of course, doesn't stop there because there are other confounding implications of RR soya which are just beginning to see the light of day. For example, RR soya is, not surprisingly, sprayed with Roundup. Is Roundup really as benign as Monsanto has repeatedly suggested?

(This article is adapted from an archived article, which originally appeared on GM-free Scotland in February 2009. Access the archived article here.)

Related video: the poison of the pampas

This report from Argentina shows some of the shocking and tragic consequences of glyphosate spraying of GM soy, including babies with birth defects.

NOTE: These videos are in Spanish, but have English subtitles. Start the video first, then click the arrow on the bottom right and select "Turn on captions."

Part 1



Part 2







ARTICLE  SOURCES
  • Padgette et al., The Composition of Glyphosate-Tolerant Soybean seeds Is Equivalent to That of
  • Conventional Soybeans, Journal of Nutrition, 1996, 126
  • Hammond et al., The Feeding Value of Soybeans Fed to rats, Chickens, Catfish and Dairy Cattle Is Not Altered by Genetic Incorporation of Glyphosate Tolerance, Journal of Nutrition, 1996 126
  • Harrison et al. The Expressed Protein in Glyphosate-Tolerant Soybean, 5-Enolypyruvylshikimate-3-Phosphate Synthase from Agrobacterium sp. Strain CP4, Is Rapidly Digested In Vitro and Is Not Toxic to Acutely Gavaged Mice, Journal of Nutrition, 1996, 126
  • Pryme and Lembcke, In vivo studies on possible health consequences of genetically modified food and feed – with particular regard to ingredients consisting of genetically modified plant materials, Nutrition and Health, 2003, 17
  • Tutel'ian et al. Medical and biological evaluation of safety of protein concentrate from genetically-modified soybeans, www.ncbi.nlm.gov, Vopr Pitan 68, 1999
  • Teshima et al. Effect of GM and Non-GM Soybeans on the Immune System of BN Rats and B10A Mice, Journal of Food Hygiene Society Japan, 41:3, 2000
  • Malatesta et al. Ultrastructural Morphometrical and Immunocytochemical Analyses of Hepatocyte Nuclei from Mice Fed on Genetically Modified Soybean, Cell Structure and Function 27, 2002
  • Malatesta et al. Ultrastructural analysis of pancreatic acinar cells from mice fed on genetically modified soybean, Journal of Anatomy, 201(5), November 2002
  • Malatesta et al. Fine structural analyses of pancreatic acinar cell nuclei from mice fed on gentically modified soybean, Letter to the Editor, European Journal of Histochemistry, 47:4 2003
  • Brake and Evenson, A generational study of glyphosate-tolerant soybeans on mouse fetal, postnatal, pubertal and adult testicular development, Food and Chemical Toxicology 42, 2004
  • Zhu et al. Nutritional assessment and fate of DNA of soybean meal from Roundup Ready or conventional soybeans using rats, Archives of Animal Nutrition, 58:4, August 2004
  • Vecchio et al. Ultrastructural analysis of testes from mice fed on genetically modified soybean, European Journal of Histochemistry, 48:4, 2004
  • Tudisco et al., Genetically modified soya bean in rabbit feeding: detection of DNA fragments and evaluation of metabolic effects by enzymatic analysis, Animal Science, 82, 2006
  • Malatesta et al. A long-term study on female mice fed on a genetically modified soybean: effects on liver ageing, Histochemical Cell Biology, 130, 2008

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