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The Problem with the
Safety of Roundup Ready Soybeans
by Judy Carman, PhD, MPH; Flinders University
The following is a critique of the methods used by Monsanto in its assessment that its product, Roundup Ready soybeans, also known as glyphosate-tolerant soybean line 40-3-2, is safe for human and animal consumption. The methods critiqued are those that appear in the "Full Assessment Report and Regulatory Impact Assessment," written by the Australian and New Zealand Food Authority (ANZFA) as the result of a request that these soybeans be permitted into Australia.
The main role of this food authority is the protection of Australia's public health and safety. However, its other roles include the promotion of fair trade and consistency between domestic and international regulations. ANZFA rarely performs any safety testing of its own, but tends to rely on information obtained from elsewhere, including applicant companies.
The conclusion of this ANZFA document was that these soybeans are safe for human consumption. I have written this critique to highlight my concerns about that conclusion.
Roundup works by inhibiting an enzyme that is necessary for the plant to synthesise certain aromatic amino acids, killing the plant. The targeted enzyme is called 5-enolpyruvyl shikimate-3-phosphate synthetase, or EPSPS. The genetic modification in Roundup Ready soybeans involves incorporating a bacterial version of this enzyme (from Agrobacterium species, strain CP4) into the soybean plant, giving the soybean protection from Roundup. In this way, the soybeans and any weeds can be sprayed with Roundup, killing the weeds and leaving the soybeans.
...there seem to have been no studies measuring quantities of this enzyme in cattle tissue, the ability of the enzyme to persist during moderate cooking or the effect that the enzyme would have on animals including humans.
Because of the way that this gene was incorporated into soybeans, several other DNA sequences are also present. They are the cauliflower mosaic virus 35S promoter, the EPSPS chloroplast transit protein (CTP) sequence from petunias and the 3' untranslated region of the nopaline synthetase gene (NOS3'). The ANZFA document completely omits discussion of the first and last of these and their proteins. For the petunia CTP, the applicant document states: "…it is generally accepted that the chloroplast transit peptides are rapidly degraded after cleavage in vivo by cellular proteases." That is, results from other general experiments are relied-upon and no evidence is provided that they have measured this to be the case in Roundup Ready soybeans.
The application states that the only new protein in these soybeans would be the EPSPS enzyme. They determined the ability of this EPSPS to be digested by setting up an in vitro mammalian gastric and intestinal mixture. It was not stated how this was done. It could involve something as primitive as a beaker on a laboratory bench with substances in it and stirred occasionally, not something that approaches a live gut. In vitro experiments should be repeated using at least a chemostat. In vivo experiments should also be done, to determine the digestibility of this enzyme and other proteins expressed in this plant, their effects on intestinal structure and function and any ability of this enzyme to cross the gut wall.
The document also states that as people cook soybeans before consumption, this would deactivate the enzyme and thus people would not consume it. However, raw soybeans will be fed to cattle. Steak is often served medium rare to rare. Therefore, there is a possibility that people will consume this new still-functional enzyme in their diet. As this does not seem to have been considered by the applicant company, there seem to have been no studies measuring quantities of this enzyme in cattle tissue, the ability of the enzyme to persist during moderate cooking or the effect that the enzyme would have on animals including humans.
A common soybean product in people's diets is lecithin, used as an emulsifier in food. The application classed lecithin as a food additive and so it was not even considered in the assessment.
Soon after the application for GM soybeans was submitted, an application was also submitted … to permit the allowable limit of glyphosate in soybeans to be increased 200-fold.
Soon after the application for GM soybeans was submitted, an application was also submitted to ANZFA to permit the allowable limit of glyphosate in soybeans to be increased 200-fold. It appears that Monsanto may be expecting much higher levels of glyphosate to be in Roundup Ready soybeans. However, the soybeans assessed in the application were not treated with Roundup. They are therefore not equivalent to the soybeans that will come out of paddocks for human consumption. Experiments should be repeated with soybeans harvested from farms before a decision is made on their safety.
The applicant company compared Roundup Ready soybeans to ordinary soybeans for moisture, fibre, ash, protein, amino acids, fatty acids, seed storage, trypsin inhibitor, lectin, isoflavone, raffinose and stachyose. They found no significant differences but the sample sizes used are not given in the ANZFA document. Nor are sample size calculations to justify the sample sizes that were used. If too small a sample size is used, any differences that may exist between Roundup Ready soybeans and ordinary soybeans will not be found. This is called the "Type I error," and is a serious scientific fault. For the amino acid analyses, they also stated that no difference would be expected between Roundup Ready soybeans sprayed and not sprayed with Roundup, without apparently measuring whether this would be the case. Yet Roundup is designed to interrupt the biochemical pathway that makes some amino acids.
...the scientific basis provided by the applicant company for considering that Roundup Ready soybeans are safe for animal and human consumption is seriously flawed.
A similar, and potentially more serious sample size problem (and Type I error) occurs in the animal experiments. Here, 10 rats per sex per group (presumably this means 20 rats per group) were fed soy meal ad libitum from ordinary soybeans and Roundup Ready soybeans at various soy meal concentrations. Twenty rats per group is a very small number of rats with which to try and find statistical significance. They measured total body weight, and at the end of the experiments, the weights of some organs. They appear to have done no biochemistry, immunology, full autopsy, histology (except on pancreas), etc. They only fed animals for four weeks. The document did not report any trends from the low-level consumption groups to the higher-consumption groups of rats.
Similar studies were done on chickens and cows, presumably to reassure farmers that Roundup Ready soybeans would not reduce the quality of their animal-derived end product. A reasonable number of chickens (60 birds/sex) were fed for about a month, but only breast muscles and abdominal fat pads seem to have been removed and weighed at the end of the study. Similarly, groups of 5-6 Holstein dairy cows were fed uncooked soybeans. This is a totally inadequate sample size and would not be expected to show any differences between the groups. Yet a difference was found. Roundup Ready soybean-fed cows produced more fat-corrected milk, explained as being due to a slight increase in food intake. This mirrored a similar result in the chickens, where a slight increase in food consumption was found. They also found "some minor differences between treated groups and the negative controls with regard to body weight gains and food consumption which may be related to palatability" for rats fed processed soy beans. Although such differences may have become significant with larger sample sizes, this does not appear to have been done and these results were not further investigated by the company.
Monsanto also investigated what was described as immunological effects of the soybeans. These were basically allergenic effects. Their experiments were done on pooled blood samples, found Roundup Ready soybeans to be as allergenic as ordinary soybeans, and stated that as known allergens tend to be glysolated, and as the EPSPS was not found to be glysolated, there should be no extra allergenic effects from this soybean. They appear to have done no human trials, however, to test this hypothesis.
Independent testing of these foods is urgently required, incorporating long-term animal and human experiments.
At least the following studies should be done by independent researchers before Roundup Ready soybeans are assessed as safe for human consumption:
1. Chemical analyses of Roundup Ready soybeans from farmers' fields to determine the range of glyphosate levels in such soybeans and how they compare to non genetically-modified soybeans.
2. Long-term feeding studies using laboratory animals of different doses of glyphosate to quite high levels, if they have not already been done.
3. Long-term feeding studies on laboratory animals, with (a) ordinary soybeans (control group), (a) Roundup Readyoybeans without Roundup applied and (c) Roundup Ready soybeans from farmers' fields (ie with Roundup applied). This would differentiate any health effects due to genetic modification vs glyphosate.
For these animal studies (ie, 2. and 3.), at least the following tests should be done: food intake, body weight, full biochemistry, full immunology, liver function, kidney function, tumor investigation, the rate of death in each group, and a full autopsy on the animals at death, including intestinal section and histology. Animals should also be allowed to breed to determine any effects in their offspring.
Randomized, double-blind feeding trials should be done with human volunteers over at least several months. They should be randomly assigned to one of the three feeding groups as in point 3., above. At least the following should be measured: body weight, full biochemistry, full immunology, liver function, kidney function, allergenic potential and general health.
In countries where Roundup Ready soybeans are permitted, cohort studies containing low-level through to high-level consumers of this product should be established to follow people over many years to check for long-term health effects.
In summary, I believe that the scientific basis provided by the applicant company for considering that Roundup Ready soybeans are safe for animal and human consumption is seriously flawed. No other independent investigations seem to have been done. It could be expected that the safety assessments of other genetically modified foods may be as flawed.
Independent testing of these foods is urgently required, incorporating long-term animal and human experiments. As these will take years, it would be wise to place a moratorium on these foods for five years, as suggested by European groups, the British Medical Association and the Public Health Association of Australia, while these investigations are done. To do otherwise could be likened to permitting a giant feeding experiment on millions of people.
In countries where these foods and their derivatives are permitted, they should be labeled so that consumers can make their own decision about whether to buy them or not...
Furthermore, the description that oils and other products derived from genetically-modified foods contain no genetically modified material is also flawed. It could not be expected that such products would be so pure that they would contain nil plant tissue or genetic material or protein. To expect this would be to expect the equivalent of analytical-reagent grade chemical purity from a food-stuff. These products also need rigorous testing, as described above.
Finally, the applicant companies appear to be resisting the labelling of genetically-modified foods or their derived products, such as oils. In countries where these foods and their derivatives are permitted, they should be labeled so that consumers can make their own decision about whether to buy them or not, and so that consumers can reassess their decision as information is provided about the relative safety of these products over the next few years.
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