Glyphosate carcinogen reactions

May 2015
The reclassification of glyphosate herbicide* as a "probable carcinogen" by the World Health Organisation Cancer Agency (IARC) predictably kick-started a well-oiled damage-limitation machine.

*Glyphosate is the active ingredient of herbicidal formulations such as 'Roundup' which is sprayed on, and accumulated by, most GM crops. It is a contaminant of animal feed and has been found in many foods.

An immediate statement was issued by the 'glyphosate Task Force' (GTF) making disparaging comments about the IARC and repeating five times in eight short paragraphs that years of reviews by regulatory authorities have found no problems with the herbicide. The GTF is a consortium of companies specifically formed "to renew the European glyphosate registration". Its member companies include Monsanto, DowAgrichemicals and Syngenta, whose business and reputation could be catastrophically damaged if the glyphosate loses it's 'safe-as-salt' image.

Three days later, Monsanto, the major manufacturer of Roundup and producer of Roundup-resistant GM crops, issued a similar statement, pouring scorn on the IARC and repeating eight times in twelve short paragraphs that regulatory reviews around the world have found no problems with the herbicide.
The UK Science Media Centre (SMC) which might helpfully have supplied an explanation of why the IARC had reached the new classification for glyphosate, subjected the public to an unhelpful collection of spoiler quotes from pro-GM scientists. It seems the SMC agenda is reassurance about Roundup at all costs. However, a failure to clarify the conflicts of interest of its experts isn't reassuring, and telling everyone that the independent World Health Organisation experts are wrong is simply confusing.

While the British public are left bewildered by PR on glyphosate pretending to be science, Argentinian ecotoxicologists, geneticists, molecular biologists, physicians and quite a few NGOs are bewildered for another reason: they can't figure out why it's taken so long for the World Health Organisation to find out what Argentinians have known for a very long time about glyphosate-based herbicides.

Could the answer be that glyphosate's carcinogenic potential has been subject to the biggest cover-up ever?

All the evidence of glyphosate safety presented to regulators and cited ad nauseam by the GTF and Monsanto was produced by industry, and has never been published nor made available for independent scrutiny.

GM-Free Cymru and others have, however, had a look at the US Environmental Protection Agency (EPA) memos leading up to glyphosate being allowed on the market. These make it clear that there were many animal experiments (using rats, mice and dogs) designed to test acute, chronic and multigenerational toxicity. "The evidence shows that by 1981 both Monsanto and the EPA were aware of malignant tumours and pre-cancerous conditions in the test animals which were fed small doses of glyphosate in secret feeding experiments." Glyphosate was, accordingly, considered a possible carcinogen. "Although concerns were expressed at the the time by EPA committees*, these concerns were later suppressed under the weight of conflicting evidence brought forward by Monsanto, some of it involving the inappropriate use of historical control data of dubious quality".

*US Environmental Protection Agency

It seems Monsanto churned out so much scientific 'noise' in the form of incomparable 'repeat' studies that the EPA declared the conflicting data presented "a mystery". By 1991 the EPA caved in to assurances from Monsanto's Chief of Product Safety and approved glyphosate for use in the field. In the course of this regulatory about-turn, three of its own scientists refused to sign off the herbicide, two of whom wrote beside their names "Do Not Concur".

There are other uncomfortable symptoms that industry and regulators are aware there are skeletons in the cupboard.

EPA and Monsanto collusion has continued to keep all the data used for glyphosate approval concealed under a Confidential Business Information lock and key despite the patent having run out.

Cynics might reasonably ask why it was anticipated that a dedicated body like the GTF would be needed for the re-registration of such an 'obviously' safe product.

That cancer was expected to be an issue is not in doubt: prior to the publication of the IARCs reclassification of glyphosate, Monsanto together with its consultants and the GTF had already prepared and published a review article entitled "Evaluation of carcinogenic potential of the herbicide glyphosate, drawing on tumour incidence data from fourteen chronic/carcinogenicity rodent studies".

The evaluation gives the basis for the earlier conclusions that no concerns exist with respect to glyphosate and cancer in humans. There's a lot of lists of material to wade through (including data on Beagles), but if you ignore the experiments recognised by the authors themselves as having substandard methodology, and those whose controls were too high or too low to lend confidence to the test results, the "extraordinarily large volume of animal data" claimed by the paper boils down to:
four studies which used two different strains of rat and all of which recorded increased tumours
three studies on an out-bred stock of mice which came up negative one study on another out-bred stock of mice which showed a whole swathe of tumours.

Significant differences were dismissed as not dose-dependent, within historical control levels, or in the case of the embarrassing mouse cancer-rate as possibly due to a viral infection because the mortality was high (although, it seems to be within historical control levels!); pooling data and changing statistical methods also managed to eliminate some differences.

The authors conclude by suggesting there's no mechanism for glyphosate to cause cancer. They are clearly dodging the question of glyphosate-induced DNA-damage due to oxidative stress in cells, an established risk-factor for cancer.

Why the UK Science Media Centre isn't pointing out the deficiencies in the safety data is a mystery. However, if you like intrigue you might wonder why the World Health Organisation which used to be a funder of the SMC, no longer sees fit to contribute.


One US Senator has asked the Environmental Protection Agency to re-evaluate glyphosate. Effectively this means a re-evaluation of most GM crops, which is now form a breath-taking proportion of US commodity agriculture, animal feed and food processing industries.

The reclassification of glyphosate as a "probable carcinogen" couldn't come at a better time for the various US GM-labelling initiatives in progress, or at a worse time for the biotech industry which is desperately trying to block any labelling legislation.

Sit back and watch the fun unfolding. But don't let the hoo-ha die down.

  • Statement of the GTF on the recent IARC decision concerning glyphosate, 20.03.15
  • Monsanto Reinforces Decades of Data and regulatory Review Clearly document Safety of Glyphosate,, 23.03.15
  • Monsanto knew of glyphosate / cancer link 35 years ago, GM Free Cymru, 8.04.15
  • Helmut Greim, et al., 2015, Evaluation of carcinogenic potential of the herbicide glyphosate, drawing on tumor incidence data from fourteen chronic/carcinogenicity rodent studies, Critical Reviews in Toxicology, 45(3)
  • Lydia Wheeler, Dem senator urges EPA to test 'probably carcinogenic' pesticides,, 1.04.15
  • Argentine independent scientists support WHO on glyphosate cancer link, GM Watch 22.04.15
  • Monsanto sued in Los Angeles Country for false advertising,, 21.04.15

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