Science in Society Archive

Don't Let Monsanto Deny Glyphosate Carcinogenicity!

Monsanto makes further attempts to undermine the WHO expert group classification of glyphosate as probable human carcinogen as its call for retraction is ignored Prof Peter Saunders

Add your name to Independent Scientists Manifesto on Glyphosate:

In May 2015, the leading medical journal Lancet Oncology published a brief account of a review by the International Agency for Research on Cancer (IARC) [1]. The IARC working party had considered five organophosphate pesticides, tetrachlorvinphos, parathion, malathion, diazinon and glyphosate, and had classified the first two as possibly carcinogenic and the other three as probably carcinogenic. Four of the evaluations appear to have been accepted with little or no comment. Glyphosate, however, is central to a highly profitable and powerful industry, the manufacture of glyphosate-based herbicides and the development and supply of glyphosate-tolerant GM crops to be used with them. So Monsanto, the leading company in the field, instead of engaging the IARC working group in a discussion of its results and their implications, immediately dismissed the review as “junk science” and demanded its immediate retraction.

The IARC Monograph

Contrary to the impression you might get from Monsanto’s press releases, this was not a study specially set up to attack glyphosate. The IARC was created by the WHO in 1965 to promote international collaboration in cancer research. It was soon being asked for advice on whether certain agents (mostly chemicals) in the environment and in food were carcinogens. Because gathering together and evaluating the relevant information turned out to be a major task, the IARC began commissioning panels of experts to review the evidence on particular agents or groups of similar agents. The latest volume of monographs, on five organophosphate pesticides, is the 112th in the sequence.

The panels do not decide for themselves how to proceed. They follow guidelines that were set up in 1971 and have since been modified from time to time in the light of experience. These are described in the Preamble to the IARC Monographs, which is available on the web [2].

A key feature of the IARC process is transparency. The members of the working group must have no real or perceived conflicts of interest. The evidence they consider must be openly available. This is in complete contrast to reviews carried out by the industry or by regulators, which are largely based on evidence that independent scientists are not allowed to see. Remember that Gilles-Eric Séralini had to resort to a Freedom of Information suit to discover the evidence on the basis of which the EU had licenced Monsanto’s GM maize MON810.

The working group must explain in detail in their report how they arrived at their evaluations. There is a strict protocol for deciding in which category a substance is to be placed, from Group 1, “The agent is carcinogenic to humans” to Group 4, “The agent is probably not carcinogenic to humans”. In this case, the Working Group explain that they have placed glyphosate in Group 2A, “probably carcinogenic to humans,” because they found sufficient evidence to establish that glyphosate is carcinogenic in animals, but that while there is a clear association between glyphosate and cancer in humans, they cannot completely rule out the possibility that this is due to chance, bias or confounding, rather than cause and effect. They also considered that the data on genotoxicity (damage to the genetic information in cells) and oxidative stress (disturbance to the balance of free radicals) provide independent support for the classification [1]. The IARC stopped just short of saying that glyphosate definitely causes cancer, but on this evidence I wouldn’t bet against it. Which is what the industry is telling us to do.

Monsanto’s response

Monsanto reacted exactly as we have come to expect: they immediately demanded that the WHO retract the monograph.  They tried to play down the importance of the classification by pointing out that Group 2A also includes working in barber shops and shift work. They did not, however, explain on what grounds they were rejecting the evidence in earlier IARC monographs that both do in fact increase the risk of cancer [3,4].  They criticised the IARC for taking only a week to carry out its evaluations [5,6], when the meeting they  were referring  to was only the final stage in a process that had taken a year.

Monsanto’s chief argument is that many regulatory agencies have found glyphosate is safe. That would carry more weight if the regulators had carried out their own research and if the results of all the experiments were available for independent scientists to study. But that isn’t what happened. It is generally a matter of the agency accepting the word of the industry, and on the basis of evidence that no one else is allowed to see.

Recently, for example, it was announced that an EU study had concluded glyphosate is safe and that therefore its licence to be used in Europe should be renewed [7]. The announcement explained that the review had been carried out not by an EU agency but had been delegated to one country, Germany, as “Rapporteur Member State.”  What the announcement did not explain was that rather than doing the work itself, the German Federal Institute for Risk Assessment (BfR) had delegated it to a body called the Glyphosate Task Force, a consortium of chemical and biotech companies including Monsanto “joining resources and efforts in order to renew the European glyphosate registration with a joint submission.” ([8], [9] Scandal of Glyphosate Re-assessment in Europe, SiS 64)  It is difficult to conceive of a more blatant conflict of interest.

The BfR’s reaction to the IARC report is interesting. They write [6], “It is not possible to fully comprehend the indications for a genotoxic potential of glyphosate based on the short report published by IARC, in particular also due to the fact that the assessment included studies using different glyphosate containing plant protection products that are not specified in any detail.” 

This sounds like someone trying to cover their back, just in case handing the review over to the biotech industry turns out not to have been such a good idea after all. The world’s regulators must be all too well aware that if the IARC conclusions are accepted, they are going to have to explain to their governments why they gave them such egregiously bad advice. Governments may have put pressure on the regulators to accept what the industry told them, but if things go wrong it is the regulators that will be hung out to dry.

The BfR does, however, raise an important point. Almost all the relevant studies have been on glyphosate alone. But no one uses pure glyphosate as a herbicide. It is always combined with adjuvants, chemicals that are added to make it more effective.

Thus what is being tested is not what we are actually being exposed to. The industry and the regulators insist that this does not matter because the adjuvants are inert. Only they are not inert. Just to cite one example, research has shown that the polyethoxylated tallowamine POE-15, a major adjuvant in Roundup, is highly toxic [10]. In any case, the whole point of adjuvants is that the mixture is a much more effective herbicide than the so-called active ingredient (in this case glyphosate) used alone. So we would expect the mixture to be more toxic and more carcinogenic too. It is possible that it might not be, but it is foolhardy to licence the herbicide without bothering to find out.

Monsanto’s next steps

Having failed to bully the WHO into retracting the monograph, Monsanto have announced that they are asking Intertek Science & Regulatory Consultancy, a commercial firm, to convene and facilitate a panel of its own. We do not yet know the members of the panel or how it will carry out its work, but Intertek states on its web site [11] that its guiding principle has always been “to protect client interests while helping our clients achieve their milestones in bringingnew products to market, or proactively defending established ones.” In this case, of course, the client will be Monsanto.

In the meantime, according to the Washington State University web site, a collaboration between a WSU researcher and Monsanto has found no glyphosate in breast milk from women in areas where Roundup is used [12]. This claim is in contradiction to earlier research, and there are several important questions about how it was carried out that cannot be answered because the work has never been published nor the details made available [13]. The US Environmental Protection Agency (EPA) has nevertheless indicated it will include this study in its review of glyphosate regulations. Why?

To conclude

The IARC has found that glyphosate is carcinogenic to animals and probably carcinogenic to humans [14]. The review was carried out by an international panel of experts, none of whom had conflicts of interest, real or perceived. It must be taken seriously, just as the 111 previous IARC volumes have been. For Monsanto to dismiss it out of hand tells us more about Monsanto than about the monograph.

The GM lobby accuses the IARC of cherry-picking the evidence because it did not take into account all the research that some others have included in their reviews, but the Working Group followed long-established criteria which specify that only evidence that is openly available and whose quality and relevance can therefore be judged by the panel may be considered. Regulators should adopt the same practice. Decisions about human safety and the environment are far too important to be taken on the basis of evidence that other scientists and the public are not allowed to see.

Article first published 03/08/15


  1. Guyton KZ, Loomis D, Grosse Y, El Ghissassi F, Benbrahim-Tallaa L, Guha N, Scoccianti C, Mattock H and Straif K. Carcinogenicity of tetrachlorvinphos, parathion, malathion, diazinon, and glyphosate. Lancet Oncology 2015, 16, 490-1.
  2. IARC. Preamble to the IARC Monographs, 2006.
  3. IARC Some aromatic amines, organic dyes, and related exposures. IARC monographs on the evaluation of carcinogenic risks to humans, Vol. 99, 2010.
  4. IARC . Painting, firefighting, and shiftwork. IARC monographs on the evaluation of carcinogenic risks to humans, Vol. 98, 2010.
  5. Farmer D. What the IARC 2A rating for glyphosate really means. 2015.  21/07/15
  6. Monsanto. IARC’s report on glyphosate. 2015.  30/07/15.
  7. Bundesinstitut für Risikobwertung. Renewal Assessment Report on Glyphosate. Vol. 1, 2015.
  8. Glyphosate Task Force. The European Glyphosate Task Force. 2013.  1/08/15
  9. Ho MW and Swanson N. Scandal of glyphosate reassessment in Europe.      Science in Society 63, 8-9, 2014.
  10. Mesnage R, Bernay B and Séralini G-E. Ethoxylated adjuvants of glyphosate-based herbicides are active principles of human cell toxicity. Toxicology 313, 122-128, 2013.
  11. “Why Intertek scientific and regulatory consultancy?” Intertek. 31/07/15.
  12. “WSY researchers find U.S breast milk is glyphosate free.” Will Ferguson, WSU News, 23 July 2015.
  13. “WSU researchers fnid glyphosate-free breast milk for Monsanto. Sustainable Pulse, 24 July 2015.
  14. IARC. Some Organophosphate Insecticides and Herbicides: Diazinon, Glyphosate, Malathion, Parathion, and Tetrachlorvinphos. IARC monographs on the evaluation of carcinogenic risks to humans, Vol. 112, 2015.

Got something to say about this page? Comment

Comment on this article

Comments may be published. All comments are moderated. Name and email details are required.

Email address:
Your comments:
Anti spam question:
How many legs on a tripod?

There are 5 comments on this article so far. Add your comment above.

Rory Short Comment left 4th August 2015 03:03:15
Monsanto's reaction to the WHO report was to be expected.Their only priority is their business. The safety of humankind probably does not feature on their list of priorities.

charlene Comment left 4th August 2015 15:03:30
Thank you for setting record straight !!! my suggestion: the man whom really invented e-mail, Dr. Shiva Ayyadurai, has a new program which aggregates? all info-from testing(s)-submitted from all different studies. I think it is called 'cytosolve' , seems a possible solution for gathering REAL + INDEPENDENT data.. perhaps someone could contact him? I think it's 'systems biology group' &/or international center for intergrative the fact that Monsanto continually disputes any findings of iarc or other independent studies, when the proof is everywhere is monstrous- if you intergrate them all it will show the 'smoking arsenal' that is monsanto + it's 'sister' terrorist corporations..

Arya Comment left 4th August 2015 22:10:07
Please read and share the following letter regarding the flawed and dangerous Risk Assessment of glyphosate/Roundup and other highly toxic pesticides by Health Canada and other regulators (EPA, EFSA, etc.) 28 July, 2015 TO: Joint FAO/WHO Meeting on Pesticide Residues (JMPR) Geneva, Switzerland cc: Ms. Rona Ambrose Minister of Health Health Canada Ottawa, Ontario, Canada Dr. Richard Aucoin Executive Director Pesticide Management Regulatory Agency (PMRA) Ottawa, Ontario, Canada. Dr. Christopher Wild Director WHO/IARC Lyon, France Ms. Adcock Catherine Expert on JMPR Taskforce Head of the Toxicological Evaluation Section 2 PMRA, Ottawa, Ontario, Canada To the Joint FAO/WHO Meeting on Pesticide Residues (JMPR), I am writing to you with regards to the Risk Assessment of glyphosate and other toxic pesticides copiously sprayed on our food, soil, water, air and environment. As you know, the International Agency for Research on Cancer (IARC) has recently found and classified glyphosate as a “probable” human carcinogen. However, Health Canada has recently favourably re-evaluated the importation, use and sale of glyphosate and entirely dismissed the credible and alarming findings of the IARC by (erroneously) arguing that a health hazard is not a health risk because a health risk is associated with the level of human exposure (i.e. Acceptable Daily Intake) Health Canada writes that: "The World Health Organization's (WHO) International Agency for Research on Cancer (IARC) recently assigned a hazard classification for glyphosate as "probably carcinogenic to humans". It is important to note that a hazard classification is not a health risk assessment. The level of human exposure, which determines the actual risk, was not taken into account by WHO (IARC). Pesticides are registered for use in Canada only if the level of exposure to Canadians does not cause any harmful effects, including cancer." Source: Glyphosate Risk Assessment: Health hazard vs health risk Personal observations: 1) “The dose makes the poison” The health hazards vs health risks assessment used by Health Canada/PMRA (and all regulatory agencies) is scientifically flawed and invalid because Health Canada erroneously believes and argues that the “dose makes the poison.” In fact toxicology peer reviewed and published scientific research and evidence (please see copy below) has shown that this belief is in many cases inaccurate and quite often the opposite is true (i.e. linear vs nonmonotonic dose-response curves) Study link: 2) Active Principle (glyphosate) vs Formulation/product (Roundup) Health Canada (and all regulatory agencies) only reviews the toxicity of the Active Principle alone (i.e. glyphosate) and not the whole product formulation (i.e Roundup) which contains other highly toxic and synergistic “secret” adjuvants. However, peer reviewed published studies (see copy below) have found Roundup and other pesticide formulation to be 125 to over 1000 times more toxic respectively than their declared Active Principle. The authors of the study alarmingly found and write: “We tested the toxicity of 9 pesticides, comparing active principles and their formulations, on three human cell lines[...] Despite its relatively benign reputation, Roundup was among the most toxic herbicides and insecticides tested. Most importantly, 8 formulations out of 9 were up to one thousand times more toxic than their active principles. Our results challenge the relevance of the acceptable daily intake for pesticides because this norm is calculated from the toxicity of the active principle alone. Chronic tests on pesticides may not reflect relevant environmental exposures if only one ingredient of these mixtures is tested alone.” Study Links: 3) Acceptable Daily Intake (ADI) Health Canada/PMRA (and all regulatory agencies) determines and sets the ADI based exclusively on the Active Principle alone (i.e. glyphosate) and not on the product formulation (i.e. Roundup.) However, the actual product that is approved by Health Canada and used copiously on our food supply, soil, water, air and environment is not only glyphosate (AP) but the whole product formulation (i.e. Roundup.) In view of the above, I think that it is fair to conclude that both the Risk Assessment and the ADI set by Health Canada/PMRA (and all regulatory agencies) are scientifically flawed and extremely dangerous to both our health and our lives since they expose us to extremely high doses of toxic chemical formulations (i.e. Monsanto's Roundup, Dow's Enlist Duo, etc.) which seriously endangers both our health and our lives. I therefore hereby request the Joint FAO/WHO Meeting on Pesticide Residues (JMPR) to meticulously study and take into account the above observations while Revisiting the International Estimate of Short-Term Intake (IESTI) in Geneva on 7-9 September for glyphosate/Roundup/Enlist Duo and other highly toxic pesticides copiously sprayed on our food, soil, water, air and environment. I welcome your comments. Sincerely, Arya Tajdin Quebec, Canada A very concerned and worried Canadian/World citizen

David Llewellyn Foster Comment left 4th August 2015 22:10:28
Professor Saunders ~ I append the text of the letter currently being circulated by Thierry Vrain (formerly with Ag-Canada) received yesterday, that is particularly relevant... "The secret ingredient in engineered food" The last poll I saw a few weeks ago was from MNBC surveying people in the USA asking if they wanted to know what is in their food, i.e. would they support some legislated mandatory food labelling policy. Ninety three out of 100 people (93%) voted their concern and distrust of the food supply by voting yes. I have seen many surveys like this over the last 10 years and the people have consistently expressed their concern and anxiety about GMOs. And the Industry and its governmental regulatory agencies in Canada and the USA laugh it up, because they have science on their side. They know very well that science has demonstrated time and again that GMOs are safe, that there is absolutely nothing to fear or be concerned about. The secret - what is not being discussed in the open, is that practically all engineered food crops and a good number of non engineered food crops are routinely sprayed with a powerful antibiotic that doubles up as a popular herbicide. There is so much of it in bread and all processed foods that contain cereals, soy and corn, canola oil and sugar, that the EPA had to raise the legal residue levels in all food and feed crops in 2013 – and Health Canada of course follows their guidelines for MRL (Maximum Residue Limits). For example, soy can now contain 20 parts per million (ppm) and cereals (wheat, oat, and barley) can contain 30 ppm. Think if you were a bread eater, someone who gulfs half a loaf every day, what your intake of glyphosate would be. With animal feed that can legally contain up to 100 ppm, imagine the residues in dairy and meat products. There are lots of areas in the USA and Canada where RoundUp Ready crops are grown, where 75% of samples of the water or the air contain traces of glyphosate. The EPA MRL for glyphosate in drinking water is below 0.7 ppm. Beyond that the EPA warns you that you will get severely ill quickly. The MRL in Europe is considerably less, in case you are interested to know what you are drinking. All this doesn’t tell you much until you learn that one part per million is antibiotic to most bacteria - glyphosate is actually a powerful antibiotic that has been masquerading as a herbicide for over 40 years. Then you learn that you and everybody around you, have a hugely diverse community of bacteria in your lower intestine, that is now commonly referred to as the Microbiome. When I was a kid my mother used to call it the intestinal flora, and somehow it was part of good health, but we did not know how important it actually is. We all have 100 trillion bacteria inside – with the same weight as our brain, that basically direct the show of our body. All those autonomic functions we have, guess what , or rather guess who ? The heart, the lungs, the digestive system, all this seems to work well without us having much to do about it. It is becoming obvious that the biochemical language of the Microbiome to each of our major organs is required for proper function. The diversity of the Microbiome is essential to the health of many organs; particularly sensitive are the brain, the immune system, and of course the digestive tract. So when you eat every day foods containing more than 1 ppm of glyphosate – the level where it kills all bacteria in the lab, you should logically expect antibiotic damage to the Microbiome with consequences of celiac, Crohn’s, allergies and asthma and many other immune deficiency symptoms, Alzheimer and dementia and autism, and eventually all manners of cancer. And that’s just for humans. We know that fish and frogs and rats and pigs become ill and die promptly. You can easily google the published and peer reviewed studies that support every word of this statement. You can also watch my lecture on YouTube “Engineered Food and your Health: the Nutritional status of GMOs”. It appears that we are back in the 1970s when the tobacco industry was spewing safety statements with the studies to prove it every few days. In this millennium the strategy about the safety of GMOs is slightly different. The Industry – read essentially the chemical company Monsanto, is keeping the public and the media focused on the engineering technology and GMOs. And they have all the studies to prove their safety. I also suspect that the Industry actually generates much of the anti-GMO rhetoric we see in the major media and on the Internet. I call it controlled opposition. Their job is to remind you that there is an intense debate about GMOs, with lots of public opposition. This Industry regularly fuels the debate about the safety of GMOs. Apparently anything goes, as long as it is keeping the focus away from the antibiotic in the food system. Only very few people bother to question the huge increase in this antibiotic - masquerading as a herbicide, in our environment, and particularly in our food where it reached toxic levels many years ago. The levels are probably so scary that Agriculture Canada or Health Canada or the USDA or the FDA, dare not even go there. Practically all agricultural chemicals of concern are measured every year and kept in check, except for glyphosate. It is regarded as completely innocuous since its first registration as a herbicide 40 years ago. Therefore there is no need to monitor its use and residue levels in food and water. The recent classification by the World Health Organization that glyphosate is a “probable carcinogen” should definitely be the trigger in Canada - as it is in many other countries. If not triggering an outright ban, at the very least the chemical residues of glyphosate in the food will be documented and made public so that the right debate can take place. If I was the vice president for promotion at Monsanto I would do a number of things to keep this secret from going public. I would do all the standard things of course, like hiring the best advertising brains in the business, emphasize safety and sing the wonders of the genetic engineering technology. I would also keep your attention on the debate about the engineering technology - i.e. are GMOs good or bad for you. I would spare no trick of the trade to keep your attention away from the toxicity of the herbicide that is sprayed on your food. I would create a small army of graduate students (and scientists of course - only the size of the bursary differs) and other mercenaries, to engage with the anti GMO “activists” and constantly remind you of the insanity of your fear. Most of the pro and anti GMO rhetoric is just that, a lot of hot air and a lot of fear. Anything goes as long as it keeps your attention away from the secret ingredient. I would even have books published on the topic, some with all the available evidence of corporate malfeasance exposed in plain view, as long as the emphasis stayed away from the secret. But I am not a vice president – although I was, more than once in my science days, but that was another millennium. Aside from being a concerned consumer, I now find myself in some leading role to alert you of this sordid story of corporate greed that causes so much illness. All I can do is to speak and write publicly about this issue and hope that you will do your part. Dr. Thierry Vrain

Todd Millions Comment left 6th August 2015 15:03:29
As important as the aggregation of accurate information on whom biowennies are using and how/when,we have election calls coming up. Federal in Canada.Then the evil little gnomes for hire will head back south to apply what they have learned on dumb ass canucks in the US federal election.This has gone on for decades.So finding out which politicians and handlers are being paid by whom(usually all possible"winners" are paid by same operatives and patrons) is vital for more than Monsanto. Remember in a whoreocracy -the candidates are prepaid with promises-these slip out in what they promise those stupid enough too vote for them.