Full IARC glyphosate report released; Anti-GMO target may have health benefits


It’s either the darling of GMO-loving Big Ag or the demon imperiling small-farmers and organic growers worldwide (or both!). It’s glyphosate (formerly patented and branded as Roundup), and it’s the most widely used pesticide in the world. Although it was introduced in 1974, more than 20 years before the introduction of GMOs, much of its increased use is because it can kill weeds without killing crops that have been genetically modified to resist glyphosate.

But what is it, really? And is it dangerous?

Most famously, this year the International Agency for Research on Cancer (IARC), an arm of the World Health Organization that evaluates the hazards (but not risks — a key distinction) of all sorts of everyday activities and products, declared that glyphosate was a Class 2a hazard, putting it in the “probably carcinogenic to humans” along with 73 other things including high temperature frying and excessive sunlight. Meanwhile, the U.S. EPA, the European Commission and other health and environmental agencies have declared it safe as used, and it’s licensed for use in 130 countries.

We’ve talked about risks, hazards and words like “probably” in other articles. Here, we’ll review what scientists have really found about glyphosate.

IARC’s full report available

IARC’s full monograph with scientific studies and references is now available, and will no doubt provide more information (or fodder) on how dangerous glyphosate may be. We won’t go over the monograph in detail in this article, but we can review a few human exposure claims to look at some issues. For human exposure, IARC cited two Ecuadoran studies:

  • The first reported statistically significant DNA damage among people who lived less than 3 kilometers from sites where the Ecuadorian government had used glyphosate formulations to kill off illegal coca plants. These were people who had exhibited symptoms of acute toxicity.
  • However, the same group studied individuals who lived in northern Ecuador 2 years after the last government spraying occurred, and found normal karyotypes compared to control groups.
  • Other human exposure studies in Colombia found increased incidences of micronucleus formation (a marker indicating chromosomal damage) in women agricultural workers living in areas that had received glyphosate spraying.
  • They did not, however, find cancer.

Andrew Kniss, plant scientist at the University of Wyoming, earlier discussed other studies that were cited in IARC’s paper in Lancet (announcing its 2a classification).

Weak cancer link

The IARC study’s main (some say only) cancer link to glyphosate is non-Hodgkin lymphoma, a cancer affecting white blood cells (more on NHL below). However, Kniss pointed out that only three studies on NHL were cited in IARC’s Lancet paper. Those studies showed that, using a 95 percent confidence interval (a statistical tool that determines how a study’s data “spreads” across the criteria its studying), there appeared to be some valid link between glyphosate and NHL. However, two of the three had data within a 95 percent confidence interval that showed no–or even a slightly negative relationship between the pesticide and cancer, meaning that based on incomplete data glyphosate could actually insulate someone exposed to cancer.

These three studies were “case control studies,” which Kniss described as a:

Type of study (that) takes a large number of ‘cases’ of the disease of interest, finds a similar group of people without the disease, and then tries to find differences in risk factors between the groups. Any factors that are more prevalent in the ‘case’ group (the group with the disease) are viewed as possible risk factors for the disease.

Kniss also pointed out that in the case control studies, very few people with NHL were actually exposed to glyphosate. Case control studies do have a limitation, in which they cannot control other variables very well. In this case, people exposed to glyphosate are probably also exposed to other pesticides. And that’s hard to rule out.

Another type of study, called a cohort study, follows people for some time (it varies among studies) and records risk factors and the research participants’ health outcomes. In a cohort study cited in IARC’s Lancet paper, Kniss notes a very different result.

These results suggest there is no discernible link between glyphosate and non-Hodgkin lymphoma among a population where glyphosate use is the most common. Over 41,000 of the 54,315 study participants had been exposed to glyphosate in this study. And 99.82% of them did not get non-Hodgkin lymphoma during the course of the study.

Scientists respond

Many scientists around the world have responded to the IARC report and other studies on glyphosate. Val Giddings, senior fellow at The Information and Technologies Innovation Center, pointed out before IARC released its full report that several studies were missing, and other studies, like the infamous retracted Seralini rat study, were included. The Seralini study is referenced in the full report, but the IARC Working Group rather politely but definitively noted the significant inadequacies of that study.glyphosate-who-programs

In his response to the findings and studies cited by IARC, Sir Colin Berry, Emeritus Professor of Pathology at Queen Mary University of London, said:

There are over 60 genotoxicity studies on glyphosate with none showing results that should cause alarm relating to any likely human exposure. For human epidemiological studies there are seven cohort and 14 case control studies, none of which support carcinogenicity.

The authors have included non-Hodgkin lymphoma (NHL), but that diagnosis is no longer used in pathology because it’s far too imprecise. Even if you do include NHL there are still 7 studies, only one of which is positive – and that one is not a good study in my view.

Berry has a point about NHL. There are, in fact, many kinds of cancers that fall under the category of “non-Hodgkin lymphoma.” The American Cancer Society lists more than 25 types and subtypes of NHL, and that doesn’t include the rare versions. Thus, since these lymphomas have no known cause (anti-glyphosate rhetoric to the contrary), studies looking at links between environmental exposure of anything and lymphoma would need to determine the exact type of lymphoma being examined.

Rounding up cancer — maybe

Glyphosate was first synthesized as a pharmaceutical drug candidate in 1950 — its herbicidal properties were not discovered for another 20 years. There are also intriguing hints that glyphosate might have medicinal properties, in particular it may actually lead to better treatments for cancer. The consumer products company Procter and Gamble filed for a patent in 1995 on glyphosate as an anti-cancer treatment. Much more recently, a research group from Tulane University in New Orleans and from China found that glyphosate and its degradation product, a compound called AMDA, halted growth of eight human cancer cell lines (while leaving two normal cell lines alone).

So, is glyphosate safe? Considering it’s many properties, that’s a narrow way to frame this issue. Yes, it can act as a pesticide, so don’t drink it. But it’s much safer that other pesticides that have been used (including some organic ones, like copper sulfate or rotenone), and its harm to humans seems limited to acute or prolonged high exposure among agricultural workers. In fact, it may directly or indirectly lead to new drugs for cancer. The anti-GMO activist community might have picked a scarier bogeyman.

Andrew Porterfield is a writer, editor and communications consultant for academic institutions, companies and non-profits in the life sciences. He is based in Camarillo, California. Follow @AMPorterfield on Twitter.

  • RobertWager

    Thank you for the analysis.

  • Brooke Heppinstall Kroenung

    “So, is glyphosate safe? Considering it’s many properties, that’s a
    narrow way to frame this issue. Yes, it can act as a pesticide, so don’t
    drink it. But it’s much safer that other pesticides that have been used
    (including some organic ones, like copper sulfate or rotenone), and its
    harm to humans seems limited to acute or prolonged high exposure among
    agricultural workers. In fact, it may directly or indirectly lead to new
    drugs for cancer. The anti-GMO activist community might have picked a
    scarier bogeyman.”

    You had me until the last paragraph! HELLO?! Pesticide? It’s an herbicide, idiot! Do you know how many average people get those labels mixed up? You are supposed to KNOW what you’re talking about here. Your spell check came through, but, your fact check needs work!! Yeah, and don’t drink it. Duh.

    • Brandon

      pesticides include herbicides, fungicides, and insecticides…

    • Greg Neal

      Incorrectly thinking that “pesticide” only means “insecticide” is a simple indicator that someone doesn’t KNOW anything about the topic, regardless of their opinions.

      It is ironic when they then rant that an expert doesn’t know the proper terminology.

      a chemical preparation for destroying plant, fungal, or animal pests.

    • Rickinreallife

      I know that many use the term pesticide and insecticide interchangeably, and consider herbicide to be something other than a pesticide. “Pesticide” is a generic term for a substance that kills (suffix cide) pests. Herbicides. insecticides, fungicides, rodenticides are all categoroes of pesticides. Herbicides are a pesticide that kill plant (herbal) pests, insecticides are a pesticide that kill insect pests, fungicides are a pesticide kill fungal pests, rodenticides are a pesticide that kill rodent pests, etc. The use of the term pesticide was not incorrect – a herbicides is a type of pesticide. Herbicide is just a more precise term.

    • lf

      nice try, who’s the idiot now ? lol

      • Rickinreallife

        I wouldn’t rush to condemn. I think it is not uncommon in popular perception for people to associate the term pesticide only with efforts to control insect damage. Over time the term might evolve to only encompass insecticides if that becomes the prevailing usage. The language might evolve to where Brooke would be right, but probably not yet. There are lots of terms that started as generic that evolved to encompass only a subset of the original universe of items the word originally referred to. The word automobile is one. The term technically describes all types of motorized vehicles with varying functions, i.e. sedans, pickups, trucks, etc. But I would venture that most of the time when people use the term, they are referring only to passenger sedans, and would use the more precise term only to refer to pickups, trucks, etc.. It works the other way around too. Sometimes a precise term acquires a generic meaning. The term “coke” originally meant a specific brand and recipe of soda. It still has that meaning, but the word “coke” is popularly used generically to refer to any type or brand of soda.

        • Greg Neal

          Yes, a word IS how it is used and pesticide could come to mean just insecticide. Besides being technically incorrect, it also leaves us without a word for the category of pesticides; but those making the error don’t care about that either.

          Unlike coke, pesticide has somewhat obvious roots: “pest” is a commonly used word. “icide” is most often seen by people in “homocide” (kill-human).

          I heard someone explain this once by saying that when used to shoot a squirrel, your 22 rifle bullet could be called a “squirrelicide”. :-)

          • Rickinreallife

            Pesticide would evolve over time to mean only something that kills insects if a critical mass of English speaking people insist on using the term incorrectly that way, and the rest concede and start using other means to refer to all substances that kill pests, including but not limited to insect pests.

            That would be unfortunate for environmental watchdogs because, you’re right, they would now need to come up with a new term to generically refer to all substances that kill all types of pests, not just substances that kill insect pests, when they meant that (nuisancicides maybe) or have to always list each type of pesticide. Instead of activists saying something like “we need to reduce the use of pesticides” they’d have to use a drawn-out cumbersome phrase something like “we need to reduce the use of pesticides (which now would only mean insecticides), herbicides, fungicides and rodenticides, and all other substances that kill pests” or use the new generic term as in “We need to reduce the use of nuisancicides”. Otherwise, when they said “we need to reduce use of pesticides”, they would only mean we need to reduce the use of substances that kill insects, and it wouldn’t say anything about the need to reduce herbicides, rodenticides, etc.

            But we aren’t there yet (and I hope we don’t ever get there) and I agree Brooke’s righteousnous was ill informed and not justified.

    • Deviljho

      I see this type of comment often when discussing pesticides. It is a good idea for authors to define pesticides as an umbrella term that includes herbicides, fungicides, insecticides, etc. to prevent such confusion.

    • Stuart M.

      I used to think herbicide and pesticide were two different things, but hanging around here at GLP disabused me of the distinction. I am a little embarrassed about it now. But live and learn…

  • RobertWager

    Check the citation list, Seralini, not one or two times but SIX times. That pop you just heard was the credibility bubble of IARC. Wow!

    • Jim Tomasko

      Funny how critical you are of Seralini’s research, but most likely have complete support in Monsanto – of the 7 manufacturers of Agent Orange, theirs was the highest in dioxin and yet they still won their lawsuit and never paid a penny for all of the health damage/death that their huge screwup caused. No worries though, the US taxpayers pay this fee on Monsanto’s behalf as the DOD recognizes 18 Agent Orange birth defects with Vietnam Viet moms (but not dad’s) and Vietnam veterans themselves. What about the EPA’s reevaluation of the safety of Glyphosate in Spring/2015, over 75% of their references were unpublished studies by Monsanto and other biotech industries. As a University Researcher, I cannot access any of these Monsanto studies and they have refused to release any of this data for outside review, why? Science is about consistency and disclosure, we need to view all scientific references with the same critical thinking – not just the work of Seralini.

  • The genetic fallacy pervades anti-GMO arguments, and glyphosate is a good example.

    It is singled out because of its origins as herbicide at Monsanto. The reasoning is simple: Monsanto made Agent Orange which caused grotesque birth defects in babies. That makes them evil incarnate, and everything they make is similarly poison. They’ve proven they only care about profits.

    There is no reasoning with such moral judgments. In fact if you don’t accept it on face value, there must be something defective about you. Accusing you of being a shill is kind in this regard, because it means you are merely greedy rather than stupid (presumably the greedy people can wake up and get right with Jesus, but the stupid people are terminal cases).

    Also it’s instructive to look at incidence trends for NHL-type cancers. There was a big uptick starting in the early 80s. Ah-hah! A smoking gun for introduction of glyphosate, right? Others try to pin the increase on aspartame, which was also part of Monsanto’s portfolio after they acquired G.D. Searle in 1985.

    But if you look a little deeper, you discover the primary culprit was likely the AIDS epidemic which was first documented in 1981. Who would have thought that a virus which attacks the lymph nodes would also cause lymphomas?

    • Jim Tomasko

      What makes Monsanto such an unethical company is that do not take any responsibility for their actions, like in the case of Agent Orange. They did not feel they did anything wrong, especially something worthy of paying out lawsuits. They sold a product with two ingredients disclosures, but a 3rd secret and highly toxic ingredient was included with no disclosure. They screwed, it disfigured, killed and poisoned millions of Americans and others from at least 13 different companies. They even had the judge said in his deliberation that they were not in any way responsible for the damages done. So yes, Monsanto only cares about profits and mitigating expensive lawsuits that can dilute profits. Monsanto has created a bunch of products that are now banned due to nefarious health side effects, why are so loyal to this super-rich and powerful company? Currently Monsanto is being sued for $1 billion by the City of San Francisco, because the bay is so polluted with BPA. Monsanto’s official response was that a different company that shares the same name as them did that, and they are not responsible. They are claiming to be different companies, solely because they prefer to sell ag chemicals now. Thats their line and they are sticking to it!

      • Eric Bjerregaard

        Look up trhe War Powers Act. they were legally required to produce the stuff. Plus the folks that went along with this are either retired or dead. The ones who are there now are not responsible. Just as you aren’t responsible for the crimes of your ancestors.

  • Whip It

    Unfortunately for Monsanto, just like any business, the consumers will ultimately decide it’s fate. Monsanto needs to be able to prove beyond a shadow of a doubt that their products are safe, something they have not done, is the consumers perception. I am assuming it may be the fact that Monsanto has made many chemicals in the past that they swore are safe yet years later have been proven to be hazardous to our health and or the environment and have subsequently been banned. Why should we believe them this time? And honestly, does anyone here truly believe that GMO corn sprayed with chemicals is healthier than organic? Because it’s 100% impossible.

    • Monsanto’s “consumers” are farmers, who buy their seeds, and their customers love their product. Their profit has been on a steady rise for 20 years. They also supply the organic market (I think they may be the largest single seed supplier to the organic market). So no sign of any customers resistance. As for growth of GM crops, it’s been rising at a higher rate than the rise in organic farming. As for safety, that issue has been settled: 244 of the world’s top independent oversight and science agencies have determined (after reviewing more than a thousand INDEPENDENT studies) that GM crops are as safe or safer than organic/conventional. As for chemical usage, the introduction of GM crops has resulted in a 37% decrease in chemical usage since their introduction (that’s based on independent meta study of 140+ studies, released last fall). As for organic pesticide use, based on a per acre/per pound basis, organic farmers use MORE chemicals than farmers using GM seeds… those statistics from the the State of California’s ag department. So essentially, not one of your points are accurate.

      • Whip It

        Consumers are those who consume, food and resources. I believe everyone qualifies, not just farmers. Monsanto has not provided sufficient proof that their products in question are safe, or they would not be in question. So the 280 million pounds of Round up dumped on the soil in the US alone last time checked is how much less than the previous. That’s about a pound for every man woman and child in the US. Doesn’t that sound excessive, especially if there are numerous studies putting it’s safety in doubt. Sorry to break it to ya John, Monsanto is definitely not preceived as a good company in the majority of the consumers eyes. You can see it in the news, social media, books, recent studies, share price drop, getting sued, losing law suits, countries banning to name a few.

        • Stuart M.

          I don’t know where your absolute glyphosate use figures come from but let’s just accept them. First, of all the 2015 population figure for the USA is 325 million not 280 million, so your “about one pound for every man, woman, and child” claim is already bogus. But even if it were true, one has to consider the acreage required to feed one American or the animals they eat. One pound of anything spread over such a great expanse means miniscule amounts eventually reaching the consumer. Yes, Monsanto is not perceived as a good company in many circles. That’s because of the prejudice and outright propaganda spread by people like you. By the way, in which countries is Monsanto banned? Oh, you mean GMOs, Roundup is actually still sold just about everywhere in Europe where GMOs were banned for hysterical, unscientific reasons.

        • Cairenn Day

          Why the ‘appeal to popularity’ fallacy? That is not how we do science. It isn’t even very good for social issues (how many states had ‘defense of marriage acts?)

          Please support your claims of numerous studies and please don’t even try to use Seralini. I am tired of debunking what would have a C grade science fair project.

          You made a boat load of claims, I want to see support for them or you can retract your claims

          • Whip It

            I’ll help you out. Read Dr Jonathan Latham’s recent article. Read Altered Genes Twisted Truth. A tad of common sense never hurts. Hey, I’m sorry that business are either cool or not, and Monsanto is not, but that’s the common consensus and what ultimately decides a company’s fate. It has to do with psychology.

          • agscienceliterate

            Oh, geez. That is a piece of c**p writing, and it is not science. You really can’t do better than that for justification of your misconceptions?
            You may call it common sense. I call it fearmongering. And you can get off your Monsanto-bashing soapbox. Monsanto produces only about 5% of the world’s seeds.

          • Cairenn Day

            Why would I look for science in a book by the hired lawyer of a cult like group that supports biodynamic farming?

            You mention ‘common sense’ and yet you seem to be lacking in that field.

            I don’t work for Monsanto or any agri business. I DO have a background in science and the the ability to read science journals and to understand them. I don’t have to get my science for someone PAID to LIE.

            Science is not done by voting for it, like you do for a prom king and queen. The fact that you seem to think it does, is a HUGE problem in your thinking, or should I say LACK of thinking.

          • Whip It

            I understand your perspective, what you need to understand is reality. A business can use science to create something great, yet if consumers aren’t convinced, it’s crap. Its called psychology. Therefore when trying to create a successful business one needs to focus on the marketing and PR more than the science.

          • Cairenn Day

            W I, Most GMO seeds/plants are for farmers, not consumers. Farmers like them.

            The fact that some consumers choose to be stupid, is not a reason to not make them.

            I have a question for you and please answer it. Folks voted for ‘defense of marriage acts’ Should their vote have been upheld? By your reasoning it should have been. Tell your gay friends that popularity is more important than their rights.

        • agscienceliterate

          Whip it, you need to go back to high school science.
          There is no way to “prove” that any chosen X is safe.
          And glyphosate is off-patent, so you can get off your Monsanto-bashing box now.

          • Whip It

            Monsanto developed Roundup as an herbicide and was responsible for all the studies to establish its safety. Monsanto lied to us about its safety, not Dow not BASF not Bayer, you get the picture. Is it fearmongering or saving your grandkids. And what are you doing here, what drives your support for Monsanto?

          • Cairenn Day

            Evidence of that from a peer reviewed source?

            You are fearmongering and lying

          • Whip It

            You ask for evidence Monsanto is lying about the safety of its products. Tell me what Altered Genes Twisted Truth is? How is this not enough proof to you. The information was required to be handed over by Monsanto per court order as part of the Right to Know Act. It has nothing to do with science and everything to do with bribing the regulators and government officials. Also what about all the info released by Dr Jonathan Latham, the original GMO researcher who says that they are dangerous and should never been a part of our food system. Tell me why should I accept your ideas on GMOs and not the pioneering scientist’s view?

    • adam

      Whip It,

      You do realize that Organic utilizes chemicals as well to control pests/weeds? Some of those that are approved for Organic Farming are worse than Glyphosate and in greater quantities per acre.

      Seriously, do you even research or pull this stuff from NaturalNews and FoodBabe?

    • Good4U

      I rely upon the decisions of the authentic regulatory agencies, such as the U.S. Environmental Protection Agency, the Canada Pest Management Regulatory Agency, and their counterparts in the European Union. They have all decided based upon Good Laboratory Practice (GLP) compliant toxicology and exposure studies, conducted with athentic scientific principles, that glyphosate demonstrates no carcinogenic properties, and that it’s one of the best alternatives to the herbicides that were used to control weeds in agricultural crops. They have all decided that biotechnically engineered crops which are resistant to the herbicidal properties of glyphosate are safe for humans and livestock to eat. All the noise and clatter from the anti-GMO fluff bombs out there in the blogosphere can’t stand up to scientific scrutiny. You have no point that is relevant.

  • Stuart M.

    “But it’s much safer that other pesticides that have been used”

    should say “…much safer than other pesticides…”

  • The evidence is massive that glyphosate is an extremely harmful chemical, which people spread around only because they are not being careful of how they are affecting others, and because they are participating in maladies common in our time among most people–chemical and ecological ignorance.


    Ethoxylated adjuvants of glyphosate-based herbicides are active principles of human cell toxicity. Mesnage R, Bernay B, Séralini GE.—Toxicology. 2013

    Major Pesticides Are More Toxic to Human Cells Than Their Declared Active Principles by Robin Mesnage, Nicolas Defarge, Joël Spiroux de Vendômois, and Gilles-Eric Seralini—Biomed Research International, 2014

    Cytotoxicity on human cells of Cry1Ab and Cry1Ac Bt insecticidal toxins alone or with a glyphosate-based herbicide by R. Mesnage, E. Clair, S. Gress, C. Then, A. Székács and G.-E. Seralini—Journal of Applied Toxicology, 2011—- They demonstrated that Roundup, by itself, is not inert on human cells.

    Glyphosate-based herbicides produce teratogenic effects on vertebrates by impairing retinoic acid signaling by Paganelli A, Gnazzo V, Acosta H, Lopez SL, Carrasco AE.–Chemical Research in Toxicology, 2010—-They found that relatively high concentrations of glyphosate-based herbicides are teratogenic.

    The High Cost of Pesticides: Human and Animal Diseases by Judy Hoy, Nancy Swanson and Stephanie Seen–Poultry, Fisheries, and Wildlife Sciences 2015

    Glyphosate, pathways to modern diseases III: Manganese, neurological diseases, and associated pathologies. by Samsel A, Seneff S.–Surgical Neurology International 2015

    A Case for Revisiting the Safety of Pesticides: A Closer Look at Neurodevelopment by Theo Colburn–Environmental Health Perspectives, 2006

    Glyphosate’s Suppression of Cytochrome P450 Enzymes and Amino Acid Biosynthesis by the Gut Microbiome: Pathways to Modern Diseases by Anthony Samsel and Stephanie Seen–Entropy, 2013

    Teratogenic Effects of Glyphosate-Based Herbicides: Divergence of Regulatory Decisions from Scientific Evidence by M Antoniou, MEM Habib, CV Howard, RC Jennings, C Leifert, RO Nodari, CJ Robinson and J Fagan–Journal of Environmental and Analytic Toxicology, 2012

    Glyphosate Induces Human Breast Cancer Cells Growth through Estrogen Receptors—Food and Chemical Toxicology 59, Sept. 2013

    This study found that glyphosate at residue levels commonly found in humans, when combined with commonly found concentrations of a component of soybeans, caused human breast cancer cells to multiply five to thirteen times as much–

    A criticism of this study by Monsanto–


    says this study should be discounted because it was done in vitro, not in vivo, whereas numerous In vivo studies found no problem. The criticism from Monsanto makes this claim–”numerous peer-reviewed studies clearly demonstrate that glyphosate does not have the potential to be an estrogen active compound, nor does it bind to estrogen receptors.”

    This claim is ludicrous. Those studies did not reveal estrogen activity–they in no way revealed that the potential for estrogen activity does not exist.

    In fact, this careful study reveals that potential is realized.

    The goal of this science is to make clear non-obvious things. Granted, In vivo studies would be more meaningful. However, it is very poor practice, really senseless, to not also be informed by in vitro studies.


    The details of the science of glyphosate, or any chemical, is complex stuff. Americans make a huge mistake in not following the precautionary principle, appropriately applied. They seem to have this crazy idea that it is perfectly OK to spread mega-tons of what are obviously extremely biologically potent chemicals all over the Earth, and in our food, until it has been clearly demonstrated by rigorous science that those specific chemicals have very bad effects on human health.

    This is just crazy–dumb–senseless. That this approach prevails in America is a disgrace to US. For the sake of profit, we seriously endanger and regularly cause real degradation–of the biosphere, and of ourselves.