Is glyphosate toxic to humans?

Of course glyphosate is toxic! It is a herbicide after all – the whole point of glyphosate (G for short in this post) is to kill unwanted plants. Like all chemicals, including water and salt, G is going to be toxic to animals (including humans) at some dose. Compared to other herbicides, though, G is a pretty safe option for killing weeds. Don’t take my word for it, check out the Glyphosate Technical Fact Sheet from the National Pesticide Information Center at Oregon State. G’s relative safety is one reason why it’s become so popular.

Wheat being harvested. Image by NDSU Ag Comm.

Wheat being harvested. Image by NDSU Ag Comm.

One interesting use of G is to dry wheat before harvest. To help reduce levels of toxic fusarium fungus on wheat, it is good to harvest the wheat as early as possible but you can’t harvest it until it’s dry. So G is used to dry (aka kill) the wheat plants so the grain can be harvested. As long as the G  is sprayed after the plants have fully matured, the G won’t be moved from the plant into the seeds. Here, G is actually helping farmers prevent a legitimately scary toxin from getting into the food supply. Want to learn more? Check out this video: Wheat School- Timing Pre Harvest Glyphosate Application In Wheat.

With G being used not only as a herbicide but also as a drying agent, and not just in our lawns but on our food, should we worry about our safety? In short, no. When used properly, G is quite safe for humans.

The EPA sets maximum safe levels of pesticide residues for crops (called tolerances), based on the latest science. These tolerances are hundreds of times higher than estimated toxic values, and they consider a person’s total exposure to pesticides (with a wide margin of error to protect children and others who may be vulnerable). The USDA tests crops each year to make sure they don’t go above the tolerances. Very few pesticides are found above the tolerance levels (despite what the Dirty Dozen list claims). If the USDA finds any pesticides above the set tolerance, or finds pesticides on crops where they aren’t supposed to be, they report that information to the FDA. The FDA puts the teeth in this whole system. They have the regulatory power to start recalls, levy fines, turn back foods at the ports, and so on (see page 5).

You can find the specific tolerance information for G in the US Code of Federal Regulations, 40 CFR, part 180, subpart C, section 180.364. Some of the tolerances for G were recently increased in the May 1, 2013 Federal Register, Vol. 78, No. 84.

EPA has reviewed the available scientific data and other relevant information in support of this action. EPA has sufficient data to assess the hazards of and to make a determination on aggregate exposure for glyphosate including exposure resulting from the tolerances established by this action. EPA’s assessment of exposures and risks associated with glyphosate follows.

Check out Vol. 78, No. 84 for a full explanation of EPA’s decision as well as insights into the safety of G in general. Scientific documents supporting this decision can be found in docket EPA-HQ-OPP-2012-0132.

Tolerances don’t set your mind at ease? Happily there’s a lot of research to peruse.

If you don’t want to dig through these dense EPA documents, you can take a look at three recent reviews that summarize the literature on glyphosate and humans: Epidemiologic studies of glyphosate and non-cancer health outcomesEpidemiologic studies of glyphosate and cancer, and Developmental and reproductive outcomes in humans and animals after glyphosate exposure. These reviews looked at epidemiological studies, ones that look at disease incidence in large numbers of humans with varying levels of exposure to G or that look at exposure to G in a population that has a disease.

Now, epidemiology isn’t perfect, but with carefully designed studies it can be a powerful way to look for connections in real human populations. Even better when we can look at reviews that put multiple studies all in one place. These reviews cover a lot of studies that find there is no correlation between glyphosate exposure and cancer or non-cancer diseases. Unfortunately these reviews are behind paywalls and I don’t know the funding source behind the reviews, but the EPA documents have summaries of many of the studies within the reviews and more.

There are occasionally alarm-inducing papers like Glyphosate induces human breast cancer cells growth via estrogen receptors. This paper, and others like it, tend to use human cells in a petri dish rather than whole animals. I had the misfortune to do some research on cultured human cells myself and let me tell you, those are some tricky buggers to work with. Even when everything is working perfectly, it’s still very hard to tell if the results you are getting will hold true when repeated in a whole animal model. Something that causes a reaction in naked cells may not react the same when applied to your skin or taken in through your digestive system (both of which have evolved to keep you safe from many things).

Only a combination of animal models and cell studies can give us the full picture (even better if we can pair these up with some epidemiology). The third review above includes some animal studies as do the EPA reports. While I am cautious about cell studies in general, the majority of such studies have not found any cause for concern, as described in Review of genotoxicity studies of glyphosate and glyphosate-based formulations (open access) as well as in the EPA reports.

In any subject there will be a few studies that find something totally different from what is found in the majority of similar studies. In closing, I leave you with this recent strangeness: Glyphosate and AMPA inhibit cancer cell growth through inhibiting intracellular glycine synthesis. This obviously tongue-in-cheek meme plays on so many scaremongering memes created about single studies. As interesting as a single study may be, we must look at the totality of evidence. And so far, the evidence does not show that that glyphosate causes – or cures- cancer.

This obviously tongue in cheek meme plays on

Review Citations

Mink P.J., Mandel J.S., Lundin J.I. & Sceurman B.K. (2011). Epidemiologic studies of glyphosate and non-cancer health outcomes: a review., Regulatory toxicology and pharmacology : RTP, PMID:

Mink P.J., Mandel J.S., Sceurman B.K. & Lundin J.I. (2012). Epidemiologic studies of glyphosate and cancer: a review., Regulatory toxicology and pharmacology : RTP, PMID:

Williams A.L., Watson R.E. & DeSesso J.M. Developmental and reproductive outcomes in humans and animals after glyphosate exposure: a critical analysis., Journal of toxicology and environmental health. Part B, Critical reviews, PMID:

Kier L.D. & Kirkland D.J. (2013). Review of genotoxicity studies of glyphosate and glyphosate-based formulations., Critical reviews in toxicology, PMID:

Anastasia is a Board Member of Biology Fortified, Inc. and the Co-Executive Editor of the Biofortified Blog. She has a PhD in genetics with a minor in sustainable agriculture from Iowa State University. Her favorite produce is artichokes! Learn more about Anastasia at Disclaimer: Anastasia's words are her own and views expressed do not necessarily represent the views of her employer(s). She is not paid to blog or conduct any social media activities. Any mention of a specific company or product does not indicate endorsement of that company or product.

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82 comments to Is glyphosate toxic to humans?

  • Steve

    Tell us more about Glyphosate as a chelator and how it “binds” minerals in the soil and doesn’t allow plants (good or bad) to access them;
    And how Glyphosate destroys beneficial micro-organisms in the soil as well (that also provide nutrients to the plant);
    And how Glyphosate promotes pathogenic organisms in the soil that have the potential of over-running the plant (the “weeds”) – eventually creating weaker plants and promoting stronger plant disease;
    And then comment on the resulting negative effects of the nutrient content of the plants (ie, nutrient deficient plants)… and then those effects on the mammals that eat those plants and whether that is sustainable?

    • Hello Steve, this post is about toxicity of glyphosate in humans. If you have reliable citations for any of your claims, I would be happy to look at them.

      I have previously written about the claim that glyphosate promotes some new pathogen: Extraordinary claims… require extraordinary evidence and I addressed the concern that glyphosate is chelating minerals in Does glyphosate restrict crop mineral uptake?

    • Chris Preston

      Steve, there is a good discussion of the issues you raise in this recent review including why glyphosate is unlikely to make a difference to the amount of available minerals in the soil.

      • The same article is also available here[]. As you can see, the paper examines recent studies that have suggested reduced mineral nutrition and increased disease susceptibility in glyphosate resistant and treated crops in context with the larger accumulation of data and understanding on this topic that both precedes and and is contemporary with this new research. The matter of whether glysophate is a sufficient chelating agent that can have consistent, persistent or significant effects on availability of micronutrients or nutrient metabolism by plants is a worthwhile and important topic, and this recent body of research is a welcome addition, provided the research was well done.

        In reality, as the document we cited makes abundantly clear, the binding qualities of glysophate, its fate in the soil and interaction with plant metabolism have been investigated extensively, and the weight of the evidence, even incorporating recent research that the biotech skeptics are championing, indicates that glysophate use and glysophate resistant traits have have very little impact on plant productivity. We are not on the verge of an agricultural collapse or an environmental armageddon. I think the author’s conclusion is a sensible and accurate one.

        “Scientific accounts about increased plant disease and mineral nutrition problems in GR crops are based on publications from a limited number of researchers. In the context of the entire body of relevant science, the significance of these reports is
        questionable. . . . Nevertheless, there might be effects of glyphosate in GR crops on mineral nutrition and/or disease under particular but uncommon conditions (e.g., specific soil, environmental conditions, particular GR crop cultivars, and/or glyphosate formulations).”

        As is typical, unfortunately, the GMO [Greenpeace manufactured outrage]literature latches on to a small segment of research and represents it as the totality of what is known on the topic. Then, this is further twisted into a narrative that science, regulators and industry have heretofore overlooked, incompetently assessed, or just plain swept a potential problem under the rug, hoping no one would find out. The last step is to embellish, overinterpret and exaggerate and amplify into a scary, doomsday scenario, i.e. were all gonna die unless citizens unite to stop science in its tracks right now. So, again, it is taking a little excerpt of truth and turning it into an X-files episode.

  • Daryl

    So Steve, since glyphosate is bad, tell us which chemical, or arsenal of chemicals, you would recommend to farmers as its replacement?

  • @Steve, Tell us how with all that binding, the crops are able to provide ever increasing yields and tell us hwo glyphosate is able to differentiate which microbes are beneficial and which are pathogenic. Do they carry signs? Then tell us how all those toxicology studies on gyphosate have answered your question about effects on mammals.

    • Stefan

      Crops yields haven’t increased because of GMO and glyphosate use: they’re lower than European yields that don’t use such things. They’ve increased by using larger and larger quantities of fertilizer, which makes the plants grow faster, but out of balance. The minerals and nutrition taken in is out of balance which weakens the plants and reduces their nutritionous value.

      It’s not that glyphosate selects beneficial or pathogenic microbes. It simply destroys the majority of microbes. But pathogenic microbes develop faster in a disturbed environment, that’s the way they survive: quick ‘n dirty. Beneficial microbes stabalize an environment and will compete the pathogenics out over the long run; slow and steady. But before they can stabalize the environment another round of spraying occurs and the pathogenic microbes get the advantage again. By repeatedly destroying the majority, you’re maintaining conditions that favor the pathogens; with any kind of poison, but glyphosates are particularily effective and thus give a bigger advantage to the pathogens.

      Independent toxicology studies over longer periods (instead of the Monsanto funded studies that last a few days) consistently show disterbances in digestive systems and cancer growth in mice, etc. There are fewer of these because they don’t get the same funding the biased studies get. It’s also well known that any scientist that publishes a too negative study quickly finds himself fired for some ad hoc created reason.

  • Ute Lehmann

    No medicine without sideeffects! If round up really stops cancer it should have sideeffects to normal growing cells. But whats about Dioxine in Round up? Agent Orange was full with dioxine..
    and round up is said to have dioxine contents too…Dioxine on food, no thanks!

  • Rick

    Oh my god, Steve has discovered the dirty little secret. Chelation, the gotcha theory of doom of the week. And chelation, what a suitably sinister sounding word. Wow, science incompetently overlooked that glysophate had chelating qualities, the ability to bind with soil minerals, or it was swept under the rug hoping no one would notice.. Actually Steve, the topic of the extent to which glysophate could conceivably lock availability of nutrients to plants is a serious one. But wouldn’t this horrible armageddon be obvious by now. I mean glysophate has been a herbicide choice since long before roundup ready crops came along, did you know that? Of course you did. Wouldn’t we by now be seeing dropoffs in yield and livestock owners noting poor performance in livestock growth. Producers monitor nutrient content closely since it is necessary to balance rations. A serious dropoff in nutrient composition of feed crops would be noticed.

    One of the advantages of glysophate is that it does bind tightly with soil minerals and surface crop residuel. This reduces opportunity for runoff as well as limits uptake through the roots. One of the reasons glysophate has been popular to producers is its low residual presence because of its relative quick degradation in the soil, thus being less limiting to crop rotation choices.

    Not sure why its taken Dr Huber’s letter alerting to issues similar to Steve’s allegations to make its way into the foodie literature, but now that it is, we can look forward to all kinds of embellishment, doomsday scaremongering. In his letter, Dr. Huber promised data and evidence. Actually, I would welcome him publishing something since it would be something to take seriously if there is anything to it. I’m surprised, Dr. Huber’s letter was two years ago and if this is the crisis that Steve in his superior ethic and intellect has so eloquently chastised the author about, one would think that the information would have been presented by now. I don’t think he has published anything yet since if the alarming concerns he raised were verified, it wouls have been the top ag story of the year. Has Dr. Huber produced anything yet.

    Meanwhile, farmers are harvesting again, so plants seemed to have suvived another year of chelation. Steve, you bring up what would be a serious topic if there was compelling evidenceit that glysophates binding qualities did indeed have the consequences you list. But at this point, it is only a theory, and one which appears to contradict real world evidence of increasing crop yields and increasing efficiency in livestock rates of gain.
    Its unfortunate you chose not to raise it in a serious manner. If you feel I am disrespectful of you, you reaped what you sowed.

    • Stefan

      A serious dropoff in nutrient composition has been noticed. Nutriotional values are now 40% of what they were before WW2. Yields have been continually dropping as well, compared to how much input is used: the bulk has increased, efficiency has decreased. GMO crops, glyphosates and having to use expensive fertilizer to get anything to grow when being forced to use them has driven thousands of farmes to commit suicide because they couldn’t get a decent yield and saw no way of going on.

      It’s also been shown that -unlike claimed- glysophates don’t degrade quickly; in reality they are still found in groundwater months later, while it’s being claimed they couldn’t even get into groundwater because they degrade so fast.

      The information has been presented but has to compete with intens lobbying from glyphosate and GMO producing companies. It is not a theory, it has been proven repeatedly for years. Just because you can get a yield by putting more and more energy in doesn’t mean that yield contradicts the fact that it’s harder to grow it. We are currently putting 10 calories of energy in the form of tilling and fertelizers into the growth of crops for each calory we get out. It’s all driven by oil.

  • Sjoerd

    Hi Anastasia, it seems that you really like glysophate. That’s a good thing, especially for the producer… However besides that whole soil ecosystems are affected, next to plants (bacteria, fungi), G also affects our own gut microbiota. The bacteria in our system represent 10x more cells and 100x more genes. Without these bacteria, our immune system malfunctions and a lot of food cannot be processed by ourselves. Because these bacteria share the same shikimate pathway that is targeted by G, it would be very interesting to see the effect on our gut populations, especially long term. Since a lot of diseases (like diabetes, Crowns disease, obesities, etc.) are recently correlated with specific types of bacteria in our gut for example, I would not be surprised if the intake of G severely influences our little friends.
    Editor’s Note: the last sentence of this comment was removed to restore civility.

    • EJ Blom


      Do you have a reliable citation for your claim that G affects gut microbes? Seems to me that the concentration of G in your gut will not reach a concentration that is high enough to have an effect. There is only “paper” that I could find on this subject:
      However, this paper doesn’t contain any actual research, just a bunch of speculative ideas and thoughts.

    • I wouldn’t say I “really like glyphosate”. I do think, based on the available evidence, that glyphosate is far more environmentally benign than other herbicides, and that herbicides can be really important in increasing yields so that we don’t need to use more land to produce the same amount of food. However, glyphosate, like all other pesticides should be used in moderation as part of an Integrated Pest Management plan.

      If you have any research showing the effect of glyphosate on gut bacteria, or an association between glyphosate and any diseases, I’d be happy to read it – but you have to keep in mind that there is very very little glyphosate in our food. It may be detectable, but that’s only because we have some amazingly sensitive detection methods.

      • Sjoerd

        Little glyphosate in our food is not a guarantee that we are little exposed! Ground water pollutions with G can also cause a major intake via our drinking water. Water companies in NL only spend millions per year trying to remove only G and its degradation products. And since G is not only used as a weed killer for food production, there are other routes with which we can take up G. A recent study covering 182 urine samples (all city-dwellers) from 18 EU countries has shown that concentrations up to 1,8 ug/L glyphosate and 2,6 ug/L AMPA have been found (see It may not be a lot, but it can be higher in other parts of our body, and we cannot exclude that little concentration have significant effects on our delicate gut populations. Since only very recently the importance and the total composition of our microbial gut communities have been shown, and I would be surprised if researchers have specifically focused on G. However, I do think that we should investigate this further and I hope that the reviews that you have cited in this article (although most of the authors of these papers have worked for/at Monsanto, which does sound a bit suspicious), reflect the truth about G…

  • Hey man, all this talk of chelation just gave me a groovy idea. Chelation therapy using glyphosate! (Yeah, chelation therapy is a real thing… in alternative medicine:

  • Mlema

    here’s an interesting article on “The fate of transgenes in the human gut”

    apparently our friendly microbes are capable of acquiring and harboring DNA sequences
    from GM plants. Trans-kingdom gene flow!

    I know this post is about glycosphate, but continuing on the subject of safety: Chinese scientists have found environmental microbes (in rivers) contaminated with synthetic plasmid vector-sourced antibiotic resistance genes. These synthetic plasmid vectors are tools used in genetic engineering. And the scientists traced genetic engineering as the source of these contaminants. So: looks like GMOs are helping to create antibiotic resistance bacteria.

    • Oh crap! So that means that our gut bacteria are busy picking up all kinds of genes from all the food we eat. And each other. Shock horror!

      Um, plasmids and the antibiotic resistance genes they (sometimes) contain originally come from bacteria. As long as you’re using a natural antibiotic (or a closely related synthetic analog), there will be a bacterium out there with the resistance gene to match it. And that Chinese paper is a mess generally. Selection pressure through antibiotic use by human – or microbes (I’m looking at you, Penicillium) is what causes antibiotic resistance. Nothing to see here.

    • I’ve looked at the issue of antibiotic resistant gene flow from GE plants to bacteria before (, and there doesn’t seem to be any evidence that this is happening at any detectable level. Antibiotic resistance genes are widespread in the environment already in many different types of bacteria (after all, most antibiotics are produced by bacteria to kill other bacteria so the “victims” evolve resistance), and it’s way easier for two bacteria to swap genes than to get a gene from a plant. And the antibiotics used in plant transformation (in my experience, kanamycin is most often used) are not used in human medicine. Nonetheless, researchers are moving away from using antibiotic resistance markers to other markers, and/or breeding the markers out so they aren’t present in the final product.

      The first paper you cite (actually you cite a letter about the paper, the actual paper is here may show that bacteria in our guts can pick up DNA from GE foods (although this is contradicted by a lot of other research, as mentioned in the letter you shared), but if that is true, it means the bacteria could pick up non GE DNA too. Since many plants have virus DNA in their own genomes, and our food can be contaminated with bacteria, viruses, insects, and parasites, I’m much more concerned about naturally occurring genes than one EPSPS gene. But, since we’ve been eating food since we crawled out of the primordial soup, I’m honestly not worried about it. When there’s evidence of actual harm, let’s talk. Until then, this is just mildly interesting.

      The second paper you cite is about bacteria picking up genes from plasmids in GE bacteria, not genes from GE plants. I agree that bioreactors should be closed from the environment to prevent escape of bacteria (but that’s true whether they are GE or not).

      Your other questions are interesting, but diverge waaayyy from the topic of this post. So I’d appreciate it if you’d ask them in the Forum ( so this conversation doesn’t get too mixed up to follow.

  • Mlema

    re: the safety of glyphosate in particular, since it’s so widely used, and since farmers seem to be putting a lot more of it on their crops than they’re supposed to, and since it’s an endocrine disrupter – I think I’ll just eat organic in hopes of avoiding it :)

    • EJ Blom

      Well, you might want to reconsider that, organic farming doesn’t necessary imply that they don’t use pesticides. You might want to read some more:

    • The use of pesticides is regulated by the EPA, and there can be fines if someone is found to be misusing or using too much. Still, we know that the EPA can’t be everywhere so maybe there is overuse happening. But then we can rely on post-harvest monitoring of pesticide residues (mentioned in this post) that find the grand majority of products to be well under the science-based tolerance set by the EPA. So, no worries, your food does not contain harmful amounts of pesticides (well, at least if it’s conventional, I haven’t seen much testing of organic foods or organic pesticides).

      As for the status of glyphosate as an endocrine disrupter, there have been a few studies claiming such, but as I mentioned in this post we can find studies claiming just about anything. There are far more studies that have not found such an effect.

      • Mlema

        Sorry, I must be confused. I saw Pamela Ronalds’s post here:
        “#16 The liberal use of glyphosate without proper management has spurred the evolution of weeds resistant to that herbicide.”
        which linked to this:

        Knowing also that RR pigweed has become a serious problem in the south, and having read that farmers were increasing their use due to resistance in general, I figured that overuse must be happening.

        Also, A meta-study out of Newcastle University concluded that organic food has less pesticide residue. True, no way to know if the ones that were used were more or less toxic. Biofortified should look into that! It would be something useful to know for those with compromised health, who might be sensitive or negatively affected by pesticide residue of either kind on their food. Thanks!

        • The issue is the overreliance on glysophate/roundup as a weed management tool that amplified selection pressure for weeds resistant to glysophate. Overuse in terms of application rates is an entirely different issue. Too low of rates of application in individual applications can also contribute to the speed at which weed populations resistant to the treatment emerge. I suspect that has been a contributing factor with glysophate as well.

          You will find a lot of agreement among farmers and agronomists that the mistake is not incorporating glysophate tolerant crops as a component of an integrated weed management strategy, but rather the overreliance on glysophate in too many situations as a substitute for integrated weed management. Again, it is not the concept of herbicide tolerance, it is how it is utilized. I know it is a favorite theme of anti-gmo literature to claim that biotech traits commercially available thus far encourage monoculture, i.e. an abandonment of crop rotations and diversity of plantings, particularly when it leads to extreme concentration of production of one type of crop in a region over time. I dispute that the introduction of crops with traits added by genetic engineering contributes in any significant amount to monoculture practices. That issue preceded introduction of biotech traits, and factors that contribute to that phenomenon would likely continue if ge technology was abandoned. That production of certain crops tend to have regional concentrations and that individual farms tend to specialize in certain crops has as much to do with availability of markets and transportation and storage technologies that enable foodstuffs to be moved long distance efficiently has encouraged concentrations of production in areas most suitable for production of particular crops. The versatility of uses for certain crops like corn and soybeans for non food uses also has created greater market signals encouraging production of those crops. One of the potential benefits of biotech is that it may be one development that actually helps reverse the trend of monoculture by making greater crop diversity even more feasilble. Here are some examples of how glysophate tolerance has encouraged and facilitated expanding cropping rotations. [;;;,;]

          It would also be a mistake to assume abandonment of glysophate and herbicide tolerant genetics inherently or necessarily means a return or transition to some utopian ideal. There will be tradeoffs as Pam Ronald notes in the article you cited: —

          “Still, glyphosate-tolerant plants could be considered victims of their own success. Farmers had historically used multiple herbicides, which slowed the development of resistance. They also controlled weeds through ploughing and tilling — practices that deplete topsoil and release carbon dioxide, but do not encourage resistance. The GM crops allowed growers to rely almost entirely on glyphosate, which is less toxic than many other chemicals and kills a broad range of weeds without ploughing.”

          • Mlema

            thanks Rickinreallife, I don’t disagree with what you’re saying. We have to keep in mind that the way farming is done in this country is driven also by the structure of federal subsidies, which tend to support monoculture. in order for farmers to shift to more diverse plantings and integrated pest management, they might need financial support because they won’t immediately see return and it’s more labor intensive. The reason I personally would support this shift is that without it we just see a continuing increase in the toxicity of pesticides. And, as I said, there are those who wish to avoid this as much as possible for health reasons. We know these pesticides are contra-indicated for the healthy development of children.

            • Mlema

              Did you know that technology contracts (like those signed by farmers who buy seeds from Monsanto) can restrict the kind of planting done?
              They include things like:
              “To use seeds containing Monsanto Technologies solely for planting a single commercial crop.”

              • Charles M. Rader

                Mlema, the agreement you posted doesn’t prevent the farmer from planting a mixture of several different crops. It doesn’t promote monoculture. The only way I see the agreement controlling the farmer’s methodology is in requiring the farmer to use the refuge strategy to delay or prevent the evolution of resistance to Bt. Most of the agreement is about protecting the patent rights.

              • Have you read more from that farmer who actually posted that tech agreement? Brian talks a lot about his farm–where he plants many kinds of seeds. Some of them are GMO, some are not. Because he can.


                If you need to talk with him about his options he’s available quite a lot on his blog and on twitter. I’m glad you’ve found his site though, maybe you can learn something.

                • Mlema

                  Yes Mary! I have enjoyed Brian’s site more than once. There was a discussion on peanut butter that was fun. I hope you’ll find a place to learn something too. :)

              • Ewan R

                I’m pretty sure that the pharse “to use seeds containign Monsanto Technologies solely for planting a single commercial crop.” in this instance means – you may only use this bag of seed to plant a crop this year, you may not save this bag of seed across multiple plantings.

                The reasoning behind this, as far as I recall, is that the value of a given trait varies season to season, and seed is priced accordingly (based on a value share model) – thus in a year/area with spectacularly low insect pressure IR traits will cost less than in years/areas with high insect pressure, thus, in order to do a fair value share you are restricted to planting the bag of seed you buy specifically for the area/time you bought it.

                It’s a pretty convoluted system, but one that works out being pretty fair (it basically allows the value share system to operate at all – without such clauses all traits would cost the same regardless of geography) while sadly, at the same time, appearing scary from a legal stance.

  • Mlema

    Hi EJ,

    do you know if they use endocrine disruptors?
    I know large, industrial organic farms have many of the same problems as non-organic ones. The practices that allow for long-term reduction in pesticides aren’t encouraged in big farms.

    So, gotta go organic AND local. Wow, gets hard to avoid the poison! :)
    Too bad the US farm subsidies don’t support better agro-science. It’s really expensive and laborious to have a non-industrial organic farm. And that makes the food cost more!

  • Jaime Costa

    Very good review, but on the tolerance issue, instead of “These tolerances are hundreds of times higher than estimated toxic values” I think you meant “These tolerances are hundreds of times lower than estimated toxic values”.

  • greg meyerson

    I’d like to compliment Mlema. M is skeptical (in the best sense of the word) of some of the claims made around glyphosate and GE and when good arguments are made in response to M’s skepticism, M listens and seems to accept the counterarguments.

    Is big necessarily bad, M? or are you confusing size with the profit imperative often accompanying big farms?

    I like Rick’s post above. Herbicide tolerance does not favor monoculture necessarily. in the same way, it seems that monoculture and size are not necessarily connected.

    • Mlema

      greg meyerson. Thank you and I agree with your viewpoint on size. Big isn’t necessarily bad. Small isn’t necessarily good. I believe that agricultural scientists have a good understanding of the best ways to manage pests, but that science isn’t as sexy or profitable as transgenics. The USDA has determined that, for farmers overall, the returns on the RR and bt technology are mixed:

      “Perhaps the biggest issue raised by these results is how to explain the rapid adoption of GE crops when farm financial impacts appear to be mixed or even negative. Both herbicide-tolerant cotton and Bt cotton showed positive economic results, so rapid growth in adoption is not surprising in these cases. However, since adoption of herbicide-tolerant corn appears to improve farm financial performance among specialized corn farms, why is its adoption relatively low? Even more puzzling, the adoption of herbicide-tolerant soybeans and Bt corn has been rapid, even though we could not find positive financial impacts in either the field-level nor the whole-farm analysis.”,d.aWc

      That study is a bit old, and what we see is that the GE crop that proved the most financially successful for farmers (bt cotton)is now contending with glyphosate resistant pigweed – a very difficult problem due to the plants prodigious reproductive capabilities.

      IMHO, we must implement those integrated pest management systems that have proven to be effective and relatively safe. They tend to be more labor intensive. My hope is that our federal budget will transform in recognition of the importance of sustainability. Right now the bulk of taxpayer-funded subsidies go to commodity corn, soy and cotton (hence the development of bt and RR traits in these crops to capitalize on the patented technology)

      • William Petersen

        For why farmers in Wisconsin use gmo corn, see
        The traits are used more as an insurance policy against losses than as a gain. Also, those that have switched to no-tillage or low tillage have reduced the need for large horsepower tractors and the fuel and time to make multiple tillage passes. Ease of operation is a plus. I know a farmer that works full time off the farm. He takes 2 weeks off in the spring to plant and 2 weeks off in the fall to harvest. 483 acres, run part time, in what used to be run by his father and the three sons. The full time job provides health benefits and stable income while the part time farm operation, depending on the year, provides profit or tax breaks.

        • Mlema

          Interesting! I think it does continue to be the case (as is noted in the USDA paper) that these crops are used best in regions where their cost is appropriate to the benefit (the “insurance” use is discussed). Unfortunately, resistance inevitably develops, and the expense of continually developing new transgenics (and the unknown environmental effects of each new round) mean increasing dependency on a model that can’t be sustained. With a shift in what we economically support, this farmer could hire many people and his land could be diversified and more likely to produce without increasing inputs in perpetuity. Did the farmer desire to work separate from his farm? The farm provides “profit or tax breaks” – I can’t tell from this whether or not this farmer is able to simply live by being a farmer, or make profit by being a farmer. As I mentioned in my remark above, currently our federal farm bill supports large-scale monocropping of corn, soy and cotton. This isn’t necessarily bad for an individual farmer as long as he can sustain his farm in this way. But there are questions about whether sustainability is promoted with transgenics.

  • Paul

    If glyphosate can kill certain plant diseases isn’t it also true that it can promote certain plant diseases as well?

  • Forgive me if this has already been addressed in a previous comment as I haven’t read them all.

    I agree that glyphosate is toxic, and also not usually present in high enough doses to be a problem as a typical toxin, as “the dose makes the poison.”

    What does scare me is the potential for glyphosate to be an endocrine disruptor. The paper you cited “Glyphosate induces human breast cancer cells growth via estrogen receptors” seems to indicate a potential mechanism for glyphosate to operate as a xenoestrogen in very low concentrations. Now it could be that this is bad science, as you seemed to indicate. But I think it is reasonable to be concerned about the possibility and at least be interested in further studies. Xenoestrogens are certainly a problem in our environment and may be contributing to breast cancer growth as well as various health problems having to do with hormone disruption, and pose a novel challenge due to violating the standard dose/response curves of toxicology (see ).

    That is a very interesting counter study though about inhibiting cancer growth, although since it doesn’t appear to cover the topic of glyphosate possibly functioning as a xenoestrogen, it doesn’t allay my concerns so much as simply present different evidence.

  • William Petersen

    Duff, What evidence is there that glyphosate is an endocrine disruptor? At what levels compared to the Maximum Residue level allowed in crops and food, or the expected level of exposure?

    Soybeans have estrogen like compounds and the story is still being figured out for their association with cancer. See

    Opponents to gmos and the use of glyphosate used to like to cite the now withdrawn Seralini paper. If one looks carefully at the data presented, one will see that the male rats which drank glyphosate, had less cancer than the control group of rats not exposed to glyphosate. I would say that trying to link glyphosate to being an endocrine disruptor, and that the levels of exposure are some how harmful, without real evidence is just speculation at best, and a scare tactic at worse.

  • Michael

    Nice article Anastasia,

    Always refreshing to read from someone who is well versed in the scientific method. Considering the title of your article, I am surprised to see that there is no reference to the studies that may indicate that G may be teratogenic. For example:

    But of course we all know that the dose makes the toxin and the amounts they used (around a 1:5,000 ratio) I assume correlates to 0.2 mg/L, which is many magnitude more than the levels found in human urine according to an above linked study in the comments (1.8 ug/L = about 1,000 x less concentrated).

    Just wondering if you have come across any studies addressing this issue as it is a hot topic in many parts of latin America.

    • Chris Preston

      Michael, not only are the concentrations use unrealistic in terms of exposure, the researchers injected formulated herbicide into chicken eggs. Mammalian embryos will never be exposed to formulated herbicide, which contains surfactants as well as the active ingredient. Frog embryos might be exposed, but not to the herbicide formulation used because that formulation cannot be used near waterways.

      • Michael

        Cheers for your input Chris,

        I am just wondering why you are able to state that mammalian embryos will never be exposed to formulated herbicide, or what the difference is between formulate herbicide and glyphosphate.

        Also you say the concentrations used in the above study are unrealistic. Not saying that I doubt you but my healthy skepticism would appreciate some documentation/studies that have looked at serum levels of glyphosphate in agricultural farmers/fruit consumers etc (all my search results have only found patients that have tried to overdose on it). I assume you have some applicable information due to your claim and am wondering if you could be kind enough to share it.

        Also worth noting that glyphosphate is able to penetrate human placentas (albeit quite weakly at around 15% penetration)

        Some minor epidemiological studies have shown higher levels of birth defects in children of pesticide sprayers which is probably at the very least worth further investigation.

        Unfortunately I have been unable to come across enough information that generates a significant concern (a few isolated studies IMO are not enough hard evidence to generate significant concern). Hence why I am here as I figured that people like yourself may be more well versed in the current scientific studies and therefore could direct me to them!

        Cheers for your time!

        • Chris Preston

          Michael, formulated glyphosate herbicide contains the active ingredient (glyphosate) as well as other compounds. The most important of these for toxicity are the surfactants (polyoxyethyleneamine). These are best compared to detergents and at high enough concentrations they will damage cells. Once the herbicide has been sprayed, the herbicide is taken up by the plant, but the surfactant remains on the leaf surface.

          So considering exposures, the only way that internal tissues will be exposed to the surfactant is if someone swallows the formulated herbicide. Even then, most of the surfactant is quickly removed in urine and faeces. Therefore, the chances of embyos being exposed to formulated herbicides is virtually nil, unless the formulate dherbicide was to be injected into the embryo – as was done here.

          Information about serum concentrations of glyphosate is hard to find, because of its short residence time. This paper measured serum concentrations in someone who swallowed 400 mL of formulated product and had 6 mg/L of glyphosate. Another paper here where someone swallowed about 500 mL of a formulated product and had 5 mmol/L glyphosate.

          This paper will give you an idea of concentrations likely in farmers and their families It only measures in urine, but you can see the concentrations are orders of magnitude smaller.

          And some more summarised here

    • is not a good source of information. Much of it is wrong, twisted, or outright fabricated. In the video on that page, skip to the 28 minute mark and you will see that Seneff has declared her belief that glyphosate is so powerful that it causes school shootings and the Boston Bombing. We just passed the 1 year anniversary of that horrific event. Think about how callous and utterly wrong it is to use an event like that for political purposes and to misrepresent science in that process. The same evidence led her to conclude that Glyphosate caused the Boston Bombings as it did to her conclusion that glyphosate causes every major human disease – and that would be zero evidence.

    • Chris Preston

      It seems they used an ELISA assay tests developed for glyphosate in water that is not suitable for fluids like blood and milk. So there is nothing to be made of the results.

      • Ben Hadd

        If you were credible you would have checked out your facts before you spoke. May I suggest you call Ben and ask him how he did the test so that you don’t flub up again. I saw these type of posters and web forums during the election, and as soon as Obama got elected they were gone. From the looks of this website, I’d say there is someones finanical interest at stake.

  • Joel Starr

    There is an interview with Dr. Stephanie Seneff about a peer-reviewed report by retired scientist Anthony Samsel (a consultant and retired scientist). The report is entitled Monsanto’s Roundup herbicide May Be the Most Important Factor in Development of Autism and Other Chronic Diseases.

    • Chris Preston

      Joel, Stephanie Seneff is a computer scientist. Sadly she doesn’t understand the first thing about human diseases, but that doesn’t stop her publishing on them in her own special issue of the journal Entropy. Anthony Samsel was not an active scientist. He worked for the management consultancy firm Arthur D. Little. His background is in chemistry. He also knows nothing about human diseases. But yet again that doesn’t stop him publishing papers in Entropy with Stephanie Seneff on diseases.

      One interesting aspect of this whole charade is that Seneff has published a paper claiming autism is caused by vaccines (something that was well and truely debunked years ago) and almost immediately publishes one with Samsel claiming autism (and every other human disease) is caused by glyphosate. Both papers cannot be true.

      If you are interested in a debunk of Samsel and Seneff’s effort, I am happy to put the work in.

      • Ben Hadd

        I saw how you brushed off Stephanie as a “computer scientist” to discredit her from knowing anything about diseases. You might want to include all of her credentials. I see a common theme by the board members to quickly douse the fire, so that they can demeanor anyone with credible evidence against GMO’s.

        • Chris Preston

          Ben, I mentioned that Stephanie Seneff was a computer scientist, because she was described as Dr Seneff and people might have confused her as a medical doctor. That doesn’t discredit her from knowning anything about human diseases: it is her own writings that do that. I could go into a long description of her cherry-picking evidence, confusing correlation with causation and a host of other errors she makes, including getting the main symptoms of diseases wrong, but the best evidence for her lack of knowledge is she published several papers in the same journal issue claiming variously that aluminium, cholesterol sulfate deficiency, vaccines, acetaminophen and glyphosate were the main cause for autism. A quick review of the literature would have identified the fact that autism has a strong heritability component.

  • Joel Starr

    Chris, I just now talked to Ben Winkler at Microbe Inotech Laboratories that did the testing for glyphosate in breast milk. He said their test is valid on breast milk and “you can take that to the bank” he said. They have also found glyphosate in urine samples in the USA. Maybe you were thinking about another test. This can’t be good news.

  • Ben Hadd

    I’m curious why Chris Preston would lie about the test. It always seems people that promote GMO’s have a financial interest in them. I’ve been in the seed business all my life and farmers are starting to realize that they were duped with promises from the chemical industry. Their interest now seem to be about non-gmo crops and getting premiums for them. Their starting to learn that roundup doesn’t dissapear when it hits the ground and its showing up in everything we eat and drink. And worst yet its it womens breast milk. How you “in the know” people can cover up something like that for your personal gain is beyond me. The word is getting around the ag community, and I think its long over due.

    • As Karl stated above, please refrain from making claims about financial interests of people when you have no proof. You can find Biology Fortified’s financial information on our about pages.

      If you would like to contribute to the conversation, please provide reliable science-based citations to back up your claims.

  • Tom

    The glyphosate also shows up in high levels in city sludge. Allot of times its over the EPA limits. Basically it comes in the food and gets passed down the sewer. Its not surprising that it shows up in breast milk and urine.

  • Ben Hadd

    At what levels is G safe for infants? and how did it get in the milk?

    • We first have to show that it actually did get into breast milk, which hasn’t happened yet. Unfortunately the group who had the testing done is not reliable, and their methods, results, and conclusions haven’t been scientifically vetted at all.
      As for safety, that’s what this post was about and you are welcome to read the post and follow the links for more information.

  • Joel Starr

    How will high levels of roundup in breast milk affect the developing infants brain. Where are the studies? DDT was considered totally safe by the same people saying Roundup is safe. Microbe Inotech Laboratories have their own beliefs on what the results will be.

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