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Points To Consider: Unfounded Claims of Glyphosate Accumulation in Breast Milk


Original Sources:  Press Release: “Glyphosate Testing Full Report: Findings in American Mothers’ Breast Milk, Urine and Water,” Mom’s Across America; Article: “World’s Number 1 Herbicide Discovered in U.S. Mothers’ Breast Milk” by Zen Honeycutt and Henry Rowlands, Sustainable Pulse

Primary Claims:

  • “In the first ever testing on glyphosate herbicide in the breast milk of American women… found ‘high’ levels in 3 out of the 10 samples tested. The shocking results point to glyphosate levels building up in women’s bodies over a period of time, which has until now been refuted by both global regulatory authorities and the biotech industry.”
  • “The levels found in the breast milk testing of 76 ug/l to 166 ug/l are 760 to 1600 times higher than the European Drinking Water Directive allows for individual pesticides (Glyphosate is both a pesticide and herbicide). They are however less than the 700 ug/l maximum contaminant level (MCL) for glyphosate in the U.S., which was decided upon by the U.S. Environmental Protection Agency (EPA) based on the now seemingly false premise that glyphosate was not bio-accumulative.”

Salient Facts and Context:  

  • This “study” is not a study, but a press release from two professional opponents of agricultural biotechnology.
  • The “paper” presents a handful of dubious data points accompanied by numerous claims that are unsupported by credible data and contradicted by the scientific literature and experience.
  • There was no scientific peer review.
  • The description of the methods used is minimal, sufficient only to dismiss the claims as being unreliable, at best.
  • The sampling technique, study design, sample size, use of appropriate controls, and other experimental design parameters all fall short of what would be expected from a High School science fair project.
  • According to the press release, the “study” was “not meant to be a full scientific study. Instead it was set up to inspire and initiate full peer-reviewed scientific studies on glyphosate.”
  • These activist claims avoid any mention of the vast number of peer-reviewed scientific studies that have already been conducted on glyphosate, documented by, among others, the European Union and the World Health Organization and corroborated by extensive real world experience  by the stewards of farmlands and landscapes around the world.

Published Analysis/Rebuttal:

This press release has been specifically discredited by multiple expert sources:


This propaganda salvo is a vehicle for claims, insinuations and innuendo that are abundantly contradicted by a mass of scientific literature and a vast body of real world experience by the stewards of farmlands and landscapes around the world.  Rather than providing the extensive corrections a full rebuttal would require, we will focus on a few salient issues that provide an overall indication of the reliability of the claims made.

Safety:  The safety of glyphosate, when used as directed, is not in question. It is inarguably safer than many of the older generation of weed control measures it has replaced. Recent reviews summarized the literature on glyphosate and human safety:

Epidemiologic studies of glyphosate and non-cancer health outcomes: a review (2011).

Epidemiologic studies of glyphosate and cancer (2012) and

Developmental and reproductive outcomes in humans and animals after glyphosate exposure: a critical analysis.

All of these confirm the longstanding findings of glyphosate’s safety to humans.

Claims of Bioaccumulation: Even if the findings claimed are repeatable, they confirm what has long been known: that glyphosate is rapidly eliminated from the body. This is the opposite of bioaccumulation, and nothing presented suggests any reason to reconsider the well founded understanding that glyphosate does not bioaccumulate. Three (allegedly) positive data points from a total of ten do not make a credible data set.

It is conspicuous that the map provided in the original press release shows an inverse correlation between the claimed detections of glyphosate in breast milk and the areas of the country where glyphosate is used more heavily in agriculture. This observation is not consistent with the claims that increased use is responsible for the reported results.

Parties interested in further considerations cannot do better than to review the analysis by Dr. Bruce Chassy . An excerpt is below.

“The results reported are not consistent with US data on glyphosate in human subjects, and at face value raise a number of questions.  Glyphosate is rapidly excreted primarily in the urine and there is no data to indicate that it accumulates in fluids such as breast milk or serum or in tissues.  Glyphosate is often not detected in urine**, and when it is observed urine values are usually about 10-fold higher than serum values since it is efficiently excreted.  Since glyphosate is not fat soluble, serum and breast milk values would be expected to be very similar which is not the case with the data reported for the 10 breast milk samples that were analyzed.  Why breast milk samples would have an uncharacteristically and unexpectedly high content of glyphosate relative to serum and urine values is open to question but sample contamination and/or unreliability of assay are plausible explanations.

The finding that 3 or the 10 samples had “high” levels of glyphosate is misleading in two ways.  Firstly, high in this case means measurable above the lower limit of detection rather than high meaning a cause for alarm.  The highest of these 3 samples, if real, contained glyphosate at levels that represent a worst-case infant exposure (33 ug/kg/day) more than 50-fold below the ADI (Acceptable Daily Intake) set by US EPA regulatory toxicologists (1750 ug/kg).  The ADI is set to provide a wide margin of safety of exposure.

The US Centers for Disease Control and Prevention note, “Just because we can detect levels of an environmental chemical in a person’s blood or urine does not necessarily mean that the chemical will cause effects or disease. Advances in analytical chemistry enable us to measure low levels of environmental chemicals in people, but separate studies of varying levels of exposure determine whether specific levels cause health effects.”  Food naturally contains a wide-array of potentially toxic chemicals such as cyanide, strychnine, carototoxin, and arsenic but they are usually present at levels that do no harm.  Any chemical, whether natural or human-made can hurt us if we consume too much of it.  Even table salt or iron can kill if too much is consumed.  The mere presence of glyphosate in serum, urine or mother’s milk is not a cause for alarm unless the levels are above those known to do harm.  Over 4 decades of research studies and real-world use, including studies on large numbers of people who have been exposed to glyphosate, have allowed regulators to understand and set safe levels of exposure.  Research has also established that the low levels of glyphosate sometimes found in bodily fluids pose no threat to health.  WHO, EFSA, EPA and other regulatory agencies around the globe have concluded that trace levels of glyphosate in food should be of no more health concern than the presence of myriad potentially toxic chemicals that occur naturally in food.”


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  • Excellent article, Val. The momsacrossamerica report is not a research study designed for scientific consideration: it is a propaganda piece designed to alarm an uneducated audience. From the buzz it received on the Internet, the report seems to have done its job. I particularly like your comparison with a high school science fair project: I cannot think of any practicing research biologist who would design a study like this (with perhaps one exception…).

  • Lisbeth

    This article was written by Monsanto. Any time you see those condescending “” quotes around words like “study” and “paper” you’re not dealing with anything scientific. If any scientist worth their weight looked at the available data they would see that all the studies people are directed to are the ones conducted by Monsanto themselves, or an associate publication or prominent slave of theirs.

    If you think a multibillion dollar company isn’t going to spend millions to defend their flagship product by any means necessary, think again. And do your own research. Do not trust these bloggers.

  • Lisbeth

    How about the 27 Monsanto studies that appear over and over, which are utterly pathetic in their transparent attempt to get the result they want. But sure, all the studies that say “bad” are wrong, and the ones that say “safe” are right. Anyone can see through this transparent gaslighting.

    Meanwhile the poisoning of an entire population is at stake, and you disgraceful types can’t even be bothered to pay attention to what you’re reading.

  • Is there a specific scientific study you would like to discuss? I’d welcome the opportunity.

    BTW there is no obvious reason why traces of glyphosate SHOULDN’T be found in human milk (just like any other substance we consume). It wasn’t detected cow’s milk, but it wouldn’t surprise me if more sensitive tests are developed in future years.

  • anthony samsel

    Daily low dose intake levels of glyphosate give the highest bioaccumulations. A Monsanto Trade Secret Study from 1988 shows glyphosate does bioaccumulate in the bones and tissues. The study: The Metabolism of Glyphosate in Sprague-Dawley Rats Part I and Part II show based on a 10 mg/kg dose /day that the oral absorption of glyphosate for males and female was 30.3% and 35.4% with a beta half-life of radio-labeled glyphosate at 7-1/2 days for males and 14 days for females. The highest accumulations were in the bone with 0.748 ppm and 0.462 ppm for males and females respectively in group six animals. Group 5 animals at 10mg/kg/day were 0.552 ppm and 0.313 ppm respectively. The males also had higher levels of glyphosate in the blood.

    The study document states: “A significantly greater percentage of the dose remained in the organs and tissues and residual carcasses for the males than for the females. Overall recoveries for group 5 (10mg/kg/day) were92.8 and 94.2 for males and females respectively.” Glyphosate was found in the bone marrow, all major glands including the thyroid, thymus, adrenals, mammaries and testes as well as all major organs i.e. heart, liver, kidneys, spleen, lungs and …..
    Its time the folks at Monsanto got their own facts straight……

  • Hi Anthony,

    Can you give us more detail about the “secret” document that you reviewed (author, date, title, etc.) It sounds rather similar to to the paper by Brewster:
    I was puzzled by your statement about bioaccumulation: do you have evidence for a long-term increase in glyphosate levels? The beta elimination half life in rats is only a few hours, not months or years:

    Perhaps I missed the point that you were trying to make?

  • anthony samsel

    Hi Peter, I have all of the Monsanto sealed studies which were submitted to the US EPA which I have been reviewing. The Monsanto in-house study conducted in 1988 title: Metabolism in Sprague-Dawley rats Vol. 1 by Ridley and Mirly with Vol.2 by Howe, Chott and McClanahan give a nicer presentation of the facts than the two PubMed articles. They show absorption and Beta half -life between 30.3 in 7-1/2 days to 35.4 % in 14 days, for males and females respectively. So residual glyphosate continues to circulate in blood, cerebrospinal fluid and lymph. Bioaccumulation is shown 1% and greater in bone and marrow along with all major glands and organs. There were a number of metabolites in the dose solutions given the animals, but mainly AMPA was the metabolite detected in the urine and feces. This does not negate the fact that the carcinogen N-Nitrosoglyphosate was also present in fractional % quantity. Interesting they found N-Nitrosoglyphosate increases by reaction to nitrites and herein lies a serious problem in human and animal biology.

  • Michael McCarthy

    It seems Anthony accidentally posted a reply but not directly to you. An oversight on his part, I am sure.

    I also note that he refers to it as a trade secret study, but it was actually just unpublished (it was submitted to the WHO).

  • Michael, thanks for the link to the German glyphosate report!

  • Hi Lisbeth — Did you see the link left by Michael McCarthy on German regulatory data, elsewhere on this thread:

    You may also want to look at the EPA data for cows’milk:

    From your comment, am I correct in assuming that you are a scientist? If so I’d be interested in hearing your interpretation of the data.

    (I agree with you that it is phenomenally expensive to perform high quality research data to satisfy the regulatory authorities. This is one of the reasons that there are few small companies developing new pesticides.)

  • Michael McCarthy

    No problem. Hope it helps!

  • SageThinker

    Indeed, the EPA report does appear to report no glyphosate found in cow’s milk even with 400 ppm in feed for 28 days. I’d like to see the underlying research reports. Can one write, under Freedom of Information, to the EPA, and request the referenced studies?

  • Lisbeth


    Thanks. I wouldn’t take the EPA as fact. They have proven to be unreliable and subjective about science when profit is involved.

    The issue is not complicated. The action of glyphosate is to destroy the digestive systems of insects.
    That anyone did not consider the similarities in digestive breakdown protein cycles among all living things (including humans), and not expect this to be a contentious point, is beyond me.

    Monsanto’s principal argument is this: “There are so many pesticides and other chemicals out there, how do you know which one is allegedly causing a disease epidemic?”

    Sadly this argument is enough to keep regulatory bodies and governments confused enough to keep waving them through.

    There is endless literature on the biological changes caused by exposure to glyphosate in all kinds of living things. This makes Monsanto’s position null and void, since they state unequivocally that it does not affect humans.

    The larger picture tells the human story, which consists of desperation, corruption, intimidation, propaganda, scientific misconduct etc etc.

    But you know what? It’s their problem. They can keep on doing what they are doing and it won’t make a difference what the millions of people consuming their product each day say. In the end, history WILL discover the answer, and history WILL tell whether they gave enough of a hoot to do anything about it.

  • Lisbeth

    There is a Danish and German study which provided the actual data, not this garbage from the EPA. Do you think the EPA puts human health in front of profits? Do you think the EPA is an unbiased or democratic agency? God no.

    This is a fundamental problem. Science is being warped and manipulated to provide the data that is DESIRED.

    Ordinary citizens don’t understand how experiments can be rigged to make results ‘negligible’ or how different standards can be applied, it’s appalling is what it is.

    Stick to the non-American studies.

  • Lisbeth

    You’re operating under the assumption that the system is perfect and not corrupted, when in fact it is perhaps the MOST corrupted. Instead of looking for data to bolster your theory, you should be looking for B.S. science, which is all over the place.

    And you are not seeing the larger picture here, which is men with money and power in control of a population’s food supply, and to a large extent, what is written about it.

  • Lisbeth

    There are plenty of recent and past studies finding bioaccumulation of glyphosate which are not secret. All you would need to do is search G-scholar. Monsanto can’t smear the entire body of international science, thank God.

  • SageThinker

    I need to know the full extent of the science, and i do look at it through glasses that include the possibility of bias by industry affiliation. I would like to see the actual studies that the EPA used to conclude that there was no glyphosate found in cow’s milk. I think i would have to use FOIA, because they are not properly cited to a source that i can access with my university affiliation of Harvard.

  • SageThinker

    Still, it just may not be in milk, because of some barrier analogous to the blood/brain barrier or the plant/berry barrier that excludes glyphosate. This would be possible, and would still not show that glyphosate is safe for human consumption in the long term. We know that it passes through the human gut, and that is the site of an important potential mode of action, selective pressure upon the human gut microbiome.

    It may be a sort of chimera that it is not found in breast milk, or we may find some problem with the assay used when the paper by McGuire actually comes out. Remember, at the moment, it is only an announcement at a conference of results, but we do not know the assay method used.

  • Let’s try a thought experiment. Let’s imagine that someone actually does find traces of glyphosate in milk (human or bovine). So what? What would you do with this information; how would this change how you live your life? Are you questioning the content of the two major reports I cited?

    What if you were presented with data on the tens of thousands of other substances in milk? Then what?

    Science is about asking interesting and worthwhile questions, and then answering them—preferably with strong data. Correct me if I’m wrong, but my sense is that you are not asking a question, but are trying to prove something that you already believe. Be honest with yourself: what is your intent? Can you distinguish between skepticism and cynicism?

  • “…proven to be unreliable and subjective…”? OK, so offer some PROOF, don’t just say it!

    “…endless literature…”? Don’t just claim it: tell us what you consider to be the most relevant and compelling literature that you have come across! I’d be glad to discuss, and I’m sure there are others who would be willing to chime in—I don’t claim to be the world’s expert.

    Only once you have established that there’s a real “problem” can we move on to discussing the social implications.

  • Sorry, what do you mean by ” bioaccumulation”? You mean like PCB’s or lead? You needn’t cite “plenty” of papers—one will do.

  • Bruce__H

    “The action of glyphosate is to destroy the digestive systems of insects.”

    I’m unfamiliar with this action of glyphosate. Do you mean a direct action or an indirect one? You’re not thinking of Bt toxin are you?

  • Bruce__H

    Peter, I think you have hit the core of the problem. People don’t understand that concentration matters. Simply detecting the presence of a potentially dangerous agent doesn’t mean that it poses a hazard.

    There should be a larger public discussion of how much research is enough when dealing with food saftey. I think this topic is pretty well understood by scientists and policy makers but the discussion doesn’t penetrate to public spaces. The problem with having standards that are too high is that it becomes very difficult for small companies to afford to bring new products to market. Only the Monsantos of the world can survive and so we fail to benefit from the inverntiveness and dynamism of small-scale reserach.

    For instance, I think that small-scale farmers interested in sustainable farming could benefit tremendously from a few key genetically engineered organisms. In a perfect world, a collective of such farmers could band together to raise the necessary funds for research and development of organisms they see a need for. It is all techncially doable since genetic engineering is actually not that expensive. But all this is less and less possible as the regulatory system becomes more and more elaborate in response to the public’s fears.

  • SageThinker

    There are two questions.

    1. Is there glyphosate in milk?
    2. If so, does it matter?

    They are separate questions. For the first, i wish to see unbiased research replicated and fully transparent. I wish to see the actual report on any research that is cited. If the EPA cites a hidden study, i do not consider that to exist. I need to see the research. I don’t buy any system in which research is hidden for so-called “trade secrets” or any other reason.

    2. Does it matter? Yes, to some degree. It matters as much as it matters. It’s a question of principle, and of integrity, if it’s found in breast milk now. The amount if any is surely less than in the regular diet of most humans, including babies who eat any baby food that is not organic. But still, it matters to the degree that it matters.

    Peter, i don’t need a lecture from you on the nature of science.

  • Bruce__H

    “It matters as much as it matters.”

    This was essentially my point. Right now, to the public, it matters too much.

    There is a modern public hunger for purity and perfect control of everything in our lives in the expectation that this will result in perfect health. I’m not enough of a historian to know if it is a peculiarly modern condition, but I do know that biologically this is nonsense. The learning and memory systems in our bodies — including the brain, the immune system, and the gut and its biome — require constant instruction from the environment if they are to deal appropriately with it. The public’s fear of even the slightest trace of a potential toxin isn’t just expensive, it’s irrational and possibly even dysfunctional.

    There will be a level of glyphosate, or of any agent, that is acceptable in breast milk or our food. What level? How do we decide? These need to become public discussions.

    On a different subject … in the past you have shown that you do not understand how a scientific attitude requires a personal commitment to just want to know the truth. If the data don’t go your way you have to be able to say to yourself “OK, that was a good idea, but it didn’t work out so I’ll move on”. Working scientists, those who apply for grants and publish their work, know this in their guts because they have been wrong so many times before.

    So I think you do need a lecture on the nature of science. I think you have seen it from the outside and don’t really get it yet. Mr. Olins seems to see the same thing in you.

  • It’s amazing to me that dose-response is not totally intuitive. If I eat a piece of chocolate, I’m happy; if I eat a whole bar, I’m queasy; if I eat 1000 bars, I’ll need an ambulance.

  • @Sage — You didn’t answer my question: if glyphosate WERE detected in milk, what would you do with the information?

    Good science depends on asking the right question—in contrast to a 2-year-old who has figured out how to annoy people by saying “why” repeatedly.

    I’ll admit, curiosity is great fun—as long as it doesn’t become an obsession.

  • SageThinker

    Hey can you tone down the condescension, please? Thanks, dad.

    What would i do with the information? I would know it.
    We seek accurate information, no matter what the effects, good or bad.

  • SageThinker

    I think you both need to step back and stop your inaccurate and onerous judgments about me. You don’t know me and your words are insulting and ad hominem, in the fallacious sense of the term.

    I’m in science. I know what it’s about. I don’t need your lectures. Thanks, Pops, but i don’t need your advice here.

  • BannedfromGLP

    Insecure people judge and insult. I’ve learned to just ignore them and use them for the little bit they are worth.

  • Bruce__H

    I believe that SageThinker is dodging an interesting question here. A questions th t deserves a more intellectually serious answer

  • @Sage — We do not “…know that…[glyphosate exerts]…selective pressure on the gut microbiome. Please don’t present your pet hypothesis as a fact.

    Where we differ is whether this idea can be tested (i.e. demonstrated or disproven), and I can’t think of a practical way to to do this, especially as it relates to the human microbiome.
    We already know that individual microbiomes differ greatly, and that there can be profound shifts resulting from a change in diet—even after a few hours.

    Even if you COULD show a change caused by minute traces of glyphosate, what would you do with the information? Your unstated assumption is that changes are “bad”. What if they are “beneficial”? Yes, then I would be interested.

    But I’m open to ideas.

  • SageThinker

    No, we don’t know it, and no i was not presenting it as fact so what’s your problem?

  • JoeFarmer

    ” In a perfect world, a collective of such farmers could band together to
    raise the necessary funds for research and development of organisms
    they see a need for. It is all techncially doable since genetic
    engineering is actually not that expensive. But all this is less and
    less possible as the regulatory system becomes more and more elaborate
    in response to the public’s fears.”

    Yep. There are tons of interesting GM crop creations sitting on lab shelves in universities across the U.S. But the deregulation process (approval process) is incredibly expensive. So there they sit and will continue to sit.

    The irony in this is activists hate the big biotech companies, but they’re they only ones who can afford to go through the process. Activists complain about lack of crop diversity, yet their complaints help keep the well funded companies in the driver’s seat. You’re not going to see a biotech trait that makes something like blueberries or chestnuts easier to grow in Iowa anytime soon.

  • Apologies, Sage, I overlooked that you said “potential”.

  • Ken Gallaher

    Michael McCarthy is a known Monsanto shill and liar.

  • Ken Gallaher

    another Monsanto shill

  • SageThinker

    Thank you for acknowledging that. I appreciate it, Peter.

  • Bruce__H

    Indeed, I’m not sure I understand how the results in the table that SageThinker posted have been rigged to make some results ‘negligible’.

    The table says that glyphosate levels in milk are below 0.05 ppm. Is this one of the results you think has been rigged? How do you imagine it was done?

  • …Danish and German study which provides the actual data…” Really? Data on milk? I suspect you may be thinking of urine, which is the major way that glyphosate appears to be cleared from the body.

    Please give a citation before launching into speculations about the evils of the the “system”.

    Lisbeth, I have asked you several times to support your claims with actual evidence, to no avail. No doubt, ALL information in this world is subject to error, or even falsification, but you seem to have crossed the line between healthy skepticism and cynicism.

  • SageThinker

    If glyphosate *were* detected in milk, which is not so likely but possible, then it would be an indicator that glyphosate is systemic in the human being. The milk in itself containing glyphosate is not so much an issue as the levels are going to be ppb (nanograms), and yet the meaning is symbolic, as it represents glyphosate being systemic in the mother because she eats a modern human diet containing glyphosate, and it means that in her, it’s ppm (micrograms) and therefore significant to the human gut microbiome, and this is what the young infant has to look forward to when s/he graduates to a solid food diet.

  • Bruce__H

    For many people who come to sites like this your reply is already beyond the pale.

    …’Human breast milk containing glyphosate not an issue!!!?’…

    … they will say. And then will follow with some reasoning about poisons and plots by governments/academia/large companies to foist something or other on all of us.

    Your response is much more rational. Indeed as you say, there is a level in breast milk that will be safe. And I am sure that ppb (you label this a “nanograms” but is it nanomolar that you mean?) is safe. But how high a concentration can you have and still see no adverse health effects? That is a proper subject for discussion but most concerned nonexperts don’t understand this. I think that safe concentrations are higher than you do … particularly with respect to effects on microorganisms in the gut … but it needs to be a discussion.

    One of my particular concerns with some of your posts is that you often state things in a way that makes it sound that any amount is too high (Glyphosatan!). I think this encourages people to abandon a rational approach to the subject. I also think that, in part, this is what Mr. Olins has been talking about recently.

    I urge you to be cautious in your advocacy. We need the public discussion and it can so easily be shoved off track.

  • Hi Samsel,
    How’ve you been? I’m thrilled that you’ve tackled the glyphosate research with Stephani! I have a question for you that I can’t figure out the answer. I got a glyphosate exposure 3 yrs ago, in the face. After the tongue swelling, lymph drainage from all mucosal tissue and bleeding subsided I was left with Achalasia. One of the things I’ve run down is that the glyphosate interferes with the acetylcholinesterase cycle much like organophosphate poisoning. I’m trying to figure out how I can undo that part of the damage. So here’s the piece of the puzzle that I can’t figure out what it means in ‘plain english.’

    “The anionic subsite, uncharged and lipophilic, binds the positive quartenary amine of choline moiety of ACh, as well as both quartenary ligands (edrophonium, N-methylacridinium) acting as competitive inhibitors [14, 15], and quartenary oximes which effectively reactivate organophosphate-inhibited AChE [16].”

    Can you tell me what that means?