7.-12. Glyphosate in Wind, Rain; Down the Drain?

Series 17 Questions about Glyphosate questions 7.-11. I go through the evidence for whether glyphosate can be detected, and if so then in which quantities, in each of the following: air and rainwater, urine, breastmilk, wine, and wheat. I have also added extra sections on glyphosate in honey, vaccines, and tampons.

Question 12. delves into the common verbal images of farmers ‘drenching’ their fields in pesticides, and how much farmers actually use.

7. Is there glyphosate in the air and rainwater?

Despite the case for there being less need to worry about glyphosate than most other pesticides, there are still many arguments around which rely rather on making scary claims about the abundance of glyphosate in our environment. They make the silent implication that this level of detection must be significant and should make us worried about health effects. But often the claims of glyphosate in something or other are misleading, and sometimes downright false.

One case of hasty reporting about glyphosate being detected in air and rain water has been outlined well in Biofortified, RoundUp in 75 % of air? What the report actually says. It serves to show how people will be quick to grab on to a factoid and make it sound scarier than it is.

The report actually showed that glyphosate use had reduced the overall traces of pesticides found, and replaced many of the older more toxic pesticide traces found earlier (see more about environmental effects in section 13) – and this directly on fields where the pesticides were used. In any case, the study deals with mind-bogglingly fine-tuned detection with mass-spectrometry (as an example, satellites and spacecraft use mass spectrometers for the identification of the small numbers of particles intercepted in space). The pesticides were present in concentrations millions of times below any biological relevance – the ability to even detect them is an ode to the wonders of modern measurement techniques.

Now let’s look at a couple of other more relevant locations (food, bodily fluids) where claims of detection of glyphosate has been used to create alarm.

8. Is there glyphosate in urine?

Hearing that there is glyphosate in your urine may make even small potential health risks seem more personal and tangible to you. Should you worry? If something can be detected in urine it is, firstly, a sign of something being cleared from your body – glyphosate does not accumulate. All of it gets removed from your system. Secondly, with the incredibly sensitive measuring techniques we have at our disposal, we can detect traces of innumerable amount of substances nowadays in most any source. We also ingest minuscule amounts of a mind-blowing number of molecules on a daily basis, a great many of which would cause great harm if they were present in high enough concentrations. But any minuscule number of certain type of molecules will have very little possibility of having a tangible effect on our body simply because of the daunting task of how many of the molecules of our biochemistry the few molecules would have to interact with to actually make a difference. They will drown in the flood of water, stomach acids, bacteria, proteins, fats, carbohydrates and minerals constantly a-flush in our digestive system.

So, what does the science say about the amounts of glyphosate residue detectable in urine? This review-article, A critical review of glyphosate findings in human urine samples and comparison with the exposure of operators and consumers, concludes as follows:

A critical review and comparison of data obtained in a total of seven studies from Europe and the US was performed. The conclusion can be drawn that no health concern was revealed because the resulting exposure estimates were by magnitudes lower than the ADI [acceptable daily intake] or the AOEL [acceptable operator exposure level].

And we know from the examples earlier that even the acceptable daily intake is set at an incredibly low level – hundred times lower than the level which has showed no observable adverse effects in the most sensitive lab animals tested. The levels of glyphosate in urine, in other words, are ridiculously small.

Anyone trying to scare others about the levels of glyphosate in their urine is making irresponsible claims and using a ethically questionable emotional tactics. If someone is making claims of harmful levels of glyphosate in urine, they are doing so without reliable scientific evidence.

9. What about breastmilk?

The claim of risky levels of glyphosate in breastmilk (along with many other out-there ideas about glyphosate – see for instance her latest claim and its flaws laid out here: ‘there is glyphosate in vaccines‘) originates from the activist organisation Moms Across the America (MAA). Journalist Kavin Senapathy has tried to engage the MAA leader Zen Honeycutt in civil discussion several times without much success. She has also written about Zen’s campaigns on Forbes. In one of her articles Kavin Senapathy writes:

MAA promotes the evidence-scarce “glyphosate as bogeyman” tale as gospel. Though the herbicide is less acutely toxic than caffeine, table salt, and some pesticides used in organic farming, Honeycutt insists that residues affect our gut microbiomes, which Moms Across America has linked to myriad ailments including autism, allergies, infertility, eczema, fibromyalgia, Crohn’s Disease, childhood tantrums and pneumonia.

If there was evidence for a role of glyphosate in any of the above mentioned ills, it would be easy to see why glyphosate in breast milk would scare you. But the evidence for that, or any realistic connection between glyphosate and tantrums, autism, or any other ailment from that list, is sorely lacking. The ‘finding’ itself – of glyphosate residue in breastmilk – comes from an incorrectly processed assay of ten samples with a method that is known to generate false positives, gathered and reported by none but Zen Honeycutt herself, and made public by her posting about it on her MAA website. Meanwhile, real scientific study by a lactation physiologist confirms the opposite. WSU reserachers find breastmilk is glyphosate free:

“The Moms Across America study flat out got it wrong,” said McGuire, who is an executive committee member for the International Society for Research in Human Milk and Lactation and a national spokesperson for the American Society for Nutrition. “Our study provides strong evidence that glyphosate is not in human milk. The MAA findings are unverified, not consistent with published safety data and are based off an assay designed to test for glyphosate in water, not breast milk.”

For a great discussion about breast milk research, as well as the ELISA assay and its limitations, you can listen to the podcast where geneticist Kevin Folta interviews the lactation researcher McGuire and the analytical chemist Thomas Colquhoun: Glyphosate in breast milk and wine?

There has also been a german study of 114 mothers, which did not find any glyphosate in breast milk, and a study outlining the flaws and implausibility of the MAA ‘finding’ based on earlier animal studies. Yet another study confirmed the lack of glyphosate in any of the following:

Residues were not detected in soy milk, soybean oil, corn oil, maltodextrin, sucrose, cow’s milk, whole milk powder, or human breast milk.

The claim from MAA is an example of a particularly unethical practice: fabricating an issue for breastfeeding parents to worry about, in a time when the world is so safe, that worry and anxiety themselves are real and larger concerns (see the Harvard overview on Anxiety and Physical Illness) than many of the things we actually worry about.

10. Should we worry about glyphosate in wine?

You may have heard a warning about glyphosate residue in wine. It also originates from not qualified use of ELISA assays by Zen Honeycutt. This warning has been coupled with an out-of-context alarm about glyphosate as a carcinogen. Sometimes the lack of perspective is so tangible it boggles the mind. Please read Kevin Folta’s apt summary on the issue below:

wine glyphosate

Kevin Folta on fears of glyphosate residue in wine. Photo at GLP

Again, for a great discussion about the unqualified wine ‘finding’, as well as ELISA assay and its limitations, you can listen to the podcast where geneticist Kevin Folta interviews the analytical chemist Thomas Colquhoun: Glyphosate in breast milk and wine?

More on glyphosate omnipresence

Considering that new scares about glyphosate in x drops in, I might as well add some here as they come.


Latest headlines: glyphosate in honey found mentioned in a FOIA request on FDA. As there isn’t much more information on the data, let’s just assume these three samples tested were accurate. They apparently found 22, 41, and 170 ppb levels of glyphosate residue, which is 0.022-0.170 mg/kg honey. If you notice, even the rumour about glyphosate in wine above claimed 1 ppm (1000 ppb). So, is there need to worry? To get to the most restrictive daily allowed limit (the European one at 0.5 mg/kg body weight per day, note this is the still safe limit with a hundred-fold safety margin) a person would have to ingest about 3 kg honey per kg body weight in one day.

To even attempt a temporary inhibitive effect from glyphosate on our gut bacteria (see more in Does Glyphosate Harm Gut Bacteria?), you’d have to aim higher – around 3000 kg, 3 tons, of honey in one go. Though we may have become pickled in honey long before, and the sugar concentration would have effectively killed most bacteria, not to mention suffocated the poor human drowned in that pool of honey, large enough to submerge even a big person.


The claim ‘there is glyphosate in vaccines’ originates from another not-qualified-use of ELISA assays by the activist organisation Moms Across the America (MAA) and Zen Honeycutt (who is not only against modern farming methods but also vaccines). This assay has not been validated for anything apart from water, and even in water is used as a first screening step because of its chance of giving false positives. That’s why these results of 0.1-3 ppb traces can’t be used as any indication that there would actually be glyphosate in vaccines. Parts per billion, meanwhile are so far below biological relevance that they could not have an effect on our health even if they were there. More about this from Vaxopedia.
For a longer discussion about these claims you can also listen to the podcast Weed killer in vaccines? by the geneticist Kevin Folta, who writes:

They use a kit you can buy on the internet, but fail to use it in the way it is designed. Instead of using it on water, they use it on complex mixtures that yield false positives that are interpreted as legitimate signals.


An Argentine scientist claims they detected glyphosate in female hygiene products at the level of 4 ppm. There is no study, there is a rumoured conference presentation and a video in Spanish from 2015. Nothing has been published. Even if the claims were true, which we can’t tell, 4 ppm is below the highest allowed residue level of 5 ppm, deemed of no risk to the consumers by all scientific literature reviews and a whole slew of scientific organisations like the WHO, FAO, EPA, EFSA… More on this claim from Dr. Jen Gunter at: No, your tampon still isn’t a GMO-impregnated toxin-filled cancer stick.

11. Is wheat toxic because of glyphosate?

Seneff is also the person behind much of the hype about wheat being toxic, for more on that, please see question 3. over at Glyphosate and Health Effects A-Z. Specifically, what comes to celiac disease, the National Academies of Science report in 2015 found no difference between incidences of celiac disease in USA and UK, whereas the countries’ glyphosate usage trends are markedly different:

Celiac-disease detection began increasing in the United States before the introduction of GE crops and the associated increased use of glyphosate; the disease appears to have increased similarly in the United Kingdom, where GE foods are not typically consumed and glyphosate use did not increase.

There are a couple of other people claiming that wheat is toxic, too, but most of those choose to put their bets on wheat itself, not glyphosate. See for instance an analysis of Dr William Davis, author of the Wheat Belly, who blames wheat for causing some 60 widely varied illnesses. The most common denominator for many of them seem simply to be obesity. Toxic wheat -claims have been widely circulated by several mommy-bloggers in many forms.

There isn’t much to add to this sorry tale, other than that it lacks evidence, that pesticide residues in food are carefully monitored and stay extremely low, and again, epidemiological studies have not found any connection between glyphosate and the numerous purported illnesses. For more on the details of glyphosate use in wheat, you can read what agricultural scientists and farmers have to say about it over at WeedControlFreaks, or from the perspective of Nurse Loves Farmer.

When it comes to diets, vilifying any one food ingredient, or even food group, such as carbohydrates, has little basis in scientific evidence. Moderation is the key. Eat a varied diet, lot of vegetables and fruit, don’t eat too much calorie-dense foods – wheat, or any other food, eaten in excess will bring any number of negative health effects, at the very latest as a consequence of obesity.

12. Are crops drenched in glyphosate?

Some very good sources to turn to on questions about pesticides, farming, and weed control, are agricultural scientist Steve Savage and the weed ecology Professor Andrew Kniss. Steve Savage writes for Forbes, and also publishes most of his journalistic pieces on his blog Applied Mythology. On top of his work on weed science, Andrew Kniss also blogs over at WeedControlFreaks to make agricultural science more accessible to the public. Steve Savage has made some apt comparisons of what we understand as drenching, dousing, or slathering, and how that relates to the amounts of pesticide applied on crops – the amounts are generally hundreds to thousands of times smaller than the words would imply. Most of any pesticide spray consists of water.

To put things in another kind of perspective, Andrew Kniss has written about a comparison of glyphosate and common home-made herbicide mixture of acetic acid, salt, and soap. In his piece Salt, Vinegar, and Glyphosate, he writes:

At the higher labeled rate of 2.5 fluid ounces of product per gallon, there would be 0.07 lbs of glyphosate acid per gallon of mixed product. Similarly converting this to the same units as the LD50 values, 0.07 lbs equals 31,751.5 mg. So it appears that glyphosate, the less toxic chemical, is being applied at a rate 6-times lower compared to acetic acid.

roundup beer

The Iowa Farm Babe made this easy illustration of the rate of glyphosate use

Andrew Kniss also comments on some of the more out-there health-claims made about glyphosate, by pointing out how easy it is to find scary sounding information about common household substances by lifting concepts out of context and misleadingly blowing up their relevance for the consumer:

Truth is, it is easy to make a chemical (any chemical) sound pretty nasty, even if you use verifiable, factual information. For example, sodium chloride, one of the ingredients in the homemade herbicide solution, is mutagenic for mammalian somatic cells and bacteria. Another ingredient, acetic acid, is highly corrosive, can aggravate respiratory disorders, and even cause permanent vision loss. Does this sound like something you want to be spraying in the same yard where your children and pets play? Should you be dousing your yard with a potent chemical cocktail that causes mutations in humans and causes blindness? And now we learn that this chemical cocktail is nearly 10 times more lethal to mammals than glyphosate, one of the most potent weed killers on the planet! If you’re less scrupulous about your sources, you can even find links between acetic acid and a multitude of disorders, including eczema, psoriasis, shingles, and herpes. You read that right; THIS HOMEMADE HERBICIDE MIXTURE MIGHT GIVE YOU HERPES!

So glyphosate is used in small amounts, and, as was outline in question 6. Is Glyphosate an Especially Dangerous Pesticide?, it has helped replace many more toxic herbicides. But there is more to the story: how other environmentally crucial farming methods have changed with glyphosate use. Next up: Glyphosate and the Environment, then Glyphosate and Field Ecosystems.

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If you are interested in other environmental or health topics, you can find my other pieces on glyphosate over at 17 Questions about Glyphosate, and further resources under Farming and GMOs, The Environment, and Vaccines and Health. If you would like to have a discussion in the comments below, please take note of my Commenting policy. In a nutshell:

  1. Be respectful.
  2. Back up your claims with evidence.

About Thoughtscapism

Cell Biologist, volunteer science communicator, and fiction writer.
This entry was posted in agriculture, biology, health and tagged , , . Bookmark the permalink.

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