Glyphosate (Active RoundUp Ingredient) Toxicity

Dan Wilson

Senior Member
Recently, the International Society of Doctors for the Environment (ISDE) called for a ban on glyphosate (the active ingredient in Roundup) use as an herbicide in agriculture, citing the International Agency for Research on Cancer's (IARC) new classification of the chemical as 2A (probably carcinogenic) as their reason. This has been spreading through social media and various news sites and people are getting behind the idea of banning glyphosate, one of the most widely used herbicides on the planet. So, is it really toxic? And should consumers worry about it?

How it works:
Let's start by talking about how glyphosate works. Glyphosate is an herbicide that targets a particular biochemical pathway in plants in order to kill them. This pathway is called the Shikimate pathway, and the purpose of it is to synthesize amino acids containing aromatic rings (tryptophan, tyrosine, and phenylalanine) which are built into proteins necessary for life. Glyphosate inhibits this pathway by mimicking a metabolite called phoshoenolpyruvate (PEP) and stopping a key enzyme in the pathway. Since plants must produce all of their energy and all of their biological molecules themselves, inhibiting this pathway means the plant can't produce particular amino acids, which means it can't produce proteins correctly, and so it dies.
Humans and other animals do not possess this pathway, the genes and corresponding proteins simply aren't there. Instead, these three aromatic amino acids are obtained through our diet. This is why two out of these three amino acids are considered essential (tyrosine is conditionally essential) and also why glyphosate cannot outright kill animals.

Toxicity:
Although it cannot kill animals the way it can plants and certain bacteria, glyphosate can be toxic. But anything can be toxic in the right context since the dosage makes the poison. Biochemically, it can be suspected to be toxic since it mimics PEP and multiple enzymes (not just the Shikimate pathway) use PEP as its substrate. But let's look at the evidence. Glyphosate has been extensively researched by multiple labs all around the world. The oral rat LD50 for glyphosate is 4,320 mg/kg. By comparison, caffeine (192 mg/kg), nicotine (0.5-1 mg/kg), and table salt (3,000 mg/kg) are more toxic than glyphosate.
Chronic toxicity to humans has also been assessed in populations of workers who spray the herbicide on a regular basis and no significant differences were detected.
http://npic.orst.edu/factsheets/glyphotech.html
https://www.ncbi.nlm.nih.gov/pubmed/2011980 (more direct link)
Glyphosate has been shown not to have any obvious immediate or long-term toxicity in those who would be exposed to it much more than a normal consumer might. The news story being sent around, however, is specifically about cancer and glyphosate.

Carcinogenicity:
Carcinogenicity (potential to cause cancer) and toxicity aren't all that different, but here we will talk about them separately. The carcinogenicity of glyphosate has been assessed as well and conflicting evidence has been collected, but the overall body of research supports the idea that glyphosate is not carcinogenic.
http://informahealthcare.com/doi/pdf/10.3109/10408444.2013.770820
http://npic.orst.edu/factsheets/glyphotech.html
In addition to the EPA's classification of glyphosate, the European Food Safety Authority also does not recommend a classification of carcinogenicity, finding insufficient evidence to support such an idea. So, take it as you will, but the IARC is, in fact, alone in its position on glyphosate. At least as far as official assessments go.

Should consumers worry about it?:
Think now about how much glyphosate actually makes it from crops in the field to the food on your plate. When glyphosate is sprayed onto crops, it acts on the plants it is meant to kill but does not linger in the environment. Glyphosate in soil is quickly broken down into aminomethylphosphonic acid (AMPA) (which further breaks down to naturally occurring soil components) and carbon dioxide. AMPA has also been determined to not be harmful to humans. After harvesting and washing the crops, it is likely that hardly any glyphosate at all is consumed. Look now at all of the doses given to rats in the various studies that have been referenced here. Humans aren't likely to ever consume glyphosate in amounts needed to see negative effects. The lowest observed adverse effect level (LOAEL) for glyphosate, determined in carcinogenicity studies, is 4,500 mg/kg/day. For a human weighing 150lb., that's 306 grams per day.

In summary, glyphosate works biochemically in a way that does not affect animals the same way it affects plants. All substances can be toxic but the dose makes the poison. Glyphosate toxicity in animal models and humans has been assessed and studied in labs all over the world and has been determined to not pose a significant risk to health at doses and concentrations that are relevant, especially to everyday people. The IARC's position on glyphosate stated as "probably carcinogenic" is not concrete, although other organizations like the EPA are currently doing more reviews on glyphosate toxicity and are giving the recommendation further consideration. The claims of negative health effects that are being used to push for a ban on the use of glyphosate are unsupported by the extensive body of research currently available.

As a last note, the Seralini paper which claims to demonstrate glyphosate and GM maize's carcinogenicity in rats is purposely not discussed here, as it has been retracted and already thoroughly criticized both on this web site and other places.

EDIT:
Myles Power recently posted a video reviewing the IARC's monograph and I highly recommend it. I think they do a better job of criticizing the classification than I do here.
 
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SR1419

Senior Member
@Dan Wilson - very timely post considering the near hysteria in the local paper here:

http://www.marinij.com/environment-...ts-herbicide-use-after-ring-mountain-concerns
 

Mick West

Administrator
Staff member
It's this much, about 3/4 of one of your American pints.


Edit although Glyphosate has a density of 1.7x water, so if it were pure glyposate it would be a bit less than half a pint by volume.

However, actual Roundup Concentrate is only 18%, so that works out as drinking two of these a day
 
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Dan Wilson

Senior Member
I was thinking about this topic again and how odd it seems that the IARC would classify glyphosate as 2A without strong evidence. I thought maybe I could have missed some papers in the literature, so I had another look. Turns out, I don't think I missed any that would strongly support it being carcingoenic. Here are just a few examples.

http://www.ncbi.nlm.nih.gov/pubmed/22202229
http://www.ncbi.nlm.nih.gov/pubmed/10854122
http://informahealthcare.com/doi/abs/10.3109/10408444.2014.1003423
I found a handful of papers that say otherwise, but they were published in low-impact journals and the tests were done on animals like earthworms, fish, and mice. I found the mice one in particular to be incomplete. If anyone is interested, I could post more about them.

Again, it seems strange that the IARC would be the only organization to classify glyphosate as such when there really does't seem to be a large body of evidence to support it. I probably should have put this in the original post, but here are their reasons in their own words.

http://www.iarc.fr/en/media-centre/iarcnews/pdf/MonographVolume112.pdf
These statements just don't seem to be supported by the data. Saying "limited evidence" even seems like a stretch. The non-Hodgkin lymphoma link consists of epidemiological data and is conflicting, with the strongest evidence pointing towards other ingredients in the RoundUp formulation as the culprits and not glyphosate itself. Same goes for the reported mutagenic properties.

http://www.researchgate.net/publica...phosate_and_Its_Technical_Formulation_Roundup
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1740618/pdf/v060p00e11.pdf
http://www.jstor.org/stable/3435746?seq=1#page_scan_tab_contents
http://www.ncbi.nlm.nih.gov/pubmed/12148884
http://cebp.aacrjournals.org/content/10/11/1155.full.pdf

When discerning whether or not a substance is carcinogenic, it has to pass multiple checkpoints. Two things normally come first. In-vitro studies must demonstrate some evidence for the substance's ability to induce tumors and a proposed mechanism for how it causes cancer normally drives the reason for running the tests (otherwise why be concerned in the first place?). Next, animal studies need to confirm that what is observed in the dish can also happen in a living body. Lastly, epidemiological data and examples in humans must also show cancerous trends. If all of these steps are not met, it is difficult to make a strong correlation let alone a causal link. So far for glyphosate, there is in-vitro evidence. A mechanism is not elucidated and although one could be hypothesized, it does't make a whole lot of sense. There is little to no in-vivo (animals models) evidence. There is conflicting epidemiological evidence with the strongest pointing to things that are not glyphosate but rather things like surfactants found in RoundUp. Furthermore, the epidemiological data was taken mostly from workers exposed to it on a regular basis. A ban on glyphosate, calling it a "poison" comparing it to agent orange, and generally being fearful of using it is not something that science can support at this point. It is always good to be cautious and always good to continue testing, but for now there is nothing that would back up the idea that it is something we should wholly avoid.

I apologize for making this so dense with sources and not putting a lot of this in the original post, but there really is a lot of research that has been done on glyphosate over the years and I hope that this page makes it easy to really dig in for those who wish to.
 

deirdre

Senior Member

night shifts? sounds like a new thread topic!
 
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A point here that is worth mentioning. It's not clear that Roundup glyphosate have the same effect. Obviously glyphostae is the main ingredient ib Roundup but there areother things as well which could when combined have toxic effects. Seralini for example made a big point that they were testing Roundup rather than glyphosate and IIRC that they said were the first ones to do that.

It's important because there is evidence that Roundup may be harmful where glyphosate is not.
http://link.springer.com/article/10.1007/s12012-014-9299-2
Abstract
Roundup (R), a glyphosate (G)-based herbicide (GBH), containing unknown adjuvants is widely dispersed around the world. Used principally by farmers, intoxications have increasingly been reported. We have studied R effects (containing 36 % of G) on right ventricular tissues (male Sprague–Dawley rats, up to 20,000 ppm and female New Zealand rabbits, at 25 and 50 ppm), to investigate R cardiac electrophysiological actions in vitro. We tested the reduced Ca++ intracellular uptake mechanism as one potential cause of the electrical abnormalities after GBH superfusion, using the Na+/K+-ATPase inhibitor ouabain or the 1,4-dihydropyridine L-type calcium channel agonist BAY K 8644 which increases I Ca. R concentrations were selected based on human blood ranges found after acute intoxication. The study showed dose-dependent V max, APD50 and APD90 variations during 45 min of R superfusion. At the highest concentrations tested, there was a high incidence of conduction blocks, and 30-min washout with normal Tyrode solution did not restore excitability. We also observed an increased incidence of arrhythmias at different doses of R. Ouabain and BAY K 8644 prevented V max decrease, APD90 increase and the cardiac inexcitability induced by R 50 ppm. Glyphosate alone (18 and 180 ppm) had no significant electrophysiological effects. Thus, the action potential prolonging effect of R pointing to I Cainterference might explain both conduction blocks and proarrhythmia in vitro. These mechanisms may well be causative of QT prolongation, atrioventricular conduction blocks and arrhythmias in man after GBH acute intoxications as reported in retrospective hospital records.
 

deirdre

Senior Member
IIRC that they said were the first ones to do that.
i could be wrong, but this 'opinion' asked for by Seralini's team, sounds like other scientists are researching this possibility as well. (Just so people dont freak out, thinking only 1 guy is looking into that :)

attached.
 

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i could be wrong, but this 'opinion' asked for by Seralini's team, sounds like other scientists are researching this possibility as well. (Just so people dont freak out, thinking only 1 guy is looking into that :)
attached.
Well my memory wasn't too bad :)
From about the 2.25 mark until 3.30

You should test Roundup because this is what is used, this was never done. We are the first. the only study that tested this commercial formulation with blood analysis of rats. If you ask the EPA."give us the raw data that leads you to authorise Roundup and these levels in the water and they will tell you we have a lot of data on glyphosate. But yes, do you have for Roundup? They will tell you
"we have no blood samples of rats fed Roundup"
then at the 3.35 mark

The studies have all been done just on glyphostae, and what you're saying is that Roundup is a combination of chemicals which have never been tested for safety other than your study
The scientist is French so it's possible something may be "lost in translation"
 
I was thinking about this topic again and how odd it seems that the IARC would classify glyphosate as 2A without strong evidence. I thought maybe I could have missed some papers in the literature, so I had another look. Turns out, I don't think I missed any that would strongly support it being carcingoenic. Here are just a few examples..
Would it have to be "strongly supported" to be 2A?
I was just looking at the list of things classified 2A, and I'm not sure it's so out of place. I can link to it, but it's going to be too difficult to list them all. Here is the list. http://monographs.iarc.fr/ENG/Classification/ClassificationsGroupOrder.pdf
Mate, hot makes the list. I'll have to remember that when I'm next in Uruguay if that's what i think it is :p Also it looks like being a barber is classified as 2A
 
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Belfrey

Senior Member
A quick Google Scholar search will show that this is false; the commercial formulation of RoundUp has frequently been used in other published rat and mouse exposure studies.



But it does bring up the point that in the US, glyphosate is off-patent, and is widely available in many other formulations and brand names. I see glyphosate in use all the time, but I rarely see anyone using the (generally more expensive) RoundUp brand from Monsanto.
 
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Dan Wilson

Senior Member
Would it have to be "strongly supported" to be 2A?
I was just looking at the list of things classified 2A, and I'm not sure it's so out of place. I can link to it, but it's going to be too difficult to list them all. Here is the list. http://monographs.iarc.fr/ENG/Classification/ClassificationsGroupOrder.pdf
Mate, hot makes the list. I'll have to remember that when I'm next in Uruguay if that's what i think it is :p Also it looks like being a barber is classified as 2A
Looking at the IARC's 2A list, it doesn't seem like glyphosate belongs.
https://en.wikipedia.org/wiki/List_of_IARC_Group_2A_carcinogens

Acrylamide is a very potent toxin that, when you're handling in the lab, needs to be treated with extreme caution because it is labeled as carcinogenic.
MNNG is VERY toxic and is used in labs to induce random mutagenesis by directly acting on DNA base pairs. Really nasty stuff, honestly I'm surprised to find it listed as only "probable."
Glyphosate being in the same category as chemicals like this doesn't really make much sense.
 

scombrid

Senior Member
The Roundup brand has been tested.

The opening post addresses people calling for a glyphosate ban, not just Roundup.

Plus glyphosate is off-patent which means that generics and alternative formulations are widely available and widely used.
 

scombrid

Senior Member
Glyphosate is widely used for invasive weed control here in Florida and Roundup is generally not the go-to formulation. Rodeo is commonly used, among others. The Material Safety Data Sheet on Rodeo is about the least scary that you'll find on anything at the home improvement store.

It does a good job and is a lot less toxic than what was being used in the 1940s and 1950s when invasive water hyacinth was choking off damn near every waterbody in the state.

Glyphosate hysteria is a nuisance for land managers as Marin County is finding out.

I'm personally using HDX (Home Depot generic) to renovate a large portion of my 18,000 square foot lawn. I'm converting about 9000 square feet of St. Augustine grass to planted beds that will not require any irrigation. Glyphosate is the choice to kill the grass that I don't physically dig out because it doesn't have residual soil activity so I can come in and plant shrubs and perenials straight away after the grass dies.
 
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The Roundup brand has been tested.
Well why didn't you link to a study?

The opening post addresses people calling for a glyphosate ban, not just Roundup.
The OP conflates the two and did not even realise that Seralini tested Roundup not glyphosate.
 

scombrid

Senior Member
The OP conflates the two and did not even realise that Seralini tested Roundup not glyphosate.
The opening post does not conflate the two.

People are calling for a generic glpyphosate ban, not a specific Roundup ban.

The opening post address those people and those claims. The opening post is not doing the conflating.

The opening post also closed with a statement on Seralini. This thread is not about Seralini.
 

scombrid

Senior Member
The Gress paper that you link tested the effects of direct acute exposure on cardiac tissue.

Roundup is very acidic. I don't recommend putting it in a galvanized tank. I'm not surprised at the possible cardiac effects from acute exposure. I can only see the abstract so I can't see their methods. I'd be curious about their delivery mechanism.

Such a finding does not support the type of ban that ISDE wants. Such a finding warrants caution regarding occupational exposure.
 
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deirdre

Senior Member
The OP conflates the two and did not even realise that Seralini tested Roundup not glyphosate.
the OP opens with:
the IARC didnt classify Round-up specific as a 2a. But youre right the thread title is a bit off, conflates the two. He kinda had to add the "Round-up" or noone would know what he was talking about or be able to find the thread in Google searches. We need to think of a better title :)


maybe "Glyphosate: the active ingredient in Round-up, toxic or not?" and then start a different thread, which can be linked from here, on Roundup-specific toxicity.

ex of misinformation campaign:
WHO-says-Round-up-probably-causes-cancer.jpg
 

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skephu

Senior Member
Actually, many other pesticides and herbicides have been shown to be carcinogenic. Glyphosate is still one of the safest herbicides. Most other herbicides are much more toxic.
 

scombrid

Senior Member
Good point about the thread title @deirdre

Off Topic: What is the source of that photo of the guy using the backpack sprayer while wearing all that gear? I think I've seen it before but I'm not sure when or in what thread. It isn't even a photo of herbicide application. The guy is in a vineyard and is spraying either insecticide or fungicide. You don't mist grape vines with herbicide. Double bunk.
 

CapnPegleg

Member
Just to add, the Seralini study has been widely debunked.

https://www.sciencebasedmedicine.org/the-seralini-gmo-study-retraction-and-response-to-critics/

 

deirdre

Senior Member
Good point about the thread title @deirdre

Off Topic: What is the source of that photo of the guy using the backpack sprayer while wearing all that gear? I think I've seen it before but I'm not sure when or in what thread. It isn't even a photo of herbicide application. The guy is in a vineyard and is spraying either insecticide or fungicide. You don't mist grape vines with herbicide. Double bunk.
yea ive seen the 'debunk' on the photo itself but cant remember where now. its just one of the highly viral memes on Facebook i've seen.
 

CapnPegleg

Member
it's been republished. although i didnt study the two to see if modifications to the origianl were made
http://www.enveurope.com/content/26/1/14/abstract

the commentary is interesting.

Republished in a crap open access journal, and still roundly criticized for designs, etc. And all of his response is basically "SHILLLZZZZ!!!"

http://www.geneticliteracyproject.o...eact-to-republished-seralini-maize-rat-study/

 

Mick West

Administrator
Staff member
Good point about the thread title @deirdre

Off Topic: What is the source of that photo of the guy using the backpack sprayer while wearing all that gear? I think I've seen it before but I'm not sure when or in what thread. It isn't even a photo of herbicide application. The guy is in a vineyard and is spraying either insecticide or fungicide. You don't mist grape vines with herbicide. Double bunk.
It's a stock photo, tagged with "Vineyard" and "Fungicide" (in the keywords at the bottom of the page)
http://www.istockphoto.com/photo/agricultural-chemistry-17721088?st=75bbb5b
 

Dan Wilson

Senior Member
The OP conflates the two and did not even realise that Seralini tested Roundup not glyphosate.
We are making a distinction between RoundUp and glyphosate here. Glyphosate alone does not need to be feared as a toxic carcinogen, yet people want to ban it and classify it in the same category as known mutagens. The title is as it is because not everyone knows what glyphosate is, so I included RoundUp just to spark interest. If RoundUp has some other compounds that are possibly carcinogenic (the evidence there seems weak as well), then that should be acknowledged rather than dragging glyphosate in as the thing we should avoid.

As others say, Seralini is not to be discussed here, there is already a thread about his (bad) paper.
https://www.metabunk.org/bad-scienc...bicide-and-a-roundup-tolerant-gm-maize.t1948/
 

Spectrar Ghost

Senior Member
Just to nitpick, glyphosate is the active ingredient in Roundup, not just an ingredient.

That's like saying acetaminophen is an ingredient in Tylenol.
 
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