Several years ago I was going to write a post about Roundup and glyphosate, its active ingredient, but decided against it because several very good science-based reports were produced by others. Unfortunately, those reviews were not directed towards gardeners and based on frequent discussions on social media, the message is still not getting through to the gardening community.
My goal in this post is not to do my usual deep dive into Roundup, but instead I want to give readers a summary overview of the facts along with references containing more details. I hope that putting all of the information in one spot will make it a useful tool for discussions in gardening social media groups.
Roundup vs Glyphosate
Roundup was originally produced by Monsanto and it contained glyphosate as its active ingredient. Most people recognize and use the name Roundup. Unfortunately, Monsanto (now Bayer) has decided that since this brand name is so well known, they could use it to promote other products, some of which don’t even contain glyphosate.
One Roundup product marketed in Europe is vinegar with no glyphosate, and some products contain both glyphosate and another herbicide.
We really should be talking about glyphosate and not Roundup.
Roundup and Monsanto
Conversations that go something like this, “Roundup is toxic because I hate Monsanto” are illogical.
If you hate Monsanto – that is fine. But your love or hate of the company does not change the chemical properties of glyphosate. One has nothing to do with the other.
Does Glyphosate (Roundup) Cause Cancer?
The general public is more convinced than ever that glyphosate (Roundup) causes cancer because of the recent court cases. I’ve discussed this in detail in Roundup (Glyphosate), Cancer and the Courts.
The result of a court case is the sum opinion of the jury, and it does not represent the scientific facts. There is no doubt that the majority of general public hate Monsanto and Roundup, and they truly believe Roundup causes cancer. But that belief does not make it true.
One of the largest agricultural human heath studies has been following workers using glyphosate, for 20 years, and reported, “Overall rates of cancer in the study remain lower than in the general population, especially cancers of the oral cavity, pancreas and lung.”
The science is quite clear on this, there is no evidence that glyphosate causes cancer and most global health and safety organisations agree. The following infographic was prepared by the Genetic Literacy Project, a group promoting truth in science.
The EU Joins the Group
Update: July 26, 2021. I just saw a report from the EU (European Community) that reviewed the science on glyphosate. This 11,000 page report, looking at over 20,000 studies, concluded that glyphosate is safe and does not cause cancer. The only danger they found was that glyphosate “causes serious eye damage”.
Why is this significant? The EU has banned glyphosate in many applications, on a purely political basis, but the average person used this as “evidence” that glyphosate was harmful and caused cancer. It is good to see that the EU scientific community has finally done a proper review. Hopefully, governments will now catch up with the science.
Glyphosate (Roundup) and GMO
A common argument agaisnt GMO plants is that it encourages the use of Roundup. These two issues are unrelated to one another.
Yes, there are some Roundup-ready GMO crops. But the majority of GMO plants have nothing to do with Roundup and they are not Roundup-ready. See GMO Myths – Understand the Truth About GMO Plants for more details.
You can be against Roundup and be for GMO.
Glyphosate (Roundup) Found in Drinking Water and Babies Milk
Studies have found glyphosate in drinking water and in mothers breast milk. The headlines claimed that this was a huge problem, but when you look at the details you realize that it’s a non-issue.
It’s all about the dose.
Our scientific instruments are so good these days that we can find just about any chemical in water and milk. I reviewed the report that found glyphosate in Spain’s drinking water and calculated that you would need to drink the equivalent of 1,000,000,000 bottles of beer, on a daily basis, in order to reach an unsafe level.
The levels found in the environment and in mothers milk are extremely low and of no health concern.
Glyphosate (Roundup) and Chronic Diseases
Some claim that glyphosate causes all kinds of diseases including, diabetes, neuropathies, obesity, asthma, infections, osteoporosis, infertility, birth defects and non-celiac gluten sensitivity. Many of these claims have been made by Samsel and Seneff.
Anyone who has followed the Roundup debate will recognize the name of Dr. Stephanie Seneff. She has made numerous claims about glyphosate which are quickly discounted by the scientific community “as outrageous use of science”. Dr. Seneff is a computer programmer with no experience in chemistry, plant science or health science. Her most recent claim is that glyphosate is a contributing factor of COVID-19.
Unfortunately, the general public eats up her publicity stunts.
A recent review of the claim that glyphosate causes chronic diseases found no support for the claim and went on to say “Our critical analysis of the commentaries published by Samsel and Seneff reveals that their conclusions are not substantiated by experimental evidence but are based on a type of failed logic known as syllogism fallacies. As Nobel Prize-winning theoretical physicist Richard Feynman famously said, “It doesn’t matter how beautiful your theory is, it doesn’t matter how smart you are. If it doesn’t agree with experiment, it’s wrong.””
Glyphosate (Roundup) and Soil Microbes
It is commonly believed that glyphosate harms soil microbes. When glyphosate was added to soil it was found that “it was rapidly degraded by microbes, even at high application rates, without adversely affecting microbial activity.”
Glyphosate (Roundup) and Gut Bacteria
Numerous recent reports in the media and online claim that science has demonstrated glyphosate affects our gut bacteria, and if true could have serious health implications.
One of the reasons glyphosate is so safe is that it only affects a well understood biochemical pathway called shikimate, which is found in plants but not animals. This is the reason it is not toxic to animals. The shikimate pathway is found in some bacteria that live in our gut.
A recent study claims to have shown that glyphosate can affect these bacteria.
Marc Brazeau is the editor of Food and Farm Discussion Lab and is the Genetic Literacy project’s senior contributing writer. He has done a thorough review of the report claiming a link between glyphosate and gut bacteria and found that the data did not support the conclusions.
The study itself does say, “more studies will be needed to ascertain if there are health implications arising from glyphosate inhibition of the shikimate pathway in the gut microbiome”. The study did not reach any conclusions about glyphosates effect on our health, even though the news reported it with sensational headlines.
Another study found that even levels 50 times larger than the Accepted Daily Intake (ADI) set by European food safety agencies had very limited effect on gut bacteria.
Glyphosate (Roundup) and Bees
A study sprayed honeybees with a normal concentration of glyphosate and found no harm to the bees.
Some studies have looked at bee behavior after exposure to glyphosate, and have reported some learning disabilities in bees. The number of bees studied was very low, and 1/4 of those were lost during the study. Other studies have looked at exposure to very high levels of glyphosate.
Bees certainly have environmental and pest problems, but glyphosate has not been shown to be one of them.
Facts About Glyphosate
Here are some important facts about glyphosate.
- our skins absorb very little
- it undergoes very little metabolism in the body and is mostly excreted
- it has a very low toxicity; the oral LD50 in rats is 4320 mg/kg, significantly less than vinegar
- it quickly adsorbs to soil and becomes inactive
- it has a soil half-life of 50 days, which is short for a pesticide
- plant uptake from soil is minimal
Not Enough Testing!
The anti-Roundup movement is quick to claim that there has not been enough testing, and that the existing testing was done by labs hired by Monsanto. That is nonsense. Over the last 45 years there have been thousands of studies by labs all around the world.
At some point you have to accept the results.
It sounds to me like they know what a deadly product they have made and they decided that the name Roundup has a really bad connotation and instead of admitting that and taking it off the market, they chose to put themselves on the opposite side of the argument and are actually pretending they desire the cancerous name and want you to believe that name will do wonders for their other wonderful products which will enable them to continue to sell/fool a large number of people even though it’s a small percentage, it’s still enough to keep their deadly company prosperous.
What a wonderful time to tell those who are unaware of this ingredient. I believe there are a few stories and obituaries as well.
I’m all for scientific discussion. We as researchers can and should put our emotions aside and uphold the basis of the hippocratic oath and shun teleological thinking. Alas this doesn’t happen because hubris also sets in. I am not going to argue in this on a scientific basis even though I am on the “there exists enough scientific study that gives enough doubt to keep the conversation going”.
All that aside there is another side now we must also consider which is the legal one. In the last two years Bayer is getting their butts handed to them. The supreme court in California has forced mass amounts of Monsanto emails to be submitted and it has been shown that some very bad corporate practices have been occurring to cover up data, and push the teleological thinking far towards their side.
This gives enough pause that even scientists should ask themselves “do I really know enough about these things beyond a shadow of doubt?”. My premise is a resounding no because we are not gods and science reforms itself despite previous assuredness. Lastly, we know so little about our own gut bacteria, I hardly think we can say we know when it is safe or not at today’s level of science.
You cannot compare the results from a civil case with those relating to the standards in toxicology.
There’s a very good reason why the scientific community, of which I am a part of, does not share your conclusions relating to glyphosate.
To date, not a single study that complies with the international standards in toxicolgoy to conclude any causal relationship exists between glyphosate exposure and any negative health effects at or below the current regulatory limit (ADI-1mg/kg/day in the US and Canada).
This doesn’t mean that the is no data relating to its toxicity, as there have been multiple studies that fully complied with the OECD-Section 400 methods, with an overall LOAEL (Lowest Observed Adverse Effect Limit) of 175mg/kg/day (for review wee Griem et al. 2015 along with the EPA and EFSA registration/renewal reports).
The emails make no indication that any of the toxicity or carcinogenicity testing to date is in error, or has been manipulated. Quite the opposite in fact.
Just looking at the OECD-453 studies to date (Combined Carcinogenicity and Chronic Toxicity) we see that, from 1990-2007, 7 fully compliant studies (again see Griem et al. 2015) were conducted by labs in the UK, US, Italy, Poland, India, and Japan.
These were not conducted by any one group, and in fact they represent industry, academic, and government labs, with differing contributors.
Despite this detail, they all produced similar results, indicating that the methods used were both accurate, and able to be replicated.
This is not the case for the anti-glyposate papers out there. Not only do they consistently fail to come close to the minimum requirements to conclude any causal relationship, their record for replications is utterly abysmal.
You need to realize that there is a VERY different burden of proof to conclude causation between the US civil courts, as compared to science as a whole.
In the US, civil courts abide by the jurisprudence established by In re Winship 1970, where a mere preponderance of evidence is sufficient to determine cause and effect.
At its most permissive this means that so long as you are >50% convinced, you can find that, in this instance, glyphosate caused NHL, or other health effects.
In science, having a TypeI error 50% of the time isn’t logical, or permitted, and a much more stringent bar is used.
To conclude causation, one must show a statistically significant increase in negative health effects between treatment and control groups, using a sample and exposure range sufficient to establish a consistent, dose-dependent response.
That’s what the OECD methods were designed to do, yet event though it’s been decades (the protocols are updated regularly), not a single study has been able to show such a relationship below the NOAEL I mentioned earlier.
For the scientific community, that’s more than enough for us to conclude that the current regulatory limits are set at a point where there is no increased risk, and we even factor in a considerable safety factor to the derived toxicology findings.
Gregory Perry, thank you for the time you took to lay this out…please consider publishing it more widely. This is a hugely important set of points that need more exposure.
I can’t say that I read every comment, but I didn’t see anything in your article or the comments I read about the soil microflora. You mentioned the human microflora and the potential for interfering with the respiration of some of those organism. I have read anecdotal accounts of the soil microflora suffering under repeated applications of glyphosate. Are you familiar with any studies on that topic?
I have not looked at that. We do know that glyphosate has a short half-life in soil and it attaches to soil, which would suggest it is not a big problem. I think the other issue is that we still don’t know a lot about soil microflora.
Im a horticulturalist.
I’ve been in the nursery / landscape industry since 1975.
I was trained to use protective gear, and taught the proper use of chemical application.
It drives me nuts seeing people wandering about their yards, unprotected spraying willy-nilly…and worse, on windy days.
The blame lies not on the chemicals, the blame is solely on the person mis-applying the chemical.
Keep emotion out of this debate.
The instructions on the label are clear and do not state…
Spray this in your face.
So how do you feel about Roundup ready soy? Organic farmers report their crops have massive swaths of burn when a neighbouring farmer sprays. I dont have firsthand knowledge of this nor if glyphosate is actually what was sprayed (sounds like dicamba to me). But PPE or not, on an industrial level it makes no sense that everyone has to switch to a GMO soy because some farmers want Roundup ready soy. The choice should always be according to the person, and it seems wrong that others would suffer from those choices.
Glyphosate has been shown to be quite nasty to fungal populations in the soil. Depending on the succession of plants you want to grow, it is counterproductive to allow them to die off. Here a summary of one of those studies.
https://theecologist.org/2016/may/05/monsantos-roundup-toxic-soil-fungus-ultra-low-doses
This is what they say, “according to a new scientific study published in the journal Environmental Science and Pollution Research.”
When an article does not include a link to the research they are discussing, they can say anything they want, and it is not a reliable article.
The Ecologist article did, in fact, include a link to the article that it referenced that was published in the “Environmental Science and Pollution Research” journal. To save everyone a mouse click or two, I’ve reproduced that link here and summarized it below: https://link.springer.com/article/10.1007/s11356-016-6596-2
The researchers who wrote that article “evaluated the toxicity of a commercial formulation of Roundup® (R450), containing 450 g/L of glyphosate (GLY), on the soil filamentous fungus Aspergillus nidulans, an experimental model microorganism.”, and they found that a “median lethal dose (LD50) on solid media was between 90 and 112 mg/L GLY (among adjuvants, which are also included in the Roundup® formulation), which corresponds to a dilution percentage about 100 times lower than that used in agriculture.”.
Let’s be mindful that when we say, “Roundup”, we could be talking about any of a number different chemical formulations (including the formulation that Bayer/Monsanto confusingly also called “Roundup”, that contains acetic acid instead of glyphosate as the active ingredient). What many researchers have found is that the combination of the adjunctive surfactants (e.g. MONO818) added to a glyphosate formulation can be far more toxic than the glyphosate by itself, particularly to trout fish. Surfactants are added to increase plant uptake of glyphosate and thus, the killing efficacy of the formulation. Unfortunately, they also negatively affect the gills of fish.
The negative impact of glyphosate on soil fungi can be easily inferred from “first principles”, i.e. from the fact that it interferes with the shikimic acid pathway that exists in beneficial fungi and bacteria as well as in plants that people want to kill. Unfortunately, modern science is only beginning to understand the importance of fungi and bacteria to maintaining good soil health and human health.
indiscriminate use of glyphosate formulations may buy some short term convenience for people who don’t like to pull weeds, but at what cost to long term soil health and the rest of the environment?
One more comment please? The common sense question to ask is, why would any company NOT want to thoroughly test its own products? What company would want to hide toxicity which would surely result in lawsuits, bad publicity, and tossing out all of their investment? That would make the stock holders very angry. RU is a product which helps us produce food on a massive scale to support 7 billion people! Yes, I would prefer give jobs to a lot of people to hand-pick weeds in the fields, and manually clear brush in forests, but I am betting every person reading this would say “no” to that job, lol. I love the environment, grow a lot of my own food, and am as green a liberal as you could meet. But fortunately I was taught how to evaluate something to determine if it is a “fact” or not. It is turning out to be a fact (the science is emerging) that bird feeders are not actually good for birds…people HATE the idea of giving up those, even if it may mean birds do better. The major bird groups are heavily subsidized by bird food and feeder manufacturers, so the science does not get much coverage there. The thing is, people get an idea in their head and it sticks there, and then they gather information that confirms their previously held beliefs. That is NOT science. The starting point for any science is to acknowledge “we don’t know (or assume) the answer”, so we test to see what the answer really is. Folks, the war on facts is a quick trip to the middle-ages. When green liberals fail to use facts to drive their agenda, it undermines our ability to actually do anything constructive, and we and our (unfounded) opinions become worse than the RU itself. It is good to beware of political agendas and money interests that negate the science or try to confuse it. To call someone a shill without proving the relationship is also not proving anything factual. If you hurl an accusation, it is YOUR job to prove it.
“The common sense question to ask is, why would any company NOT want to thoroughly test its own products?”
Simple- when the results of thorough testing are negative and are likely to eat into profits. Lots of examples, from DuPont, to tobacco industries.
In the face of lack of science literacy, we are left with lore and the stories we tell ourselves to try to make sense of the universe, to look for culprits to blame when things don’t go right for us. So many people here say “I don’t need science to tell me that…xyz is bad.” Science is how we got to our ultra-comfortable lifestyle…science is how we got out long life. It concerns me to no end that we simply dismiss it out of hand or make the scientist the villain…in a time when the world is being impacted by several huge problems that only science will save us from.
People/farmers are using it more than 50 years now…so what’s the problem….
Robert you have either been bought or are brainwashed or both
Or maybe, I’ve looked at the scientific evidence, and came to a scientific conclusion, based on the facts available. Yes – that is what I did.
I suppose the 20 + global organizations that agree with my analysis have also been bought and brainwashed? How likely is that?
I don’t know about the chemical in ? I still use it on my farm.
But the argument about the use for 20 years and being played off. And I am not saying you are.
But how long did the public use cigarette? And I remember the ads from doc. Saying use menthol cigarettes when you were sick instead of the normal ones.
So going by what any one or group says can be dangerous.
Why people think they are smarter than scientifically proven facts, I’ll never understand. This world is full of uneducated haters that only believe what they want to! They have no evidence of the untruths they believe in and have no intension of facing reality.
There is only one country in the world which doesn’t us pesticides and it is Cuba and it has the best ecosystem ever and the largest quantities of insect and birds wildlife by square metre, so we don’t need to debate much of the damage to the environment just look at the facts…..
I am having a difficult time finding these facts you speak of regarding Cuba’s use of pesticides. Could you please provide some references for these claims? Thank you.
Roundup is a herbicide not a pesticide. I use it to kill plants not bugs.
All herbicides are pesticides.
Haters gonna hate! Learn the facts!