Is Glyphosate (Monsanto’s Roundup) Dangerous?

Update: A few weeks after this article came out, Monsanto lost a huge lawsuit over Roundup.  I’ve added a brief summary at the end of the article.   

You may not have heard of glyphosate, but you’ve definitely come into contact with it.  It’s in much of the food you eat.  You might have gotten it on your skin while gardening, or even hanging out in a public park.  And many people think it causes cancer. 

So what is it?  Glyphosate is an herbicide that’s used in agriculture, gardening and groundskeeping.  It’s also the main ingredient- in Roundup, Monsanto’s flagship pesticide product, as well as several off-brand versions now that Monsanto’s patent on glyphosate has expired. It’s not the only ingredient, but it’s supposed to be the only active ingredient, although that isn’t really true, as we’ll see in a bit. 

Recently, an appeals court upheld the State of California’s decision to list glyphosate as a known carcinogen.  However, the EPA continues to label glyphosate as “likely non-carcinogenic.” 

Monstanto claims Roundup is perfectly safe.  One of their lobbyists even once claimed it was safe enough to drink- then freaked out when he was actually offered some to drink.

So how safe is glyphosate?  That’s a complicated question, both because glyphosate is used for several different purposes and because the scientific data is somewhat mixed. 

The three uses of glyphosate

Before we dive into the data on Glyphosate, one thing needs to be clarified: it’s used a few different ways, some of which present a greater exposure risk than others.

First, it’s used as an herbicide on agricultural crops to kill weeds.  Used in this capacity, it will have mostly dissipated or washed off by the time crops are harvested.  As such, the main concerns here are that runoff will contaminate local groundwater, and that agricultural workers will be exposed to it.

Second, it’s sprayed on grain crops such as wheat, barley and oats as a desiccant immediately before harvesting.  Used as a desiccant, glyphosate rapidly kills the plants so that they dry quickly and evenly, allowing them to be harvested faster and more cheaply.  It is this usage that causes significant amounts of glyphosate to enter our food supply.

Third, glyphosate is used in gardening, both in private homes and in public areas such as parks and sidewalks.  This presents a possibility of exposure to both gardeners and passerby.

Monsanto has also patented glyphosate as an anti-parasitic for killing protozoans of the phylum Apicomplexa, which have been implicated in malaria.  However, it doesn’t seem to have been commercialized for this use. 

Regulations and Lawsuits Around Glyphosate

Glyphosate is currently legal almost everywhere, including the United States and the European Union.  It has been banned in a few smaller countries, including El Salvador, Sri Lanka, and Bermuda.  In Colombia, the government has banned it from use for forcibly defoliating illegal cocaine plantations, out of a concern over involuntary human exposure.    

The United States has set an acceptable daily intake of glyphosate of 1.75 mg per kg of bodyweight.  This number is highly debated, since the European Union sets the tolerable daily intake at .3 mg per kg of bodyweight- one-sixth of the level judged as safe by the U.S. government. 

Roundup is currently the subject of over four thousand lawsuits, the vast majority of which allege that exposure to Roundup caused the plaintiffs to contract non-Hodgkin’s lymphoma.  Most or all of the cases involve direct exposure to glyphosate formulations by farmers, gardeners and groundskeepers, as opposed to ingestion of it in food or water.  This could be because it’s actually more dangerous to workers than to consumers, or because it’s harder to prove that you got sick from consuming glyphosate when we eat so much other crap that could make us sick.  Most likely, it’s a combination of both. 

If the primary danger is towards agricultural workers, rather than consumers, that creates a huge problem with the research, and the data being used in said research.  Can you guess what that problem is?  I’ll get back to that in a few minutes. 

Research on Glyphosate

First we’ll look at studies on glyphosate alone.  Not glyphosate formulas like Roundup- just pure glyphosate.  That’s a crucial distinction, but I’ll get to that in a minute 

In March 2015, the World Health Organization classified glyphosate as “probably carcinogenic in humans.”  On the other hand, in 2016 a joint UN/WHO panel stated that glyphosate was “unlikely to pose a carcinogenic risk to humans” from dietary exposure.

Acute exposure to glyphosate is known to cause irritation to the skin and eyes.  Accidental ingestion of small doses generally causes only minor intestinal discomfort, while deliberate ingestion of larger doses (85 to 200 ml of Roundup) has been fatal in some cases, and has been used as a means of suicide in a few cases.

Different analyses have looked at the same evidence and reached opposing conclusions.  A 2012 meta-analysis of studies on glyphosate found no evidence of a link to cancer, while a 2014 meta-analysis of the same studies did find a link to non-Hodgkin’s lymphoma.  Without going into too much detail, meta-analyses are not an easy way to produce better science, and the statistical methods used to conduct them matter a lot. 

Suffice to say, the research on glyphosate by itself is mixed, and in my estimation there’s no clear conclusion on it so far.  But for glyphosate formulations, the data tells a different story.

Research on Roundup and Other Glyphosate Formulations

Research on glyphosate formulations- that is, Roundup with all of its many ingredients- is also mixed, albeit tilted a little bit more towards Roundup being dangerous.  A 2000 research review stated that “under present and expected conditions of new use, there is no potential for Roundup herbicide to pose a health risk to humans”.

A 2012 meta-analysis of all epidemiological studies of exposure to glyphosate formulations found no correlation with any kind of cancer. On the other hand, a 2014 meta-analysis of the same studies found a correlation between occupational exposure to glyphosate formulations and increased risk of B cell lymphoma, the most common form of non-Hodgkin lymphoma. Workers exposed to glyphosate were about twice as likely to get B cell lymphoma.

A 2015 systematic review of observational studies found no evidence that glyphosate exposure among pregnant mothers caused adverse developmental outcomes in their children.  A 2016 systematic review and meta-analysis found limited and weak evidence of an association between glyphosate exposure and risk of non-Hodgkin lymphoma and multiple myeloma, while no association was found between glyphosate and risk of other lymphohematopoietic cancers. This review did note, however, that the positive associations found may be due to bias and confounding.

As mentioned above, glyphosate formulas like Roundup contain other ingredients, which are supposedly inactive.  Water, obviously, but also other stuff, including some chemicals whose identities are unknown.  From Wikipedia:

Glyphosate-based formulations may contain a number of adjuvants, the identities of which are considered trade secrets. Surfactants are used in herbicide formulations as wetting agents, to maximize coverage and aid penetration of the herbicide(s) through plant leaves. As agricultural spray adjuvants, surfactants may be mixed into commercial formulations, such as Roundup, or they may be purchased separately and mixed on-site (tank mix).

The most notable of these adjuvants- at least among those whose identities are known- is Polyethoxylated tallow amine, or POEA.  POEA is a surfactant- it helps glyphosate penetrate into plant cells, making it more effective and preventing it from being quickly washed off by rain.  At least, that’s the official story.  Studies on POEA in isolation paint a very different picture.

One study found that POEA is 3450 times more toxic to human embryonic kidney cells than glyphosate is.  The same study noted that POEA is far more toxic than glyphosate to a variety of human cells, as well as plant cells. 

Indeed, the authors of that study noted that based on the evidence, POEA, not glyphosate, looks like the principal active ingredient in Roundup.  And yet, it’s listed as an inactive ingredient. 

POEA is highly toxic to fish and amphibians.  It has a half-life in soil of about 7 days.  In deep bodies of water, its half-life can be up to 2 weeks, but in shallow water it can be as little as 13 hours, suggesting that any danger from POEA is likely to stem from exposure during or shortly after use, rather than from POEA lingering long after being applied.  However, as noted, it penetrates into plant cells, meaning it could potentially last a long time inside our food. 

POEA is many times more lethal than glyphosate– anywhere from 4x to 369x as lethal, depending on which animal you’re talking about and the pH level of the water it’s in.  A lethal dosage for humans hasn’t been established.  For comparison purposes, Roundup is about 45% glyphosate and 15% POEA, meaning that if human tolerances for each chemicals are in line with animal tolerances, the POEA content in Roundup is many times more dangerous than the glyphosate content.

In experiments, Roundup and POEA have been shown to be severely toxic to rats– even causing lethal respiratory and digestive effects– at dosages in line with what animals could be exposed to if they’re nearby when Roundup is applied.

The evidence is compelling that Roundup, and POEA in particular, are highly toxic and even lethal to animals.  It’s also clear that POEA can’t be labelled as “inactive” in any sense of the word, and it seems Monsanto has been lying about glyphosate being the active ingredient in Rondup.  And yet, studies on the effects of Roundup on humans are still inconclusive.  Why is that?

Can the Research Be Trusted?

As you might have guessed, Monsanto has engaged in some seriously sketchy behavior to try and protect Roundup’s reputation.

They’ve conducted a shadow PR campaign to discredit reports that suggested Roundup is carcinogenic- and in at lest one case, they had an opinion piece published in Forbes by a writer who didn’t disclose that he worked for Monsanto.

Monsanto has even managed to convince scientists to give its own internal studies equal weight to studies conducted by independent researchers.  According to a 2016 EFSA report “almost no weight is given to studies from the published literature and there is an over-reliance on non-publicly available industry-provided studies.”  In effect, Monsanto is being allowed to police itself.

Now, to reiterate- non-Hodgkin’s lymphoma seems to be the main health issue in which Roundup is implicated.  Rates of non-Hodgkin’s lymhpoma skyrocketed beginning in the mid-70’s, right around or shortly after Roundup was first commercialized.  They grew alongside Roundup’s sales figures for a long time; however they stabilized in the 2000’s,  and have slightly declined since then, while sales of Roundup have continued to grow since then, albeit at a lower rate.  This could indicate that Roundup isn’t really making people sick, or that safety practices improved around that time.  But it could also be symptomatic of a problem with data collection. 

Remember how the research on animals consistently shows that Roundup is poisonous, while human research is usually inconclusive?  That might have something to do with animal studies usually using experimental methods where animals are deliberately exposed to Roundup, while human studies are purely observational in nature.  We’re not Nazis, can’t feed people poison in our research. 

Remember how I said that most of the lawsuits around Roundup stemmed from gardeners and agricultural workers being exposed to it at work, rather than consumers eating glyphosate-tainted food?  Alright, now I want you to think about what an agricultural worker looks like.  What kind of people do most of the (low-skill) work on farms? 

Are you picturing a migrant worker from somewhere in Latin America, most likely here illegally?  Me too.  Now think about what that means in terms of health care.  These workers mostly don’t have insurance or regular access to health care. 

Now imagine what happens when one of them gets seriously ill- like, say, with cancer.  First, they probably try to keep working.  If it gets bad enough for long enough, they get fired, or maybe just quit.  Now they’re poor and undocumented, in a country with a quite frankly terrible health care system, and too sick to work. 

At this point, they’re probably going to go back home, because in Mexico they can at least get Seguro Popular– Mexican Medicaid, essentially- which isn’t great but is at least free.  And since they probably weren’t even properly diagnosed here in America, they’re not even getting counted in most of these studies. 

To truly get a good look at how many farm workers are getting sick from glyphosate and/or POEA, you’d have to go to Latin America and look at people who used to work in the U.S.  To the best of my knowledge, nobody has ever done that.  The actual incidence of illness caused by POEA and glyphosate may be many times higher than any of the estimates in any of these studies- you’d just never know if the people getting sick can’t be counted. 

Further reading: How to not be fooled by fake science

So what do we do about Glyphosate and POEA?

Based on the research, glyphosate doesn’t seem particularly dangerous.  You wouldn’t want to drink it, and should probably avoid getting it on your skin, but it’s unlikely to be dangerous at the levels found in our food supply.  Agricultural workers should be careful around it, but even for them, the worst effect it can cause is probably  moderate and temporary skin or airway irritation.

POEA is a different story.  It might be dangerous in our food supply.  It’s definitely dangerous to fish and wildlife, and it’s certainly dangerous to gardeners and agricultural workers.  Exactly how dangerous, we don’t know due to the aforementioned problems with the research.

As a society, we should be placing much, much stricter limits on the usage of POEA.  Maybe glyphosate as well, maybe not.  I don’t necessarily think we need to ban them altogether, since the alternatives may be something even worse like Agent Orange, but we should reduce the amount companies are allowed to use. 

At the same time, we need stricter safety rules for garden and agricultural workers- and we need to actually enforce those rules, rather than looking the other way so long as the workers in question are illegal immigrants.  Better still would be to issue enough work visas so that the agriculture industry can employ legal immigrants or guest workers, rather than undocumented labor. 

And of course, we need better research, and a scientific community that’s genuinely independent from the chemical industry. 

On a personal level, you should avoid using gardening products that contain POEA, ever.  Glyphosate, as such, is probably alright, just wear gloves and a mask and don’t get it on yourself. Or it would be, if you could find glyphosate products that didn’t also contain POEA.  

As far as food goes- the main crops that Roundup is used on are wheat and soybeans.  The data here is less clear- Roundup in our food supply is probably mildly toxic, but not extremely dangerous.  That’s just an educated guess though, and I wouldn’t gamble my health on it.  In any case, you shouldn’t be eating much wheat or soy due to the FODMAPs in wheat and the xenoestrogens in soybeans, but those are subjects for future articles. 

Update: A few weeks after this article came out, a jury awarded $289M to a man who allegedly got cancer from exposure to Roundup.  In response, parent company Bayer has announced that it will discontinue the Monsanto brand name, following a time-honored tradition of “fixing” problems by simply renaming the problematic brands.  This didn’t stop Bayer’s stock from dropping by 10%.  With something like two thousand other plaintiffs launching lawsuits against Monsanto, this could very well bankrupt the company.  Suffice to say, I think this is a good thing.