Does Glyphosate Cause Cancer?

Glyphosate and cancer. This is something we are hearing so much about, seemingly all of the sudden, with major stories breaking in the last week. Just last Friday, a court case in California resulted in a $289 million dollar payment to a man named Dewayne Johnson, who claimed his years of using glyphosate (also known as Roundup) caused him to develop cancer. A few days before this story broke, glyphosate use was suspended by a judge in Brazil pending a government reevaluation of its toxicity.

What is going on here?

I am a farmer who uses glyphosate. My dad started using it decades ago, and it has absolutely been the single greatest invention in agricultural history. And it is unequivocally, fantastically safe. It is one of the lowest toxicity herbicides we use on our farm. It is less toxic than alcohol. Less toxic than caffeine. So what is all this about?

Why Do We Need It?

I am apart of a multi-generation family farm in southeast Saskatchewan, Canada. We grow canola, wheat, durum, peas, lentils, flax and soybeans, along with a few other crops. I farm with my sister, my mom and dad, my brother-in-law and my wife and two little boys. I love what I do.

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In my part of the Canadian Prairies, we farm in some pretty dry conditions. Our average growing-season rainfall is about 9 inches, or 225 mm. Snow and fall rains provide us with another 4-5 inches. This is semi-arid agriculture, where the next rain really can provide the difference between profit and loss. So, we work very hard to use every drop of moisture we get. We have to. That means we cannot allow weeds to grow, and we must leave the soil undisturbed as much as possible – we do not want to till our land if we can at all avoid it.

What glyphosate allows us to do is to kill every weed in the field before the crop emerges. In the days before glyphosate, my grandfather had the very same goal – but he only had one way to do it. He had to work the land, over and over and over. The goal was to make it absolutely black. That was the only tool they had, and sadly, it was the direct cause of the great dust storms of the Dirty 30’s. Why would we ever want to go back to that?

Moreover, glyphosate allows us to control weeds in certain crops as they grow. Canola and soybeans are two crops I grow that are genetically engineered to be resistant to glyphosate. This means we can spray it over the crops, while they are young and struggle to compete with weeds, to keep them clean. We use different chemicals in other crops to accomplish the same thing, but none have the broad spectrum control that glyphosate has – and few of them are as cheap, or as safe.

The introduction of Roundup-Ready crops, including corn, soybean, canola, cotton and so on, has allowed for safe, simple, very cost-effective weed control.

Is It Safe?

This is the big question, and if you follow the news at all, I could certainly understand if you don’t feel it is safe. You may think it causes cancer, autism, and any number of diseases. That is what you’ll find on the Internet.

Here’s the experience of a farmer.

I use glyphosate hundreds of hours every year. I load and run our sprayers (along with farm employees and my family) over thousands and thousands of acres spraying glyphosate. My son rides in the sprayer with me sometimes. And I don’t worry at all about glyphosate being dangerous.

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Here’s the thing about spraying a chemical like glyphosate. An acre of land is 43,560 square feet, which is a little smaller than an American football field. On that acre, 360 grams of glyphosate active ingredient is sprayed. Put another way: 2 cans of beer of glyphosate sprayed over an area almost the size of a football field. That’s .015 mL of beer on each square foot – and that includes the solution the glyphosate active ingredient is suspended in. That is an incredibly low concentration. A standard “drop” of water is .05 mL. That’s less than a third of a drop of water!

Sure, some chemicals are highly toxic in even very small doses. Glyphosate is not one of those chemicals. Its LD50, or the lethal dose for 50% of rats in testing, is 5,600 mg/kg. The LD50 for caffeine? 192 mg/kg. Don’t panic about your coffee though – that’s still very safe!

Does Glyphosate Cause Cancer?

While I have explained that an acute dose of glyphosate is safe, that doesn’t really answer the cancer question. That is something that would accrue over many years, and may have little to do with the aforementioned LD50. Has this been studied thoroughly enough to be sure glyphosate is indeed safe? And has it been studied by independent organizations and scientists?

John Giesy, a professor and research chair in environmental toxicology at the University of Saskatchewan, would argue that yes, glyphosate is safe. He has quite the resume, as a professor or honorary professor at six other universities and is the most cited author in the world in the combined fields of ecology and environmental sciences. In an article you can find here, when speaking about the subject of cancer, he had this to say:

“Certainly you wouldn’t wish it on anyone. But whether it’s caused by glyphosate, in my opinion, is highly unlikely.”

In 2015, the International Agency for Research on Cancer (IARC), a WHO agency, claimed that glyphosate was a  “probable carcinogen”. Glyphosate is hardly alone in this category, with such partners as high temperature frying, working as a hairdresser, red meat or shiftwork. Stuff that is actually carcinogenic on their list? Alcoholic beverages, sawdust and processed meat (to name a few). Yes, beer and hot dogs are considered more likely to cause cancer than glyphosate (source).

It was this IARC report that started all of this, and there are some real questions as to their methodology. In fact, according to the then- European Crop Protection Director, General Jean-Charles Bocquet,

“From the summary conclusions it appears that IARC has made its conclusions as a result of an incomplete data review that has omitted key evidence.” (source)

It was recently discovered that the IARC had removed findings from studies that concluded glyphosate was not a carcinogen before they published the final version. They also used the infamous, now retracted Seralini rat study in their analysis.

The fact is that numerous organizations conclude glyphosate is safe, including the UN’s Food and Agriculture Organization, the European Food Safety Administration, Health Canada, the German Risk Agency, and on and on. A massive study run on 89,000 farmers and their familes in Iowa and North Carolina since 1993 has failed to find any link between glyphosate and cancer. How much more evidence do we need?

I need glyphosate on my farm. It helps me be more sustainable, both environmentally and economically, it helps me protect my soil from erosion and build soil health, and it helps me sequester carbon, reducing greenhouse gas emissions. The fear over glyphosate is unfounded, and we need to slow down and have a real discussion about it. If you want to come to my farm and see how we use this contentious chemical, please let me know. My door is open for anyone who wants to have their questions answered.

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Rise of the Superweeds

One of the arguments against GMOs has been that they caused the evolution of so-called “superweeds”, an epidemic that apparently has the world headed for a crisis. Some claim that we will soon be unable to sustain our modern agriculture techniques, and GMOs are at fault.

Fortunately, the reality is quite different. Superweeds are indeed a problem, and their evolution is causing significant problems for farmers. However, we do have options to control them, and emerging technology is going to help us out.

Superweeds – What Are They?

Superweeds really aren’t that super. They aren’t bigger, faster growing, or more competitive than “normal” weeds. All a superweed actually is is a weed that is resistant to a certain type of control. Becoming resistant to Roundup (glyphosate) doesn’t automatically make a weed more competitive, it just makes it more difficult for us to control them. It eliminates one of the tools we have in our toolbox.

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Palmer amaranth is one of the most prolific glyphosate resistant weeds in the US, producing up to a million seeds per plant. (Superior Ag Resources photo/Tom Sinnot)

A common misconception is that superweeds are only resistant to glyphosate, but that is actually not accurate. Weeds have been evolving resistance to many kinds of control for as long as agriculture has been around. In fact, in India, farmers used to hand weed barnyard grass out of rice. Barnyard grass was very similar in appearance to rice, but it had a distinctive red stem. As farmers removed those weeds year after year, a different strain of barnyard grass with a green stem became more prevalent. Eventually, farmers could no longer tell the difference between barnyard grass and rice; they had selected for green stems (read more here). Essentially, you could call that particular strain of barnyard grass a superweed. 

What Causes Superweeds to Develop?

Like the example of the red-stemmed barnyard grass, evolution of resistance to glyphosate and other chemicals is really rather simple. Continuous application of the same chemistry to the same fields year after year will allow that one weed with natural resistance to proliferate. One year, there’s one of them. That weed produces dozens or – believe it or not – millions of offspring. In year two, depending on how many germinate, survive and reproduce, an exponential increase in resistant populations begins.

All that particular weed has is a mutation that allows it to survive the chemical. Lentil harvestSometimes, it can only survive a lower rate, which is why proper application rates are
so important. As that weed begins to spread, it finds its way into other fields and other farms. Combines do a great job of blasting weed seeds hundreds of feet through the air, and with the right wind, weed seeds can even be blown into adjacent fields.

Whose Fault Is It?

Are farmers to blame for this? In a word, yes. We are responsible for understanding the chemicals we apply on our own fields. Don’t get me wrong; I’m not trying to throw myself and my colleagues under a bus here. But there have been many farmers that simply grew Roundup Ready crops over and over for over a decade – applying incredible selection pressure to their weeds. Could pesticide companies do more to educate farmers on this subject? Yes, but they have vastly improved their education efforts. A fantastic example is Bayer Crop Science’s Mix It Up campaign, which informs farmers how their products can improve resistance management (read more here). I think the key going forward is that assigning blame gets us nowhere. Let’s instead focus on solutions.

When Roundup was first released, it was a novel herbicide that was considered to have “Low” susceptibility to resistance. Because of its mode of action, weeds would have to develop a complex resistance mechanism. Sadly, this assumption led to an overapplication of glyphosate, much of it at rates too low to be totally effective, and has thereby resulted in the loss of one of the great inventions of the modern age to many regions.

How Do GMOs Fit In?

The introduction of Roundup Ready crops in the 1990’s caused a surge in the use of glyphosate. It was cheap, safe, very effective on weeds and easy to apply. Despite what has been coming out in the media about glyphosate lately (read more here), it is actually a very safe product with no known health effects in humans or animals. It was a breakthrough in agriculture, one of the greatest of our time. It is because of this that its overuse was simply inevitable.

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A young GM canola crop with developing weed competition.

It is, however, important to distinguish that although Roundup Ready crops contributed to the overuse of glyphosate, they did not cause resistance themselves. Glyphosate is not the only product with resistance problems. Other chemical groups also have issues, such as sulfonylureas, imidazolinones, PPO inhibitors, plant growth regulators and so on have all led to the proliferation of their own resistant weeds. None of these products are tied to glyphosate resistant crops. In fact, even insects and plant diseases have evolved pesticide resistance. In Europe, for example, flea beetles have become resistant to pyrethroid insecticides. Canada thistle became a problem in the prairies largely because of cultivation, which allowed their roots to be spread all over the fields.

Any type of pest control can and will cause pest resistance if the selection pressure is high enough. Unfortunately for RR crops in the United States, the selection pressure was simply too high.

What Are We Doing About It?

Every problem has a solution, and superweeds are no different. The way to fix this problem is actually pretty simple – rotation. Using a variety of crops combined with a variety of chemicals prevents weeds from building resistance. Take that Roundup-resistant weed and hit it with something else. Maybe a different chemical, maybe a little bit of strategic tillage, maybe even just a more competitive crop.

There are some incredibly exciting developments in the world of crop protection. RNA interference technology may just be the new frontier in weed management. Palmer amaranth, a particularly problematic weed in the US, resists glyphosate by producing extra copies of EPSPS, an enzyme required for amino acid synthesis that glyphosate binds to and prevents growth, eventually causing death. It overcomes the glyphosate application by simply producing so many copies of EPSPS enzyme that it overwhelms the glyphosate molecules. To stop this from happening, RNAi prevents the production of the EPSPS enzyme. With less of it produced, glyphosate is once again effective (read more here and here).

While RNAi is very new and is probably years away from production, it is promising to see innovations like this on the horizon. In Australia, where weed resistance is a major problem, some farmers are using the Harrington Seed Destructor to destroy weeds as they leave the back of the combine, which is proving to be incredible effective. Robotic weed destroyers are prototypes today, but could be a game changer in the near future. But in the meantime, we must protect what we have. Careful rotations and proper application techniques will go far to secure the usefulness of the chemicals we have for the foreseeable future.

Superweeds are nothing new. Weeds always have and always will evolve survival mechanisms against our strategies to control them. GMOs are not the culprit here; a lack of discipline in the use of our most valuable chemistries is the reason we are having the problems we are having. Panic by local governments and knee-jerk reactions will not help us deal with weed resistance. Education, research and new ideas are what we need to combat this problem. Weeds have always been one of farmers’ greatest challenges, and we will have to continue to be innovative and determined to stay ahead of them.

Glyphosate: A Carcinogen?

John Deere 4940Every once in a while, a news story is released that has no basis in any real science whatsoever. A few days ago, the International Agency for Research on Cancer (IARC) declared glyphosate, the active ingredient in Roundup and many other brands, to be a class 2A probable human carcinogen.

What does this mean? Does glyphosate, long heralded as one of the safest agricultural pesticides on the market, really cause cancer? Should it be ripped from store and retail shelves, buried, burned and otherwise disposed of? Even banned?

Let’s slow down for a minute here. Glyphosate has been tested inside and out for the past 30 years and has not been shown to be a cancer risk for humans. A mind-numbing number of studies have consistently shown, time and again, that glyphosate is safe. So why the controversy? First, let’s look at the basics.

What is glyphosate and how is it used?

Glyphosate was originally patented by Monsanto in the early 1970’s as the active ingredient in Roundup herbicide. It was introduced to the market in 1974 and has since become one of the DSC_0614best-selling herbicides in the world. Its non-selective mode of action means that it does not discriminate in which weeds it kills. The introduction of this product revolutionized the herbicide market and changed the way farmers kill weeds.

For those interested in the details, glyphosate, a derivative of the amino acid glycine, targets and blocks a pathway called the shikimic acid pathway; which, suffice to say, is required for amino acid synthesis in plants. With amino acid synthesis shut down, plants wilt and die from starvation. Since the shikimite pathway is not found in humans (or any other animal), glyphosate is of very low toxicity. Find even more details here.

Before herbicides were broadly and economically available, farmers were forced to use tillage to control weeds. While other methods helped, such as crop rotation, cover crops and late seeding, tillage was the primary method with which weeds were killed. The problem with tillage is that it is extremely damaging to soil structure and leaves soil exposed to erosion. With the introduction of herbicides, and eventually Roundup, minimum-till agriculture became a realistic possibility, which has decreased erosion substantially on farms that utilize it.

The introduction of Roundup-Ready crops, including corn, soybean, canola, cotton and so on, has allowed for safe, simple, very cost-effective weed control.

Where did this cancer label come from?

Sorting through the rhetoric of glyphosate is a challenge all on its own. Type “glyphosate” into a Google search and you’ll find all kinds of wild claims about cancer, autism, poison, and the like. The fact is that most of what you see is sensationalist news articles with little fact-based information. Let’s cut through some of that rhetoric.

First of all, what does IARC, a semi-autonomous extension of the World Health Organization, mean when it classes glyphosate as a 2A human carcinogen? There are five categories of carcinogens that the IARC lists on their website:

  • Group 1: Carcinogenic to humans
  • Group 2A: Probably carcinogenic to humans
  • Group 2B: Possibly carcinogenic to humans
  • Group 3: Not classifiable as to its carcinogenicity to humans
  • Group 4: Probably not carcinogenic to humans

They listed glyphosate in Group 2A, in which there are 73 agents, which includes the occupational exposure as a hairdresser, shiftwork and high temperature frying. Group 1 includes alcoholic beverages, estrogen and wood dust (source). Yes, that means beer is a greater carcinogenic risk than glyphosate.

What’s everyone else saying?

I think one very important detail that is not being reported on is that the IARC is not the only group that has studied glyphosate. For example, the European Crop Protection Director, General Jean-Charles Bocquet, had this to say:

“The IARC conclusions published in Lancet Oncology contradict the world’s most robust and stringent regulatory systems – namely the European Union and the United States – in which crop protection products have undergone extensive reviews based on multi-year testing and in which active ingredients such as glyphosate and malathion been found not to present a carcinogenic risk to humans.”

 “From the summary conclusions it appears that IARC has made its conclusions as a result of an incomplete data review that has omitted key evidence.” (source)

He’s not the only one. The Environmental Protection Group of the US has done extensive testing of glyphosate, and does not consider glyphosate to be a carcinogen. Other groups, such as Health Canada and the German Risk Agency, are firmly against the notion that glyphosate causes cancer. Put simply, the IARC is the first and only group to label glyphosate as a carcinogen.

Oddly, one of the very few studies they allegedly took into consideration was the fatally flawed Seralini rat study. If you’re unfamiliar with it, it was a shocking study that apparently proved that GMOs caused tumours in rats- but the methodology of the study was so poorly exercised that the journal that published it later retracted it. It is now a laughingstock of the scientific community, and any credible organization that references “information” such as this should thoroughly re-evaluate their credibility.

Is glyphosate actually safe?

I could go into the thousands of studies on the safety of glyphosate, and go into a detailed literature review of why it is such a safe product. But this is a blog; not a scientific journal, and as such I’ll leave the science to the scientists with some links for further reading below. Let me summarize instead; glyphosate lacks the structural characteristics of known carcinogens, and the IARC has failed miserably to link cancer to glyphosate. Interestingly, the IARC actually does not conduct their own research; instead, they look at the data that’s out there and form their own conclusion. Isn’t it telling that they are the first and only group to label glyphosate this way?

The reality is that glyphosate has been applied on billions of acres over the past 40 years, and if it really were that dangerous, wouldn’t there have been some real consequences by now? Wouldn’t livestock and people be getting cancer in droves? This has simply not been the case, and glyphosate has been a wonderful alternative to hundreds of other far more dangerous chemistries out there.

My experience

I have been spraying glyphosate, whether it be Roundup, Touchdown Total, Vantage Plus or whichever of its dozens of formulations, for the past ten years of my life. My father has been spraying it most of his life. My experience with this product is that it is safe, effective, cheap, and is a fantastic tool to combat weeds on our farm. Nobody, in all the years we have applied it, on this farm has ever gotten sick from glyphosate. Not a single friend, neighbor or colleague of mine has ever had a negative health effect from this chemical. Too small of a sample size? How about 60 independent genotoxicity studies with none that imply danger to humans (source)?

The message here is that you can’t believe everything you see and hear. IARC reviewed the data on glyphosate- among other chemicals- for less than a week before making a decision. In contrast, a German study conducted on behalf of the European Union has only just seen its first draft released; a study they have been working on since 2012. Their result? Not a carcinogen!

Don’t trust my claims? Check out my sources. Take the time to understand this issue, and understand the science behind glyphosate and modern agriculture. Glyphosate has been a modern miracle; it’s time we treated it that way.

Further reading:

Along with the links embedded in the post itself, check out these pages for some interesting reading on glyphosate:

Genetic Literacy Project. Is glyphosate–herbicide linked to GMOs–carcinogenic? Not if science matters.

Glyphosate Technical Fact Sheet. National Pesticide Information Center.

Greim, H. et. al. 2015. Evaluation of carcinogenic potential of the herbicide glyphosate, drawing on tumor incidence data from fourteen chronic/carcinogenicity rodent studies.

Kier, LD. 2015. Review of genotoxicity biomonitoring studies of glyphosate-based formulations.

Mink, PJ et. al. 2012. Epidemiologic studies of glyphosate and cancer: A review.

Niemann, L. et. al. 2015. A critical review of glyphosate findings in human urine samples and comparison with the exposure of operators and consumers.

Sorahan, T. 2015. Multiple myeloma and glyphosate use: a re-analysis of US Agricultural Health Study (AHS) data.

The Farmer’s Daughter USA. Glyphosate as a carcinogen, explained. (excellent blog)

Why I Grow GMOs

What do you think about GMOs?

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Is there a more emotionally charged question out there in this part of today’s world? Certainly, it is understandable that the food we eat be an engaging issue for consumer and producer alike. There has been a drive from the consumer to learn about the food they eat. They want to know how it is produced, and whether it is in a sustainable fashion. Ultimately, and most importantly, they want to know if it is safe.  An unknown factor like genetic modification is a cause for concern for these people, because the long-term effects are not readily available to us.

I support and applaud those in the public that ask these critical questions. Too many people don’t think about the things that are done by the government, business and other organizations. The problem isn’t in people asking questions; it is in people asking the wrong questions to the wrong sources – and believing the answers without question.

I am a farmer that grows genetically modified (GM) crops. Not all of my crops are GMOs. In fact, in a usual rotation of 5-7 different crops, only two are GMOs. Canola and soybeans, two of my farm’s most economically important crops, are GMOs. Other crops, like wheat, peas and flax, are not GMOs, for there are simply none available. Contrary to popular belief, I do have a choice to buy GM crops or alternatives. So why do I grow GM crops when there are so many other cropping options?

That is a good question, and the answer will be different for every farm. In my life on the farm, canola and soybeans are our two newest crop options. In Western Canada, we have been growing wheat for as long as we’ve been farming. Flax and peas are old crops for us as well. Canola is one that we have really only been growing in earnest on our farm for the past 15 or so years. We only just started growing soybeans 3 years ago.

I suppose we could grow old open-pollinated canola and conventional soybeans (these are not GMOs). But would we do that? The claim I hear from some consumers is that GMOs are hazardous. By association then, I must be either cruel or naïve to grow these dangerous crops, putting other people at risk.

But here is the question I pose to the GMO haters: do you really believe I would grow these crops if I believed they were unsafe? My family eats the food we grow. I would not put them at risk if I truly believed GMOs were hazardous.

Honestly, I don’t believe they are. GM crops are not dangerous1. In the almost 20 years since Monsanto started genetically modifying corn, soybeans and canola, the evidence has become clear that the benefits of genetic modification far outweigh the risks1. This isn’t an opinion by a biased industry representative. The information I use comes directly from peer reviewed journal articles, the best source of information on anything scientific. GM crops also have dramatically reduced use of the most dangerous and volatile chemicals to control weeds2. Most of the GM plants we deal with are “Roundup Ready”, which means they are resistant to the active ingredient of Roundup, which is glyphosate. The way we measure the toxicity of chemicals like glyphosate is its LD50 number. This refers to the amount of the chemical, given all at once, which results in the death of 50% of the test animals3. The acute Low Acute Toxicity for oral consumption of glyphosate in rats is an LD50 value greater than 5,000 mg/kg of body weight4. This means that if you were a rat, and you weighed in at 3 kg, you would have to consume 15 grams of glyphosate for it to become toxic to you. That is quite a lot. Comparatively, the LD50 of caffeine is 192 mg/kg body weight. How much coffee do you have in a day? The point is, the dosage makes the poison, and any chemical can be toxic in a large enough dose.

Today’s farm operation is a complicated business. Every year, we run through the numbers on each crop to decide which ones to grow and on how many acres. Canola and soybeans, and especially canola, are profitable crop options for us. So yes, we do grow these GM crops because they allow our farm to make money. Are they making us rich? I wish! But they do allow our farm business to make enough money to survive, and hopefully, over time, prosper. Is this not the dream for us all?

Ultimately, the question of why I grow GMOs comes down to the fundamental freedom that we all have in our democratic society: the freedom of choice. It is my choice to grow GM crops. Conversely, if you don’t approve of them, it is your choice to buy something else. However, keep in mind the unintended consequences of doing so. GM crops allow us to use less toxic pesticides at lower rates. Furthermore, we can achieve unprecedented yields with the incredible biological advances made with these GM varieties. We need to grow 70% more food by 2050 to feed this growing world5; we are going to need all the tools we can get to accomplish this.

My farm grows GM crops, and I am proud to say that we do.  They are safe and sustainable crop options that we have the right to grow if we choose to. I hope that you will think about what I have said the next time someone asks you, “what do you think about GMOs?”

References:

  1. Stella G. Uzogara, 2000. The impact of genetic modification of human foods in the 21st century: A review. Biotechnology Advances 18 (2000): 179-206.
  2. RH. Phipps and J.R. Park, 2002. Environmental benefits of genetically modified crops: Global and European perspectives on their ability to reduce pesticide use. Journal of Animal and Feed Sciences, Vol. 11, pp. 1-18.
  3. United States Environmental Protection Agency, 2012. Lethal Dosage (LD50) Values. http://www.epa.gov/oecaagct/ag101/pestlethal.html
  4. Cornell University, 1994. Extension Toxicology Network. http://pmep.cce.cornell.edu/profiles/extoxnet/dienochlor-glyphosate/glyphosate-ext.html
  5. Agricultural Development Economics Division, 2009. High Level Expert Forum – How to Feed the World in 2050. http://www.fao.org/fileadmin/templates/wsfs/docs/Issues_papers/HLEF2050_Global_Agriculture.pdf