The Great Glyphosate Debate

Posted in: Global Ag     

In March the World Health Organization’s cancer arm classified glyphosate, the world’s most heavily used herbicide, as a probable carcinogen. Its manufacturers are crying foul, special interest groups are applauding and farmers are caught in the middle.


When Ron Krahn heard that a branch of the World Health Organization announced that glyphosate — the popular herbicide he uses in his 5,200-acre farm operation near Rivers, Manitoba, — probably causes cancer, he sighed.
“As a farmer, I feel very much caught in the middle,” says Krahn, 39, who runs the operation with his father and brother. “No one wants to grow unhealthy food — the questions for many farmers are, What’s that study? What’s the bias? Who paid for it?”
They are good questions.
However, he and many other farmers who are pondering them may find themselves steered toward wildly different answers — depending on who they’re listening to.
News that the International Agency for Research on Cancer (IARC), an arm of the WHO that specializes in cancer prevention, classified glyphosate, the world’s most heavily used herbicide, as a probable carcinogen sent shock waves across the industry. Some farm groups reacted defensively, while the companies that manufacture and sell crop inputs attacked the scientific credibility of the study and the objectivity of the international panel of the world’s top cancer scientists.
Meanwhile, many special interest groups were quick to latch onto the WHO agency findings in a bid to leverage their own agendas, suggesting that the new glyphosate classification validates their claims that GMOs, pesticides and other agricultural technologies could be damaging the environment, creating health concerns and putting the world’s food supply at risk.
As Dan Mazier, president of the Manitoba farm group Keystone Agricultural Producers and a Brandon-area grower, puts it: “Monsanto says one thing, special interest groups say another, while farmers and the general public are wondering, what does this mean?”

Understanding the Hazard

Dr. John McLaughlin, Chief Science Officer of Public Health Ontario, one of Canada’s top epidemiologists and a leader of the largest cross-Canada study on pesticides and health, empathizes with farmers like Mazier and Krahn.
“I can understand how your readers might be feeling a bit caught in the middle,” McLaughlin told the AgAdvance Journal during a recent interview. “They are among the most informed about the use of this product, but even well informed people can be confused by what is largely a false debate.”
McLaughlin, who is also a professor in the School of Public Health at the University of Toronto, says he expected there would be some backlash to IARC’s findings, given the widespread use of a product such as glyphosate.
However, he bristles at accusations questioning the scientific credibility of the WHO agency or the professional integrity of the medical experts from around the world who worked on the review.
A senior official with Monsanto, which manufactures glyphosate under the name Roundup as well as many of the seed varieties genetically modified to tolerate it, told the Wall Street Journal in March that the company was “outraged” with the IARC findings, suggesting it “cherry picked” the data and had an underlying agenda.
And in a recent interview with the AgAdvance Journal, Monsanto’s Winnipeg-based director of public and industry affairs, Trish Jordan, also questioned IARC’s motives.
“Conclusions like this that deal with human safety need to be non-biased and based on scientific standards that are globally recognized,” she said.
McLaughlin concurs completely. “It’s been said by some that, ‘Oh, this group must have some kind of agenda.’ Well, yes — its agenda is to reduce the burden of cancer around the world.”
The review by IARC may be complete, but McLaughlin says one way he can assist further is to explain IARC’s scientific process and address some of the false claims.
“I’m not surprised by the reaction of people who are fully invested in this,” he says. “There needs to be full disclosure about where those people are coming from, and then there can be debate about the evidence and facts.”

According to McLaughlin, the process IARC developed is “very rigorous, they are very careful about removing conflicts of interest and they are very careful to use only the best science of the highest quality in their assessment.”
In response to the suggestion that the IARC ignored valid research, McLaughlin says, “Yes we cherry picked, and we picked only the cherries that were ripe — the most informative, high-quality and unbiased research out there.”
As an arm of the WHO, IARC’s role is different from many cancer agencies that focus on treating the disease. IARC’s mission includes cancer prevention, i.e. finding ways to reduce cancer risk and burden around the world.
A year ago, IARC asked a panel of some the world’s top scientists to provide strategic direction on where it should focus its attention in terms of existing and potential carcinogens. For this process, IARC did not conduct research itself, rather it brings together and reviews the best existing research from around the world to provide overall cancer hazard assessments. (Risk assessments, on the other hand, are left to each country’s own regulatory bodies.)
McLaughlin, who was on that panel, says it looked for areas of research where enough new evidence was available to make an IARC review both feasible and informative. “If there’s no new evidence, there’s no need to summarize it.”
Glyphosate has never been reviewed, or thereby classified, by IARC. It was included in the recent review because enough new evidence and research was available.
However, not all research qualifies for consideration by IARC. Papers must be rigorous, well-designed, large scale and provide meaningful evidence about the subject at hand.
Also, the research must have actually measured glyphosate use, rather than simply measuring people living on farms or in areas where it’s used, and the results must have been published in a peer-reviewed scientific journal. (A German study on glyphosate that critics say was ignored had still not been published at press time.)
The panel reviewed all available evidence concerning five pesticides, of which one was glyphosate. In March, after a year reviewing this evidence, the 17-member IARC panel published a summary of its findings in Lancet Oncology, in which it classified glyphosate ‘Group 2A’, which means it’s probably carcinogenic. Group 1, for example, includes UV radiation, which is a known carcinogen. IARC will be publishing a book outlining its findings in greater detail this July.
As part of its effort to ensure integrity of the organization, credibility of the findings and transparency of the process, IARC invites organizations or industry groups that are involved with a product under review to sit in on the discussions.
“They are welcome to participate and they did,” says McLaughlin, noting that a Monsanto representative sat in for over a week. “There are strict rules to ensure industry doesn’t influence conclusions, but they can inform and ensure all research is on the table.”
The panel — which includes a wide spectrum of cancer experts such as microbiologists, environmental scientists, oncologists and epidemiologists — looks at three types of studies: human health, animal health and what McLaughlin calls mechanistic studies.
Under human health, the IARC reviewed four major glyphosate studies that focussed on not just glyphosate, but also causes of non-Hodgkin’s lymphoma, a type of cancer, from Sweden and Canada, as well as two American studies.
Three of these studies found links between glyphosate and NHL that were consistent, similar and statistically significant, says McLaughlin. The fourth study, done in the U.S., did not find the same association, which contributed to the panel’s decision to classify it as Group 2A rather than Group 1. “The IARC process is rigorous and careful not to overstate a conclusion, but when there’s sufficient reason for concern it doesn’t want to understate that.”
Its review of the animal toxicity studies related to glyphosate led to the conclusion that “there is sufficient evidence to say glyphosate is carcinogenic in animals,” says McLaughlin.
The third line of evidence, mechanistic, is the newest. It considers the mechanisms that underlie cancer. “In lab settings it’s now possible with large scale machinery to scan through large numbers of chemicals and molecules and assess their biological effect in ways that hasn’t traditionally been done by toxicologists,” says McLaughlin. “The mechanisms that happen within our body to give rise to cancer are much better understood now.”
He adds, “One of the comments is that we didn’t do any new studies, and that’s true. But what we did was bring all of the latest information from around the world from many new disciplines, and part of that is a new understanding of what cancer is and how it acts.”
Mechanistic studies also presented “supportive evidence for the conclusion that glyphosate is probably carcinogenic.”
McLaughlin points out that the conclusions related only to those who used glyphosate most often, and that there was no evidence showing that low levels of exposure or occasional use would have any cancer risk.
“What IARC has shown is that at higher levels of use there’s probably going to be a cancer concern,” McLaughlin says. “The purpose of this classification is to heighten awareness and raise attention of the importance of taking risk assessments [which consider dose] from Health Canada and the [U.S. Environmental Protection Agency] seriously.”
Both regulators recently conducted a re-evaluation of glyphosate. Health Canada’s risk assessment changed slightly to include direction not to use it near populated areas and take steps to keep it out of waterways. It is open to public review and comments until June 12 (visit The EPA’s risk assessment is expected to be released soon.
Risk and hazard assessments go hand-in-hand, says McLaughlin. “The purpose of hazard assessment is to know that something has the potential to cause cancer,” he says. “This is important to know. The hazard assessment done by IARC is complementary to risk assessment done by national regulatory agencies, with one difference being that risk assessment identifies levels and practices that can be safely used, with most evidence being based on short term studies, whereas cancer can usually takes many years to arise so any hazard that might be detected would be based on exposures up to 20 ago.”
Ultimately, he says the value is the ability to use the information to balance the risks and benefits of a certain product, whether that’s glyphosate or sunlight or a chemotherapy drug that is also classified as Group 2A because it can stymie certain cancer cells in the short term, while increasing the longer-term development of others.
To strike this balance effectively, however, one needs the facts.
Many people, farmers and the public at large, have become conditioned to veer toward one of two extremes when it comes to scientific claims about food — either approach it with skepticism and question its credibility, or accept all science (even junk science) that supports their current beliefs, disregarding even the most legitimate science that calls those beliefs into question.
What McLaughlin, and others such as Dr. Joe Schwarcz, director of McGill University’s Office of Science and Society and author of Monkeys, Myths and Molecules: Separating fact from fiction and the science of everyday life, suggest is that people need to respect legitimate science, and scientists need to do a better job of communicating it.
“It makes no difference to me whether or not glyphosate is banned,” Schwarcz told listeners on CBC Radio’s The Current on May 6. “Our allegiance is to the scientific methods, and that right decisions are made based on evidence, which is furnished by peer-reviewed literature.”

Making Sense of Science

Yet, are farmers, or anyone who isn’t a scientist for that matter, going to wade through complex scientific journals? 
Not likely.
However, the glyphosate debate may indicate that this is exactly what’s required. Like many public debates shrouded in equal parts controversy and passion, this one is being fed by a combination of fact and fiction, good science and bad science, being offered up by experts, both legitimate and self-proclaimed, from both sides of the spectrum.
No wonder some farmers are rolling their eyes.
It’s a debate that has exploded far beyond the ag media’s purview — The Wall Street Journal, New York Times, Fortune magazine, Globe and Mail, NPR and CBC’s The Current have all been covering the story in recent months.
What started out as a shocking headline has morphed into a wider story about GMOs, pesticide and food safety — all within the context of consumers’ and farmers’ ongoing plight to separate scientific fact from fiction.
A big part of that, say experts, is to understand where people are coming from.
Special interest groups have an obvious agenda; it is their special interest, after all. Corporations also have a special interest, which is their bottom line and their duty to shareholders to protect it.
Industry representatives such as Jordan and Pierre Petelle, vice president of chemistry with CropLife Canada, are critical of IARC’s review, which casts a negative light on their line of business (CropLife Canada is a trade association representing the plant science industry).
“It’s very clear that the risk of this product has not changed and it continues to be a valuable tool for farmers, but bad news makes it around the globe in a minute,” says Petelle.
Often, the media or consumers will try to counter-balance this by speaking to presumably objective experts at universities — though, this can also be murky.
Stuart Smyth, who teaches in the Bioresources, Policy, Business and Economics department at the University of Saskatchewan, is a paid research chair, fully funded by industry, including Bayer CropSciences, CropLife Canada, SaskCanola, Monsanto and Syngenta.
Smyth writes a popular blog, SAIFood — Sustainable Agricultural Innovations & Food, which promises to break down complex research to help consumers understand agriculture research, innovation and technology.
Of IARC’s recent classification of glyphosate, he says the agency has moved from science-based evidence toward hypothetical evidence (a claim McLaughlin clearly refutes).
“I think this is a very irresponsible report released by the WHO,” Smyth told the AgAdvance. “It underscores how significant this is for an international organization to shift away from science-based processes to speculative rationale to make this decision. That’s unprecedented.”
McLaughlin says these positions are understandable, given business realities. However, the context of these comments must be understood by farmers and the general public. In other words, Ron Krahn’s questions about the motivations of those disseminating information are good ones to ask across the board.
“My purpose is disease prevention and health promotion, and the scientists that came together on that international panel shared that perspective,” he says. “I’m not surprised that people will be critical, they’re defending their own interests. And yet we have an opportunity here to get back to the evidence that comes from the studies of highest quality, and I’m quite happy to be part of that dialogue.”

The Fallout Effect

One thing that can’t be refuted is Smyth, Jordan and Petelle’s assertion that special interest groups are actively playing up IARC’s report.
“They now have an international agency come out and condemn glyphosate so they have got the golden ring — the ‘precious’ of the Hobbit movies — and they will milk it for every drop,” says Smyth.
He adds that an outright ban of glyphosate would have a devastating impact on food security, not to mention farmers’ bottom lines. It is far less toxic than the pesticides it replaced, and reduces soil erosion by limiting the need for tillage.
“If the environmental movement spins this against GM crops in developing countries, they could reject these technologies and remain food insecure.”
Another development that curiously coincided with IARC’s report was the decision by Grain Millers Inc., which has the largest oat milling capacity in North America, to stop buying oats that have a pre-harvest application of glyphosate.
Management stressed that the decision was solely based on quality, not concerns over health or food safety. A two-year study showed that oats desiccated with glyphosate showed frost-like damage.
“Still, it’s a series of unrelated events that people are drawing a connection to,” says Petelle.
Also alongside glyphosate’s new classification is a movement by regulators toward implementing new restrictions on inputs such as glyphosate that will help address the increasing number of weed species that are resistant to the herbicide.
Weed resistance is not a new issue, and it is not limited to glyphosate, says Markus Braaten, a Senior Agri-Coach and U.S. Director of Agri-Knowledge with Agri-Trend Inc., the publisher of this magazine.
“Genetic diversity is such that if you choose to use any product that controls weeds, you have the potential to develop resistance,” says Braaten, noting that the solution lies in agronomic best-practices. “Are there risks associated with glyphosate? There’s risk with anything we do and with crop protection products in general, that’s why we’re judicious and have good regulatory regimes.”
Meanwhile, back in Brandon, Manitoba, Mazier says regardless of this debate, the majority of farmers will continue to use glyphosate if it’s the most effective tool available, and they’ll continue to respect the safety guidelines governing its use.
“All the pesticides we use have come through the regulatory agencies, and my job is to put them on at recommended rates within the recommended time frames. If I don’t I put my crop at risk and my livelihood at risk,” says Mazier. “I don’t want my crop burning up or poisoned — I need a valuable crop I can sell. Guys won’t over-apply; there’s too much at risk.”

About the Author
Tracy Tjaden

Tjaden is a Canadian journalist who has spent the majority of her career writing and editing for magazines, primarily business-related titles.

She grew up on a farm near Winnipeg, worked at several newspapers in Canada before specializing in magazines, with a focus on business, finance and agriculture.

Tjaden was Editor of BCBusiness Magazine in Vancouver and Managing Editor of a financial magazine in New York City before returning to Winnipeg. She is currently editor of the AgAdvance Journal and agadvance online, and can be reached at


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