~100 Scientists Weigh In on Debate on Most Used Herbicide | Civil Eats

The Battle Over the Most Used Herbicide Heats Up as Nearly 100 Scientists Weigh In

Several powerful agencies have recently disagreed about the health effects of glyphosate. Now, an independent group of scientists says the herbicide is probably carcinogenic.

glyphosate sceince

Test Tubes with GlyphosateOne year ago, an agency of the World Health Organization’s International Agency for Cancer Research (IARC) declared that glyphosate (or Roundup), the world’s most widely used herbicide, probably causes cancer. Then, in the fall, the European Food Safety Agency’s (EFSA) responded with an assessment that disagreed with the WHO’s findings.

In response, 94 scientists came out in support of the IARC’s original findings. This week, the group—which includes scientists from around the world—released their article in the peer-reviewed Journal of Epidemiology and Community Health saying:

The most appropriate and scientifically based evaluation of the cancers reported in humans and laboratory animals as well as supportive mechanistic data is that glyphosate is a probable human carcinogen. On the basis of this conclusion and in the absence of evidence to the contrary, it is reasonable to conclude that glyphosate formulations should also be considered likely human carcinogens.

And their endorsement is no small matter. In fact, as the U.S. Environmental Protection Agency (EPA) reassesses the safety of glyphosate, and the U.S. Food and Drug Administration (FDA) plans to begin testing food for its residue, this volley has important implications.

Glyphosate is applied to 89 percent of U.S. corn crop and 94 percent of the soybeans, as well as with dozens of other crops. Since the herbicide (and the genetically engineered crops that were created to withstand its use) is a core component of today’s productive but extremely harmful industrial farm landscape, the results of this debate could have far reaching consequences.

Why should we trust IARC’s determination that glyphosate is probably carcinogenic?

IARC is a highly respected and independent organization with stringent guidelines for an assessment of this kind. Its determination was unanimous and based on a comprehensive analysis of decades of research. The fact that it was quickly attacked by Monsanto, the largest producer of glyphosate, is no surprise. But the conclusion by EFSA that glyphosate is not carcinogenic is harder to understand, and has led to ongoing debate.

The article makes a complex but compelling argument in IARC’s defense. For example, the authors explain how EFSA unfairly discounted several good long-running epidemiology studies that showed higher-than-average levels of non-hodgkin’s lymphoma in farmers or farmworkers. They also argue that EFSA did not adequately account for the long latency period before cancer develops. In other words, lack of cancer in some studies is not compelling because they may have not been conducted for a long enough period of time.Glyphosate Use by Year and Crop

On a related note, the most dramatic increases in glyphosate use have occurred only in the past five to 10 years—not long enough for most cancers to develop. According to the U.S. Geological survey (see the chart on the right), we now use about 280 million pounds of glyphosate per year as of 2013, compared to only about 30 million pounds a year before genetically engineered crops were first commercialized 20 years ago.

The authors of the new paper also found that EFSA discounted or dismissed many studies that used test animals or lab-based studies published in peer-reviewed journals, despite the fact that they are the professional standard for science research.
Instead, EFSA relied heavily on research supplied by the pesticide industry that conforms to its internally vetted—but unnecessarily and excessively limited—experimental protocols. This process tilts heavily in favor of industry studies not always available to the public, contrary to accepted norms of scientific transparency.

The new paper also found that EFSA relied on statistical methods that unreasonably restrict and limit the value of important research, and run counter to accepted methods. When these and other biases imposed by EFSA were removed, the data strongly suggest that glyphosate is a likely carcinogen.

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For all of these reasons, the 94 scientists deemed the IARC study to be a better analysis of the research data, and therefore ultimately more protective of the public.

How could this paper impact the EPA’s upcoming assessment? It’s tough to say. But when the EPA does publish a reassessment of glyphosate, it could have important implications for agriculture.

And, it is disconcerting that the EPA’s risk assessment process shares many of the same flaws that have seriously marred the EFSA risk assessment, including often discounting or dismissing epidemiological research and peer-reviewed toxicology data, and instead favoring industry supplied toxicology data acquired through EPA approved protocols.

Glyphosate, and the engineered crops that it is most widely used on, epitomize the agriculture system that is now dominant in the U.S. In addition to the potential for human health risks, especially to farmers and farmworkers, glyphosate use has decimated monarch butterflies by killing the only food source of their larvae.

And the tens of millions of acres of glyphosate resistant weeds that have emerged are leading to the resurrection of tillage practices that control the weeds, but often can lead to soil erosion. The solution of the pesticide industry to the epidemic of glyphosate resistant weeds is a new generation of crops engineered for resistant to older herbicides like 2,4-D, which will only increase herbicide use even further.

The EPA assesses the benefits of pesticides as well as their risks. If the agency determines that a pesticide provides important benefits, and that there are no good alternatives, it may be less inclined to eliminate or greatly restrict its use. But a robust analysis of alternatives to glyphosate must assess the inherent vulnerabilities of industrial agriculture to pests and the great environmental harm the herbicide causes. In examining the impact of glyphosate, the EPA should also look closely at the lack of crop diversity—and coinciding lack of landscape and genetic diversity—on today’s industrial farms.

Research shows that when farmers adopt systematic approaches based on agroecology, there are large, and multiple, environmental benefits. These include reduced vulnerability to pests, diseases, and weeds, and hence reduced justification for the use of herbicides like glyphosate, or other pesticides. Research also shows that these systems are more resilient to drought, providing higher productivity, and are practical and profitable as well. And both research and working farms are showing that these methods can work commercially.

But this kind of farming is also knowledge-intensive and requires experimentation. Most farmers who are used to simplified cropping systems are understandably reluctant to take the plunge without support. So we need to shift from subsidizing harmful industrial practices to instead provide farms with financial incentive to shift to practices that build soil, support biodiversity, and manage pests without relying on millions of pounds of glyphosate.

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The EPA can help begin to move more farmers in that direction by thoroughly assessing both the risk and benefits of glyphosate and affirming the IARC assessment.



Doug Gurian-Sherman is a research consultant with Strategic Expansion and Trainings, LLC, in Minneapolis, Minnesota, focused on supporting ecologically based sustainable agriculture, food sovereignty, and food equity. He was senior scientist at the the Food and Environment Program at the Union of Concerned Scientists from 2006-2014, where he authored several major reports on genetic engineering, CAFOs, and agroecology, as well as numerous articles. He was previously a scientist at the U.S. Environmental Protection Agency (EPA), responsible for assessing human health and environmental risks from engineered plants and microorganisms and developing biotechnology policy. He was appointed to the inaugural FDA biotechnology advisory subcommittee, has advised the National Research Council, and is widely cited in national media. He holds a Ph.D. in plant pathology from the University of California, Berkeley. Read more >

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  1. Cynthia Murphy
    The moral of this story - Eat organic non-GMO
  2. DaleInOklahoma
    This is my main problem with GMO's. People like to say that GMO simply means that we've taken two plants and made a better plant. Sure, that's possible and it is called hybridization which has been done since the beginning of time. What they don't explain is that these plants have been altered so that the massive 'farming' companies can absolutely SOAK our food in this cancer causing poison. Or how about the corn that emits a poison that kills bugs when they eat it. There has been absolutely ZERO long term studies on the effects that this has on human health, yet they claim that GMO's are just hybrids and are good for us. This is why we continue to grow large gardens using heirloom seeds and all natural fertilizers and weed control.
  3. Stuart
    Glyphosate is an endocrine disruptor as was Agent Orange used in the Viet Nam War (and I might add in Laos and Cambodia) and even in some places in the US and around bases in Thailand. We, meaning those of us who fought the war, did not start coming down with a raft of illnesses including twelve types of cancer, skin diseases, type two diabetes, etc. until long after the war.
    Now Monsanto, the maker of Agent Orange along with Dow Chemical is doing it again. Many cancers are already chemical related. Is Monsanto again at war with Americans for profit?

    Nam Combat Vet disabled by Monsanto and Dow Chemical. Are you next?!
  4. Long gone are the days when Americans could trust the EPA, FDA, or the EFSA.
  5. Dan C
    The one thing not mentioned here is the increased rates of Celiac Disease and the possibility that glyphosate is the link. While the use of this chemical might be safe for a good portion of the population, those with a genetic predisposition to Celiac Disease may be at risk as glyphosate might be a triggering mechanism for the disease.

    One should also question the practice of spraying food crops with glyphosate just before harvest to increase yields, and get a jump on the next season's weed control. Is this adding a level of toxicity that would not be seen if the product was used in a more tradtional fashion during the growing season?
  6. Noel
    My question, is why we had to reach this ridiculous position, before the protection of our government stepped in and cleared the air. The answer , opposed by many, is that corporate profits, and political contributions take precedence over the safety and health of our nation and the world!!!
  7. Kevin Hancey
    I think there's a lot of money at stake here so I would want to know if these agencies are interdependent on the monies as well as do the scientists have an affiliation with these companies and monies ?
  8. Finally, we are getting non-bias and scientifically sound analysis of the RoundUp components. We have generously applied RoundUp for decades on lawns in public parks, around playground where the infants and pregnant women are present for hours at a time and with a little or very insufficient public notice. It has been a chemical attack on our civilians with no other enemy than just our own corporate greed! We have to start looking at the whole synergy, not just one single argument: we need some weed control! I like how we were combed into a firm belief that dandylions (that are actually eatable) and clover are worse than chemicals and that the only benefit is a eye-pleasing green "desert" on that nothing by grass public or private lawn.
  9. Dan Sanford
    Monsanto has way too much power through large payoffs to the right people. Scientists are bought off everyday. Graft rules the world of science and the judiciary.
    Remember agent orange? Monsanto touted it as safe. We know better now.
  10. Jane Sooby
    If indeed the IARC is the body whom we should believe, how does their finding that there is "limited evidence of carcinogenicity in humans" translate into "glyphosate is probably carcinogenic"?
  11. Those "tests" only look at "active" ingredients in mixes such as Roundup, where recent test have shown that 7 out of 8 Roundup products (with toxic "inerts" and toxic interaction with "active" ingredients) are up to 1000x as toxic. And this is just "short-term exposure". Another recent report used FOI info from EPA exposing that Monsanto AND EPA worked together to hide the toxicity that they both have known for 35 years. Then there is the trans-generation impacts of VERY LOW exposures . . . .
  12. "Research shows that when farmers adopt systematic approaches based on agroecology, there are large, and multiple, environmental benefits."

    And financial benefits in the long term.
    So many "sustainable" methods based on "agroecology" or whatever buzzword you want to stick on it have been relied on long before big industry agriculture erupted onto the scene.

    Farmers that are choosing to return to these old school methods are now deemed "progressive," as if growing food without the addition of chemicals or heavy machinery was a radical new trend.

    If it ain't broke...
  13. farmer ron
    Farmers and agricultural businesses that are dependent on glyphosate are equatable to slaveholders who discounted the human toll of their production system.
    they will stop poisoning the land water and people only when they are forced to do so. Make the EPA a servant of the people as it was designed.
  14. Doug Gurian-Sherman
    Jane, IARC's assessment is based on multiple sources of evidence and research. In addition to the epidemiology data you mention, there is also toxicology (lab-based testing), and data from human exposure incidents and response. IARC found the toxicology data to be stronger than the epidemiology. And data associated with biochemical mechanisms in those exposed were also consistent with carcinogenicity.

    Also, it is important to understand that "limited evidence" does not mean that the evidence suggests lack of carcinogenicity, but only that there is not enough to be confident in carcinogenicity based on the epidemiology alone. But again, the epidemiology is only is only one piece of the whole picture.
  15. Andrea
    All you have to do for facts is look at the increase in the past 5 years of the cancer Multiple Myloma. Just 10 years ago you might not known anyone today it's 10x more. My husband had a marker for it 10 years ago and was watching carefully for it not to rise to cancer. At the same time he kept spraying roundup and eating non organic corn, soy etc. Well in 2016 he had full blown chemo needed Multiple Myloma CANCER. Need I say more?

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