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Glyphosate: the real science

Will new studies that confirm the safety of glyphosate actually stop politicians from banning an essential herbicide?

The study published in the November 9, 2017 Journal of the National Cancer Institute is crystal clear. Called “Glyphosate Use and Cancer Incidence in the Agricultural Health Study”, it says: “In conclusion, we found no evidence of an association between glyphosate use and risk of any solid tumours or lymphoid malignancies, including NHL (Non-Hodgkins Lymphoma) and its subtypes.”

One of the study’s authors, Dr. Laura Beane Freeman, senior investigator with the National Cancer Institute, Rockville, Maryland, was even clearer: “The study did not find correlation between use of glyphosate and cancer.”

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Spraying machine working on the green field

However, Beane Freeman notes “the study did support an increased risk of acute myeloid leukemia amongst the highest exposed group; but no other study has looked at this and this requires confirmation.”

Beane Freeman noted this study came to the same conclusion as was reached in 2005 when the Agricultural Health Study (AHS) first evaluated the glyphosate cancer risk. She noted the current study is basically an update of that 2005 study and is a re-evaluation of the same study participants based on updated health and cancer reporting roughly a decade later.

According to Beane Freeman, the AHS is among the largest and longest-running studies of the health of farmers in the world. More than 89,000 people have participated in the AHS. Between 1993 and 1997, 52,394 licensed private pesticide applicators, most of them farmers, and 32,345 of their spouses registered with the AHS.

At registration as well as in interviews, they provided the AHS with detailed information on their farming practices, lifestyle and health. They also completed a dietary questionnaire and provided a DNA sample.

All participants lived in either Iowa or North Carolina. These two states were selected for the study because each has a large number of farmers and a large rural presence. The two states have different kinds of farm operations, however, and this ensured the study results reflected a wide range of crops and farm types. As well, both states also already had cancer registries in 1993 which allowed researchers to track the incidence of cancer in the study participants.

From the initial interview plus a questionnaire five years after registation and another followup in 2011, researchers were able to estimate lifetime usage of glyphosate and 49 other pesticides.

Researchers were also able to identify a control group of farmers for comparison, based on the 17.2 per cent of participants in the study who had never used glyphosate.

With this information, researchers used statistical analysis to compare the incidence of each type of cancer based on whether the participant had used or did not use glyphosate. The results are publicly available on the web at the Journal of the National Cancer Institute website.

Beane Freeman points out this study is unique and important because not only is the risk assessment based on actual cases of cancer in humans, it is also a long-term study of the cancer risk. She notes cancer may not appear until years after exposure to a carcinogen, and she hopes the study continues for the next 20 or 30 years, tracking the incidence of cancer and other health risks not only in the original AHS participants, but also in the offspring of the participants.

What this means for glyphosate

There is no question it is good news that the AHS study has found no correlation between glyphosate and cancer after 20 years of monitoring the health of a large number of farmers. It is likely many farmers who have seen the study results will assume this will mitigate the arguments that glyphosate is unsafe and should be banned. Unfortunately, this assumption may be premature.

The International Agency for Research on Cancer 2015 report that classified glyphosate as “probably carcinogenic” still carries a lot of weight, and it is important to recognize that IARC had considered the 2005 AHS study that found no relationship between glyphosate and cancer before releasing its 2A classification of the herbicide.

  • Read more: In glyphosate review, WHO cancer agency edited out ‘non-carcinogenic’ findings

Nor should farmers put too much hope in the November 27, 2017 decision by the European Commission to renew the licence of glyphosate in Europe for five years. Initially, the commission had been seeking a 10-year renewal but scaled back licensing terms after the European Parliament in October called for banning glyphosate by 2022.

It seems there can be no question that some lawmakers were influenced by a petition signed by 1.3 million people calling for an outright ban of glyphosate.

After two years of acrimonious debate, only 18 of the 28 EU countries represented on the commission voted to renew the licence for glyphosate. (Nine countries opposed renewal of the licence and one country abstained from the vote).

In fact, though, the decision was closer than the vote seems to show because EU rules say at least 16 states representing at least 65 per cent of the EU population had to approve. In the end, the 18 states that voted yes represent only 65.7 per cent of the population.

And, in spite of the approval, some EU countries such as France are still intending to ban use of glyphosate within their borders.

After the vote, French President Emmanuel Macron stated that glyphosate would be banned in his country as soon as an alternative was found, and at latest, after three years.

The San Francisco trial

Even so, the biggest risk to glyphosate may be a court case in California. As I reported in the March 1, 2017 issue of Country Guide, personal injury lawsuits have been filed both in state and in U.S. district courts by persons claiming that exposure to glyphosate has caused their (or a family member’s) cancer.

The most prominent case is being heard in San Francisco District Court where now more than 300 lawsuits have been combined in a single multi-district litigation, with the first trial scheduled to begin in the County of San Francisco Superior Court on June 18, 2018.

Another hurdle to glyphosate acceptance was the July 7, 2017 addition of glyphosate to California’s list of carcinogens by California’s Office of Environmental Health Hazard Assessment. Besides just increasing public perception that glyphosate is unsafe, the listing calls for warnings to be placed on the glyphosate label.

Meanwhile in Canada…

In 2015, Canada’s PMRA re-evaluated glyphosate and in “Decision RVD2017-01 Glyphosate” determined:

  • Glyphosate is not genotoxic and is unlikely to pose a human cancer risk.
  • Dietary (food and drinking water) exposure associated with the use of glyphosate is not expected to pose a risk of concern to human health.
  • Occupational and residential risks associated with the use of glyphosate are not of concern, provided that updated label instructions are followed.
  • The environmental assessment concluded that spray buffer zones are necessary to mitigate potential risks to non-target species (for example, vegetation near treated areas, aquatic invertebrates and fish) from spray drift.
  • When used according to revised label directions, glyphosate products are not expected to pose risks of concern to the environment.
  • All registered glyphosate uses have value for weed control in agriculture and non-agricultural land management.

Yet Health Canada has ordered the updating of glyphosate labels by 2019 with additional requirements to further protect human health and the environment

Finally, the U.S. Environmental Protection Agency is still working on the review of glyphosate it started back in 2009. It hopes to issue a draft document in early 2018 for public comment on glyphosate.

Far from resolving the question of the safety of the most used herbicide in the world, the Agricultural Health Study will only add to the debate. It is a debate that every farmer needs to be aware of and informed about. While it may have lessened the impact of the IARC report to some degree, it has prompted those opposed to glyphosate to widen their attack of the herbicide on new fronts such as the development of weed resistance to glyphosate.

It really is up to farmers to inform consumers and the general public about the AHS study and the importance of glyphosate to agriculture and food production. Farmers have to explain what we do and why we do it.

Consumers who are interested in health, the environment and food safety must hear that these are our concerns too. We are on their side.

More on agricultural health

To learn more, consider checking out the Agricultural Health Study website this winter.

The Agricultural Health Survey does much more than just track cancer risk posed by pesticides. Researchers use data from the survey to monitor the health risks from factors ranging from the use of smokeless tobacco to the correlation of health to body mass index.

The AHS has provided the data needed for the research that has led to the publication of more than 200 scientific papers; all of which are available for public viewing through the AHS website.

AHS provides a quarterly newsletter to participants of the study informing them of findings. AHS also provides valuable education through news releases as well as on their website for farmers to consider in protecting their health.

As an example, here is a listing of recent observations made by AHS researchers as presented on the AHS website:

  • Farmers have lower rates of many diseases compared to the rest of the population, perhaps because they are less likely to smoke and are more physically active.
  • Farmers have a higher risk for developing some cancers, including prostate cancer
  • Gloves matter. Use of chemically resistant gloves can reduce pesticide exposure by 50 to 80 per cent.
  • Rotenone and paraquat are linked to increased use of developing Parkinson’s disease.
  • Allergic asthma in men and women may be associated with use of some organophosphate insecticides.
  • Accidental high pesticide exposure events may affect health later in life.
  • Diabetes and thyroid disease risk may increase for users of some organochlorine chemicals.

About the author


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  • dario

    in Europe, the EFSA (European food safety authority), the body that
    controls the effect of pesticides in agriculture, has declared that
    there is no danger in the use of the glyphosate, but it turned out that
    its research was a copy paste the research done by Monsanto itself !!!! And
    these gentlemen did not have the courage to present themselves to any
    meeting of the European commission that was discussing the renewal of
    the license over the next 10 years! Germany for a long time abstained in the votes, then taking into account Bayer partner of Monsanto has changed its mind.
    in Europe the general orientation made by consumers and farmers is now
    moving towards “sustainable” agriculture and with the increasingly low
    use of phytosanitary products.
    So this is the road that
    even North American agriculture will be forced to follow if it wants to
    propose itself on the European markets.

    • FarmersSon63

      40 years of extensive use and still not even one confirmed illness or death from consuming ultra munute glyphosate residues on foods.
      Guess how many people got sick or died from consuming alcohol LAST WEEK?

      • JoeFarmer

        Let Europe turn back the clock on agriculture to the point where there are food shortages like in and after WWII. Then they’ll come to their senses.

        And I sure wouldn’t look at any policy decisions by Germany in roughly the last decade as very bright – look what happened to them when they decided no more nuclear power – power prices skyrocketed and now they’re burning really low grade coal which is really polluting their country.

      • dario

        me why the only agriculture that grows in two figures is the biological
        one that, I agree, can not solve the problems, but in Europe people for
        national culture wants to eat better and better, that is, healthier,
        and remember that in Italy the consumption of
        pasta (durum wheat) is about 28/29 kg in a year unlike other states that
        consume 5/6 kg and it is right that our companies produce an
        increasingly healthy and tasty product

        • FarmersSon63

          Because pesticides are currently being used on over 96% of all US crop acres. Not much room for growth.

          • E. Sandwich

            Maybe that is why the people in the U.S. are so unhealthy, even after they spend the most per person on the planet for what they call health care.

          • FarmersSon63

            We are the healthiest and are living longer than any time in history.

          • E. Sandwich

            Nonsense. The U.S. Spends more money per person on health care than any country in the world and we have a third world life expectancy that is shorter than 33 other countries. Right between Costa Rica and Cuba.


          • FarmersSon63

            Again, Ted.
            US citizens are living longer than any time in history, are more fit and healthy than any time in history.

          • E. Sandwich

            Nope. I have posted the facts and you don’t even know who you are talking too.

      • patzagame

        So you claim…how scientific.

        • FarmersSon63

          Prove me wrong.

    • Rob Bright

      Pay no mind to the antiscience gibberish from the two fake farmers below. Both are well known, pro-GMO, pro-agrochemical industry spokespeople and propagandists who troll social media 24/7 for articles on GMOs and pesticides. They spread misinformation and pseudoscience on behalf of the agrochemical/ biotech industry and have zero credibility.


    This is a cohort study. Cohorts are considered to be weak to mid-range at best. cohorts need to be replicated before they are considered to be good science.

    They were unable to find over 30% of the study participants when they did the long term follow-up questionnaire by telephone survey. We should be asking what happened to the health of these 30% of the study subjects.

    Monsanto toxicologist Donna Farmer said this about this study in internal Monsanto correspondence. “Many groups have been highly critical of the study as being a flawed study, in fact some have gone so far as to call it junk science. It is small in scope and the retrospective questioneer on pesticide usage and self reported diagnoses also from the questioneer is thought to be unreliable”

    This study is not a reliable indicator for glyphosate safety.

  • grinninglibber

    Flawed study…but the usual Monsnato operatives (phake pharmers and the like) are here to cheer it on – your health or their profits?

  • Rob Bright

    Completely bogus research findings based on completely bogus research. Anyone who buys into the AHS study findings has no clue how flawed the research design was. Here’s why:

    ” Prior to the introduction of genetically modified seeds, glyphosate/GBFs accounted for only 3.8% of the total volume of herbicide active ingredients applied in agriculture, while this changed to 180–185 million pounds by 2007 [EPA reports; Coupe 2015]. This substantial increase established glyphosate/GBFs as 53.5% of total agricultural herbicide use in 2009 according to USGS [Thelin and Stone 2016]; annual farm-sector glyphosate/GBF usage further increased to approximately 240 million pounds in 2014 [based on average annual crop use reported by the NASS; Service. USDoANAS 2016, Benbrook 2015. The original AHS enrollment (Dec 1993-Dec 1997) preceded this tremendous increase in agricultural use of glyphosate/GBFs. Thus, this increase in use was never captured for members of the AHS cohort who did not respond to follow-up interviews in phase 2 (1999-2003) or phase 3 (2005-2010) of the AHS, as set forth below.
    Importantly, the second phase of the AHS was plagued by low response: i.e. it generated no more than a 64% response rate among AHS cohort members who were private applicators contacted in 1998-2004 (or a 36% non-response). This is an extremely low response rate when usage increased this much and this fast (furthermore, concerning future glyphosate/GBF analyses in AHS, only 46%, less than half, of all private applicators responded to the third phase 2005-2010 interviews). Thus, one-third Case 3:16-md-02741-VC Document 653-2 Filed 10/28/17 Page 4 of 144 of all cohort subjects never reported their actual exposures or changes in exposures after enrolment interviews were conducted, even though use of glyphosate/GBFs started to change dramatically.
    The AHS researchers knew that such a large non-response rate would raise questions about the validity of certain results of their study, so they were forced to come up with a method to address this problem. Otherwise, these studies would be questioned by peer reviewers and unlikely to be published. The AHS researchers attempted to address the loss of active participants with a method called ‘imputation’ to avoid having large amounts of missing exposure data –for those who did not respond – or generating selection bias (cohort studies may be affected by selection bias due to ‘differential’ loss to follow-up among the exposed or unexposed cases and controls) (Heltsche, et al. 2012). The method the authors used was a “data driven imputations of exposures”; or, in other words, a ‘guestimation’ of what exposures would have been in those who did not respond and report. This procedure assumes that it is sufficient to use the data in hand to predict/guestimate all future exposure in AHS participants who did not respond; i.e. that the past and current exposures and characteristics of the participants who responded to multiple interviews over time would accurately predict the use of those who did not respond. For glyphosate/GBFs with a use pattern change as dramatic as described above, it is a flawed approach to predict who would or would not start using Roundup® Ready crops after baseline, and likewise to predict the use of glyphosate/GBFs. ”

    MDL No. 2741
    Case No. 16-md-02741-VC


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