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See also Food and Farm Discussion Lab links on Glyphosate.


Glyphosate is a broad-spectrum systemic herbicide and crop desiccant. It is an organophosphorus compound, specifically a phosphonate. It is used to kill weeds, especially annual broadleaf weeds and grasses that compete with crops. It was discovered to be an herbicide by Monsanto chemist John E. Franz in 1970. Monsanto brought it to market in 1974 under the trade name Roundup, and Monsanto's last commercially relevant United States patent expired in 2000.

Many claims have been made that Glyphosate, and Monsanto's proprietary Roundup formulation, are harmful to health and the environment, often by anti-Monsanto and anti-GM campaigners.

Iida Ruishalme discusses most if not all of the claimed issues with Glyphosate at her Thoughtscapism blog:

17 Questions About Glyphosate

2. Could glyphosate have other health effects? What about the surfactants in RoundUp, or glyphosate breakdown products?
What about the surfactants (soap-like substances) in pesticides?
Glyphosate breakdown product AMPA
Could glyphosate be an endocrine disruptor?
3. What about studies claiming glyphosate causes celiac disease, autism, and obesity, etc? A look at Seneff et al.
5. Could glyphosate be another case like DDT or Thalidomide?
5a) Are there parallels between glyphosate and the case of thalidomide?
5b) But what about DDT?
A word on persistent vs non-persistent pesticides
Regulatory (r)evolution – why DDT could not happen today
6. Is glyphosate an especially dangerous pesticide?
7. Is there glyphosate in the air and rainwater?
8. Is there glyphosate in urine?
9. What about breastmilk?
10. Should we worry about glyphosate in wine? (and honey, vaccines, tampons ...?)
11. Is wheat toxic because of glyphosate?
12. Are crops drenched in glyphosate?
13. Does glyphosate use enable bad farming practices?
14. What about resistance and superweeds?
15. Does glyphosate interfere with soil organisms or nutrient availability?
About earthworms
16. Does glyphosate harm Monarch butterflies or bees?
What about conflicts of interest and industry funding?
But haven’t industries influenced the state of research before?


Concerns over use of glyphosate-based herbicides and risks associated with exposures: a consensus statement John Peterson Myers, Michael N. Antoniou, Bruce Blumberg, Lynn Carroll, Theo Colborn, Lorne G. Everett, Michael Hansen, Philip J. Landrigan, Bruce P. Lanphear, Robin Mesnage, Laura N. Vandenberg, Frederick S. vom Saal, Wade V. Welshons and Charles M. Benbrook; Environmental Health17 Feb 2016

This Statement of Concern is directed to scientists, physicians, and regulatory officials around the world. We highlight changes in the scope and magnitude of risks to humans and the environment stemming from applications of glyphosate-based herbicides (GBHs). The objectives of this statement are to: 1) demonstrate the need for better monitoring of GBH residues in water, food, and humans; (2) identify limitations or weaknesses in the way the EPA, the German Federal Institute for Risk Assessment, and others have previously assessed the potential risks to humans from exposure to GBHs; and (3) provide recommendations on data needs and ways to structure future studies addressing potential health risks arising from GBH exposures.
Our focus is on the unanticipated effects arising from the worldwide increase in use of GBHs, coupled with recent discoveries about the toxicity and human health risks stemming from use of GBHs. Our concern deepened when the World Health Organization’s International Agency for Research on Cancer (IARC) re-classified glyphosate as “probably carcinogenic to humans” (i.e., Group 2A) [1].
We highlight a number of issues that influence our concern about GBHs including: 1) increased use of GBHs over the past decade, including new uses for these herbicides just prior to harvest that can lead to high dietary exposures; 2) detection of glyphosate and its metabolites in foods; 3) recent studies that reveal possible endocrine system-mediated and developmental impacts of GBH exposures; and 4) additional complications for farmers, most acutely the emergence and spread of weeds resistant to glyphosate and the concomitant use of multiple herbicides in mixtures, both of which increase the risk of human and environmental harm. We discuss evidence pointing to the need to adjust downward the acceptable daily intake for glyphosate. Our major concerns are embodied in a series of consensus points that explicitly address the strength of the supporting evidence, and our recommendations focus on research essential in narrowing uncertainty in future GBH risk assessments.

Glyphosate poisoning Bradberry SM1, Proudfoot AT, Vale JA.; Toxicological Reviews; 2004

"There is insufficient evidence to conclude that glyphosate preparations containing POEA are more toxic than those containing alternative surfactants. Although surfactants probably contribute to the acute toxicity of glyphosate formulations, the weight of evidence is against surfactants potentiating the toxicity of glyphosate. Accidental ingestion of glyphosate formulations is generally associated with only mild, transient, gastrointestinal features. Most reported cases have followed the deliberate ingestion of the concentrated formulation of Roundup (The use of trade names is for product identification purposes only and does not imply endorsement.) (41% glyphosate as the IPA salt and 15% POEA). There is a reasonable correlation between the amount ingested and the likelihood of serious systemic sequelae or death. Advancing age is also associated with a less favourable prognosis. Ingestion of >85 mL of the concentrated formulation is likely to cause significant toxicity in adults. "

Glyphosate - general fact sheet National Pesticide Information Center

  • What is glyphosate?
  • What are some products that contain glyphosate?
  • How does glyphosate work?
  • How might I be exposed to glyphosate?
  • What are some signs and symptoms from a brief exposure to glyphosate?
  • What happens to glyphosate when it enters the body?
  • Is glyphosate likely to contribute to the development of cancer?
  • Has anyone studied non-cancer effects from long-term exposure to glyphosate?
  • Are children more sensitive to glyphosate than adults?
  • What happens to glyphosate in the environment?
  • Can glyphosate affect birds, fish, and other wildlife?


Carcinogenicity of tetrachlorvinphos, parathion, malathion, diazinon, and glyphosate Kathryn Z Guyton, Dana Loomis, Yann Grosse, Fatiha El Ghissassi, Lamia Benbrahim-Tallaa, Neela Guha, Chiara Scoccianti, Heidi Mattock, Kurt Straif, on behalf of the International Agency for Research on Cancer Monograph Working Group, IARC, Lyon, France; The Lancet; 20 Mar 2015

In March, 2015, 17 experts from 11 countries met at the International Agency for Research on Cancer (IARC; Lyon, France) to assess the carcinogenicity of the organophosphate pesticides tetrachlorvinphos, parathion, malathion, diazinon, and glyphosate (table). These assessments will be published as volume 112 of the IARC Monographs.

Glyphosate IARC monographs

Missing AHS study

Cancer agency left in the dark over glyphosate evidence KATE KELLAND; Reuters; 14 Jun 2017

When Aaron Blair sat down to chair a week-long meeting of 17 specialists at the International Agency for Research on Cancer in France in March 2015, there was something he wasn’t telling them.
The epidemiologist from the U.S. National Cancer Institute had seen important unpublished scientific data relating directly to a key question the IARC specialists were about to consider: Whether research shows that the weedkiller glyphosate, a key ingredient in Monsanto’s best-selling RoundUp brand, causes cancer.
Previously unreported court documents reviewed by Reuters from an ongoing U.S. legal case against Monsanto show that Blair knew the unpublished research found no evidence of a link between glyphosate and cancer. In a sworn deposition given in March this year in connection with the case, Blair also said the data would have altered IARC’s analysis. He said it would have made it less likely that glyphosate would meet the agency’s criteria for being classed as “probably carcinogenic.”
But IARC, a semi-autonomous part of the World Health Organization, never got to consider the data. The agency’s rules on assessing substances for carcinogenicity say it can consider only published research – and this new data, which came from a large American study on which Blair was a senior researcher, had not been published.
The lack of publication has sparked debate and contention. A leading U.S. epidemiologist and a leading UK statistician – both independent of Monsanto – told Reuters the data was strong and relevant and they could see no reason why it had not surfaced.

Responses to IARC

Conclusion on the peer review of the pesticide risk assessment of the active substance glyphosate European Food Safety Authority; 12 Nov 2015

The conclusions of the European Food Safety Authority (EFSA), following the peer review of the initial risk assessments carried out by the competent authority of the rapporteur Member State Germany, for the pesticide active substance glyphosate are reported. The context of the peer review was that required by Commission Regulation (EU) No 1141/2010 as amended by Commission Implementing Regulation (EU) No 380/2013. The conclusions were reached on the basis of the evaluation of the representative uses of glyphosate as a herbicide on emerged annual, perennial and biennial weeds in all crops [crops including but not restricted to root and tuber vegetables, bulb vegetables, stem vegetables, field vegetables (fruiting vegetables, brassica vegetables, leaf vegetables and fresh herbs, legume vegetables), pulses, oil seeds, potatoes, cereals, and sugar- and fodder beet; orchard crops and vine, before planting fruit crops, ornamentals, trees, nursery plants etc.] and foliar spraying for desiccation in cereals and oilseeds (pre-harvest). The reliable endpoints, concluded as being appropriate for use in regulatory risk assessment and derived from the available studies and literature in the dossier peer reviewed, are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are identified. Following a second mandate from the European Commission to consider the findings from the International Agency for Research on Cancer (IARC) regarding the potential carcinogenicity of glyphosate or glyphosate-containing plant protection products in the on-going peer review of the active substance, EFSA concluded that glyphosate is unlikely to pose a carcinogenic hazard to humans and the evidence does not support classification with regard to its carcinogenic potential according to Regulation (EC) No 1272/2008.

Expert reaction to carcinogenicity classification of five pesticides by the International Agency for Research on Cancer (IARC) Science Media Centre; 20 Mar 2015

So Roundup “probably” causes cancer. This means what, exactly? Nathanael Johnson; Grist; 24 Mar 2015

Here are the takeaways:
  • There is a real chance that these pesticides could cause cancer, and we should be careful with them.
  • There’s controversy — several scientists disagreed with the designation.
  • Don’t forget that the list of things that probably cause cancer includes … just about everything.
That last point is worth dwelling on a bit. Here’s the WHO’s full list of “known” (group 1), “probable” (group 2A), and “possible” (group 2B) carcinogens. It’s a weird list. Sunshine, alcoholic beverages (the ethanol therein), wood dust, and outdoor pollution are “known” carcinogens. The “probable” group includes wood smoke, night shifts (they disrupt circadian rhythms), and hot mate (the South American drink).

No, Roundup does not cause cancer James Cooper; Examiner; 28 Apr 2016

The scientific world was astonished (to put it mildly) when the IARC (International Agency for Research on Cancer), a sub-unit of the WHO declared that Roundup (glyphosate) probably causes cancer, putting an herbicide that has been in use for over 40 years into their Group 2A. Their report was published initially as a summary in The Lancet, and then as a complete IARC monograph.

GLYPHOSATE: Report of the Cancer Assessment Review Committee UNITED STATES ENVIRONMENT AL PROTECTION AGENCY; 1 Oct 2015

In accordance with the 2005 Guidelines for Carcinogen Risk Assessment, based on the weight-ofevidence, glyphosate is classified as “Not Likely to be Carcinogenic to Humans”.

Glyphosate: What's the lowdown? Sense About Science;

Notes From The Glyphosate Dust Up Marc Brazeau; Food and Farm Discussion Lab; 4 May 2015

I don’t have much to add to the recent dustup over the WHO’s International Agency for Research on Cancer (IARC) designating that glyphosate is a probable carcinogen, but I’d like to highlight some of the most useful coverage.
“What the IARC performs is hazard assessment,” says Aaron Blair, who chaired the group of scientists that prepared the IARC’s assessment of glyphosate. Blair is a scientist emeritus at the National Cancer Institute. Hazard assessment, he explains, is concerned with a simple question: Could a substance cause damage “in some circumstance, at some level of exposure?” How commonly such circumstances or exposures actually occur in the real world, he says, is an entirely different question, and not one that IARC tries to answer.
In other words, the IARC is saying that glyphosate probably could cause cancer in humans, but not that it probably does.

Does glyphosate cause cancer? Iida Ruishalme; Thoughtscapism; 7 Sep 2016

Much media and public attention on glyphosate followed after World Health Organisations subgroup, International Agency for Research on Cancer (IARC) declared that according to their classification, glyphosate falls under substances 2a – “probably carcinogenic”. What the media attention often failed to report is that IARC does not actually look at risk – how big is the risk for said carcinogenic effects? What levels are safe and what aren’t?

IARC Under Fire from Scientists: Mission Outdated, Methods Lacking Iida Ruishalme; Thoughtscapism; 6 Nov 2016

Considering recently published scientific reviews on the International Agency on Cancer Research (IARC) concerning their methods and overall mission, as well as their specific conclusion on glyphosate, I thought the topic deserved an update of its own.

Toxicologist pans UN glyphosate report Robert Arnason; The Western Producer; 27 Mar 2015

In a brief statement explaining the new designation, the scientists cited a number of research papers, such as a study on rural Colombians who were exposed to a spray of Roundup. IARC said the study demonstrated that glyphosate can cause genotoxicity, or DNA damage, and cause cellular mutations that may result in cancer. Keith Solomon, a University of Guelph professor emeritus and a globally recognized authority on pesticides, said the conclusion is “totally wrong.” Solomon should know because he wrote the Colombian study.

Why regulators conclude glyphosate safe while IARC, alone, claims it could cause cancer? Andrew Porterfield; Genetic Literacy Project; 24 Jul 2015

What’s been overlooked is that the classification that IARC assigned glyphosate—a “2A, Probably carcinogenic to humans”—is the same classification the organization gave to grapefruit juice, fruits (including apples), and working the night shift. At least glyphosate didn’t rate a “1, carcinogenic to humans,” so it’s not as dangerous as sunlight, sunlamps, oral contraceptives, Chinese style salted fish and alcoholic beverages, among a long list.
When IARC comes to a determination of what may cause cancer, it combs through existing literature (which does raise the risk of cherry-picking studies that satisfy your point of view). But it’s assessing the hazard of a chemical. A hazard assessment simply states that a certain chemical, environmental element or behavior is somehow related to cancer. It’ll then note whether something “is,” “is probable” or “is possible”, or “isn’t,” so far as we know.
What a hazard evaluation does not tell you is how likely you are to get cancer. That’s the domain of a risk assessment, which will use the same words–“is,” “probable” and “possible”–but in a different way.

Glyphosate and Cancer: What does the data say? Andrew Kniss; Weed Control Freaks; 28 Mar 2015

also at Food and Farm Discussion Lab / GMO Building Blocks 12 Apr 2017
I wanted to actually take a thorough look at the evidence supporting this classification. I work with pesticides (especially glyphosate) on a regular basis, so I take this classification very seriously. If glyphosate is indeed likely to cause cancer, I am in the group of people who is most likely to be affected. As most of the reasonable write-ups have previously noted, IARC group 2A agents are problematic mostly for occupational exposure; that is, people who work with (or around) the chemical on a regular basis over a long period of time. The general public is highly unlikely to see any ill effects from any agent with this classification based on available evidence.
... based on the data I could find, I don’t see any evidence for alarm. And I say that as someone who is exposed to more glyphosate than a vast majority of the population.

Christopher Portier

Differences in the carcinogenic evaluation of glyphosate between the International Agency for Research on Cancer (IARC) and the European Food Safety Authority (EFSA) Christopher J Portier & others; J Epidemiol Community Health doi:10.1136/jech-2015-207005;

The International Agency for Research on Cancer (IARC) Monographs Programme identifies chemicals, drugs, mixtures, occupational exposures, lifestyles and personal habits, and physical and biological agents that cause cancer in humans and has evaluated about 1000 agents since 1971. Monographs are written by ad hoc Working Groups (WGs) of international scientific experts over a period of about 12 months ending in an eight-day meeting. The WG evaluates all of the publicly available scientific information on each substance and, through a transparent and rigorous process,1 decides on the degree to which the scientific evidence supports that substance's potential to cause or not cause cancer in humans.
For Monograph 112,2 17 expert scientists evaluated the carcinogenic hazard for four insecticides and the herbicide glyphosate.3 The WG concluded that the data for glyphosate meet the criteria for classification as a probable human carcinogen.
The European Food Safety Authority (EFSA) is the primary agency of the European Union for risk assessments regarding food safety. In October 2015, EFSA reported4 on their evaluation of the Renewal Assessment Report5 (RAR) for glyphosate that was prepared by the Rapporteur Member State, the German Federal Institute for Risk Assessment (BfR). EFSA concluded that ‘glyphosate is unlikely to pose a carcinogenic hazard to humans and the evidence does not support classification with regard to its carcinogenic potential’. Addendum 1 (the BfR Addendum) of the RAR5 discusses the scientific rationale for differing from the IARC WG conclusion.
Serious flaws in the scientific evaluation in the RAR incorrectly characterise the potential for a carcinogenic hazard from exposure to glyphosate. Since the RAR is the basis for the European Food Safety Agency (EFSA) conclusion,4 it is critical that these shortcomings are corrected.

IARC-Gate? Are Europe’s anti-chemical enviros conspiring to suppress conflict-of-interest scandal? David Zaruk & Jon Entine; Genetic Literacy Project; 7 Apr 2016

IARC’s unprofessional and unethical behaviour. Time to retract their glyphosate monograph RISKMONGER; 13 Apr 2016

  • Christopher Portier was employed by the anti-pesticide American NGO, Environmental Defense Fund (EDF).
  • In 2014 Portier chaired the IARC expert advisory committee on priorities for the coming years (including glyphosate). IARC did not declare his employment with the activist NGO EDF.
  • In 2015, Portier served as the only external representative on the IARC glyphosate team with the role of technical adviser, even though he was working for an anti-pesticides NGO, had published many articles against Monsanto and was not even a toxicologist.
  • The IARC study rejected thousands of documents on glyphosate that had industry involvement and based their decision on carcinogenicity on the basis of eight studies (rejecting a further six because they did not like their conclusions).

Greed, Lies and Glyphosate: The Portier Papers RISKMONGER; 13 Oct 2017

This is an exposé of how one scientist, Christopher Portier, is bringing down the reputation of science, scientific regulatory advice and a WHO agency. It calls to question the funding, transparency and motivation of the anti-glyphosate campaigners, the role of IARC in the American anti-corporate litigation practices, and the quality of the scientists who engage with them. It demonstrates how the entire campaign against glyphosate has been built on greed and deceit.
This blog is based on statements in Christopher Portier’s deposition in the liability litigation hearings related to the cases against Monsanto’s Roundup (commonly known as the “Monsanto Papers”). Portier was the external special adviser to the IARC working group that prepared their famous “glyphosate is probably carcinogenic” decision. This exposé will highlight the following information:
  • During the same week that IARC had published its opinion on glyphosate’s carcinogenicity, Christopher Portier signed a lucrative contract to be a litigation consultant for two law firms preparing to sue Monsanto on behalf of glyphosate cancer victims.
  • This contract has remunerated Portier for at least 160,000 USD (until June, 2017) for initial preparatory work as a litigation consultant (plus travel).
  • This contract contained a confidentiality clause restricting Portier from transparently declaring this employment to others he comes in contact with. Further to that, Portier has even stated that he has not been paid a cent for work he’s done on glyphosate.
  • It became clear, in emails provided in the deposition, that Portier’s role in the ban-glyphosate movement was crucial. He promised in an email to IARC that he would protect their reputation, the monograph conclusion and handle the BfR and EFSA rejections of IARC’s findings.
  • Portier admitted in the deposition that prior to the IARC glyphosate meetings, where he served as the only external expert adviser, he had never worked and had no experience with glyphosate.

IARC's Glyphosate-gate Scandal Geoffrey Kabat; Forbes; 23 Oct 2017

Over the past few years, when scientists have questioned the agency’s process and some of its recent classifications, rather than addressing specific criticisms, IARC officials have argued that their methods are sound and not in need of improvement, and have implied that their critics have conflicts-of-interest.
In the past year, however, as IARC’s glyphosate report has been subjected to scrutiny by scientists and investigative journalists, a number of increasingly disturbing questions have come to light. Three major, independent pieces of the “back-story” on IARC’s glyphosate assessment are presented below.

Europe still burns witches — if they’re named Monsanto Mark Lynas; Cornell Alliance for Science; 28 Nov 2017

The glyphosate saga is a fascinating case study in how easily politics can derail science. In watching the glyphosate issue evolve I found myself gradually becoming more and more aghast at how quickly and thoughtlessly evidence-based policymaking was thrown away in European centers of power.
I don't want to over-hype it, but it felt a little like mob rule. You can still burn the witch in Europe — if the witch is called Monsanto. Over glyphosate Monsanto was stitched up good and proper, as we say in England.
... this isn’t just about glyphosate. It’s about the principle at stake here. Decisions about licensing chemicals should be based on scientifically objective risk assessment, not on activist campaigns or on industry reassurances. It's a tough thing to say, but science is not democratic. One person's opinion is not as valid as another's. Expertise counts — just as it does with airplane pilots and heart surgeons.
An even deeper principle is that the truth is for everyone. Scientific truth is there to defend people against corporations, but equally sometimes to defend corporations against people. Truth is truth, and fairness is not selective. Otherwise, it’s not fair.

Edits to IARC review

In glyphosate review, WHO cancer agency edited out 'non-carcinogenic' findings Kate Kelland; Reuters; 19 Oct 2017

LONDON (Reuters) - The World Health Organization’s cancer agency dismissed and edited findings from a draft of its review of the weedkiller glyphosate that were at odds with its final conclusion that the chemical probably causes cancer.
Documents seen by Reuters show how a draft of a key section of the International Agency for Research on Cancer’s (IARC) assessment of glyphosate - a report that has prompted international disputes and multi-million-dollar lawsuits - underwent significant changes and deletions before the report was finalised and made public.
The edits identified by Reuters occurred in the chapter of IARC’s review focusing on animal studies. This chapter was important in IARC’s assessment of glyphosate, since it was in animal studies that IARC decided there was “sufficient” evidence of carcinogenicity.
One effect of the changes to the draft, reviewed by Reuters in a comparison with the published report, was the removal of multiple scientists’ conclusions that their studies had found no link between glyphosate and cancer in laboratory animals.
In one instance, a fresh statistical analysis was inserted - effectively reversing the original finding of a study being reviewed by IARC.
In another, a sentence in the draft referenced a pathology report ordered by experts at the U.S. Environmental Protection Agency. It noted the report “firmly” and “unanimously” agreed that the “compound” – glyphosate – had not caused abnormal growths in the mice being studied. In the final published IARC monograph, this sentence had been deleted.
Reuters found 10 significant changes that were made between the draft chapter on animal studies and the published version of IARC’s glyphosate assessment. In each case, a negative conclusion about glyphosate leading to tumors was either deleted or replaced with a neutral or positive one. Reuters was unable to determine who made the changes.
IARC did not respond to questions about the alterations. It said the draft was “confidential” and “deliberative in nature.” After Reuters asked about the changes, the agency posted a statement on its website advising the scientists who participate in its working groups “not to feel pressured to discuss their deliberations” outside the confines of IARC.
Reuters contacted 16 scientists who served in the IARC expert working group that conducted the weedkiller review to ask them about the edits and deletions. Most did not respond; five said they could not answer questions about the draft; none was willing or able to say who made the changes, or why or when they were made.
The chairman of the IARC sub-group tasked with reviewing evidence of glyphosate’s effect on laboratory animals was Charles Jameson, an American toxicologist. In testimony as part of personal-injury lawsuits against Monsanto in the United States, Jameson told lawyers for Monsanto he did not know when, why or by whom the edits had been made.


Monsanto Stunned – California Confirms ‘Roundup’ Will Be Labeled “Cancer Causing” EDITOR; The Event Chronicle; 23 Feb 2016

Sacramento, CA — California just dealt Monsanto a blow as the state’s Environmental Protection Agency will now list glyphosate — the toxic main ingredient in the U.S.’ best-selling weedkiller, Roundup — as known to cause cancer. Under the Safe Drinking Water and Toxic Enforcement Act of 1986 — usually referred to as Proposition 65, its original name — chemicals that cause cancer, birth defects, or other reproductive harm are required to be listed and published by the state. Chemicals also end up on the list if found to be carcinogenic by the International Agency for Research on Cancer (IARC) — a branch of the World Health Organization.


Proposed Re-evaluation Decision PRVD2015-01, Glyphosate Health Canada; 17 Jun 2015

An evaluation of available scientific information found that products containing glyphosate do not present unacceptable risks to human health or the environment when used according to the proposed label directions.


The BfR has finalised its draft report for the re-evaluation of glyphosate Bundesinstitut für Risikobewertung (BfR)

In conclusion of this re-evaluation process of the active substance glyphosate by BfR the available data do not show carcinogenic or mutagenic properties of glyphosate nor that glyphosate is toxic to fertility, reproduction or embryonal/fetal development in laboratory animals.

New Zealand

Cancer all-clear given to weedkiller glyphosate by New Zealand scientific review GERARD HUTCHING; New Zealand Farmer; 12 Aug 2016

New Zealand scientists have reviewed the evidence on the weedkiller glyphosate and announced it is "unlikely" to be carcinogenic and should not be classified as a mutagen or carcinogen under the HSNO Act. Poisons expert Dr Wayne Temple and his colleague from the National Poisons Centre, Michael Beasley, carried out the review, which was commissioned by the Environmental Protection Authority (EPA).

Review of the Evidence Relating to Glyphosate and Carcinogenicity Wayne Temple; Environmental Protection Authority; Aug 2016

This report discusses the relevant data on glyphosate, especially the more recent studies, and reviews the basis on which the IWG classified it as a probable human carcinogen (Group 2A). This involves review of the quality of evidence for carcinogenicity in humans and experimental animals and the mechanistic arguments.


U.N. experts find weed killer glyphosate unlikely to cause cancer Kate Kelland; Reuters; 16 May 2016

The pesticide glyphosate, sold by Monsanto in its Roundup weed killer product and widely used in agriculture and by gardeners, is unlikely to cause cancer in people, according to a new safety review by United Nations health, agriculture and food experts. In a statement likely to intensify a row over its potential health impact, experts from the U.N.'s Food and Agriculture Organization (FAO) and World Health Organization (WHO) said glyphosate is "unlikely to pose a carcinogenic risk to humans" exposed to it through food. It is mostly used on crops.

Contradicting IARC, World Health Organization says glyphosate unlikely to cause cancer Kate Kelland; Reuters; 17 May 2016

Court cases

San Francisco case 2017

Monsanto Weed Killer Roundup Faces New Doubts on Safety in Unsealed Documents Danny Hakim; Now York Times; 14 Mar 2017

The reputation of Roundup, whose active ingredient is the world’s most widely used weed killer, took a hit on Tuesday when a federal court unsealed documents raising questions about its safety and the research practices of its manufacturer, the chemical giant Monsanto.

Discussion on Food and Farm Discussion Lab Facebook

California ruling 2018

Courts don’t determine scientific facts The Logic of Science; 11 Aug 2018

Most people have probably seen the recent news that Monsanto has been ordered to pay $289 million following the ruling by a California jury that Monsanto’s glyphosate (a.k.a. Roundup) is dangerous and likely contributed to Dewayne Johnson’s cancer. I could write many lengthy posts about why that ruling is wrong. I could talk about the numerous scientific studies that found that failed to find evidence that glyphosate causes cancer (e.g., this large, long-term cohort study with over 50,000 participants that wasn’t funded by Monsanto and failed to find an association between glyphosate use and cancer among farmers [Andreotti et al. 2017]). I could talk about the well-established fact that the toxicity of glyphosate is quite low. I could talk about the fact that multiple well-respected scientific bodies have examined the evidence and concluded that it does not suggest that glyphosate causes cancer. I could also talk about how the one dissenting scientific report (i.e., WHO’s IARC report) cherry-picked their evidence and reached a conclusion that has been widely criticized by the scientific community. Plenty of other pages have, however, already done all of those things, so I won’t spend more time on them here. Rather, I want to discuss why trials like this one are inherently problematic. Citing court rulings is an extremely common tactic among science deniers (anti-vaccers do it all the time), but it is not a logically valid tactic because courts don’t determine what is and is not a scientific fact.

Application rates

Inconvenient Glyphosate Math Kevin Folta; Food and Farm Discussion Lab; 17 Oct 2016

There is a lot of discussion about glyphosate use and its relative toxicity lately. ... You can read on any activist website or comment section that “Roundup Ready seeds are doused in massive amounts of glyphosate- getting this deadly chemical into your body”. Let’s do some math.
  • How much is this massive amount?
  • When is it applied to the crop?
  • How do amounts used translate to toxicity risks?

soil microbes

Non-Target Effects of Glyphosate on Soil Microbes Matt D. Busse, Alice W. Ratcliff, Carol J. Shestak, Robert F. Powers : Pacific Southwest Research Station, USDA Forest Service, Redding, CA; 2000 Proceedings of the California Weed Science Society (Volume 52)

Glyphosate is among the most popular herbicides registered for forest use in California. Noted for its broad effectiveness on competing vegetation, mild effect on conifers, rapid inactivation in soil, and low mammalian toxicity (DiTomaso 1997), glyphosate is an integral component of conifer release programs and has led to improvements in the growth of intensively managed forests (Powers and Reynolds 1999). Benefits of herbicide use must be viewed cautiously, however. Public concerns about environmental risks makes their forestry use controversial. Policy makers and forest managers thus need scientific documentation of the ecological effects of herbicides that go beyond the toxicological requirements met during product registration. In particular, our knowledge of the effect of glyphosate on non-target organisms in forest ecosystems is incomplete.

Crop drying

Why Is Glyphosate Sprayed on Crops Right Before Harvest? Ken Roseboro; EcoWatch; 5 Mar 2016

Glyphosate, the main ingredient in Monsanto’s Roundup herbicide, is recognized as the world’s most widely used weed killer. What is not so well known is that farmers also use glyphosate on crops such as wheat, oats, edible beans and other crops right before harvest, raising concerns that the herbicide could get into food products. Glyphosate has come under increased scrutiny in the past year. Last year the World Health Organization’s cancer group, the International Agency for Research on Cancer, classified it as a probable carcinogen. The state of California has also moved to classify the herbicide as a probable carcinogen. A growing body of research is documenting health concerns of glyphosate as an endocrine disruptor and that it kills beneficial gut bacteria, damages the DNA in human embryonic, placental and umbilical cord cells and is linked to birth defects and reproductive problems in laboratory animals.

The Truth About Glyphosate and Wheat Sarah Schultz; 16 Nov 2014

One of the practices that is highly misunderstood is the application of glyphosate for pre-harvesting wheat. In layman’s terms, this simply means spraying our mature wheat crop with glyphosate before it’s ready to be harvested. Though glyphosate is not a true desiccant (a desiccant is applied for rapid dry down & early harvest), it is generally used for weed control and can aid in dry down of crops, but the effects take much longer. This is done with care, precise timing, it is backed by science and it is regulated and monitored.

Mark Keating, Food and Farm Discussion Lab Facebook

One of glyphosate's most valuable uses on our farm is as a pre-harvest desiccant of a mature wheat crop. There is obviously potential cause for considerable concern here for those unfamiliar with this practice, as applying any pesticide to any crop so close to harvest seems an unwarranted risk.
While I don't want to create the false impression that it is completely non-toxic (it isn't) and that its use doesn't have undesirable consequences (it does) I also feel it important that non-farmers understand the true "why" and "how" of glyphosate's role as a management tool on the farm, so here goes.

Grain of Truth? Are U.S. farmers saturating wheat crops with Monsanto's Roundup herbicide as a desiccant to facilitate a quicker harvest? David Mikkelson; Snopes

Claim: U.S. farmers are saturating wheat crops with Roundup herbicide as a desiccant before each harvest, causing an increase in wheat-related ailments.
Verdict: Mixture

"Toxic wheat"

The Real Reason Wheat is Toxic (it’s not the gluten) Sarah; The Healthy Home Economist; updated 20 Feb 2017

"Common wheat harvest protocol in the United States is to drench the wheat fields with Roundup several days before the combine harvesters work through the fields as the practice allows for an earlier, easier and bigger harvest."
Cites Stephanie Seneff claiming "when you expose wheat to a toxic chemical like glyphosate, it actually releases more seeds resulting in a slightly greater yield"
Claims: "the active ingredient in Roundup lethally disrupts the all important shikimate pathway found in beneficial gut microbes which is responsible for synthesis of critical amino acids." and "Roundup significantly disrupts the functioning of beneficial bacteria in the gut and contributes to permeability of the intestinal wall and consequent expression of autoimmune disease symptoms."

THE TRUTH ABOUT TOXIC WHEAT Prairie Californian; 17 Nov 2014

You may or may not have seen this article from the Healthy Home Economist touting wheat is toxic due to being sprayed with Round up (glyphosate) as a pre-harvest. This article brings up some pretty fear inducing statistics for both farmers and non-farmers. Farming is our life and our passion and when someone spreads fear in regards to our livelihood, it is hard not to take it personal. So we respond in the best way we know how, through our own experiences and how we run our own farms.

Peterson Farm Bros Facebook; 15 Nov 2014

This blog has been traveling all over the Internet the last couple of days. Maybe you have seen it. Here is our official response

Samsel & Senef

Glyphosate’s Suppression of Cytochrome P450 Enzymes and Amino Acid Biosynthesis by the Gut Microbiome: Pathways to Modern Diseases Anthony Samsel, Stephanie Seneff; entropy; 18 Apr 2013

Note added by the Publisher: The editors of the journal have been alerted to concerns over potential bias in opinions and bias in the choice of citation sources used in this article. We note that the authors stand by the content as published. Since the nature of the claims against the paper concern speculation and opinion, and not fraud or academic misconduct, the editors would like to issue an Expression of Concern to make readers aware that the approach to collating literature citations for this article was likely not systematic and may not reflect the spectrum of opinions on the issues covered by the article.
Glyphosate, the active ingredient in Roundup®, is the most popular herbicide used worldwide. The industry asserts it is minimally toxic to humans, but here we argue otherwise. Residues are found in the main foods of the Western diet, comprised primarily of sugar, corn, soy and wheat. Glyphosate's inhibition of cytochrome P450 (CYP) enzymes is an overlooked component of its toxicity to mammals. CYP enzymes play crucial roles in biology, one of which is to detoxify xenobiotics. Thus, glyphosate enhances the damaging effects of other food borne chemical residues and environmental toxins. Negative impact on the body is insidious and manifests slowly over time as inflammation damages cellular systems throughout the body. Here, we show how interference with CYP enzymes acts synergistically with disruption of the biosynthesis of aromatic amino acids by gut bacteria, as well as impairment in serum sulfate transport. Consequences are most of the diseases and conditions associated with a Western diet, which include gastrointestinal disorders, obesity, diabetes, heart disease, depression, autism, infertility, cancer and Alzheimer’s disease. We explain the documented effects of glyphosate and its ability to induce disease, and we show that glyphosate is the “textbook example” of exogenous semiotic entropy: the disruption of homeostasis by environmental toxins.

Condemning Monsanto With Bad Science Is Dumb Tamar Haspel; Huffington Post blog; 26 Apr 2013

Did you see the latest indictment of Monsanto making the rounds? It’s a “peer-reviewed” paper in the journal Entropy, co-authored by Anthony Samsel and Stephanie Seneff, blaming glyphosate, the compound in the herbicide Roundup, for virtually all the ills that can befall us.

A Fishy Attempt To Link Glyphosate and Celiac Disease Steve Savage; Applied Mythology; 30 Mar 2014

Stephanie Seneff (a computer scientist at MIT), and Anthony Samsel (a retired consultant), have recently been attempting to link the use of the herbicide glyphosate to a long list of modern maladies. Their latest such attempt to is Celiac disease. The overall argument for the glyphosate/Celiac link has already been quite thoroughly debunked by a Celiac expert, but there is one other good reason to dismiss the "link" which I would like to describe. It has to do with a "Fishy" study about glyphosate and fish which is so flawed that it should never have been published in the first place. That is why it can't be used to support this chemical/disease link.

Meet the Controversial MIT Scientist Who Claims She Discovered a Cause of Gluten Intolerance Ari LeVaux; AlterNet; 27 Feb 2014

Stephanie Seneff is a senior research scientist at MIT. Based in the university’s Computer Science and Artificial Intelligence Laboratory, Seneff’s focus is, according to her web page, “the intersection of biology and computation.” She is also, according to many in the science community, a "quack,” meaning a poseur at the business of science, and a practitioner of pseudoscience.
Since she began publishing papers on biology, in journals considered fringe by the mainstream scientific establishment, Seneff has posited explanations for a host of disorders, and drawn heated objections from experts in most every field she’s delved into. She is, in short, a controversial figure in the scientific community, which is an unusual position to occupy for someone with three degrees from MIT.
In recent months, Seneff co-authored two papers proposing a connection between the herbicide glyphosate and gluten sensitivity. I spoke with Seneff by phone about this hypothesis, her transition from computer science into biology, and her reputation in the scientific community.

Glyphosate in urine

Results of Glyphosate Pee Test Are in ‘And It’s Not Good News’ Lorraine Chow; EcoWatch; 12 May 2016

Last month, Members of the European Parliament (MEPs) volunteered to take a urine test to see if glyphosate—the cancer-linked weedkiller—is in their system. Forty-eight MEPs from 13 different European Union countries participated in the test, and now the results are in.

A critical review of glyphosate findings in human urine samples and comparison with the exposure of operators and consumers Lars Niemann, Christian Sieke, Rudolf Pfeil, Roland Solecki; Journal für Verbraucherschutz und Lebensmittelsicherheit; 8 Jan 2015

For example: If a urinary concentration of 6 µg glyphosate/L would have been measured, a daily excretion of 12 µg can be assumed. For a 60 kg weighing person, an internal dose of 0.2 µg/kg bw would result. If exposure of this person can be reasonably assumed as mainly occupational or residential, i.e., occurring predominantly by the dermal and inhalative routes, this dose of 0.0002 mg/kg bw might be directly compared to the AOEL and would account for only 0.2 % of this reference dose.
If dietary exposure is considered the more likely route of glyphosate intake, a 20 % oral absorption must be taken into account ... Therefore, an internal dose of 12 µg would be expected to result from a totally ingested amount of 60 µg, equivalent to an “external dose” of 1 µg/kg bw. This dose of 0.001 mg/kg bw would account for 0.2 % of the ADI that is, in this case, the more appropriate reference dose to compare with.

Glyphosate in breast milk

McGuire et al

Glyphosate and aminomethylphosphonic acid are not detectable in human milk Michelle K McGuire, Mark A McGuire, William J Price, Bahman Shafii, Janae M Carrothers, Kimberly A Lackey, Daniel A Goldstein, Pamela K Jensen, and John L Vicini; The American Journal of Clinical Nutrition; 30 Mar 2016

U.S. breast milk is glyphosate free Science Daily; 23 Jul 2015

Study is first independently verified look for the presence of Roundup ingredient in human milk

Moms Across America

Glyphosate Testing Full Report: Findings in American Mothers’ Breast Milk, Urine and Water Zen Honeycutt - Moms Across America, Henry Rowlands - Sustainable Pulse; Moms Across America; 7 Apr 2014 (pdf)

In the first ever testing on glyphosate herbicide in the breast milk of American women, Moms Across America and Sustainable Pulse have found ‘high’ levels in 3 out of the 10 samples tested. The shocking results point to glyphosate levels building up in women’s bodies over a period of time, which has until now been refuted by both global regulatory authorities and the biotech industry.

Debunking pseudo science “lab testing” health risk claims about glyphosate (Roundup) Academics Review; 10 Apr 2014

Willingham commentary on McGuire and MAA

Monsanto-Linked Study Finds No Monsanto-Linked Herbicide Glyphosate In Breast Milk Emily Willingham; Forbes, 4 Apr 2016

The herbicide glyphosate does not show up in breast milk, according to findings from a study published in the American Journal of Clinical Nutrition. The study, however, is weighted with conflicts of interest that include having three Monsanto employees as authors. The first two authors also have received grants from Monsanto, and the costs of the chemical analyses for the study were covered by Monsanto. This study is not, however, the only one reporting this outcome.

Monsanto, Monsanto, blah blah breast milk, Monsanto Bill Price; BioFortified blog; Apr 2016

Complaint about Willingham's article by a McGuire co-author

France ban

Glyphosate ban will kill ‘conservation agriculture’, French farmers warn Sarantis Michalopoulos;; 1 Sep 2017

Arnaud Rousseau, President of the French Federation of Oil Producers (FOP) wrote on Twitter that “banning glyphosate would mean “the end of agroecology”.
“All farmers who practice conservation agriculture and have stopped tillage to capture carbon in soils, according to the principles set up at COP21, will have to stop this type of agriculture if they cannot use glyphosate punctually to clean the fields just prior to seeding, when the frost did not remove the plant cover planted just after the harvest,” he told AFP.
Conservation agriculture (CA) is based on three principles: no-till (or minimal soil disturbance), organic soil cover, and diversified crop sequence. In this way, this type of agriculture enables farmers to increase productivity, adapt to climate change and reverse environmental degradation.
Speaking at the AGRI Committee of the European Parliament in July, Gottlieb Basch, President of the European Conservation Agriculture Federation (ECAF), told MEPs, “Glyphosate is an important substance for agriculture, not just for Conservation Agriculture but for conventional agriculture too”.
Conservation farmers claim that glyphosate is a crucial element in the development of conservation systems. The active ingredients used in the pre-seeding weed control are diverse, but normally glyphosate alone or in combination with other herbicides, such as hormonal ones, are a common choice among farmers.
Glyphosate controls many weeds and leaves no residue in the soil that could prevent or delay seeding, they say.

Snopes article

ConfoundUp Alex Kasprak; Snopes; 16 Nov 2016

A laboratory test performed by food activists is going viral, but its results and the allegations drawn from them are not reliable.

Snopes Claims About Glyphosate in Food Kevin Folta; blog; 17 Nov 2016

I like Snopes. So many times I've been rescued from a critical debunking excursion because someone had provided excellent analysis that I could use as a starting point. It is really disappointing to see them go soft and conflate unrelated issues that just confuse the reader. The article about the Food Babe's claims about Monsanto covering up glyphosate in food items seemed like it would follow the science and once again foist her on her own critically underpowered petard. But instead the article by Alex Kasprak just creates confusion. Even the subhead says, "Monsanto suppressing evidence of cancerous herbicide in food?"

Comparison with toxicity of other herbicides

Herbicides: How Toxic Are They? Fred Fishel, Jason Ferrell, Greg MacDonald, Brent Sellers; University of Florida IFAS Extension;

Comparison of Paraquat, Caffeine, Bleach, Pendimethalin (Prowl), Tylenol, Atrazine, Household ammonia (10%), Glyphosate (Roundup), Codeine, Table salt etc

About those harsher herbicides that glyphosate helped replace CREDIBLE HULK; 2 Jun 2015

One of the common criticisms of commercially available Genetically Engineered (GE) seeds is the idea that they have led to an increase in pesticide use. In actuality, it turns out that they’ve corresponded to a decrease in total pesticide use, but this is attributable primarily to insect resistant GE crops, and critics argue that herbicide resistant crops have led to an increase in herbicide usage. It is true that the rise in popularity of glyphosate-resistant (GR) crops in particular has coincided with an increase in the use of glyphosate, which had already been in use to some degree for a couple of decades before the implementation of glyphosate-resistant crops. However, what critics invariably fail to mention is that its rise in popularity also coincided with the phasing out of other herbicides, most of which were significantly more toxic than glyphosate (about which I’ve written in detail here). The purpose of this article is not to claim that glyphosate and GR crops are the be all end all of weed control (they’re not), nor is it to claim that they were causally responsible for any and every desirable change we see in herbicide usages patterns. Rather, the purpose of this is to show that when opponents of GE technology and of glyphosate claim that GR crops are bad on the grounds that they increased glyphosate use, they are leaving out critical information that would be highly inconvenient for their narrative.

Aquatic use

Glyphosate on digestive enzymes activity in piava (Leporinus obtusidens) Joseânia Salbego, Alexandra Pretto, Vera Maria Machado da Silva, Vania Lucia Loro, Rafael Lazzari, Carolina Rosa Gioda, Bernardo Baldisserotto; Ciência Rural; Sep 2014

The effects of glyphosate, a nonselective herbicide (1.0 or 5.0mg L-1) on digestive enzymes activity (stomach and intestine) were evaluated in juveniles of piava (Leporinus obtusidens) after 90 days of exposure. The activity of acid protease, trypsin, chymotrypsin and amylase increased with the increase of glyphosate concentration. These results indicate that glyphosate affects digestive enzyme activities in this species, and may be an indicator of poor nutrient availability when fish survive in herbicide-contaminated water.

discussion Food and Farm Discussion Lab; facebook, Jul 2016