New analysis of glyphosate industry studies finds them outdated, flawed

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See Carey Gillam’s article in The Guardian, Corporate studies asserting herbicide safety show many flaws, new analysis finds (July 2, 2021). In this post we provide links to the 53 once-secret studies and related materials. 

Questions about the safety of glyphosate-based herbicides (GBHs) have persisted for years, as scientific research has split over whether or not the widely used weed killing chemical introduced by Monsanto in the 1970s causes cancer or other human health problems.

A number of independent studies show links between glyphosate herbicides and cancer and other health problems, leading the International Agency for Research on Cancer in 2015 to classify glyphosate as a probable human carcinogen.

But Monsanto, purchased by Bayer AG in 2018, has maintained glyphosate is not carcinogenic, nor does it cause other health problems when used as directed. Other large chemical companies that sell glyphosate or related products echo Monsanto’s safety assurances.

Regulators in Europe and the United States, Canada and elsewhere have affirmed the corporate assertions of glyphosate safety. They point to decades of tests conducted by or for the companies that have not been published but which regulators have reviewed, as well as published studies in the scientific literature.

The corporate studies have long been kept secret, even by regulators. But in Europe, litigation by a group of European Parliament lawmakers led to the release of dozens of such studies.

A consumer advocacy group, SumOfUs, provided more than 50 studies to two independent scientists for review – Armen Nersesyan and Siegfried Knasmueller, both from the Institute of Cancer Research, Department of Medicine at the Medical University of Vienna.

Knasmueller, the lead author, is an expert in genetic toxicology and along with his work at the cancer institute is editor-in-chief of two prominent scientific journals, including Mutation Research – Genetic Toxicology and Environmental Mutagenesis.

The goal of the evaluation was to determine if the industry studies examined comply with current international guidelines for chemical testing. The studies are those concerning the genotoxic properties of glyphosate.

The resulting analysis was released July 2, 2021 and concluded that the bulk of the industry studies were outdated and did not meet current guidelines. An array of shortcomings and flaws were found in the studies, rendering most of them unreliable, according to the analysis.

In fact, of the 53 studies submitted to regulators by the companies, only two were acceptable under current internationally recognized scientific standards, said Knasmueller.

Knasmueller said there are more reliable methods for detecting carcinogens but those were not used in the industry tests. Read the evaluation here. 

Regulatory renewal sought

The analysis of the older studies comes as the companies that sell glyphosate products are seeking reauthorization in Europe and trying to fight against calls for restrictions and bans on glyphosate across the globe.

In June 2021, the European Union’s (EU) Assessment Group on Glyphosate (AGG) issued an 11,000-page draft report concluding that glyphosate is safe when used as directed and does not cause cancer. The finding is based in part on a dossier of roughly 1,500 studies submitted to European regulators by the “Glyphosate Renewal Group (GRG),” a collection of companies that includes Bayer.

Bayer confirmed that the older studies were included in the new dossier given to European regulators, but said the GRG was “required to submit all genotoxicity studies that have been conducted, including those submitted in past registration review cycles.” The company said the dossier also includes “new genotoxicity studies conducted since the previous re-approval of glyphosate and a vast review of thousands of published scientific publications regarding glyphosate.”

The companies are seeking the renewal of the EU authorization of glyphosate. Current authorization in Europe expires in December 2022. The companies say they also gave regulators a “literature review” of around 12,000 published scientific articles on glyphosate.

 The European Food Safety Authority (EFSA) and the European Chemicals Agency (ECHA) are organizing public consultations to start in September.

The Knasmueller analysis drew both criticism and support from a mix of scientists who reviewed the work. Here are two comments:

Paul Demers,  director of the Occupational Cancer Research Centre, Ontario Health, in Canada:

The classification of the carcinogenicity of glyphosate has been particularly contentious with international bodies disagreeing not only on areas of interpretation but even on which studies to consider. The critical evaluation, using the latest OECD criteria, of 53 studies submitted to Bundesinstitut für Risikobewertung and European Food Safety Authority is a valuable contribution to the ongoing debate on the carcinogenicity of glyphosate. The observation by the authors that few of these studies met the OECD criteria should be considered by regulatory authorities tasked with protecting workers and the public. Personally, I agree with the approaches for evaluation taken by the International Agency for Research on Cancer, which were used for glyphosate. That said, I also believe that there needs to room for scientific debate and disagreements on issues of interpretation, criteria for evaluation, and even what studies to include. However, there should not be a debate on transparency when it comes to the evidence considered by public bodies in determining the safety of chemicals.  Studies of health effects, with sufficient details regarding the methods used and the results, need to be accessible and open to the critical eyes of the scientific community and other concerned parties.” 

Raymond Tice, retired scientist, U.S. National Institute of Environmental Health Sciences, former  President of the U.S. Environmental Mutagen Society: “An analysis of the experimental data supporting the safety of any chemical should be conducted using systematic review methodology… which takes into account not only the completeness of the information but also categorizes the risk of bias, whether positive or negative.  Clearly, this was not conducted by EFSA or by Dr. Knasmueller.  In general, it is not appropriate to disregard all studies that do not meet current standards, but rather to consider the results in terms of their limitations. Overall, It seems to me that Knasmueller is selective (i.e., exhibits bias) in what he presents and does not present. At the same time, I would fault EFSA for not doing due diligence in what they considered…  Also, I agree that there is a suggestion that (glyphosate) is linked to the induction of oxidative stress which can result in DNA damage (i.e., oxidative stress is one of the key characteristics of carcinogens) but would be expected to have a threshold below which damage is not likely to result in an adverse effect.”

Once-secret studies

See the full analysis, authors’ comments, industry summaries, a list of studies submitted for the current European Union re-authorization, and links to 53 previously secret corporate glyphosate studies below:

Reference-List-of-Glyphosate-Studies-submitted-for-the-Renewal-of-Approval-AIR5-of-Glyphosate-in-2020-EN

European Assessment Group on Glyphosate report on glyphosate renewal

Evaluation of the scientific quality of industry studies of genotoxic properties of glyphosate

Comments concerning the mutagenic/genotoxic properties of glyphosate

Toxicological and Metabolism Studies summary by industry

Albaugh 2014 glyphosate reverse mutation assay Switzerland

Syngenta 2012 glyphosate technical micronucleus assay in bone marrow cells of the mouse

Dow Chemical 2012 Micronucleus test of glyphosate TGAI in mice

Industrias Afrasa 2012 reverse mutation with glyphosate

Helm 2010 Reverse Mutation Assay glyphosate using bacteria

Helm 2010 reverse mutation assay 

Helm 2010 mutagenicity of glyphosate testing

Helm 2009 mutagenicity study of glyphosate Germany

Helm 2009 Micronucleus test of glyphosate in bone marrow cells of rat

Syngenta 2009 glyphosate reverse mutation

Jingma Chemicals China 2008 evaluation of the mutagenic potential of glyphosate by reverse mutation assay 

Jingma 2008 evaluation of mutagenic potential of glyphosate by micronucleus assay in mice

Syngenta 2008 glyphosate micronucleus assay in bone marrow cells of the mouse

Helm 2007 Mammalian erythrocyte micronucleus test for glyphosate

Helm Do Brasil 2007 Bacterial reverse mutation test glyphosate

Nufarm 2007 reverse mutation glyphosate technical 05068

Nufarm 2007 1061403 reverse mutation glyphosate technical 05067

Nufarm 2007 1061402 reverse mutation glyphosate technical 05070 

Nufarm 2005 glyphosate technical micronucleus test in the mouse

Monsanto 1998 Mouse micronucleus screening assay of MON-0818

Zeneca Glyphosate 1998 acid Invitro 

Cheminova 1996 reverse mutation glyphosate Brazil

Cheminova 1996 A micronucleus study in mice for the product GILFOS

Zeneca 1996 glyphosate mutagenicity potential

Zeneca 1996 Glyphosate acid mouse bone marrow micronucleus test

Zeneca 1996 glyphosate acid mouse lymphoma gene mutation assay

Sanko 1995 glyphosate in vitro cytogenetics

Sanko 1995 glyphosate DNA Repair Test

Sankyo 1995 reverse mutation study 

Mastra and Maruzen Kako 1995 Technical glyphosate

Mastra and Maruzen Kako 1995 reverse mutation assay glyphosate

Agrichem 1995 Evaluation of ability of glyphosate to induce chromosome aberrations

Feinchemie Schwebda 1994 DNA repair test with primary rat hepatocytes

Feinchemie Schwebda 1994 in vivo mammalian bone marrow cytogenetic test

Feinchemie Schwebda 1993 Mutagenicity-micronucleus glyphosate test in swiss albino mice

Feinchemie Schwebda 1992 Dominant lethal test in Wistar rats

Monsanto 1992 Mouse micronucleus study of Roundup

Monsanto 1992 glyphosate mutagenicity assay on Roundup

Monsanto 1992 Mouse micronucleus study of RODEO glyphosate formulation

Monsanto 1992 glyphosate mutagenicity assay on RODEO herbicide

Monsanto 1992 mouse micronucleus study of DIRECT formulation

Monsanto 1992 glyphosate mutagenicity potential DIRECT brand

Hoechst Dodigen 4022 1992 study of mutagenic potential in strains of salmonella and E Coli

Hoechst Dodigen 4022 1992 Chromosome aberrations in vitro in V79 Chinese hamster cells

Cheminova 1991 #12323 glyphosate mutagenicity test

Cheminova 1991 #12324 Mutagenicity test micronucleus glyphosate

Cheminova 1991 #12325 glyphosate mutagenicity test in vitro mammalian cell gene mutation test

Monsanto 1990 Ames Salmonella mutagenicity assay of MON 0818

Monsanto 1983 In vivo bone marrow cytogenetics study of glyphosate in Sprague-Dawley rats

Monsanto 1983 glyphosate gene mutation assay

Monsanto 1981 Ames salmonella mutagenicity assay of MON 8080

Monsanto 1980 Dominant lethal mutagenicity assay with technical glyphosate in mice

Institute of Environmental Toxicology 1978 Glyphosate report of mutagenic study with bacteria

New research adds evidence that weed killer glyphosate disrupts hormones

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New research is adding worrisome evidence to concerns that the widely used weedkilling chemical glyphosate may have the potential to interfere with human hormones.

In a paper published in the journal Chemosphere titled Glyphosate and the key characteristics of an endocrine disruptor: A review, a trio of scientists concluded that glyphosate appears to have eight out of ten key characteristics associated with endocrine disrupting chemicals . The authors cautioned, however, that prospective cohort studies are still needed to more clearly understand the impacts of glyphosate on the human endocrine system.

The authors, Juan Munoz, Tammy Bleak and Gloria Calaf, each affiliated with the University of Tarapacá in Chile, said their paper is the first review to consolidate the mechanistic evidence on glyphosate as an endocrine-disrupting chemical (EDC).

Some of the evidence suggests that Roundup, Monsanto’s well-known glyphosate-based herbicide, can alter the biosynthesis of the sexual hormones, according to the researchers.

EDCs may mimic or interfere with the body’s hormones and are linked with developmental and reproductive problems as well as brain and immune system dysfunction.

The new paper follows publication earlier this year of an assortment of animal studies that indicated glyphosate exposures impact reproductive organs and threaten fertility.

Glyphosate is the world’s most widely used herbicide, sold in 140 countries. Introduced commercially in 1974 by Monsanto Co, the chemical is the active ingredient in popular products such as Roundup and hundreds of other weed killers used by consumers, municipalities, utilities, farmers, golf course operators, and others around the world.

Dana Barr, a professor at Emory University’s Rollins School of Public Health, said the evidence “tends to overwhelmingly indicate that glyphosate has endocrine disrupting properties.”

“It’s not necessarily unexpected since glyphosate has some structural similarities with many other endocrine disrupting pesticides; however, it is more concerning because glyphosate use far surpasses other pesticides,” said Barr, who directs a program within a National Institutes of Health-funded human exposure research center housed at Emory. “Glyphosate is used on so many crops and in so many residential applications such that aggregate and cumulative exposures can be considerable.”

Phil Landrigan, director of the Global Observatory on Pollution and Health, and a professor of biology
at Boston College, said the review pulled together “strong evidence” that glyphosate is an endocrine disruptor.

“The report is consistent with a larger body of literature indicating that glyphosate has a wide range of adverse health effects – findings that overturn Monsanto’s long-standing portrayal of glyphosate as a benign chemical with no negative impacts on human health,” said Landrigan.

EDCs have been a subject of concern since the 1990s after a series of publications suggested that some chemicals commonly used in pesticides, industrial solvents, plastics, detergents, and other substances could have the capacity to disrupt connections between hormones and their receptors.

Scientists generally recognized ten functional properties of agents that alter hormone action, referring to these as ten “key characteristics” of endocrine-disruptors. The ten characteristics are as follows:

EDC’s can:

  • Alter hormone distribution of circulating levels of hormones
  • Induce alterations in hormone metabolism or clearance
  • Alter the fate of hormone-producing or hormone-responsive cells
  • Alter hormone receptor expression
  • Antagonize hormone receptors
  • Interact with or activate hormone receptors
  • Alter signal transduction in hormone-responsive cells
  • Induce epigenetic modifications in hormone-producing or hormone-responsive cells
  • Alter hormone synthesis
  • Alter hormone transport across cell membranes

The authors of the new paper said a review of the mechanistic data showed that glyphosate met all of the key characteristics with the exception of two:  “Regarding glyphosate, there is no evidence associated with the antagonistic capacity of hormonal receptors,” they said. As well, “there is no evidence of its impact on hormonal metabolism or clearance,” according to the authors.

Research over the last few decades has largely focused on links found between glyphosate and cancer, particularly non-Hodgkin lymphoma (NHL.) In 2015, the World Health Organization’s International Agency for Research on Cancer classified glyphosate as a probable human carcinogen.

More than 100,000 people have sued Monsanto in the United States alleging exposure to the company’s glyphosate-based herbicides caused them or their loved ones to develop NHL.

The plaintiffs in the nationwide litigation also claim Monsanto has long sought to hide the risks of its herbicides. Monsanto lost three out of three trials and its German owner Bayer AG has spent the last year and a half trying to settle the litigation out of court.

The authors of the new paper took note of the ubiquitous nature of glyphosate, saying “massive use” of the chemical has “led to a wide environmental diffusion,” including rising exposures tied to human consumption of the weed killer through food.

The researchers said that though regulators say the levels of glyphosate residue commonly found in foods are low enough to be safe, they “cannot rule out” a “potential risk” to people consuming foods containing contaminated with the chemical,  particularly grains and other plant-based foods, which often have higher levels than milk, meat or fish products.

U.S. government documents show glyphosate residues have been detected in a range of foods, including organic honey, and granola and crackers.

Canadian government researchers have also reported glyphosate residues in foods. One report issued in 2019 by scientists from Canada’s Agri-Food Laboratories at the Alberta Ministry of Agriculture and Forestry found glyphosate in 197 of 200 samples of honey they examined.

Despite the concerns about glyphosate impacts on human health, including through dietary exposure, U.S. regulators have steadfastly defended the safety of the chemical. The Environmental Protection Agency maintains that it has not found any human health risks from exposure to glyphosate.”