Known Health Concerns About Glyphosate, the Main Ingredient in Roundup

January 23rd, 2019

Cornucopia’s Take: Use of the herbicide glyphosate has skyrocketed around the world since the introduction of crops genetically engineered to be Roundup Ready (resistant) in 1996. While the EPA insists that glyphosate does not cause cancer in humans, some research reviews have come to different findings. U.S. Right to Know seeks transparency in the food system, and the article below catalogs the science and the politics of glyphosate safety studies.


Glyphosate: Health Concerns About the Most Widely Used Pesticide
U.S. Right to Know
by Stacy Malkan

Source: NRCS, Tim McCabe

Glyphosate, a synthetic herbicide patented in 1974 by the Monsanto Company and now manufactured and sold by many companies in hundreds of products around the world, has been associated with various health concerns. Glyphosate is best known as the active ingredient in Roundup-branded herbicides, and the herbicide used with “Roundup Ready” genetically modified organisms (GMOs).

Herbicide tolerance is the most prevalent GMO trait engineered into food crops, with some 90% of corn and 94% of soybeans in the U.S. engineered to tolerate herbicides, according to USDA data. A 2017 study found that Americans’ exposure to glyphosate increased approximately 500 percent since Roundup Ready GMO crops were introduced in the U.S in 1996. Here are some key facts about glyphosate:

Most Widely Used Pesticide

According to a February 2016 study, glyphosate is the most widely used pesticide. “In the U.S., no pesticide has come remotely close to such intensive and widespread use,” according to the study. Findings include:

  • Americans have applied 1.8 million tons of glyphosate since its introduction in 1974.
  • Worldwide 9.4 million tons of the chemical has been sprayed on fields – enough to spray nearly half a pound of Roundup on every cultivated acre of land in the world.
  • Globally, glyphosate use has risen almost 15-fold since Roundup Ready GMO crops were introduced.

Cancer Concerns

The scientific literature and regulatory conclusions regarding glyphosate and glyphosate-based herbicides show a mix of findings, making the safety of the herbicide a hotly debated subject:

In 2015, the World Health Organization’s International Agency for Research on Cancer (IARC) classified glyphosate as “probably carcinogenic to humans” after reviewing years of published and peer-reviewed scientific studies. The team of international scientists found there was a particular association between glyphosate and non-Hodgkin lymphoma.

At the time of the IARC classification, the Environmental Protection Agency (EPA) was conducting a registration review. The EPA’s Cancer Assessment Review Committee (CARC) issued a report in September 2016 concluding that glyphosate was “not likely to be carcinogenic to humans” at doses relevant to human health. In publishing the CARC report, the EPA said that it was beginning work with the National Toxicology Program to investigate the mechanisms and toxic effects of glyphosate formulations.

The agency then convened a Scientific Advisory Panel (SAP) in December 2016 to review the CARC report conclusion that glyphosate was not likely to be carcinogenic. The scientific advisory panel members were divided in their assessment of EPA’s work, with some finding the EPA erred in how it evaluated certain research. Additionally, the EPA’s Office of Research and Development determined that the agency’s Office of Pesticide Programs had not followed proper protocols in its evaluation of glyphosate. An ORD memo stated that the government scientists agreed in part with IARC and believed EPA was not properly following guidelines in coming to the conclusion that glyphosate was not likely to be carcinogenic. ORD said the evidence could be deemed to support a “likely” carcinogenic or “suggestive” evidence of carcinogenicity classification. Nevertheless the EPA issued a draft report on glyphosate in December 2017 continuing to hold that the chemical is not likely to be carcinogenic.

The European Food Safety Authority and the European Chemicals Agency have said glyphosate is not likely to be carcinogenic to humans. But a March 2017 report by environmental and consumer groups argued that regulators relied improperly on research that was directed and manipulated by the chemical industry.

The WHO/FAO Joint Meeting on Pesticide Residues determined that glyphosate was unlikely to pose a carcinogenic risk to humans from exposure through the diet, though the finding was tarnished by conflict of interest concerns after it was revealed that certain members of the group, including its chair, worked for the International Life Sciences Institute, a group funded in part by Monsanto and one of its lobbying organizations.

On March 28, 2017, the California Environmental Protection Agency’s Office of Environmental Health Hazard Assessment confirmed that it would add glyphosate to California’s Proposition 65 list of chemicals known to cause cancer. Monsanto sued to block the action but the case was dismissed. In a separate case, the court found that California could not require cancer warnings for products containing glyphosate. On June 12, 2018, the United States District Court for the Eastern District of California denied the California Attorney General’s request for the court to reconsider the decision. The court found that California could only require commercial speech that disclosed “purely factual and uncontroversial information,” and the science surrounding glyphosate carcinogenicity was not proven.

A long-running U.S. government-backed prospective cohort study of farm families in Iowa and North Carolina has not found any connections between glyphosate use and non-Hodgkin lymphoma, though researchers found that “among applicators in the highest exposure quartile, there was an increased risk of acute myeloid leukemia (AML) compared with never users…” The most recent published update to the study was made public in late 2017.

An analysis published January 14, 2019 in Environmental Sciences Europe argues that the U.S. EPA’s classification of glyphosate disregarded substantial scientific evidence of genotoxicity (the negative impact on a cell’s genetic material) associated with weed killing products such as Roundup. In an editorial, the journal editors described a robust peer review with 10 expert reviewers, and wrote, “We are convinced that the article provides new insights on why different conclusions regarding the carcinogenicity of glyphosate and (glyphosate-based herbicides) were reached by the US EPA and IARC.” See article by Carey Gillam, “New analysis raises questions about EPA’s classification on glyphosate weed killer.”

Cancer Lawsuits

More than 650 lawsuits against Monsanto Co. are part of multi district litigation (MDL) being overseen by Judge Vince Chhabria in U.S. District Court in San Francisco, filed by people alleging that exposure to Roundup herbicide caused them or their loved ones to develop non-Hodgkin lymphoma, and that Monsanto covered up the risks. An estimated 9,000 similar actions are pending in state courts. U.S. Right to Know is posting key documents from the litigation on our Monsanto Papers pages.

In March 2017, the federal court judge unsealed some internal Monsanto documents that raised new questions about Monsanto’s influence on the EPA process and about the research regulators rely on. The documents suggest that Monsanto’s long-standing claims about the safety of glyphosate and Roundup do not necessarily rely on sound science as the company asserts, but on efforts to manipulate the science.

study for the European Parliament published January 15, 2019 asserts that the EU approval of glyphosate was based on plagiarized text from Monsanto. The study found plagiarism in 50.1 percent of chapters dealing with the assessment of published studies on health risks related to glyphosate in Germany’s Federal Institute for Risk Assessment,including whole paragraphs and entire pages of plagiarized text.

See also 2018 journal articles about scientific interference:

The first trial concluded in August 2018 with the jury ruling that Monsanto’s weed killer was a substantial contributing factor in causing DeWayne “Lee” Johnson’s cancer, and ordering Monsanto to pay $289.25 million in damages, including $250 million in punitive damages. The judge in the case reduced the punitive damages to $39 million, bringing the total award to $78 million. Monsanto declared it would appeal and Johnson has cross-appealed, seeking to reinstate the jury award. Follow updates in our Roundup Trial Tracker blog.

Endocrine Disruption and Other Health Concerns

Some research suggests that glyphosate may be an endocrine disruptor. It has also been linked to liver diseasebirth defects and reproductive problems in laboratory animals; and may kill beneficial gut bacteria and damage the DNA in human embryonic, placental and umbilical cord cells. Many scientists have raised concerns about the health risks of glyphosate. See:

Recent studies have shown adverse biological effects from low-dose exposures to glyphosate at levels to which people are routinely exposed.

  • A birth cohort study in Indiana published in 2017 – the first study of glyphosate exposure in US pregnant women using urine specimens as a direct measure of exposure – found detectable levels of glyphosate in more than 90% of the pregnant women tested and found the levels were significantly correlated with shortened pregnancy lengths.
  • A 2018 ecological and population study conducted in Argentina found high concentrations of glyphosate in the soil and dust in agricultural areas that also reported higher rates of spontaneous abortion and congenital abnormalities in children, suggesting a link between environmental exposure to glyphosate and reproductive problems. No other relevant sources of pollution were identified.
  • A 2017 study associated chronic, very low-level glyphosate exposures to non-alcoholic fatty liver disease in rats. According to the researchers, the results “imply that chronic consumption of extremely low levels of a GBH formulation (Roundup), at admissible glyphosate-equivalent concentrations, are associated with marked alterations of the liver proteome and metabolome,” the biomarkers for NAFLD.
  • A 2018 rat study conducted by the Ramazzini Institute reported that low-dose exposures to Roundup at levels considered safe significantly altered the gut microbiota in some of the rat pups.Another 2018 study reported that higher levels of glyphosate administered to mice disrupted the gut microbiota and caused anxiety and depression-like behaviors.
  • A 2018 rat study by Argentinian researchers linked low-level perinatal glyphosate exposures to impaired female reproductive performance and congenital anomalies in the next generation of offspring.

Glyphosate has also been linked by recent studies to harmful impacts on bees and monarch butterflies.

Desiccation

Some farmers use glyphosate on non-GMO crops such as wheat, barley, oats, and lentils to dry down the crop ahead of harvest in order to accelerate the harvest. This practice, known as desiccation, may be a significant source of dietary exposure to glyphosate.

Glyphosate Found in Food: U.S. Drags Its Feet on Testing

The USDA quietly dropped a plan to start testing food for residues of glyphosate in 2017. Internal agency documents obtained by U.S. Right to Know show the agency had planned to start testing over 300 samples of corn syrup for glyphosate in April 2017. But the agency killed the project before it started. The U.S. Food and Drug Administration began a limited testing program in 2016, but the effort was fraught with controversy and internal difficulties and the program was suspended in September 2016. Both agencies have programs that annually test foods for pesticide residues but both have routinely skipped testing for glyphosate.

Before the suspension, one FDA chemist found alarming levels of glyphosate in many samples of U.S. honey, levels that were technically illegal because there have been no allowable levels established for honey by the EPA. Here is a recap of news about glyphosate found in food:

Pesticides in Our Food: Where’s the Safety Data?

USDA data from 2016 shows detectable pesticide levels in 85% of more than 10,000 foods sampled, everything from mushrooms to grapes to green beans. The government says there are little to no health risks, but some scientists say there is little to no data to back up that claim. See “Chemicals on our food: When “safe” may not really be safe: Scientific scrutiny of pesticide residue in food grows; regulatory protections questioned,”by Carey Gillam (11/2018).

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