The following review takes a deep dive into Monsanto’s Roundup weed killer and its active ingredient, glyphosate. Brought to market by Monsanto in 1974, Roundup lost its patent protection in 2000.

Glyphosate remains the world’s most commonly used herbicide. It comes in many forms, including as an acid and several salts. These can be either solids or an amber-colored liquid. There are over 750 products containing glyphosate for sale in the United States alone.

In this analysis and series of infographics, we look at the evolving legal trial timelines, human exposure, agricultural use, the science behind the product, genetically modified crops, the fight over glyphosate, its cancer risk, as well as the research behind glyphosate and its formulations.

Monsanto Faces Legal Challenge

The legal health issue began in 2014, when California school groundskeeper Dewayne Johnson was diagnosed with terminal non-Hodgkin’s lymphoma. Although he has outlived the median life expectancy of someone with the disease, Johnson’s doctors do not expect him to live beyond 2020.

After being recruited by a law firm looking for a test case challenging the safety of Roundup, Johnson alleged in 2016 that his cancer was caused by prolonged use of and contact with Roundup Pro and Ranger Pro glyphosate-based herbicides, both products owned by agricultural biotechnology giant Monsanto, now a division of Bayer. He sued Monsanto in the first ever lawsuit to go to trial alleging that glyphosate caused his cancer.

On August 10, 2018, the jury announced its verdict, awardeding Johnson $39 million in compensatory and $250 million in punitive damages. The jury concluded:

The potential risks of Roundup Pro or Ranger Pro presented a “substantial danger” to users.

Monsanto knew or should reasonably have known that Roundup Pro and Ranger Pro were dangerous or were likely to be dangerous.

Roundup Pro or Ranger Pro had potential risks that were known or knowable in light of the scientific knowledge that was generally accepted in the scientific community.

Monsanto failed to adequately warn of the danger or instruct on the safe use of Roundup Pro and Ranger Pro.

Monsanto acted with malice or oppression.

Monsanto responded, asking the judge, Suzanne R. Bolanos, to overrule the jury’s verdict. At first, Bolanos’ tentative ruling favored Monsanto, stating: “Given the state of medical and scientific knowledge there is no clear and convincing evidence that Monsanto acted with malice or oppression in manufacturing and selling its GBH (Roundup) products.”

On October 22, 2018, Bolanos upheld the jury’s verdict. In her ruling, Bolanos wrote, “[T]he court does not sit as a replacement for the jury, but only as a check on arbitrary awards.” The ruling reduced Johnson’s punitive damages to $39 million, matching compensatory damages awarded by the jury. Johnson accepted the judge’s ruling, leaving him with around $78 million in total damages. But Bayer, which acquired Monsanto in June, is planning to appeal.

In January 2019, in a ruling that will help determine the range of damages and define settlement options for the rest of the 620 Roundup cases, the presiding judge determined that evidence of Monsanto’s alleged misconduct would be allowed only if glyphosate was found to have caused the plaintiff’s cancer; The trial proceeded to a second phase to determine Bayer’s liability.

Is Roundup really a carcinogen? Let’s break down how we got to this point.

Monsanto and the Fight Over Glyphosate

Monsanto was once one of the largest agrochemical and agricultural biotechnology companies in the world. In June 2018, St. Louis-based Monsanto was acquired by German-based pharmaceutical and life sciences giant Bayer AG for $66 billion.

In 2017, sales in Monsanto’s agricultural productivity segment, of which glyphosates reportedly make up a significant portion, totalled $3.7 billion, about 25 percent of total net sales. By contrast, Whole Foods, the organic supermarket chain, brought in $16.03 billion in global sales for 2017.

For years, environmental activists have been concerned about the effects of Monsanto’s Roundup on human health, despite the lack of evidence in studies. Every regulatory agency around the world that has evaluated the potential dangers of glyphosate has concluded on multiple occasions that it is not a human carcinogen. Then, in March 2015, the International Agency for Research on Cancer (IARC)―an arm of the World Health Organization (WHO)―published a review of existing glyphosate research that changed the public debate.

In its report, the IARC classified glyphosate as “Probably carcinogenic to humans.” This means there was “Limited evidence of carcinogenicity in humans” (including workers) and “Sufficient evidence of carcinogenicity in experimental animals.” There was no evidence that glyphosate posed any harm to humans exposed to glyphosate residue in food.

The meaningfulness of the IARC assessment is still confusing to many in the media and public. Unlike regulatory agencies that evaluate health “risks” faced by the public, IARC evaluates “hazard,” independent of exposure. It has evaluated more than 1,000 substances or situations and found only one that did not pose a carcinogenic health risk.

The classification that IARC assigned glyphosate—“2A, Probably carcinogenic to humans”—is the same one the organization gave to grapefruit juice, fruits (including apples) and working the night shift. The more serious “1, carcinogenic to humans” category includes sunlight, sunlamps, oral contraceptives, Chinese style salted fish and alcoholic beverages, including wine and beer.

These nuances were largely ignored by the media and by anti-biotechnology advocacy groups that widely publicized the IARC assessment as confirmation of what they had always suspected. Most of the scientific community decried the report as taken out of context. Subsequent investigations by Reuters and other independent journalists raised questions of bias by IARC and manipulation of the final report, which before release had originally concluded that glyphosate was non-carcinogenic.

In Jan. 2018, the IARC published a defense of its findings, addressing claims that the report had been edited and some data deliberately excluded. The IARC claimed that most of these attacks had come from the agrochemical industry.

In July 2017, in response to the IARC’s findings, the state of California listed glyphosate as a chemical known to cause cancer, per the California Safe Drinking Water and Toxic Enforcement Act of 1986 (aka Prop 65), enforced by the Office of Environmental Health Hazard Assessment (OEHHA). The IARC’s study is the sole evidence upon which the listing is based.

Prop 65 does not assess the actual risk of a substance ー just its potential to cause cancer. Coffee and visits to Disneyland have been founded as potentially cancer-causing under Prop 65 and were required to carry warning labels. The FDA eventually intervened to quash the label requirement on coffee but the Prop 65 warning signs are required throughout Disneyland.

California attempted to require labels on bottles of Roundup and other glyphosate herbicides to warn users that the product may cause cancer. Current labels on bottles of Roundup Pro Concentrate read only CAUTION: CAUSES MODERATE EYE IRRITATION, followed by directions to safe use, including “Avoid contact with eyes or clothing” and “Applicators and other handlers must wear: long-sleeved shirt and long pants, shoes plus socks.”

In Nov. 2017, Monsanto, the National Association of Wheat Growers, and other agricultural groups sued the government of California over the planned cancer warnings. In Feb. 2018, U.S. District Judge William Shubb ruled against the label change, writing: “Given the heavy weight of evidence in the record that glyphosate is not in fact known to cause cancer, the required warning is factually inaccurate and controversial.” However, the judge allowed glyphosate to remain on the California’s list of cancer-causing agents.

The Science of Roundup and the Argument for Herbicides

Glyphosate is a systemic, non-selective herbicide. What does that mean?