Glyphosate: A timeline of a pesticide"s rise and legal cases

Glyphosate, a chemical that was first used to clean out mineral deposits in pipes and boilers, is commonly used as a herbicide to protect a farmer’s crops from being overtaken by noxious weeds. Glyphosate comes in many forms but is most commonly applied as an acid or a salt. It is a nonselective herbicide, meaning it will kill most plants that it comes in contact with unless that plant has been genetically modified for resistance.

"Roundup was the first herbicide to control weeds above and below the ground which made it possible, for the first time, to control tough yield-robbing perennial weeds like Johnsongrass, Quackgrass, Canada Thistle, Field Bindweed and many other tough to control weed species," explained Glenn Stith, a former Monsanto crop protection executive who is president of Top Hand Consulting and also works as a consultant for The Context Network.

"Because of the broad spectrum of weeds controlled and the fact that it was virtually inactive in the soil, Roundup was used as a replacement for pre-plant tillage in many annual cropping systems around the world."

The herbicide became popular among producers for its ability to manage noxious weeds on a large agricultural scale, saving time and money. Before, Monsanto commercialized Roundup, of which glyphosate is a key ingredient, farmers would manage weeds by tilling up the ground, making multiple passes across a field with large machinery and exposing the topsoil — which could lead to soil erosion and compaction. Or, a producer would use a variety of selective herbicides, which each targets a specific weed, resulting in multiple trips across a field and greater use of resources like fuel, labor, and time. In other situations, producers would have to physically walk a field and hand remove weeds.

"The advent of Roundup Ready Soy, Cotton, Corn and Canola revolutionized in-crop weed management by simplifying operations, lowering overall chemical costs and reducing the number of trips across the field, triggering a major expansion in zero till and other forms of conservation tillage agriculture in these major broad acre crops," noted Stith. "Roundup has also been widely used to control weeds in perennial specialty crops such as tree nuts, tree fruits, citrus and grapes as well as landscape, ornamental nursery, forestry, roadside and turf management."

Since the advent of glyphosate-tolerant crops such as corn, cotton, and soybeans in the mid-1990s, agricultural use has increased steadily. By 2016, glyphosate accounted for nearly 44% of the total herbicide use on crops, according to the U.S. Geological Survey.

But the discourse around glyphosate took a different turn after concerns over the safety of the product and its cancer risks. According to a 2017 determination from the Environmental Protection Agency, glyphosate is not likely to be carcinogenic to humans. But in a different study completed in March 2015 by the International Agency for Research on Cancer, a group of 17 scientists classified glyphosate as “probably carcinogenic to humans.” EPA said it “considered a significantly more extensive and relevant data set than the International Agency for Research on Cancer,” including studies submitted to support registration of glyphosate and studies EPA identified in the open literature.

Glyphosate’s safety has also been challenged in the U.S. court system. In 2016, Dewayne “Lee” Johnson, a groundskeeper for Benicia Unified School District in the San Francisco Bay area, claimed exposure to Roundup — the trade name for Monsanto"s glyphosate-based herbicide — caused his non-Hodgkin Lymphoma.

During the first set of Roundup court cases, Monsanto was in the process of being acquired by German pharmaceutical company Bayer. Once the acquisition was complete, Bayer also acquired the Roundup lawsuits filed against Monsanto.

Today, Bayer is under pressure to address what it estimates as about 30,000 currently unsettled claims — and any future claims — that the company"s Roundup products caused Non-Hodgkin lymphoma. In addition to announcing it will withdraw glyphosate-based products from the residential market, it has said it is working to find alternatives to glyphosate while continuing to insist the chemical is safe to use as directed. (Bayer says about 107,000 cases have been settled.)

The company also was hoping the Supreme Court would review a federal appeals court decision that concluded the Federal Insecticide, Fungicide, and Rodenticide Act does not preempt state law tort claims, as were brought in three widely publicized cases that resulted in massive jury verdicts for plaintiffs. The court, however, rejected that petition (the Hardeman case) and followed that up by denying a second petition from Monsanto that made similar arguments about a California Court of Appeal decision (the Pilliod case).

How did we get here? The timeline below includes some of the more significant events, starting with Monsanto"s founding.

Roundup History Timeline

1901: The Monsanto Chemical Works company was founded.

1933: Name changed to the Monsanto Chemical Co. During World War II, Monsanto produced styrene, a component of synthetic rubber, which was vital in supporting the war.

1961: Glyphosate was patented in the U.S. by the Stauffer Chemical Co. and was used as a descaling agent to clean out calcium and other mineral deposits in pipes and boilers of residential and commercial hot water systems.

1970: Monsanto scientist John Franz discovered glyphosate could be used as an herbicide and patented the discovery.

1974: Monsanto brought glyphosate to market under the trade name Roundup.

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