Glyphosate

Glyphosate is a chemical known as a herbicide. Herbicides are substances that kill plants and are used to control unwanted plants, such as weeds. Glyphosate is widely used to kill broadleaf plants and grasses; it is used in commercial agriculture, by landscaping professionals, and by homeowners and home gardeners. It has been in use in the United States and in more than 160 other countries for more than four decades and, in the past, was considered safe with some precautions. However, by 2019, researchers from the University of Washington concluded that being exposed to the chemical gave individuals a 41 percent increased risk of developing cancer.

Background

Glyphosate was discovered in 1970 by Monsanto, the company that makes the most popular commercial form of the herbicide, Roundup. Chemists working for the company had found several compounds they thought might be useful as water softeners. These substances were also passed on to a Monsanto employee working in the newly formed agricultural division. The chemist, John Franz, was tasked by the head of Monsanto's herbicide program, Philip C. Hamm, with testing the possibility that these substances could be used as herbicides. The first two attempts Franz made to synthesize a herbicide from one of the would-be water softeners failed, but the third one showed promise.

The substance had one key problem, however. Many herbicides are selective, killing only certain types of plants. This new substance killed every kind of plant that it came into contact with. Monsanto chemists spent nearly three years attempting to find a way to use the new herbicide without killing desirable plants.

Monsanto was interested in finding a way to market this particular herbicide because it appeared to be very environmentally friendly, while some other available products were not. Many herbicides of the time worked by killing the weed seedlings as they emerged. This meant the herbicide had to be applied broadly over the entire field and needed to be long-lasting enough to remain effective when the seedlings began to sprout. These requirements meant that many herbicides washed into water supplies, where they had undesirable effects. Glyphosate did not appear to have any similar issues.

Monsanto began selling products containing glyphosate in 1974 for use in situations where it could be sprayed directly on the weeds, though users had to avoid getting it on desirable plants. At the same time, the company took another approach to making the product more useful in agricultural settings: it developed crop seeds that were resistant to the effects of glyphosate. Growers could plant the seeds and then treat the entire crop with glyphosate and only the weeds would die. Beginning in 1979, Monsanto developed corn, cotton, and soybean seeds that were genetically modified to withstand the use of glyphosate. Within forty years of its discovery, more than 1.4 billion pounds of glyphosate were used each year; in the United States alone, about 280 million pounds were used on farms annually as of 2020.

Overview

Glyphosate works by preventing plants from making proteins the plants need to survive. It does this by interfering with the shikimic acid pathway. Also known as the shikimate acid pathway, this is part of the biological process by which plants and some other organisms, such as bacteria, algae, and fungi, make certain enzymes necessary for metabolism, or the process of converting food or fuel into energy.

Glyphosate is very disruptive to the metabolic processes of plants. It was thought at first that it did not have a similar effect on other life forms. However, it was later reported that individuals who are exposed to the chemical have a greater chance of developing cancer, in particular non-Hodgkin lymphoma (NHL), a cancer of the immune system.

Like other chemicals, glyphosate is subject to review by the Environmental Protection Agency (EPA) and other regulatory agencies. Early reviews by these agencies indicated that the 750 products made with glyphosate that were sold in the United States were safe when used as directed. In 2015, the International Agency for Research on Cancer (IARC), an arm of the World Health Organization, deemed glyphosate a probable human carcinogen. However, in subsequent years, experts, including scientists and statisticians, analyzed and criticized the methodology used in the IARC's report, and the media began reporting in 2017 that the agency was suspected of having altered initial drafts of the report to selectively leave out reportedly legitimate findings supporting that the chemical is not carcinogenic. The portion of the report identified as having been most edited before being finalized, pertaining to animal testing, was allegedly the part that served as the foundation of the agency's decision. Despite such accusations, the IARC continued to defend its monograph and conclusion; Monsanto, on the other hand, has still refuted the finding and defended its products. By 2019, researchers at the University of Washington concluded that glyphosate causes cancer. The EPA also released a draft of a biological evaluation in 2020 indicating that glyphosate was likely to harm or kill 92 percent of the world's plants and animals that were protected by the Endangered Species Act. According to the EPA, glyphosate modified the habitat of 759 endangered species.

Thousands of lawsuits were brought against Monsanto by individuals suffering from cancer on the basis that the company did not warn the public of the potential risk to their health. Though Monsanto brought a legal challenge against California's Office of Environmental Health and Hazard Assessment in April 2018 in an effort to prevent the state from listing glyphosate as a potential cancer-causing agent, the company lost the court case. By May, the case of a California groundskeeper for a county school system, who had worked with Monsanto's glyphosate products for years, had been cleared to proceed to trial; the case, the first to go to trial, had been expedited after its filing in 2016 due to the terminal nature of the plaintiff's non-Hodgkin's lymphoma. In August, a jury found, after three days of deliberation, that there was a connection between the company's glyphosate weed killers and the plaintiff's cancer, and they ordered Monsanto to pay $289 million in damages. The result of this first case left commentators speculating that many of the other individuals who had filed lawsuits would have a precedent to plead their case in court as well.

Some questions have arisen about the potential for health issues caused by indirect contact through consuming food from crops treated with glyphosate. Studies have found that glyphosate traces remain in water that runs off fields treated with it. Tests on some of the soybeans farmed with the use of glyphosate have also found trace amounts of the substance on the harvested crop, and it has been found in processed food, including cookies and cold cereals. Significant amounts of glyphosate have been found in the majority of honey samples tested by the Food and Drug Administration (FDA). Tests on the people who work fields treated with glyphosate have found traces in the blood and urine.

Concerns have also been raised about the possibility that other chemicals that are present in glyphosate products may increase the chemical's hazard to human and wildlife; some may even be harmful in and of themselves. While regulatory agencies test the active ingredient in herbicides—in this case, the glyphosate—they do not test what are known as "inert ingredients," or the ingredients that form the rest of the herbicidal product, such as binders, stabilizing agents, preservatives, or chemicals that help increase the effectiveness of the primary ingredient.

For instance, many formulations of Roundup, Monsanto's trademarked product containing glyphosate, use a chemical known as polyoxyethylene tallow amine, or POEA, a surfactant made of animal fat. It is a detergent that helps glyphosate get into the plant cells, making it more effective at eliminating the plant. However, POEA has been found to be toxic; researchers have determined some instances of death resulting from the accidental or intentional consumption of Roundup were caused by POEA, not glyphosate. Some experts are concerned that the combination of these two chemicals may also increase the health risks associated with glyphosate and have called for additional testing and increased oversight of herbicides.

Supporters of the products state that those containing glyphosate are helpful to farmers because they minimize the work and expense of controlling weeds. The products reduce the need to till the soil, helping to also reduce erosion as well as the emissions from farm equipment. They stress that when used according to instructions, glyphosate is a safe and effective tool to help farmers produce necessary crops.

Bibliography

Gammon, Crystal. "Weed-Whacking Herbicide Proves Deadly to Human Cells." Scientific American, 23 June 2009, www.scientificamerican.com/article/weed-whacking-herbicide-p/. Accessed 3 Apr. 2017.

Gillam, Carey. "FDA Finds Monsanto's Weed Killer in U.S. Honey." Huffington Post, 15 Sept. 2016, www.huffingtonpost.com/carey-gillam/fda-finds-monsantos-weed‗b‗12008680.html. Accessed 5 Apr. 2017.

"Glyphosate." National Pesticide Information Center, npic.orst.edu/factsheets/glyphogen.html. Accessed 3 Apr. 2017.

"Glyphosate." US Environmental Protection Agency, www.epa.gov/ingredients-used-pesticide-products/glyphosate. Accessed 3 Apr. 2017.

"Glyphosate and Roundup Brand Herbicides." Monsanto, www.monsanto.com/glyphosate/pages/default.aspx. Accessed 3 Apr. 2017.

Grossman, Elizabeth. "What Do We Really Know About Roundup Weed Killer?" National Geographic, 23 Apr. 2015, news.nationalgeographic.com/2015/04/150422-glyphosate-roundup-herbicide-weeds/. Accessed 3 Apr. 2017.

Herrmann, Klaus M. "The Shikimate Pathway: Early Steps in the Biosynthesis of Aromatic Compounds." The Plant Cell, July 1995, www.ncbi.nlm.nih.gov/pmc/articles/PMC160886/pdf/070907.pdf. Accessed 3 Apr. 2017.

"The History of Roundup." Roundup Canada, www.roundup.ca/en/rounduphistory. Accessed 3 Apr. 2017.

"Jurors Give $289 Million to a Man They Say Got Cancer from Monsanto's Roundup Weedkiller." CNN, 11 Aug. 2018, www.cnn.com/2018/08/10/health/monsanto-johnson-trial-verdict/index.html. Accessed 5 Sept. 2018.

"Measuring POEA, a Surfactant Mixture in Herbicide Formulations." US Geological Survey, Department of the Interior, toxics.usgs.gov/highlights/glyphosate‗poea.html. Accessed 3 Apr. 2017.

"Number Eighty-Seven: Glyphosate." Heal the Planet, 5 Oct. 2024, healtheplanet.com/100-ways-to-heal-the-planet/glyphosate. Accessed 19 Nov. 2024.