Glyphosate is a broad-spectrum systemic herbicide that kills weeds and prevents unwanted plants from growing.
The herbicide works by preventing the plant from making specific proteins essential to growth through a metabolic pathway that is critical in plants but not in humans or animals.
More research is needed on glyphosate's long-term effects, but there is growing evidence that glyphosate may be harmful in multiple ways, including increased risks for cancer, adverse effects on the microbiome, and endocrine disruption.
To reduce your exposure to glyphosate, stick with organic foods, be mindful of oat-based products (many oats are sprayed with glyphosate before harvest), and consider natural alternatives for controlling weeds in your garden.
In 1970, Monsanto chemist John E. Franz discovered the herbicidal properties of glyphosate, a chemical compound that can be used in different forms both to kill weeds and to ripen crops. (Source) After patenting the chemical, Monsanto began selling it commercially in 1974 as the active ingredient in its Roundup weedkiller. The company trademarked the name, claiming that their product was “safer than table salt” and used it to aggressively market their product to farmers and consumers.
In the decades since, glyphosate use has skyrocketed. The weedkiller has become the most commonly used herbicide in the history of agriculture. The U.S. Environmental Protection Agency (EPA) estimates that more than 3 billion pounds of glyphosate have been used in the US alone since it became commercially available in 1974, and use continues at the rate of 280 million pounds per year. (Source, Source)
Despite its popularity, the herbicide has come under increasing scrutiny in recent years. After reviewing nearly 1,000 peer-reviewed, published studies on the chemical, the International Agency for Research on Cancer (IARC), a branch of the World Health Organization, classified glyphosate as “probably carcinogenic to humans” in 2015. (Source) In 2017, the California EPA Office of Environmental Health Hazard Assessment (OEHHA) added glyphosate to the list of known carcinogens under California's Safe Drinking Water and Toxic Enforcement Act of 1986 (Proposition 65). (Source)
In 2018, German chemical company Bayer acquired Monsanto and its signature product, Roundup. Since the acquisition, an estimated 95,000 lawsuits have been filed against Bayer claiming Roundup caused litigants to develop non-Hodgkin's lymphoma. In 2020 Bayer agreed to set aside nearly $10 billion to settle current and future claims. The settlement is intended to end the litigation rather than validate the claims, and the company continues to sell the product without adding warning labels about its safety. (Source)
In today's edition, we'll examine the history of glyphosate and its impact on public health, uncovering the reason why you might want to put the Honey Nut Cheerios back on the shelf.
Glyphosate is a broad-spectrum systemic herbicide that kills weeds and prevents unwanted plants from growing. The herbicide works by preventing the plant from making specific proteins essential to growth through a metabolic pathway that is critical in plants but not in humans or animals. Products containing glyphosate, like Roundup, are sold in different commercial formulations, including liquid concentrate, solid, and ready-to-use liquid. Over the years, Monsanto produced genetically modified plants to resist glyphosate, allowing farmers to spray their fields with the herbicide and kill weeds while sparing the crop. (Source, Source)
Beyond farmers' orchards and fields, our lawns, parks, and playgrounds are often sprayed with the pesticide. Unlike persistent organic pollutants (POPs), glyphosate degrades in the environment (thankfully!). Still, it binds to soil particles and can persist for up to six months, which means other crops grown in a treated area could absorb the herbicide even if they aren't a direct target. Although glyphosate has been detected in air and rain samples, diet is the primary source of exposure. According to the EPA, glyphosate is sprayed on more than 100 different food crops, including soy, corn, canola, and wheat. There's also evidence that glyphosate residues on those items transfer into our bodies — in 2015 the University of California–San Francisco found the pesticide was present in 93% of urine samples tested. (Source, Source, Source)
Studies show that glyphosate may be associated with chromosomal damage, neurotoxicity, and oxidative stress. Other studies have linked the herbicide to various possible human health risks such as kidney disease, obesity, Parkinson's disease, and reproductive problems. These findings have prompted some countries to ban the chemical, including Germany, Saudi Arabia, and Vietnam, while many other countries have restricted its use. However, to date, the EPA has not identified any human health risks from exposure to glyphosate. (Source, Source)
Controversy has arisen over the pesticide's classification as possibly or probably carcinogenic, and the manufacturer has aggressively lobbied to discredit the findings. In January 2020, the EPA declared glyphosate “unlikely” to cause cancer when used according to its label. The EPA is alleged to have disregarded the findings and supporting research by the IARC, and allegations were made that some EPA officials may have colluded with Monsanto to stall the release of another federal assessment evaluating its toxicity. In its statement, the EPA relied on non-peer-reviewed research commissioned by Monsanto, further undermining its determination. (Source, Source, Source)
More research is needed on glyphosate's long-term effects, but there is increasing evidence in human and animal models that glyphosate may be harmful in multiple ways.
Studies have found an increased risk of non-Hodgkin lymphoma and other cancers in agricultural workers with high occupational exposures to glyphosate. Researchers from the University of Washington concluded that among these workers non-Hodgkin lymphoma risk is increased by more than 40%. Another study in the Agricultural Health Study found that exposure to glyphosate doubled the risk of the immune-related cancer in those who work with the herbicide. (Source, Source, Source)
Research suggests the pesticide may upset the gut microbiome. In 2010 Monsanto was granted a patent for use of glyphosate as an antimicrobial, based on its adverse effect on the shikimate pathway. The shikimate pathway is a multi-step process for metabolizing carbohydrates and synthesizing amino acids that is used by plants and microorganisms, but not animals. Although human cells don’t utilize the shikimate pathway, microbes that make up the gut microbiome do, suggesting that ingestion of glyphosate could play a role in the increased incidence of dysbiosis and leaky gut. (Source, Source, Source)
Researchers have found that glyphosate — even in low doses — may act as an endocrine disruptor in mammals, altering hormonal function. In a 2013 study, glyphosate exposure caused breast cancer cells to proliferate in vitro by mimicking estrogen. Another recent in vitro study utilizing porcine sperm found pure glyphosate had no significant effect on spermatozoa except in very high amounts, but commercial preparations of Roundup had a greater impact on motility, viability, and mitochondrial activity. (Source, Source, Source)
Because spraying with glyphosate is prohibited in organic agriculture, people eating an organic diet have significantly lower detectable levels in their systems. Unfortunately, certifications guaranteeing that a product is glyphosate-free aren't widely used yet, although one nonprofit group is working on it. For now, your best bet is to stick to organic foods — one study found that eating an organic diet reduced the amount of glyphosate in a person's urine levels by 70% after just six days. (Source)
Many of the foods contaminated with glyphosate are oat-based products, like oatmeal, cereal, and granola bars. The pesticide is sprayed on oats just before harvest as a drying agent to harvest the crop sooner. In 2018, the Environmental Working Group (EWG) released the results of lab tests it commissioned to test 61 conventional and organic oat products for glyphosate. Forty-three of the 45 conventionally grown products tested positive for pesticide residues, with almost 75% of samples scoring levels above the EWG's own threshold for safety. Which popular cereal was the worst offender? Quaker Oatmeal Squares Honey Nut, which came in at a whopping 2837 ppb, nearly 18 times higher than the EWG's recommended level of 160 ppb. (Source, Source)
There are less-toxic alternatives to glyphosate for controlling weeds in your lawn or garden — including vinegar, soaps, even goats and geese — that are better for you, your neighbors, and the environment. Alternatively, you can learn to make the most of your local weeds, as some are edible and some are natural pest repellents. (Source)
In case you're curious about the reach of glyphosate, this timelapse created by the EWG shows trends of the herbicide's expansion in the US from 1992 to 2012 (note: the midwest appears to be one of the denser regions).
In 2019, the EWG independently tested and analyzed the results of 12 wheat-based products, including five samples of dried pasta and seven cereal samples. This report also shares findings from both the Canadian Food Inspection Agency and the FDA, which found the weedkiller in 80% to 90% of wheat-based products and 67% of soybean samples, respectively.
If you want to take action and help get glyphosate out of our food supply, sign EWG's petition to urge food companies like General Mills, Quaker, and Kellogg's to stop using crops sprayed with glyphosate.