Being in a county with above average glyphosate use does not necessarily result in increased exposure. A 2020 Department of Health and Human Services report notes that the greatest potential exposure is to agricultural workers and gardeners who use glyphosate-based herbicides and those who live near farms, produce manufacturing plants containing glyphosate and hazardous waste disposal sites containing it.
For the general public, the report notes that exposure to glyphosate typically occurs by touching or eating food or water containing residues or by inhaling mists or aerosols during its use. For those exposed only through food, the EPA says glyphosate residues on food are safe up to certain thresholds.
Some studies have found a link between increased cancer rates and higher exposure levels, although other researchers say limited data on glyphosate exposure levels in humans make it difficult to analysis of a relationship between exposure and disease. Other studies have concluded that it is not carcinogenic.
Chemical giant Monsanto introduced glyphosate in its Roundup product in 1974. Bayer acquired Monsanto in 2018.
“Glyphosate is the most widely used chemical weedkiller in human history due to genetic engineering,” said Dave Murphy, the founder of Food Democracy Now, an advocacy group that tests glyphosate in foods. “It is sprayed ubiquitously and Monsanto has maintained for decades that it is the safest agricultural chemical ever made.”
EPA safety limits for exposure to glyphosate from food are double the levels allowed in the European Union. Its runoff is recognized by the agency as a drinking water contaminant at levels corresponding to about 1 gallon of Roundup in an Olympic-sized swimming pool, according to an NBC News calculation.
Much of the debate over the health implications of glyphosate revolves around a potential link to non-Hodgkin’s lymphoma. A 2019 analysis conducted by former members of the EPA’s Scientific Review Panel indicated a “compelling link” to the disease. Several peer-reviewed studies have also suggested that herbicides containing glyphosate may disrupt hormones and alter the gut microbiome.
The 2015 IARC report, which stated that “a positive association was observed for non-Hodgkin’s lymphoma”, launched a wave of lawsuits that cost Bayer more than $10 billion in settlements, although the company has won five consecutive personal injury trials through September. 1.
Bayer continued to advocate the safety of glyphosate. The company has repeatedly challenged the validity of IARC studies and other studies, some backed by organic food groups, that have linked the chemical to cancer. The company pointed NBC News to other studies — some of which it sponsored — that either refuted a cancer link or disputed the relationship between acres sprayed and exposure levels.
In California, glyphosate is on a list of chemicals known to cause cancer, a designation that requires manufacturers to print warning labels on products sold in the state. However, after Monsanto and the EPA challenged the requirement, a judge concluded that “virtually all other regulators have concluded that there is insufficient evidence that it causes cancer”, preventing such warnings.
The litigation is ongoing. In a statement to NBC News, Bayer said it continues to oppose California’s classification and requirement because they conflict with “the long-standing consensus of key health regulators in the world.” world supporting the safety and non-carcinogenicity of glyphosate products”.
The use of glyphosate in the United States has skyrocketed since 1996, the year Monsanto introduced genetically modified seeds that could survive the spraying of higher amounts of herbicides.
Today, nearly 90% of corn, cotton and soybean crops are engineered to be tolerant of glyphosate and other chemical treatments used by farmers, according to data from the US Department of Agriculture.
A 2017 study by researchers at the University of California, San Diego showed that the amount of glyphosate in urine samples taken from a group of 100 adults increased between 1993 and 2016. Glyphosate residues have also been detected in air and rain samples, according to a University of Minnesota study.
A national health survey released in June by the Centers for Disease Control and Prevention found detectable levels of glyphosate in 80% of urine samples tested.
Bayer said finding traces of glyphosate in urine does not mean there is a health risk. The company told NBC News in a statement that the highest value found in the CDC survey “corresponds to exposures below 0.14% of the U.S. Environmental Protection Agency safety threshold.” – a measurement that equals 16 millionths of an ounce per pound of body weight.
“CDC data confirms that human exposures to glyphosate are well below these levels, confirming that glyphosate can be used safely following label directions,” the statement read.
But Robin Mesnage, a toxicologist at King’s College London – who has studied the health effects of environmental contaminants for more than a decade and was a consultant in glyphosate litigation against Bayer in the United States – s is asked if the current safety thresholds were too high.
His own research, he said, showed that glyphosate can induce DNA damage and changes in liver metabolism at doses up to 100 times lower than permitted levels – which was still higher. to any value found in the CDC study. He added that the combination of glyphosate with the other ingredients in herbicides can make the end product more toxic than its active ingredient alone. In a statement, Bayer objected to Mesnage’s research methodologies.
The EPA concluded in 2020 that glyphosate poses “no risk to human health” and is not likely to cause cancer. But a federal appeals court overturned that decision in June, saying the EPA failed to adequately assess the risks to endangered species and human health. The court also pointed to inconsistencies in the agency’s 2016 assessment of potential links to non-Hodgkin’s lymphoma. The EPA withdrew its decision in September.
An internal EPA advisory committee also found inconsistencies in this 2016 assessment, including that some tumor responses in animals were overlooked. The panel recommended that the EPA obtain updated data in order to draw a conclusion on the risk of non-Hodgkin’s lymphoma.
“Animals got tumors and they got more tumors at high doses,” said Bill Freese, chief scientific officer of the Center for Food Safety, a nonprofit environmental advocacy organization that was one of the groups that have challenged the EPA’s review of glyphosate in court.
“Their conclusion about cancer just didn’t make sense,” Freese said.
EPA spokeswoman Melissa Sullivan said in an email that the agency plans to revise and better explain its assessment of the carcinogenic potential of glyphosate by 2026, as well as consider evaluating other impacts it may have on human health. Until this review is complete, products containing glyphosate may continue to be sold.
As for residues in food, the EPA has stated that traces are acceptable as long as they do not exceed its safety limits. But environmental and organic advocates note that these thresholds have increased over the past two decades. In 2013, following a petition from Monsanto, the EPA raised allowable levels of glyphosate residues on certain foods, doubling the allowable limit for oilseeds and raising it to more than 15 times the previous level for oilseeds. sweet potatoes and carrots.
Bayer plans to replace glyphosate in some versions of Roundup by next year. The company said in its statement that this decision was made “exclusively to manage the risk of litigation in the United States and not for security reasons”. The current formula will still be available to farmers, pest control companies and other professional services.
CORRECTION (October 28, 2:57 PM ET): A previous version of this article and map miscalculated the rate of glyphosate herbicide use for 41 counties in Colorado and incorrectly claimed that the county of Lake, Colorado had the highest rate in the country. Nueces County, Texas had the highest utilization rate, while Lake County was among the lowest.
CLARIFICATION: This article has been updated to clarify how people can be exposed to glyphosate. It has also been updated to distinguish between use and exposure – that not everyone in a high-use area is necessarily exposed or at health risk. It also specifies where and on what types of crops glyphosate residues were found. It also includes updated statements from Bayer. It also includes additional information about the court ruling ending California’s labeling requirements. And information about Robin Mesnage’s work advising plaintiffs suing Bayer has also been added.