Quick summary:
• Glyphosate exposure in mice caused persistent brain inflammation and Alzheimer’s-like pathology.
• Even low doses of glyphosate, deemed safe for humans, resulted in lasting neurological damage.
• Glyphosate’s metabolite, AMPA, accumulates in brain tissue and crosses the blood-brain barrier.
• Widespread use of glyphosate exposes most Americans, especially farmworkers, to potential risks.
• Researchers challenge EPA safety standards, urging reevaluation of acceptable exposure limits.
• The herbicide’s effects on brain health add to existing concerns about its environmental impact.
• Scientists call for more research and stricter regulations to mitigate public health risks.
Glyphosate, the world’s most widely used herbicide, has been linked to lasting brain inflammation and neurodegenerative effects in a new study led by Arizona State University (ASU). Published in the Journal of Neuroinflammation, the research demonstrates that even low doses of glyphosate can cause persistent damage to brain health in mice, raising urgent questions about its safety for human populations.
The study tracked glyphosate exposure in mice over a 13-week period and observed impacts for six months after exposure had ended. Researchers tested two doses of glyphosate: a low dose (50 mg/kg), which mirrors the levels used to determine acceptable human exposure, and a high dose (500 mg/kg). The findings were troubling: both levels of exposure resulted in significant neuroinflammation, Alzheimer’s-like symptoms, and, in some cases, premature death.
“Our work contributes to the growing literature highlighting the brain’s vulnerability to glyphosate,” said Ramon Velazquez, a co-author of the study and assistant professor at ASU’s Biodesign Institute. “Given the increasing incidence of cognitive decline in the aging population, particularly in rural communities where exposure to glyphosate is more common due to large-scale farming, there is an urgent need for more basic research on the effects of this herbicide.”
The ASU research team found that glyphosate exposure leads to lasting damage to the brain. The herbicide’s primary metabolite, aminomethylphosphonic acid (AMPA), was detected in brain tissue long after exposure ended, suggesting glyphosate can cross the blood-brain barrier—a protective layer designed to prevent harmful substances from entering the brain.
The study revealed troubling outcomes, including persistent neuroinflammation and elevated markers of Alzheimer’s disease pathology, such as amyloid-β plaques and tau tangles. These features are known to disrupt neural function and contribute to memory loss and cognitive decline. Mice exposed to glyphosate also exhibited anxiety-like behaviors and other neurological symptoms.
Even the low dose of glyphosate, comparable to levels deemed safe for human exposure, caused significant harm. “These findings highlight that many chemicals we regularly encounter, previously considered safe, may pose potential health risks,” said Patrick Pirrotte, co-senior author of the study and a researcher at the Translational Genomics Research Institute (TGen).
Glyphosate is pervasive in agriculture, making human exposure nearly unavoidable. Approximately 300 million pounds of glyphosate are applied annually in the United States, primarily on crops like corn, soybeans, and wheat. Residues of the herbicide are often detected on food, in water, and even in the air, contributing to chronic exposure for most Americans.
Farmworkers and agricultural communities are particularly vulnerable to glyphosate exposure. These populations already face higher rates of cognitive decline, and researchers warn that glyphosate may exacerbate the problem. The study’s findings also raise concerns about glyphosate residues on food and their potential long-term health effects.
The U.S. Environmental Protection Agency (EPA) considers certain levels of glyphosate safe for human exposure, asserting that the chemical is minimally absorbed into the body and is excreted unchanged. However, the ASU study challenges these assumptions, showing that glyphosate and its metabolite AMPA can accumulate in brain tissue, potentially causing lasting damage.
“My hope is that our work drives further investigation into the effects of glyphosate exposure, which may lead to a reexamination of its long-term safety and perhaps spark discussion about other prevalent toxins in our environment that may affect the brain,” said Samantha Bartholomew, first author of the study and a Ph.D. candidate at ASU.
Glyphosate’s widespread use has long raised environmental concerns, including its impact on soil health, water systems, and biodiversity. This new research adds another layer to the debate by highlighting potential neurological risks.
The herbicide has already been classified as “possibly carcinogenic to humans” by the International Agency for Research on Cancer (IARC). Now, emerging evidence suggests glyphosate could also play a role in worsening neurodegenerative diseases, particularly Alzheimer’s. These findings challenge existing regulatory standards, which often rely on outdated data or limited research on long-term exposure effects.
Regulatory oversight varies globally, with some countries banning glyphosate outright while others, like the United States, continue to permit its widespread use. The ASU study underscores the need for stricter enforcement of safety limits and more comprehensive evaluations of glyphosate’s health impacts.
The findings also highlight the broader challenge of studying complex brain functions and environmental toxins. While animal testing remains common in this field, there is growing interest in non-animal research methods, such as AI modeling, tissue cultures, and “human-on-a-chip” systems.
Although promising, these alternatives require significant development and regulatory approval before they can fully replace animal testing. As researchers strive to understand glyphosate’s effects, they also hope to advance testing methods that minimize harm while delivering robust results.
The ASU study is a wake-up call for governments, industry leaders, and the public. It highlights the urgent need for reevaluating glyphosate’s safety and developing policies to protect vulnerable populations from its potential harm.
“Herbicides are used heavily and ubiquitously around the world,” said Pirrotte. “These findings highlight that many chemicals we regularly encounter, previously considered safe, may pose potential health risks. However, further research is needed to fully assess the public health impact and identify safer alternatives.”
As the prevalence of neurodegenerative diseases continues to rise, especially in aging populations, understanding environmental risk factors like glyphosate exposure will be critical. Researchers hope their work sparks meaningful action to minimize exposure and improve public health outcomes.
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