New research has highlighted a link between glyphosate exposure in mice and signs of neuroinflammation, along with the hastening of Alzheimer’s disease-like symptoms. This research follows the effects of glyphosate’s byproducts in the brain long after the exposure has ended, revealing a range of ongoing, harmful impacts on brain health. The results imply that the brain might be more vulnerable to the negative consequences of this herbicide than previously recognized. Glyphosate is one of the most widely used herbicides both in the U.S. and globally.
The human brain is remarkably resilient, often capable of healing from severe injuries. However, new findings indicate that even short exposure to a common herbicide can result in lasting damage to the brain, which may persist well after the exposure has ceased.
In a pioneering study conducted by Arizona State University researcher Ramon Velazquez and his team at the Translational Genomics Research Institute (TGen), part of City of Hope, it was found that mice exposed to glyphosate exhibited significant brain inflammation related to neurodegenerative diseases. The results suggest that glyphosate may pose greater risks to brain health than previously assumed. Glyphosate is one of the most commonly used herbicides across the U.S. and beyond.
This research, published in the Journal of Neuroinflammation, establishes a connection between glyphosate exposure in mice and symptoms of neuroinflammation, as well as a quickened onset of Alzheimer’s disease-like characteristics. The study monitored both glyphosate and its byproducts in the brain for a long period post-exposure, showcasing a variety of persistent, harmful effects on cognitive health.
Mice subjected to glyphosate exposure also experienced untimely death and anxiety-like behaviors, consistent with findings from other studies on glyphosate’s effects on rodents. Notably, these issues remained even after a six-month recovery period during which no exposure occurred.
The investigation also revealed that one glyphosate byproduct, aminomethylphosphonic acid, accumulates in brain tissue, raising serious safety concerns about glyphosate’s impact on humans.
“Our research adds to the increasing body of evidence pointing to the brain’s susceptibility to glyphosate,” stated Velazquez. “With a rise in cognitive decline among the aging population, especially in rural areas where glyphosate exposure is prevalent due to large-scale agriculture, there’s an urgent need for further research on this herbicide’s effects.”
Velazquez is affiliated with the ASU-Banner Neurodegenerative Disease Research Center at the ASU Biodesign Institute and is an assistant professor at the School of Life Sciences. He collaborated with first author Samantha K. Bartholomew, a PhD candidate in his lab, along with other ASU colleagues and co-senior author Patrick Pirrotte, an associate professor at TGen and researcher at the City of Hope Comprehensive Cancer Center in California.
The Centers for Disease Research indicate that farmers, landscapers, and others working in agriculture may be more likely to encounter glyphosate through inhalation or skin contact. Moreover, the new findings suggest that consuming food treated with glyphosate could pose health risks. It is estimated that most individuals in the U.S. have been exposed to glyphosate at some point in their lives.
“I hope our findings encourage more investigation into glyphosate’s impacts, possibly leading to a reassessment of its long-term safety and prompting discussions about other widespread toxins in our environment that may influence brain health,” said Bartholomew.
The team’s results build upon earlier ASU studies revealing an association between glyphosate exposure and an increased risk of developing neurodegenerative diseases.
Previous research illustrated that glyphosate can breach the blood-brain barrier, a protective barrier that usually safeguards the brain from harmful substances. Once it penetrates this barrier, glyphosate interacts with brain tissue and appears to incite neuroinflammation and other detrimental effects on neural health.
While the EPA deems certain levels of glyphosate safe for human contact, claiming that the chemical is minimally absorbed by the body and primarily eliminated unchanged, recent studies, including this one, suggest that glyphosate and its main metabolite, aminomethylphosphonic acid, can survive in the body, accumulating in brain tissue over time, leading to questions about the current safety limits and the overall safety of glyphosate use.
Herbicide may harm more than just weeds
Glyphosate is the most widely utilized herbicide worldwide, applied to various crops, including corn, soybeans, sugar beets, alfalfa, cotton, and wheat. Usage of glyphosate has surged since the introduction of glyphosate-resistant crops in 1996, which can be treated with glyphosate without dying. Most applications occur in agricultural contexts.
The U.S. Geological Survey reports that approximately 300 million pounds of glyphosate are used each year in the United States alone. Although glyphosate levels in foods imported into the U.S. are regulated, enforcement and specific limits may vary. Its extensive use means glyphosate is prevalent throughout the food supply, accumulating in the air, soil, and water sources.
Despite the EPA’s classification of glyphosate as safe, the International Agency for Research on Cancer considers it “possibly carcinogenic to humans.” Emerging studies, including the one at hand, suggest glyphosate might contribute to the advancement of neurodegenerative conditions by exacerbating pathologies similar to those seen in Alzheimer’s disease.
This herbicide operates by inhibiting an essential enzyme pathway in plants that is vital for producing necessary amino acids. However, its effects go beyond the intended target plants, adversely impacting biological systems in mammals, which is evident in its accumulation in brain tissue and involvement in inflammatory processes.
“Herbicides are used extensively and everywhere globally,” states Pirrotte, an associate professor in TGen’s Early Detection and Prevention Division and director of Integrated Mass Spectrometry Shared Resource at TGen and City of Hope, as well as the senior author of the paper. “These findings underscore that many chemicals we frequently encounter, once thought to be safe, may pose health risks. However, more detailed research is crucial to thoroughly evaluate the public health implications and to recognize safer alternatives.”
Is glyphosate truly safe to use?
The researchers anticipated that glyphosate exposure would provoke neuroinflammation in regular mice and exacerbate neuroinflammation in mice introduced with Alzheimer’s-like traits, resulting in increased Amyloid-β and tau protein levels along with deteriorating spatial cognition post-recovery. Amyloid-β and Tau are critical proteins forming plaques and tangles, the hallmark indicators of Alzheimer’s disease, disrupting neural functions and directly correlating with memory loss and cognitive decline.
The experiments unfolded over 13 weeks, succeeded by a six-month recovery period. Aminomethylphosphonic acid was identified in the brains of both normal and transgenic mice exhibiting Alzheimer’s-like symptoms. Transgenic mice are genetically modified to develop symptoms analogous to Alzheimer’s, allowing for controlled studies on the disease’s progression and effects.
The researchers tested two glyphosate exposure levels: a high dose akin to what has been previously researched and a lower dose approximating the currently accepted human exposure threshold.
Even the lower dose resulted in harmful effects in the mice’s brains, persisting months after stopping the exposure. While it has been reported that most Americans come into contact with glyphosate daily, these findings suggest that even a short exposure can potentially result in neurological harm.
Glyphosate induced a long-lasting rise in inflammatory markers in both brain and blood, persisting beyond the recovery phase. This sustained inflammation could trigger the advancement of neurodegenerative disorders like Alzheimer’s, indicating that even brief glyphosate exposure can initiate lasting inflammatory effects detrimental to brain health.
The data reveals that glyphosate exposure might pose significant health risks for human populations. The study emphasizes the necessity for ongoing monitoring and more extensively investigating glyphosate’s neurological and other long-term adverse health impacts.
“We aim to pinpoint environmental factors contributing to the growing prevalence of cognitive decline and neurodegenerative diseases in our society,” Velazquez stated. “By identifying such factors, we can formulate strategies to reduce exposure, ultimately enhancing living standards for the increasing aging population.”
This study was funded by the National Institutes on Aging, the National Cancer Institute of the National Institutes of Health, and the ASU Biodesign Institute.
