Insight into Roundup® Weed Killer’s Neurological Impact – Collaborative Lab Makes Dramatic Findings

FORT LAUDERDALE/DAVIE, Fla. – It’s a product that is used worldwide, by homeowners and industrial farmers.

Weed killer.

For many years, researchers have been studying the chemicals that make up weed killer to determine potential health implications for a wide variety of animals as well as humans. A recent report by the United States Centers for Disease Control and Prevention (CDC) found more than 80% of urine samples from children and adults in the U.S. contained the herbicide glyphosate. And now, a study by Florida Atlantic University and Nova Southeastern University takes this research one step further and is the first to link the use of the herbicide Roundup®, a widely used weed killer, to convulsions in animals.

The study focused on the impacts of Glyphosate, the weed killer component in Roundup® and the world’s most commonly used herbicide by volume and by land-area treated. Roundup® is used at both industrial and consumer levels, and its use is projected to dramatically increase over the coming years. Glyphosate-resistant crops account for almost 80% of transgenic crop cultivated land, which has resulted in an estimated 6.1 billion kilos of glyphosate sprayed across the world from 2005-2014. 

“It is concerning how little we understand the impact of glyphosate on the nervous system,” said Akshay Naraine, MSc., project lead and a Ph.D. student at FAU and the International Max Planck Research School for Synapses and Circuits. “More evidence is mounting for how prevalent exposure to glyphosate is, so this work hopefully pushes other researchers to expand on these findings and solidify where our concerns should be.”

Study co-authors include Naraine; Ken Dawson-Scully, Ph.D., lab head, professor, and senior vice president and associate provost at NSU’s Division of Research and Economic Development, and Venkatesh Shanbhag, Ph.D., lead chemist and professor of chemistry at NSU’s Halmos College of Arts and Sciences; Rebecca Aker, who was a master’s student at FAU while contributing to this research; Isis Sweeney, Meghan Kalvey and Alexis Surtel, undergraduate students who contributed at FAU.

Results, published in Scientific Reports, showed that glyphosate and Roundup® increased seizure-like behavior in soil-dwelling roundworms and provides significant evidence that glyphosate targets GABA-A receptors. These communication points are essential for locomotion and are heavily involved in regulating sleep and mood in humans. What truly sets this research apart is that it was done at significantly less levels than recommended by the EPA and those used in past studies. 

“The concentration listed for best results on the Roundup® Super Concentrate label is 0.98 percent glyphosate, which is about five tablespoons of Roundup® in one gallon of water,” said Naraine. “A significant finding from our study reveals that just 0.002 percent glyphosate, a difference of about 300 times less herbicide than the lowest concentration recommended for consumer use, had concerning effects on the nervous system.”

To put that into perspective, Naraine said the difference between the levels the EPA recommends and the levels used in this research is the weight difference between an average 3-year-old (27 lbs.) and an adult male African Bush Elephant (13,000 lbs.)

The NSU/FAU study provides significant evidence that glyphosate targets GABA-A receptors. These communication points are essential for locomotion and are heavily involved in regulating sleep and mood in humans.

“Given how widespread the use of these products is, we must learn as much as we can about the potential negative impacts that may exist,” said Dawson-Scully, Ph.D. “There have been studies done in the past that showed the potential dangers, and our study takes that one step further with some pretty dramatic results.”

Using C. elegans, a soil-dwelling roundworm, researchers first tested glyphosate alone and then both the U.S. and United Kingdom (UK) formulations of Roundup® from two distinct time-periods – before and after the UK’s 2016 ban on polyethoxylated tallowamine (POEAs). These conditions were selected to pinpoint which effects are specific to the active ingredient, Roundup® formulations in general, the POEAs surfactants, or any combination of these.

The worms were exposed to the Glyphosate, and then induced into having convulsions. What the research team found was while the exposure to glyphosate did not induce the seizure-like behavior, if an animal had been previously exposed then experienced an electrical stress, the convulsion lasted longer than if the convulsion occurred and there was no exposure.

Key environmental and health takeaways from the study “Roundup® and glyphosate’s impact on GABA to elicit extended proconvulsant behavior in Caenorhabditis elegans” include: 

• Glyphosate and Roundup® are detrimental to recovery of normal movement of  elegansin an Electroshock Assay. 
• GABA, a neurotransmitter heavily involved in regulating sleep and mood in humans, seems to play a critical role in these effects, particularly potential impact on GABA-A receptors. 
• Though there may be an effect in humans and concern for those with seizure disorders, there is evidence that essential, soil-dwelling microorganisms are neurologically impacted by glyphosate. 
• In January 2020, the United States Environmental Protection Agency (EPA) concluded that “…there are no risks of concern to human health when glyphosate is used according to the label…”.
  • The concentration listed for best results on the Roundup® Super Concentrate label is 0.98% glyphosate (5 tbs Roundup® in 1 gallon of water), but the research team uncovered all their most significant findings at just 0.002% glyphosate, a difference of more than 300 times/fold. 
• External stress seems to be critical for our findings as we found little evidence that glyphosate and Roundup® had effects before the electroshock was administered (to induce convulsions). That being said, over three-seconds of electrical stress, researchers found profound physiological changes that were linked to effects in the nervous system. 

Dawson-Scully said that, given this research involved invertebrates, we cannot make the jump to saying similar results would occur in mammals, including humans. He said what this study’s findings show is that further research must be done given the widespread use of these products.

“As of now, there is no information for how exposure to glyphosate and Roundup® may affect humans diagnosed with epilepsy or other seizure disorders,” said Dawson-Scully. “Our study indicates that there is significant disruption in locomotion and should prompt further vertebrate studies.”

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About Nova Southeastern University (NSU): At NSU, students don’t just get an education, they get the competitive edge they need for real careers, real contributions and real life. A dynamic, private research university, NSU is providing high-quality educational and research programs at the undergraduate, graduate, and professional degree levels. Established in 1964, the university includes 14 colleges, the “theme park” for start-ups, scale-ups , and entrepreneurs, the Alan B. Levan | NSU Broward Center of Innovation, the 215,000-square-foot Center for Collaborative Research, the private PK1-12 grade University School, the world-class NSU Art Museum Fort Lauderdale, and the Alvin Sherman Library, Research and Information Technology Center, one of Florida’s largest public libraries. NSU students learn at our campuses in Fort Lauderdale, Fort Myers, Jacksonville, Miami, Miramar, Orlando, Palm Beach, and Tampa, Florida, as well as San Juan, Puerto Rico, and online globally. With more than 200,000 alumni across the globe, the reach of the NSU community is worldwide.  Classified as having “high research activity” by the Carnegie Foundation for the Advancement of Teaching, NSU is one of only 59 universities nationwide to also be awarded Carnegie’s Community Engagement Classification, and is also the largest private institution in the United States that meets the U.S. Department of Education’s criteria as a Hispanic-serving Institution. Please visit www.nova.edu for more information.