Scientists have linked the common weed killer to convulsions in animals

Scientists have found a link between the world’s most commonly used weed killer and convulsions in animals – raising questions about the herbicide’s potential impact on the human nervous system as well.

Exposure to glyphosate, the active ingredient in Roundup, increases seizure-like behavior in soil-dwelling roundworms, according to researchers who published their findings in Scientific Reports on Tuesday.

As glyphosate use is expected to increase dramatically in the coming years, understanding its possible effects on human health is critical, according to the study.

“It is concerning how little we understand about the effects of glyphosate on the nervous system,” lead author Akshay Narain, Ph.D. candidate at Florida Atlantic University and the Max Planck International Research School for Synapses and Circuits, said in a statement.

“More evidence is accumulating about how widespread glyphosate exposure is, so this work will hopefully prompt other researchers to expand on these findings and confirm our concerns,” added Narain.

Just last month, data from the Centers for Disease Control and Prevention revealed that more than 80 percent of the urine sampled by the agency was at or above the detection limit for glyphosate, as The Hill reported.

Bayer, which makes Roundup, is facing thousands of lawsuits alleging the product causes cancer. While the International Agency for Research on Cancer designated glyphosate as a “probable” carcinogen in 2015, the Environmental Protection Agency said in 2020 that there is not enough evidence to show that the chemical is a probable or probable carcinogen.

In Tuesday’s study, Narain and his colleagues said they used the roundworm C. elegans to test the effects of glyphosate alone and both the American formulation of Roundup and the British product from two different periods.

The two windows in question were before and after 2016, at which time the UK banned a surfactant – called polyethoxylated talovamine – that was in the earlier formulation.

These different conditions, the scientists explained, helped them determine which effects were specific to the active ingredient glyphosate.

Ultimately, the authors found that glyphosate worsened seizures C. elegans and concluded that a receptor protein called GABA-A was the neurological target for the observed physiological changes. In humans, these receptors are essential for movement and contribute to sleep and mood regulation, according to the authors.

Scientists often study C. elegans to gain insight into human disease and development because they share a common ancestor.

The data revealed a significant difference between glyphosate exposure alone and Roundup—with Roundup exposure increasing the rate of C. elegans who did not recover from seizures, according to the study.

The scientists also used significantly lower levels of glyphosate and Roundup than is available in the product — more than 300 times less herbicide than the lowest concentration recommended for consumer use.

Still, they found the roundworms writhed at concentrations that were diluted 1,000 times the concentrations previously considered toxic, according to the study.

“Given how widespread the use of these products is, we need to learn as much as we can about the potential negative impacts that may exist,” Ken Dawson-Scully, professor of neurobiology and Narine’s mentor, said in a statement.

“There are studies that have been done in the past that show the potential dangers, and our study takes that a step forward with some pretty dramatic results,” added Dawson-Scully, who also serves as senior vice president and associate provost at Nova Southeastern University.

Roundworms already experience convulsions when faced with heat stress—and these new findings show that exposure to glyphosate and Roundup may exacerbate those effects, according to Naraine.

“This could prove vital as we experience the effects of climate change,” Narain said.

Dawson-Scully admits she has no idea at this stage “how exposure to glyphosate and Roundup might affect people diagnosed with epilepsy or other seizures.”

“Our study shows that there is significant perturbation in locomotion and should prompt further research in vertebrates,” he said.

The Hill has reached out to Bayer for comment.

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