A new study has linked the common weed-killer Roundup to convulsion in worms. 

Glyphosate, the weed killer component in Roundup, is the world’s most commonly used herbicide. An estimated 6.1 billion kilos of glyphosate was sprayed across the world from 2005 to 2014, and its use is projected to dramatically increase over the coming years. 

A recent report by the United States Centers for Disease Control and Prevention found more than 80 percent of urine samples from children and adults in the US contained the herbicide.

A major question, yet to be fully understood, is the potential impact of glyphosate on the nervous system.

A study by Florida Atlantic University and Nova Southeastern University has become the first to link the use of the herbicide Roundup to convulsions in animals.

The results showed that glyphosate and Roundup increased seizure-like behaviour in soil-dwelling roundworms, providing 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. A key, and possibly concerning, point of the research is that tests were performed at significantly lower 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 per cent glyphosate, which is about 5 tablespoons of Roundup in 1 gallon of water,” said researcher Akshay Naraine, project lead and a Ph.D. student at FAU and the International Max Planck Research School for Synapses and Circuits. 

“A significant finding from our study reveals that just 0.002 per cent glyphosate, a difference of about 300 times less herbicide than the lowest concentration recommended for consumer use, had concerning effects on the nervous system.”

Using C. elegans, a soil-dwelling roundworm, researchers first tested glyphosate alone and then both the US and United Kingdom 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 glyphosate, Roundup formulations in general, the POEAs surfactants, or any combination of these.   

The study found that the active ingredient glyphosate exacerbated convulsions in C. elegans and suggest the GABA-A receptor as a neurological target for the observed physiological changes. 

The data also indicated that there is an important distinction between exposure to glyphosate and Roundup, with Roundup exposure increasing the percentage of C. elegans that did not recover from seizure activity. 

The non-recovery phenotype and prolonged convulsions in C. elegans from this study have helped to set a foundation for understanding nuanced physiological effects of herbicide that occur at concentrations exponentially below neurotoxic levels.

“It is concerning how little we understand the impact of glyphosate on the nervous system,” Naraine said. 

“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.

“These roundworms undergo convulsions under thermal stress, and our data strongly implicates glyphosate and Roundup exposure in exacerbating convulsive effects. This could prove vital as we experience the effects of climate change.”

The study provides evidence to further investigate how chronic exposure and accumulation may lead to neurodegenerative diseases such as Parkinson’s disease. 

Importantly, there also is a sub-neurodegenerative threshold that may dramatically impact dysregulation of neurotransmission.

“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 Dr Ken Dawson-Scully from Nova Southeastern University. 

“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.

“As of now, there is no information for how exposure to glyphosate and Roundup may affect humans diagnosed with epilepsy or other seizure disorders. 

“Our study indicates that there is significant disruption in locomotion and should prompt further vertebrate studies.”

The full study is accessible here.