Glyphosate is the chemical in a product called Roundup (trademark®) that kills weeds, especially grasses and broadleaf weeds that compete with crops (glyphosate works by interfering with the action of a plant enzyme). Roundup is the most common herbicide in the world, whether the measurement is volume used or area of land treated. It was discovered and popularized by Monsanto, a company that also created Roundup Ready crops, which are genetically engineered to resist the effects of the herbicide. As of 2016, it was estimated that about 56 of the world's transgenic crops were glyphosate-resistant; that percentage is significantly higher in the United States, where over 90 percent of soy and corn crops are now herbicide-tolerant. It's estimated that 6.1 billion kilos of Roundup is already used, and the market is expect to increase dramatically in the coming years.
So how safe is this stuff? Independent research by the EPA has suggested that it's totally safe. Other studies have suggested, however, that people have reason to be concerned.
“It is concerning how little we understand the impact of glyphosate on the nervous system,” noted Akshay S. Naraine, MSc., project lead and graduate 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.”
Recent research from the United States Centers for Disease Control and Prevention has shown that glyphosate can now be found in 80 percent of urine samples taken from American children and adults.
Scientists have now learned that Roundup seems to lead to convulsions in a roundworm animal model called Caenorhabditis elegans, an organism that has many genetic similarities with humans. The findings, which were published in Scientific Reports, have suggested that glyphosate can target GABA-A receptors. In humans, these receptors are involved in movement and sleep regulation.
In this study, the researchers observed these effects at levels that are lower than what has been used in previous studies of Roundup. “The concentration listed for best results on the Roundup Super Concentrate label is 0.98 percent glyphosate, which is about 5 tablespoons of Roundup in 1 gallon of water,” explained 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.”
C. elegans was exposed to various formulations of Roundup. The investigators found that convulsions in C. elegans were exacerbated by glyphosate. Exposure to Roundup caused a higher percentage of C. elegans to have seizure activity they did not recover from. This phenotype could help researchers learn more about the potentially toxic effects of herbicides.
The scientists noted that right now, we do not know if glyphosate or Roundup exposure could be affecting people that have seizure disorders such as epilepsy.
“Our study indicates that there is significant disruption in locomotion and should prompt further vertebrate studies," said Ken Dawson-Scully, Ph.D., a professor, senior vice president and associate provost at Nova Southeastern University.