Everyday exposure to the popular weedkiller glyphosate at levels deemed safe by government regulators causes heightened anxiety and alters the gut microbiome in animal models. The researchers observed that rats drinking the chemical developed hypervigilance toward harmless objects and sounds. This altered behavior was accompanied by abnormal changes in a specific dread-inducing region of the brain. The new research was published in the journal Frontiers in Toxicology. Glyphosate is the active ingredient in many commercial weedkillers used around the globe. It destroys weeds by blocking a specific chemical pathway found in plants and bacteria. Because human and animal cells lack this specific biological machinery, regulators previously concluded that the chemical was entirely harmless to mammals. The Environmental Protection Agency currently sets the safe daily limit for long-term human exposure at 2.0 milligrams per kilogram of body weight. In recent years, medical professionals have noticed a correlation between heavy weedkiller use and human mental health conditions. Past laboratory experiments have also shown that rodents exposed to the chemical display excessive fear. But those prior experiments exposed …