For decades, regulators viewed chlorpyrifos — widely used in the U.S. and around the world — primarily as a neurotoxin that disrupts signaling in the brain and nervous system. But a new review of nearly 300 studies found the pesticide may damage the brain, hormones, liver, gut microbiome, muscles, reproductive organs and bones. Studies also link chlorpyrifos to DNA damage that may increase the risk of chronic disease.