For decades, regulators viewed chlorpyrifos a pesticide widely used in the U.S. and around the world " primarily as a neurotoxin that disrupts signaling in the brain and nervous system. Growing evidence suggests chlorpyrifos may damage the brain, hormones, liver, gut microbiome, muscles, reproductive organs, and bones. Studies also link the pesticide to DNA damage and lasting changes in gene activity that may increase the risk of chronic disease. Together, the findings portray chlorpyrifos as what the reviewers call a "multi-system toxicant" that poses a more significant threat to public health than previously understood. It suggests the pesticide acts on the body in ways far beyond disrupted nerve signaling or obvious poisoning. Pregnancy and early childhood are especially sensitive periods for chemical exposure. "What has genuinely evolved over time is our understanding that chlorpyrifos causes harm in ways that go beyond its effects on the nervous system including damage to DNA, changes in how genes are switched on or off, interference with hormones, and disruption of the healthy bacteria that live in the gut," said Dr. Dana Boyd Barr. current regulatory systems may not fully capture the complexity of chlorpyrifos' dangers to the body. Many occur at levels too low to be detected by current safety testing, which looks for the disruption of an enzyme involved in nerve cell communication.