Toxic chemicals pumped underground to break up seams of rock and increase oil and gas production have a fun nickname: fracking fluids, short for fracturing. (Go on, say it: frack!) But the fun stops there. Fracking fluids go largely unregulated, despite millions of gallons of use and hundreds of reported spills each year. Thanks to proprietary trade laws, energy companies don’t have to disclose the ingredients of the chemical mix they pump into the earth, but the U.S. EPA nonetheless says fracking fluids are safe for the environment and groundwater. In a recent incident in Colorado, emergency-room worker Cathy Behr was diagnosed with chemical poisoning after treating a man who had been caught in a fracking-fluid spill that was never officially reported. “I always thought that the industry probably took chances,” says Behr. “But I always thought someone was watching them.” Colorado issued its first regulations for fracking fluid this week, applauded by environmentalists and opposed by industry.