US environmental regulators can now block new uses of old chemicals

The US environmental regulators are proposing new rules for certain chemicals already on the market. Companies will have to tell the regulators 90 days before they use these chemicals in a new way, and they cannot start until the regulators approve it.

Before this, companies could often introduce new uses for existing chemicals without much oversight, especially if the chemical itself was already approved. This change means the regulators can now stop a company from using a chemical in a new way if they think it is too risky. It shifts the burden of proof to the companies, making it harder to quietly expand chemical applications.