California's attorney general on Wednesday sent letters to top plastic bag manufacturers requesting information about their claims that the bags they produce are recyclable, the latest move by the state to scrutinize the plastics industry and their role in the global plastic pollution crisis.

Nearly a decade ago, a California law required manufacturers of plastic bags to make their bags recyclable. The state’s top cop says this doesn’t appear to be happening. On Wednesday, Attorney General Rob Bonta sent letters to seven plastic bag producers that supply the bulk of California’s grocery stories, demanding they provide proof that their bags can really be recycled.