To encourage more recycling, the U.K. taxes single-use plastic products containing less than 30% recycled material. But aside from a manufacturer's word, there isn't an easy way to verify this composition. Now, researchers reporting in ACS Sustainable Chemistry & Engineering have developed a simple, fraud-resistant technique to evaluate the recycled content of new plastic products. They added a fluorescent tag to plastic resins, successfully tracking their amount in products made with various polymers and colors.