June 2, 2008 - No. 7 plastic contains PC (polycarbonate), which recently gained notoriety because it is used Nalgene's reusable water bottles and leaches bisphenol A, a hormone disruptor that mimics estrogen. Nalgene is switching to using plastic No. 2 (HDPE). Another growing category of No. 7 plastics are called "bioplastics" because they are plant-based rather than petroleum-based. It's not easily recycled but it can be composted in industrial composters.