Polypropylene: A popular BPA- and phthalate-free plastic used food packaging (including sippy cups and bottles), toys, diapers, carpeting, and furniture. The Environmental Working Group considers polypropylene a probable immune system toxicant if aerosolized. Polypropylene is recyclable (#5). While generally regarded as safe, polypropylene contains additives that have been shown to leach, raising safety concerns. Skin Deep score: 1-3, depending on usage.