Plastic labels do more than direct recycling. These symbols can help you avoid bisphenol A (BPA), a chemical that mimics estrogen and has been linked to breast cancer, obesity, infertility and insulin resistance in rodents. Use the plastic coding system to identify the safest solutions: number 2 HDPE, number 4 LDPE and number 5 PP. These plastics are typically opaque and not known to contain carcinogens or hormone-disrupting chemicals. Avoid number 7 plastics, which contain polycarbonate, the hard plastic that can potentially leach bisphenol A.