No known health hazards:

Polyethylene Terephthalate (PET or PETE)

High Density Polyethylene (HDPE)

Low Density Polyethylene (LDPE)

Polypropylene (PP)

Potential health hazards:

Polyvinyl Chloride (PVC or vinyl): Some research has shown that the phthalates in PVC cling wraps (commonly used in delis and supermarkets) and vinyl flooring are endocrine disruptors linked to various health problems. Water and vegetable oils sometimes are bottled in PVC, and many toys and baby teethers contain PVC.

Polystyrene (PS or Styrofoam): Styrene is a possible carcinogen and endocrine disruptor. Avoid consuming hot liquids, fatty foods, or alcoholic drinks from Styrofoam containers, which leach out styrene. Some opaque plastic cutlery is PS as well.

Other resins, including polycarbonate (PC): Bisphenol-A (BPA), a main building block for PC plastics, is an endocrine disruptor. Most clear baby bottles and 5-gallon water bottles, as well as Lexan (Nalgene) water bottles and plastic-lined food cans, are made of PC.

—J.R.L.