Plastic bottles and containers are categorized based on what they are made of and how they can be recycled. This is given a number contained in a triangle on the bottom. This code allows us to know which ones are unsafe and to avoid.
1 (PET) Polyethylene terephthalate is used in many water and soft drink bottles and is considered safe for one time use and if not exposed to heat but will degrade over time and should not be reused.
2. (HDPE) High-density polyethylene is used for opaque or cloudy containers of personal care products, vitamins, detergents, etc. It’s considered safe under normal conditions but will degrade over time.
3. (PVC) Polyvinyl chloride is commonly found in some food wrap, plastic utensils, shower curtains, plumbing materials, computer keyboards, credit cards, and many other products. PVC should be avoided whenever possible.
4. (LDPE) Low density polyethylene is found in most food wrap now, shopping bags, CD cases, and most product packaging, and is considered safe.
5. (PP) Polypropylene is found in bottle caps, diapers, kitchenware, yogurt containers, ropes, and carpets, and is considered the safest plastic for human use.
6. (PS) Polystyrene, aka styrofoam, is used in take-out food containers, drinking cups, egg cartons, and building materials. Polystyrene contains carcinogens and is known to degrade and leach toxins when exposed to heat or oil. It should be avoided whenever possible.
7. (O) “O” stands for Other and this category includes plastics other than the first six categories. This group includes polycarbonate, acryllic, fiberglass, nylon and environmentally friendly hybrid plastics. Many of these are safe, though this category also contains polycarbonate bottles with BPA, which is an endocrine disrupting substance and is to be avoided.
(This information is extracted from the wonderful book that I highly recommend, The Healthy Home, by Dr. Myron and Dave Wentz published by Vanguard Press this year (2011).