2nd best -- plastics #2 and #4
Stay away from #1, 3, 5, 6, 7
- #2 and #4 polyethylene ( #2 is HDPE , which is milk gallons , #4 is LDPE)
- #1 polyethylene terephalate (PET or PETE)
- # 5 polypropylene (catsup bottles, yogurt containers)
- #6 polystyrene (Styrofoam)
- #7 (other) some are polycarbonate water bottles unknown if delivered water is polycarbonate, it states #7 "other" (5 gallon bottled delivered water)
- Food or drinks heated in plastic containers in a microwave.
- Styrofoam cups (polystyrene #6), especially for hot liquids.
- #7 polycarbonate (Nalgene) water bottles
- Plastic baby bottles. If you must use bottles, use only glass baby bottles with silicone, not latex, nipples.
Not all #7 plastic is polycarbonate, nor are all Nalgene bottles made from polycarbonate. Unlike #1-#6,#7 is the official "other" plastics category. Nalgene makes several varieties of water bottle, made from different kinds of plastic, including polyethylene and polypropylene. Nalgene's Lexan bottles are made of polycarbonate plastic (PC), a plastic known to leach the hormone-disrupting chemical bisphenol-A (BPA). This puts it in the company of two other plastics which studies have determined are prone to leaching and pose environmental and/or health concerns: 1) Polyvinyl Chloride (PVC) which can leaches phthalates, a hormone disruptor, and dioxin, a carcinogen; and 2) polystyrene, which can leach styrene, a possible human carcinogen.
Does that mean Nalgene Lexan water bottles are unsafe? We cannot say categorically that Nalgene Lexan bottles are unsafe or even that they leach BPA, until the product has been properly tested. According to Our Stolen Future: "No tests on bisphenol-A leaching have been carried out specifically on Nalgene water bottles, to the knowledge of www.OurstolenFuture.org, nor were Nalgene bottles the brand used in the experiments demonstrating a link between polycarbonate and chromosomal aberrations. There may be some reason why Nalgene bottles do not leach bisphenol-A. This would be highly unexpected, however, given their chemical composition."
PC is a durable and heat resistant plastic, making it a popular material for food storage and laboratory equipment, including baby bottles, water bottles, petri dishes and animal cages. In the late 1990s, studies testing PC baby bottles found they leached low levels of BPA. After several tests of the same bottles the presence of BPA decreased dramatically. The studies suggested that while residual amounts of BPA may be present on some baby bottles, it would disappear after a short period of use. The studies concluded that the PC baby bottles currently on the market are not a health risk to children.
In 2003, a study, published in Environmental Health Perspectives (EHP), reproduced the same results as the earlier studies when new bottles were tested. However, after repeated washings and scrubbings, the levels of BPA leaching from the bottles increased significantly. The study concludes, "The increased migration levels may be due to polymer degradation."
During the same year, two more studies were published in EHP, which came about after researchers traced BPA in lab mice to the PC cages in which the mice were housed. These studies share several of the same conclusions: 1) Polycarbonate exposed to harsh detergent is prone to leaching; 2) The older the polycarbonate, the more it leaches; 3) High temperatures cause higher rates of leaching. One study found that polycarbonate will leach into water at room temperature. Of even greater concern, the laboratory plastics studies were initiated by sudden abnormalities in mice egg cells after polycarbonate animal cages were mistakenly washed with the wrong detergent.