What Plastics Should People Avoid in Water Bottles?

Your water bottle may deliver more than water -- bottles made of certain types of plastic leach chemicals and have the potential to develop bacteria. Plastics that leach chemicals cause negative health affects over time. To avoid these plastics, use only water bottles marked #2, #4 and #5. Avoid reusing water bottles marked #1 #3 #6 and #7.

#1 PETE

• People most commonly buy #1 PETE (polyethylene terephthalate) as a single-serving disposable bottled water. People can safely use #1 bottles but should avoid repeatedly refilling them due to possible bacteria buildup. The bottles feature narrow necks, making cleaning them thoroughly problematic. In a study, researchers from the University of Calgary found that one-third of the reused #1 bottles had "severe" bacteria contamination.

#3 V

• Polyvinyl chloride / PVC, or #3 plastic, leaches hormone-disrupting chemicals.The #3 bottles release pthalates, the chemicals that comprise the bottle. A 2007 study showed correlations between pthalates and abdominal obesity and insulin resistance. Europe banned pthalates in toys and personal products in 2007. People most often use #3 plastic for pipes and outdoor furniture, but bottles made of #3 plastic should be avoided.

#6 PS

• Bottle #6 (styrene), often used for disposable drink containers, leaches styrene into liquids. It is safe for a single use, but people should not reuse #6 bottles. The World Health Organization's International Agency names styrene a possible human carcinogen. Additionally, a study in Environmental Health Perspectives found exposure to styrene disrupts normal hormone function.

#7 PC

• Bottle # 7 plastic (lexan polycarbonate resin) has been shown to leach BPA, or bisphenol A. BPA is a chemical that interferes with the body's hormonal system. The Environment California Research & Policy Center linked BPA to breast and uterine cancer, an increased risk of miscarriage, decreased testosterone levels and negative effects on children. Most #7 plastics contain bisphenol A, and the only way to find out if any single #7 bottle does is to contact the manufacturer. Because of this, avoiding #7 plastics altogether is the best way to avoid exposure to BPA.