You think you're doing the eco-friendly thing by reusing your plastic water bottle, but you've heard rumors that it can actually be bad for your health. While it's true that bacteria can grow in unwashed bottles, reports of toxic chemicals leaching into the water from PET (polyethylene terephthalate) bottles after multiple refillings have been proved false. This means you don't have to choose between your health, the environment and thirst.
The word "bacteria" instantly sends many people into a panic, lunging for the hand sanitizer, but not all bacteria are harmful. Some, like the probiotics found in yogurt, are good for you, while others have no effect on health whatsoever. A 2005 study in "Applied and Environmental Microbiology" found at least eight different kinds of bacteria living in noncarbonated bottled mineral water within three weeks of bottling (See References 1, fig 3). Mineral water comes from underground, and these bacteria just happen to live there --- the study concluded that none of strains identified were related to any disease-causing bacteria.
Of course, some bacteria do cause disease, and they grow best in warm, moist places. Capping your nearly-empty water bottle traps humidity inside and provides a perfect growing medium. Bacteria are better able to form a colony if they have a place to cling to as they multiply, and the threads on the mouthpiece of your bottle provide a perfect hangout by trapping moisture and providing a safe environment --- right where you put your mouth. To prevent this, simply wash your bottle with hot, soapy water after each use, and leave it open to dry.
Rumors have suggested the plastic in water bottles leaches out a chemical called DEHA, a carcinogen that is more harmful than any bacteria. This claim was quickly disproved on multiple fronts. First, the "study" it came from was actually a master's degree thesis and not subject to peer review, so the claims were scientifically unreliable. Second, DEHA is not classified as a carcinogen by any governing agency and is not present in PET, the plastic used to make water bottles. It is, however, present in laboratory equipment, which could have contaminated the study in question. Third, the U.S. Food and Drug Administration has approved PET plastic as safe for food contact after careful study, and repeated usage doesn't change the safety factor. (See References 2) However, some studies indicate that a potential carcinogen, bisphenol A, may leach into bottles made out of polycarbonates, such as baby bottles and sports bottles.
What to Do
Don't be concerned about the plastic in your water bottle, but practice standard hygiene to avoid bacterial contamination. Instead of reusing disposable bottles, purchase a sturdy sports bottle with a flip-up or pop-up spout rather than a threaded mouthpiece. This gives bacteria less opportunity to take hold on the very place you put your mouth. Wash your bottle after every use, but especially when it has held anything other than water --- sugary beverages can provide food for microbes and encourage faster growth. Use wide-mouthed bottles that are easier to dry inside, and wipe the mouthpiece frequently if you use it while wearing lipstick or lip balm, which provides a separate growing medium.
- "Applied and Environmental Microbiology"; Diversity of Bacteria Growing in Natural Mineral Water After Bottling; Alexander Loy, et al.; July 2005
- Food Advisory Consumer Service; Reuse of PET-Water Containers; 2009
- International Life Sciences Institute; Plyethylene Terephthalate (PET) for Food Packaging Applications; V. Matthews; 2000
- Food Additives & Contaminants; Increased Migration Levels of Bisphenol A From Polycarbonate Baby Bottles After Dishwashing, Boiling and Brushing ; C. Brede, et al; 2003
Angela Brady has been writing since 1997. She works as a certified personal trainer, weight-loss consultant and sports nutritionist. A lifelong dancer and yoga devotee, she has competed in gymnastics, swimming, volleyball, softball and soccer. She is also an authority on sustainable design, having studied, practiced and written extensively on the subject.
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