Recently there has been much discussion about the safety of drinking water. Concerns about tap water, bottled water, and reusable plastic bottles can be overwhelming. The main issue concerning plastic bottles is the leaching of the chemical bisphenol-A (BPA) which is used in the manufacturing of polycarbonate, the hard clear plastic that is characteristic of many water bottles. It is used to make household goods because of its characteristics: it is very durable, moldable, and has good temperature resistance. Almost all polycarbonate bottles contain BPA. Not all Nalgene bottles are polycarbonate, but they are the number one producer of polycarbonate water bottles. Polycarbonate plastics can be found in numerous other products, like beverage and food storage containers, dishes, five-gallon water jugs, and baby bottles.

Polycarbonate water bottles that contain BPA can be distinguished by a few characteristics. They are usually clear hard plastic and have a number 7 resin code (a small number 7 enclosed by the “chasing arrows” symbol) stamped on the bottom of the bottle. If your water bottle is soft, cloudy-colored, or does not have a number 7, it probably does not contain BPA.

BPA has been proven to leach: it migrates out of the plastic into foods or liquids stored in the plastic and ends up in human cells when those foods or liquids are consumed. Leaching can increase when a polycarbonate container is old or scratched, exposed to high heat, heated in a microwave, cleaned with harsh cleaners, or used to store acidic foods like tomato sauce or fatty foods like gravy.

BPA is a chemical that mimics the human hormone estrogen and has been linked to breast and prostrate cancers, miscarriages, low sperm count, infertility, reproductive problems, enlargement of male breasts, and early puberty. This is why it is sometimes referred to as a “hormone disruptor” or an “endocrine-mimicking” chemical.

Currently there are no bans or recalls in the United States. However, in April 2008, Canada banned BPA from use in baby bottle plastics. Due to rising concern among citizens, some stores have announced the elimination of BPA-containing children’s products. Many companies still do not openly acknowledge the dangers of BPA but are making changes to provide alternatives.

Are other kinds of plastic bottles safer? Replacing a polycarbonate plastic bottle with another kind of plastic does not necessarily mean it is safe or even safer than plastics that contain BPA. Indeed, there are many studies showing concerns about many different kinds of plastics and chemical additives. You may want to consider alternatives such as glass or stainless steel drinking containers.

So I should throw all my polycarbonate water bottles away? Since plastics are completely synthetic, they never biodegrade. They do, however, break into small particles over time, and we are now finding pieces of plastic in the smallest life forms and in our water supplies. When you discard plastic, it often finds its way into the environment via our water or air. Because of these environmental and health issues, it is best to find healthy (re)use options for your water bottle.