I’ve had a few questions this past week about plastic water bottles, as some readers have budget considerations about purchasing metal resuable water bottles.

To respond to this, I want to give you a little primer on plastics and toxicity, so that you all can evaluate for yourselves which plastics are toxic and which are not.

The primary concern about plastic water bottles is the leaching of bisphenol-A, which has been well publicized. The best source I’ve found to learn about the health effects is Our Stolen Future.

There is now another website BisphenolA-Free that is posting items on the dangers of bisphenol-A as they occur in the news.

The main message is that polycarbonate plastic leaches bisphenol-A and so all polycarbonate should be avoided.

But there’s a little more to the story.

Many years ago, when I first started researching plastics, I learned three important things, which I wrote about in Home Safe Home.

1. There are many many many many plastics. Each are different in their toxicity. When we say “plastic” we are referring to a huge field of materials. So it’s not really fair to say, “It’s plastic, therefore it must be toxic.” Because that’s just not a true statement. There are plastics which are very toxic, and plastics which are pretty safe, and plastics that are in between.

How do you tell which is which? There are two very easy-to-use and helpful documents that can help you sort this out. I’m glad others put these together.

* Quick Start: Plastics at a Glance notes the plastics to avoid and those which are OK to use, giving brand names for both in different common product categories.

For water bottles, they recommend some BPA-free bottles on this guide, but I was unable to find them online. This list has been around for at least a couple of years, so my recommendation is to look on the bottom of any plastic bottles you are considering and choose those with a #4 (LDPE–low density polyethylene) or #5 (PP–polyreopylene). Check the bottles you find in local stores and search on “LDPE water bottle” and “PP water bottle” on the internet (more results came up than I can list here).

* Smart Plastics Guide has more information on identifying plastics, along with data on the dangers of specific plastics and general guidelines about what you can do.

Here’s the shortcut tip to remember: 1-2-4-5 are OK. Forget the rest.

2. The form of the plastic makes a difference. A single type of plastic can be used to make many different products. Various plasticizers are added to the basic formula to make the plastic softer. The general rule is that the harder the plastic, the less it outgasees, and the softer the plastic, the more it outgasses.

Let’s look at polycarbonate again. The polycarbonate used to make water bottles is fairly soft. The plastic itself is stiff, but you can squeeze the bottle. The Vita-Mix blender container is also made out of polycarbonate, but it is very thick and hard by comparison. You can’t squeeze this container. So, given the same conditions, the softer water bottle would release more bisphenol-A than the Vita-Mix container, which may not release any because the molecules are so tightly bonded together in the hard plastic.

3. Heat causes plasticizers to outgas. Whenevre you expose a plastic to heat, it will release molecules of plasticizer. And conversely, cold lessens the release of plasticizers. So if you have a case of plastic water bottles sitting in the sun on a truck or in front of a store, they are going to warm up and leach plastic into the water. Likewise, if you wash a water bottle to reuse it and use very hot water, it will leach. Also, whem you put plastics in the microwave they can leach, and the use of harsh chemicals like bleach can make them leach as well. So don’t try to sanitize a water bottle with hot water if you want to reuse it. Wipe it with vinegar, a natural disinfectant, instead.

I hope this has been helpful to clear up the confusions about plastics. Feel free to post any questions you have by clicking on POST A COMMENT.