I want to say one word to you. Just one word.

Plastics.

According to WebMD, there is still some question whether bisphenol A (BPA), a chemical found in plastics (baby bottles, food containers, water bottles, Nalgenes, etc.) poses a health risk.

BPA acts like estrogen, this effect first noticed back in the '30s on rats who had oopherectomies. DES came along and was found to be more powerful than BPA, and well, we all know the rest of that story. Apparently, BPA is not all that stable and over time is released into food, water, nature, sippy cups...whatever it comes in contact with.

Although the "jury is still out" on the actual effects of BPA on humans, there is definitive proof of it's estrogenic effects as well as it's ubiquitous presence due to constant exposure.

I won't quote the entire article, click on the above link and read for yourself. I am posting these bulletpoints from the WebMD article:

A panel of 38 BPA researchers recently issued a report saying they are "confident" that:
• Low doses of BPA have biological effects.
• BPA is everywhere -- in the water, in the air, and in the ground. Estrogen-like effects now seen in wild animals are similar to those seen in lab animals exposed to low doses of BPA.
• BPA levels commonly seen in humans are higher than those that cause adverse effects in lab animals.
• BPA has different effects at different stages of life.
• BPA "reprograms" genes -- meaning that toxic effects may show up long after exposure.

It goes on to say that expert panels have minimal to some concern with regards to the health risks of BPA.

We learned in school (and it's also on the EWG website - see link below) that if plastics cannot be avoided to reduce exposure by not heating plastic containers (like hot water in Nalgenes or nuking leftovers), removing foods (especially high fat content foods) from plastic wrap and storing in alternative wrappings (wax paper) or glass containers and avoiding containers with the 7 recycling code (1, 2, & 4 are safer). Also look for plastic wraps that are labelled BPA free.

Another reference
Link to Environmental Health Perspectives
BPA's official MySpace page - 'cause this is fair and equal blogging
Environmental Working Group's BPA info page