plastic containers

More and more research has fuled a recent debate over the safety of plastic containers. In particular, a chemical called BPA (found in certain plastics and the lining of canned foods) has been associated with estrogen-mimicking effects and possible endocrine disruption.

Consider taking these steps to reduce the potential risk. Avoid or reduce your use of polycarbonate plastic bottles (including Nalgene) labeled #7 on the bottom. If you do use them, wash the bottles by hand and not in the dishwasher. Use glass or stainless steel containers, particularly for cooking or storage of warm food items. Throw out any plastic containers with cracks or cloudiness.

To answer your specific question, it appears that polypropylene (#5), tends to be one of the "safer" plastics compared to others such as #7, although that may be partly due to the fact that enough is not known about it yet.

National Geographic publishes on online resource called "The Green Guide". Here's a link to an article containing additional information on plastic containers:
http://www.thegreenguide.com/products/Kitchen/Plastic_Containers

-Dr. Marci Scott