Flip over your food storage containers and take a look at the small number printed on the bottom. If the recycling number is #3 or #7, it likely contains either BPA (bisphenol A) or phthalates (used to make PVC plastics) which mimic estrogen and can interfere with hormone levels. These can be especially harmful for still-developing bodies so, unless the container clearly states that it is BPA and PVC-free, the safest thing to do is to get rid of them. Canada and the European Union have already banned BPA use in baby bottles and many people, including me, are not going to wait around for the U.S. to follow suit. If you don't want to part with your plastics completely, be sure that your containers are either #2, #4 or #5, which are widely considered safe for food storage.