There are plenty of reasons to avoid using so much plastic, both environmental and health wise. For instance, marine researchers have shown that plastic debris outweighs zooplankton in remote parts of the Pacific. Health wise, phthalates, a chemical added to normally rigid PVC to make soft products, are potential hormone disruptors and may increase infertility in men.
When it comes to packing lunch, most of us use plastic wrap, plastic baggies, and/or plastic containers to transport our food. First off we should all be packing our food in reusable containers to avoid adding excess plastic to landfills. I like to use pyrex containers since they are glass and microwaveable, but let's face it that is just impractical for little kids. Pyrex is too heavy, plus it's breakable. When shopping for reusable food containers, avoid plastics with the following number inside the recycling symbol: #3 (PVC), #6 (Polystyrene), and #7 (Polycarbonate). These chemicals are no good for our bodies or the planet!
Ideal Bite has some great suggestions for non-plastic food containers if you brown bag your lunch.