Glass Food Storage Container

Because many plastic food storage containers contain a chemical called bisphenol A (aka BPA), which is used to make many types of plastic. Examples are polycarbonate (hard, clear, lightweight) plastic containers with #7 on the bottom, baby bottles, water bottles, as well as some safety equipment and medical devices. BPA is also used in to coat the metal in food cans and on bottle tops. BPA has been found to affect behavior and neural development in young animals.

When polycarbonate plastic containers are exposed to hot liquids or foods, the BPA in them has been shown to leach (seep) into the food or liquid held by the container.

Canada is the first country to declare BPA a health hazard and has banned BPA in the production of baby bottles.

Over time, you will save money by purchasing a glass food storage container set, since they are much more durable and you will not need to buy plastic containers repeatedly when they begin to break down/get scratched/etc.

Glass containers can go from freezer/fridge/oven to dinner table and still look classy as a serving dish, where as plastic cannot.

Glass Bottoms with Plastic Lids
These containers are great for storage, as many of them are airtight as well. However, obviously, the lids will not be oven-safe and should not be used in the microwave in order to avoid BPA-leaching possibilities.

Glass Bottoms with Glass/Metal Lids
These containers are the most complete BPA-free solution, but they most likely will not be airtight.

Some glass food storage containers are microwave/dishwasher/freezer-safe, but not oven-safe, so read the product descriptions carefully.

Also consider ceramic food storage containers before making your final decision.

References:
Government of Canada's website: Questions and Answers for Action on Bisphenol A Under the Chemicals Management Plan

National Institutes of Health/National Institute of Environmental Health Sciences National Toxicology Program BPA Factsheet