Plastics are in our cars, computers, phones, toys, food cans, containers, packaging, composite dental fillings, and nearly everything we use every day. They're truly ubiquitous and impossible to avoid. But it's a good idea to avoid plastic containers for food whenever we possibly can.
Virtually all plastic contains endocrine disruptors, such as (but not limited to) bisphenol-A (BPA), which was originally manufactured as a synthetic estrogen. It was soon discovered that BPA worked even better as an additive to plastics, making them tough and durable. But we're learning that what's good for plastics is bad for the human body. Endocrine disruptors can affect the immune system, cause weight gain, infertility, initiate premature puberty, and worsen PMS and perimenopause symptoms.
Temperature also makes a difference. Heat causes more toxins to leach out of plastic containers and into the food they hold. Food that is frozen and then placed in a plastic freezer bag will cause leaching. Warm or hot food will cause more.
It would be difficult, and perhaps impossible, to entirely avoid plastic. Sometimes, it's simply a great deal more convenient to use plastic. Favourable alternatives, depending on what needs to be stored, are glass, stainless steel containers or jars. Other items will do well wrapped in paper or cloth. Paper or cloth bags work well for both transport and storage.
Source: Lisa Viger - author of Easy, Affordable Raw - How to go raw on $10 a day.