Originally Posted by ErikC
My only concern about plastic is that it can absorb fat molecules, which means a) they can absorb odors and flavors, and perhaps impart them to other foods, and b) it is really hard to whip egg whites in a bowl that has absorbed fat, since the fat prevents the bubbles from forming somehow. ...
Plastics are chemically "cousins" of fats ... flexible plastics contain "plasticizers" which are even more closely related (kissing cousins). The plastric doesn't absorb
the fat per se - the fat chemically bonds to the surface of the plastic. That's why you can't wash it out or get rid of the stains from something like a tomato sauce no matter what you try (vinegar, bleach, etc.). It's like trying to wash out the seasoning on a 25-year old cast iron skillet with only cold water.
Rigid plastics without plasticizers - like polycarbonate plastics - are far enough removed chemically from fats that they do not stain - but I've never tried to whip egg whites in polycarbonate plastic simply because I don't have any containers that are an appropriate shape.
As for the microwave - I only use "microwave safe" items - plastic, glass, pottery, etc.
As for the cancer causing items liberated by the microwave ... you probably get more from grilling a steak on an outdoor grill.