What do you think of those new bags and containers that let you steam vegetables in the microwave?

As much as I love the idea of convenient methods that help people enjoy more fresh vegetables-and which cook them without overcooking them-I have yet to be convinced that the new microwave bags are a good idea. A variety of manufacturers offer products that provide an amazingly convenient and kitchenware-free way to steam vegetables or even whole meals, but the companies' claims about safety do not match up very well with the history of research in this area.

"Food-contact plastics" have been the subject of toxicology research for the past 15 years. While it is true, as some of the manufacturers point out, that plasticizers (like DEHP, or diethylhexylphthalate) from polyvinyl chloride (PVC) plastics have been the primary target of safety investigation, these toxic chemicals are by no means the only chemicals that have been investigated or found to be potentially risky. The polyethylene polymer, polyethylene terphthalate (PET), and plasticizers from both vinyl chloride (VC) and vinylidene chloride (VDC) have also been shown to migrate from microwavable plastics into food at potentially harmful levels. So have volatile compounds like cyclopentanone, 2-cyclopentyl cyclopentanone, hexadecane, heptadecane, octadecane, and epsilon-caprolactam. Non-volatile compounds have also been shown to pass from packaging into food during microwave heating. Polyisobutylene from polyethylene films, melamine and formaldehyde from microwavable cups, benzene from t-butyl perbenzoate found in plastic polymers, and other potential toxins have all been shown to migrate at higher temperatures from microwave packaging into pre-packaged microwavable foods.

Some of the debate over safety and packaging involves the level of health analysis being considered. If the impact of potential toxins from plastic packaging is examined on a cellular level, potentially unwanted and health-damaging events are almost always recognized at this microscopic, cellular level. In a broader context, however, where the triggering of a clinical disease is being considered, the impact of these toxins often seems either negligible or totally non-existent.

The bottom line: I don't see any reason to take risks-even at a cellular level-when there are such ideal alternatives available. The steaming of vegetables is simply not complicated-or even time-consuming-on the stovetop in a covered pot with a stainless steel steamer basket. And if microwave cooking is for some reason much more desirable, a covered glass or Pyrex container can easily be used in the microwave for this purpose. The cutting of fresh vegetables does take more time, but if this time is also a major obstacle, pre-cut organic frozen vegetables are widely available and can be very quickly and deliciously steamed in the microwave using a plastic-free approach.

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