WSU Extension Q&A: Should food be heated in microwave with plastic bags, butter containers?
Q. Several of my friends heat foods in the microwave using plastic bags and butter containers. Is that safe?
A. First, the plastic materials must be food grade. Second, the plastic should be used within the guidelines of how the manufacturer recommends using the product.
In the United States, the Food & Drug Administration requires that all plastics used for food packaging must be of greater purity than plastics used for nonfood purposes. Food-grade plastics do not contain dyes or recycled plastic deemed harmful to humans. Unfortunately, in the U.S., there is no universal symbol to identify a food-grade plastic. At this time, the best advice is for the consumer to consider the intended use of the plastic by the manufacturer. If the product is being sold for use with food, it must be manufactured to the food-grade standard.
The second issue concerns how food-grade plastics are used. It is potentially unsafe to use plastics differently than they were originally intended. For example, zip-top plastic bags designed for refrigeration and freezing are not designed for heating, and should not be used to heat or cook foods. For example, do not use a plastic margarine container to melt margarine in the microwave. Soft plastics are likely to flake, blister, deform and melt, allowing migration of packaging materials into food.
Q. I wanted to plant a tree this past spring but was advised not to because of the predicted limited availability of irrigation water for the season. Is now a good time to plant a tree?
A. In fall months, the soil temperature is warm enough for new root growth. This makes fall a good time to plant a tree if you can provide water, and you can keep the root ball and surrounding soil through mild, dry, fall and winter weather. Based on surface moisture during the cooler months, we sometimes perceive that the soil is wetter than it actually is, so periodically dig down 6 inches using a trowel to check the moisture. However, you should not water the tree when the soil is frozen during severely cold weather.
Questions should be called in to the WSU Extension offices in Kennewick at 735-3551 or Pasco at 545-3511.
This story was originally published November 1, 2015 at 12:59 AM with the headline "WSU Extension Q&A: Should food be heated in microwave with plastic bags, butter containers?."