In general, Le says, it’s safe to reuse plastic bags in the most common ways, “such as using them to carry non-refrigerated food containers in place of a lunchbox, or even to transport clothes ...

Mr. Wallace packs 3,600-calorie SOS food bars ($6) in his bag. Canned goods work too — just remember to buy the kind with a pop top, or pack a can opener as well. Medical necessities ...