Look for the number 5 before you toss that old lunch box.

Most old plastic lunch boxes are fine to reuse, but flip it over and check the recycling number first. That little triangle tells you everything you need to know.

Number 5 (polypropylene) is the good stuff — it’s what most modern food containers are made of and it’s safe to reuse for years. Hang onto it as long as it isn’t cracked, badly scratched, or warped. Number 1, 2, and 4 are fine for food too, though #1 doesn’t love repeated use.

Number 7 is the catch-all and the one to watch. Old hard, clear boxes marked #7 were often polycarbonate, which contains BPA. If it’s #7 and more than 10-15 years old, recycle it. Same goes for #3 (PVC) and #6 (polystyrene) — those leach questionable stuff as they age.

Trust your senses too. Wash it and look at it: cloudy, stained, scratched, or still smells after a good clean? The plastic has degraded. Scratches are bacteria hotels and leaching hotspots, so that box has retired. When in doubt, recycle it — a new container costs a few bucks, and your liver doesn’t need the overtime.