Scratched plastic is the only real deadline.

There’s no fixed expiration date for a lunch box — replace it when it shows real wear, and the thing to actually worry about is scratched or cracked plastic.

Plastic is the only material with a real shelf life. Those little scratches from forks and scrubbing are bacteria hangouts; germs survive washing inside a scratch, and the deeper they get, the worse it becomes. Once a plastic container is visibly scratched, cracked, or warped, that’s your sign to retire it. Daily use usually lands you there in a couple of years, but it really depends on how rough you are with it.

Glass and stainless steel basically last forever. They don’t scratch the same way, so they’re safe until they break. The parts that do wear out are the plastic lids and silicone seals — swap those out when they stop closing tight or start holding odors. Lingering smells or stains after a good wash are warning signs too, and warping from the microwave means the plastic is degrading.

A ten-dollar container is cheaper than a week of food poisoning.