Is It Safe To Keep Using Old Plastic Food Containers? Here's How To Tell.

Some telltale signs can indicate whether they're ready for their trash can funeral.

When it comes to low-cost kitchen items that can stand the test of time, plastic food storage containers count among my personal favorites. I’m a huge fan of big-batch cooking, so I rely on these little vessels to keep my leftover soups and braises fresh in the fridge and freezer.

But recently, after pulling a particularly well-worn container out of my kitchen cabinet, I found myself wondering just how long it had been hanging out in there and whether it might be showing its age in some undesirable ways. If you’re also wondering how vintage is too vintage for food storage containers, read on to get some answers from food scientists.

The longevity and safety of food storage containers depend on the type of plastic.

When trying to evaluate a plastic food storage container for durability and safety, you should first turn the container over and check out the recycling code.

Inside a triangular symbol, you’ll find a number from 1 to 7. According to Michael Tunick, a research chemist in Drexel University’s Food and Hospitality Management Department, the numbers you want to see are 2, 4 or 5. A 2 represents “HDPE, or high-density polyethylene, found in [items like] cooking oil bottles and milk jugs. It’s hard to break down and considered [food] safe,” Tunick said. He noted that a 4 stands for “LDPE, or low-density polyethylene, found in [items like] squeeze bottles and bread bags, considered safe and reusable.” A 5 is for “PP, or polypropylene, found in potato chip bags and yogurt containers, and safe to reuse,” he said. In addition to being food-safe, containers with the numbers 2, 4 or 5 are durable enough to be washed and reused multiple times.