Between sturdy take-out boxes, margarine tubs, and inexpensive plastic containers, it’s not hard in today’s day and age to find a home for your leftover pasta. In fact, the average American woman owns 22 plastic food containers, and half of women repurpose food packaging as storage containers.
That may sound resourceful, but among experts, it’s actually some cause for concern. In the short term, the biggest risk is bacterial contamination. If a plastic container is intended for one-time use, it may not be designed for easy cleaning, potentially allowing germs to proliferate the longer you hang on to it.
For example, if you have a very narrow opening, like a soda bottle, it’s essentially impossible to clean effectively, other than pouring a boiling liquid inside to kill all the bacteria. And that would compromise the plastic. Some researchers tested water from elementary school students’ water bottles, many of which had been continually refilled without being washed, and found that nearly two-thirds of the samples contained enough bacteria to be rendered unfit for consumption.
But what about easy-to-clean containers, like those little plastic soup bowls from take-out joints? Although you may be able to thoroughly rinse out any food residue, that doesn’t mean you should add these containers to your lunchbox repertoire.
Why? Chemicals lurking in some containers, especially those that aren’t designed for reuse, could leach out of the plastic and into your food if you heat them in the microwave, toss them in the dishwasher, or leave them in the sun for a long period of time.
But before your toss your tub, check the bottom for the recycling code, a number that can help you identify what type of plastic your container is made from. If you see #2, #4, or #5, then you’re most likely in the clear for chemicals, which means you can safely reuse your container.
Most of the reusable containers you buy at the store are made of plastic #5, or polypropylene, which has a low risk of chemical leaching. It’s also commonly used for yogurt containers, margarine tubs, and bottles for pourable foods, like syrup.
The same goes for low-density polyethylene (recycling code #4), often used for packaging films, and high-density polyethylene (recycling code #2), from which milk jugs are made. Plasticizers aren’t typically used in these plastics, so the only thing you’d have to watch out for is exceeding the maximum-use temperature, just to avoid warping or deforming them.
For the sake of caution, if you’re reusing plastic containers, even those with “safe” recycling codes, try to limit their use to foods with similar acidity, sugar, fat, and alcohol content to the item that originally came in them. For example, don’t use a plastic shortening container to store a vinegar-based salad dressing. That way, the plastic container will maintain its integrity for as long as possible.