Is It Safe To Eat Out Of Reusable Plastic Food Containers?

Just about every home kitchen has “that” space — the one where all the old butter tubs and takeout containers are crammed, along with tons of mismatched lids. The next time you’re reaching in there to find a place to store that last bite of breakfast burrito, you might want to think about using plastic that was manufactured during the Bush administration.

See all those cracks and nicks? The tomato sauce stain from the batch of spaghetti sauce you made in 2022? The way the smell of garlic butter still lingers? Turns out, those signs of aging are signals that you should toss this stuff out or use old plastic only to store non-food items.

“As plastic containers age, they undergo physical and chemical degradation from heat, sunlight, washing and mechanical wear,” explained Chamali Kodikara, chair of the food safety and quality management division at the Institute of Food Technologists. She mentioned scary words like “shedding” and “chemical leaching” before mentioning how, after a few years and a hundred cycles in the dishwasher, that plastic can develop microscopic cracks. Food (and worse) can be sneaking into those cracks, and plastic can be leaking out.

Another problem is that some of the stuff hiding those cracks is invisible, but potentially dangerous. Keith Warriner, a professor in the department of food science at the University of Guelph in Ontario, said: “If you’re using a worn container for food, microbes could form biofilms in cracks, scratches and seals. Microbes that hide in those biofilms can live through washing and sanitizing cycles, so the risk is that they can form a constant source of contamination by pathogens such as Listeria monocytogenes,” he said. Listeria monocytogenes is currently the third leading cause of death from foodborne illness in the United States.

How you treat old plastic containers day to day can make things much worse. For example, perhaps your takeout arrived a little chilly, or maybe you have leftovers you’d like to eat the next day. Don’t just pop that plastic container from the restaurant in the microwave and start hitting the “Add 1 min” button.

Kodikara said that reused single-use containers can pose a greater health risk when microwaved, because they were not designed for repeated use or heating. “Many disposable plastics degrade faster, releasing microplastics and potentially hazardous additives such as flame retardants or plasticizers,” she said. “Research shows that takeout plastics can release particles and chemicals when exposed to heat or repeated use.”

For those same reasons, we also need to stop putting them in the dishwasher. Not only that, said Amarat Simonne, professor and extension specialist in food safety and quality at the University of Florida, but you need to be cautious when you’re cooking and storing food, too. “Avoid pouring hot foods into plastic containers, and let food cool before storage,” she said.

You can cause even greater damage to containers depending on the type of food you put into them, explained Mary M. Johnson, principal research scientist at the Harvard T. H. Chan School of Public Health.

“Acidic food, like tomato sauce, or fatty food, like mayonnaise, can do more damage to plastic,” she said. “There’s a concern that some of the chemicals in the plastic will be at higher risk for getting onto your food if you store acid or fats in there,” she said.

The good news is that it’s not that hard to eliminate some of the dangers that worn-out plastic can pose. “You can take reasonable steps that are easy to manage,” Johnson said. One quick thing she suggested is to check the recycling codes on containers. These Resin Identification Codes (RIC) are numbers 1 through 7 inside an arrow-triangle symbol, usually on the bottom of packages. These codes were created by the plastics industry to indicate the type of resin used to make the item, not their recyclability.

Johnson said, “It’s been suggested that 3 (polyvinyl chloride), 6 (polystyrene)and 7 (other plastics) codes are best to be avoided in food containers,” she said. “Products packaged with 1 (polyethylene terephthalate), 2 (high-density polyethylene), 4 (low-density polyethylene) or 5 (polypropylene) codes are considered somewhat safer, if you have the option to choose that packaging, instead.”

It might take a bit of rearranging, but you can get that old plastic-storage cabinet looking a little fresher in no time. “People can only do so much, so do the best you can,” Johnson said. And who knows, maybe you’ll start an old-timey trend.

“In the end, maybe our grandparents were right to use ceramic, glass and stainless steel containers,” Warriner said. “Time will tell.”