Keeping food safe when using plastic containers

Keeping food safe when using plastic containers

Keep your leftover food safe when using plastic containers by following these tips.

The art of meal prepping and storing leftovers for next day’s lunch are a convenience for many families. It is also a great way to extend the pleasures of family gatherings, parties or holiday meals. Many kitchens are well stocked with plastic tubs, cling wrap and other containers when it comes to food storage. Although they cut down on food waste, some containers may pose more of a burden on the environment and potentially to your health than others. The Public Health and Safety Organization NSF and Michigan State University Extension offer consumers suggestions for food storage containers. 

Use food grade plastic containers. A food grade container is one that will not transfer non-food chemicals into the food. According to the U.S. Food and Drug Administration, non-food grade plastic containers may contaminate food. Plastic food containers must follow specific regulations to make sure they are safe for food.

Use single-use containers once. Plastics designed for single use should be used only once. Plastic breaks down over time, and some items are not designed to withstand heating and cooling. Most plastics with recycling code number “one” are intended for single use, such as disposable water bottles. Instead of reusing these plastics, transfer your food to specific containers designed for storing or reheating meals.

Wash plastic containers by hand. Only put plastics into the dishwasher if they have a dishwasher-safe label. Plastic containers may also be washed by hand. Make sure the grooves around the openings are clean so pathogens do not contaminate other food. When washing the plastic containers, be aware of any lids that no longer seal well, or the container is worn and has scratches, cracks or has become misshaped should no longer be used.  If washing does not remove odors that plastic containers absorb, these containers should be disposed of.

Only freeze food in plastic containers designed for the freezer. Only put plastics in the freezer if they have a freezer-safe label. Single use containers, such as ice cream or milk cartons, should be avoided for freezer use. According to MSU Extension, use containers in the freezer that are moisture-vapor resistant, leak proof, and easy to seal.

Use appropriate food containers for the microwave. The U.S. Department of Agriculture recommends to only use containers that are specially manufactured for microwave use. Glass, ceramic and certain plastics are safe for microwaving if they are labeled as “microwave safe.” The U.S. Department of Agriculture warns against microwaving in single-use containers not intended for that purpose, such as yogurt cartons, margarine tubs or foam-insulated cups.

Following these recommendations will help to prevent illness and to keep your food safe. For more information on keeping your family's food safe, visit MSU Extension's Safe Food & Water website.

What we do know is that almost all of the plastics that have been studied and tested show signs of leaching, to varying degrees, some of the chemical additives that go into them. Díaz Leiva explains that these additives are there to contribute properties deemed desirable by manufacturers—we’re talking things like flexibility or resistance to degradation in UV light.

Perhaps the most notorious of these chemical additives are bisphenol A (commonly known as BPA) and a class of chemicals called phthalates (also known as plasticizers), both of which are proven endocrine disrupting chemicals (EDCs). The issue with EDCs is that they do things like mimic estrogen within the body and can therefore affect bodily systems in which hormones play a role. Some, for instance, are obesogenic, altering metabolism and the storage of fat, while others can affect reproductive health.

The more notorious chemical additives like BPA and phthalates have been (and continue to be) the subject of extensive research, resulting in actions such as the FDA’s banning of BPA from use in baby bottles and sippy cups. But there’s a huge knowledge gap around those thousands of lesser-known chemical additives that show up in plastics—including, for instance, some of the chemicals that have replaced known threats like BPA. Geller points to a database of over 12,000 food contact chemicals (FCCs) that was compiled by the Food Packaging Forum, a nonprofit based in Switzerland, in an effort to “systematically collect, analyze, and publicly share information on FCCs” based on publicly available information.

In their analysis of these chemicals they identified a huge need for more research: Based on the “authoritative sources of hazard information” they consulted in their research, they concluded that we lack hazard data and thus require more research on over a quarter of those 12,000 chemicals known to be intentionally added to food contact materials. According to Geller, “that in itself gives us caution around whether we would want to recommend that users and their households reuse those products.”

Chemical additives aside, we also know that plastics are made up of incredibly strong chemical bonds. Geller explains that because of those bonds, plastics don’t readily biodegrade—instead, they break into smaller and smaller fragments. The result? Microplastics and nanoplastics, which can end up in the air, in the environment, and—just like those chemical additives—in your food.

So what can I store in plastic containers?

If you’re dead set on reusing your take-out containers, it’s best to keep cold or room-temperature things in them—this is best practice with any plastic container, really, whether it’s marketed as “reusable” or not. You’ll also want to avoid anything acidic or saucy, which can further encourage leaching. “Dry goods at room temperature are much less risky than hot tomato soup,” says Warner. And know that even if you’re only storing dry goods, those containers will inevitably start to degrade from sunlight and continued washing. If you see signs of discoloration or cloudiness in a container, that’s a good sign that it’s past its prime—it means the material is starting to break down and is more likely to leach chemicals or microplastics. If you’ve got a pile of containers in your cupboard that you’ve been reusing since before you can remember, it’s time to recycle them.

Can you put plastic deli containers in the microwave and dishwasher?

I’ll cut to the chase: None of the experts I spoke with advised using plastic containers at all if you can avoid them (even the sturdier types that are sold as reusable storage containers). They certainly did not advise putting deli containers in the microwave or dishwasher. Warner puts it simply: “The more you reuse them, the more they would be likely to leach chemicals because of the repeated washing and exposure to acidic things and soap, and scouring them in cycles. And definitely don’t microwave them.” Heat will only make plastic more likely to leach chemicals, so the safest route here is to avoid it at all costs.

But my take-out containers are labeled “microwave-” or “dishwasher-safe.” Does that mean that they’re fine?

As it turns out, that microwave- or dishwasher-safe symbol refers largely to whether the plastic itself can withstand the microwave or dishwasher. “You can do it, they’re not going to completely melt,” says Warner, “but that doesn’t mean it’s good for your health.”