Reusing plastic containers from food delivery seems like an easy way to reduce waste and save money, but this common practice raises an important question about what happens when that plastic is reused or reheated. With growing concerns about microplastics in our food and environment, this everyday habit has come under closer scrutiny. While research is still uncovering the full impact of microplastics on human health, many people are looking for practical ways to minimize their exposure.
The short answer to whether it’s safe to reheat food in plastic takeout containers is that it depends. Many people assume all plastic is the same, but that’s not the case, as shown by the different recycling numbers on packaging, explains Dr. Robert Glowacki, a microbiologist, immunologist, and associate professor of biology at Hope College. He notes that single-use containers like clamshells, salad boxes, and sandwich containers are typically made from less durable materials that break down more easily and should not be reused. Products like Tupperware, on the other hand, are generally made from sturdier plastic designed for repeated use, including microwaving and dishwasher cleaning.
Dr. Chris DeArmitt, a polymer scientist and founder of the Plastics Research Council, agrees that if a takeout container is explicitly labeled as reusable and safe for microwave and dishwasher use, the likelihood of it releasing microplastics into your food is low. “As a doctor of chemistry, I wouldn’t do it if it wasn’t safe, and I reheat food this way myself,” DeArmitt says. He adds that the term microplastics is new to the public, but thousands of studies from the FDA and European Food Safety Agency spanning more than 50 years have thoroughly investigated this and found no cause for concern because any exposure is extremely low. However, plastic can degrade over time, so Glowacki advises regularly checking containers for signs of damage such as cracks, dents, or discoloration, which often appears as cloudiness.
According to Dr. Victoria Fulfer, a microplastics scientist at the 5 Gyres Institute, microplastics are plastic particles smaller than 0.2 inches in diameter that vary in shape, size, and chemical composition. Many are thinner than a human hair and invisible to the naked eye, making them nearly impossible to remove from the environment. Unlike ordinary dust, microplastics include microfibers from textiles, tire particles from vehicles, microbeads from personal care products, and fragments of larger plastic items that break down over time. Because they continuously break into smaller pieces, microplastic particles accumulate in the environment and travel through food chains, from oceans to fish and eventually to humans, Glowacki explains.
It’s known that ingesting microplastics harms mice, fish, and other organisms, causing changes in behavior and physiology, oxidative stress, and stunted growth, Fulfer says. To date, there are no comprehensive studies that definitively link microplastics to any specific disease in humans. However, research suggests that similar effects could be related to oxidative stress and inflammation, which are associated with endocrine disorders, cardiovascular disease, reproductive problems, and dementia. There is also increasing evidence that microplastics can disrupt gut bacteria and cause intestinal inflammation, which is linked to infections, poor nutrient absorption, and increased risk of gastrointestinal cancers, Glowacki adds. Since we are exposed to microplastics through the air we breathe, the food we eat, the water we drink, and the clothes we wear, direct human studies are difficult to conduct because there are no true control groups, Fulfer notes.
Not all plastic containers are designed for reuse, and once plastic starts breaking down, it’s more likely to release microplastics into food. If a plastic takeout container is labeled as single-use, Fulfer recommends discarding it after one use, recycling it, or repurposing it for storing non-food items like office supplies. Products like Tupperware are designed for reuse and are generally safe for storing food or microwaving, DeArmitt says. It’s important to remember that if a container is damaged and shows cracks, scratches, or discoloration, the risk of microplastic exposure increases and it’s worth investing in a new one. “There are no specific guidelines on how many times plastic containers can be reused, but brands like Tupperware that are made specifically for reheating and storing food will be safer than single-use takeout containers,” Glowacki concludes.
Time to discard a container includes signs like cloudiness or discoloration, deep scratches or dents on the surface, cracks, deformations or melted edges, and if there’s a plastic smell after reheating. For those who want to reduce plastic use in the kitchen, small changes can make a big difference, especially with food that’s frequently reheated. Simple alternatives for reheating leftovers include glass or ceramic containers, while stainless steel or silicone products are good options for meal prep and storage, and silicone bags or glass safe for low temperatures work well for freezing. “It’s almost impossible to completely avoid plastic, but changes in the kitchen and less food storage in plastic are a good start to reducing exposure,” Fulfer says.
Understanding plastic types and their intended use is crucial for making informed decisions about food storage. The recycling symbols on plastic containers range from 1 to 7, with each number representing a different type of plastic polymer. Type 5 plastic, also known as polypropylene, is commonly used in reusable food containers because it has a higher melting point and is considered safer for hot foods and microwave use. Types 3, 6, and 7 plastics are generally not recommended for food storage or reheating as they may contain chemicals that can leach into food when heated. The FDA regulates food contact substances in the United States and requires manufacturers to demonstrate that materials used in food packaging are safe before they reach consumers, though these regulations primarily focus on chemical migration rather than microplastic particle release.
What are your thoughts on reusing plastic takeout containers in the comments?
