Is It Bad To Use Plastics In The Microwave?
The microwave oven is the go-to appliance for reheating leftovers from last night’s dinner or takeouts from restaurants. It’s easy to pop the plastic storage container or restaurant container into the microwave, heat up the food and eat from the container. After all, eating food out of containers saves you from getting out the dinnerware set.
While plastic containers are convenient, are they safe to heat in a microwave? For the most part, scientists and medical professionals advise against it since exposing plastics to heat increases the risk of transferring dangerous chemicals, namely Bisphenol A (BPA) and phthalates (“THAL-ates), into food.
“There have been several experiments that heating liquids or foods in plastics that contain these chemicals will certainly increase your exposure to them,” Dr. Sheela Sathyanarayana, a professor of pediatrics at the University of Washington, told Scienceline. “And so that’s why we don’t recommend putting plastics in the microwave.”
BPA and phthalates are human-made chemicals that help plastics keep their shape and make them more durable and flexible. BPA and phthalates are found in a variety of products, including water bottles, bottle tops, personal care products, and food packaging. In addition, BPA is found in epoxy resins that coat some metal food and soda pop cans, bottle tops, and water supply pipes.
Studies have found that BPA and phthalates can increase the risk of serious diseases when the plastics are exposed to heat, such as microwaving or the heat of a dishwasher. Exposure to heat increases the risk of the chemicals leaching into food. Plastic containers pose a problem even if they are not heated. Plastic breaks down over time and the tiny plastic particles, called microplastics, can also leach into food stored in the container.
According to scientists, BPA and some phthalates are considered endocrine disruptors, which are natural or human-made chemicals that block or interfere with hormones in the body.
Dr. Neelima Chu, a board-certified endocrinologist and internal medicine doctor with Sharp Rees-Stealy.Medical Group in San Diego, California, said it’s important to avoid substances that interfere with hormone production.
“These substances can lead to infertility; thyroid disease; early puberty; leukemia; breast, uterine and prostate cancers; neurobehavioral issues; obesity; and metabolic dysfunction,” Dr. Chu said in a news release.
Similarly, a 2021 study on phthalates found that the chemical may lead to roughly 100,000 premature deaths each year among people ages 55 to 64 in the United States. The study, published in the journal Environmental Pollution, reported that participants with the highest level of chemicals had a greater risk of death from any cause, especially from heart disease.
In addition, reviews of previous studies show that exposure to BPA and phthalates can lead to developing an allergy, asthma, immune dysfunction, and cardiovascular diseases.
Dr. Kelly Johnson-Arbor, a physician, toxicologist and medical director at the National Capital Poison Center in Washington, DC told Scienceline that most studies on plastic chemical exposure focused on fetuses and animals, and not on exposure on human adults. According to Dr. Johnson-Arbor, to have the best studies on humans would require creating a control group that had not been exposed to the chemicals.
“In the U.S., we are all exposed to plastics,” Dr. Johnson-Arbor said. “You’d have to use a control group from…somewhere they don’t have any plastic. And that’s going to be hard.”
How to safely use plastic and microwave food
The U.S.Department of Agriculture recommends reheating cooked foods in a microwave oven by covering the food with a lid or a microwave-safe plastic wrap to hold in moisture and provide safe, even heating. When it comes to plastic wrap, the U.S. Food and Drug Administration (FDA) recommends placing the wrap loosely over food to allow the steam to escape. The wrap should not directly touch the food, particularly if the foods are high in fat and sugar.
The following are additional recommendations for safely reheating food in microwaves and using plastics:
- • Heat food in microwave-safe glass, porcelain or ceramic containers.
- • Use paper towels, rather non-microwave-safe plastics to cover food. Condensation from plastic lids could contain phthalates.
- • Always read directions on plastic wraps you are going to use in the microwave.
- • Do not place hot foods or liquids in plastics.
- • When thawing frozen food in a microwave, do not use foam trays, plastic containers, and plastic wraps because they may melt at high temperatures and allow chemicals from the containers or wraps to leach into the food.
- • Avoid plastic with recycling code No. 3, which contains phthalates; No. 6, which contains styrene, a possible carcinogen; and No. 7, which contains BPA.
In addition to microwaves, dishwashers also have an effect on plastics. According to Don Huber, director of product safety for Consumer Reports, phthalates, BPA, and other harmful chemicals can leach from plastics due to heat from the dishwasher. Even if the plastic says, “dishwasher safe,” Huber recommends placing the plastic on the top rack, away from the heating element. It’s also recommended to avoid selecting cycles that use higher wash or dry temperatures, such as the “sanitize” cycle when washing plastic.
Dr. Johnson-Arbor issued a general word of caution about using plastic products in microwaves. According to Dr. Johnson-Arbor, even if a plastic container is labeled microwave safe, “it simply means that it won’t melt. It can still contain BPA, phthalates or harmful materials unless it specifically says those aren’t included.”