Plastics used for baby food packaging release large numbers of microparticles when microwaved

A team of food scientists, engineers, and environmental specialists at the University of Nebraska-Lincoln has found that plastic baby pouches release large numbers of microplastic particles when heated in a microwave oven. The study is reported in the journal Environmental Science & Technology.

Over the past several years, scientists worldwide have found that plastics break down into tiny particles that contaminate the environment. Microplastics have been found in plants and the bodies of animals and humans. In this new effort, the researchers noticed that many baby foods are now packaged in small plastic pouches that can be conveniently heated in a microwave oven. Some are even marketed as organic, implying they are healthier than other foods. The team members explored what happens to the plastic when heated in a microwave. They purchased microwavable baby food products and brought them to their lab for testing.

To ensure testing of the plastic rather than the food inside, the team removed the food and washed the containers. They then filled some of them with nanopore-deionized water to simulate watery foods and others with 3% ACS-grade acetic acid to simulate acidic foods. They heated the containers in the microwave for different amounts of time, then removed them and tested them to see how many particles of plastic had made their way into the simulated food. The team also tested to see how much plastic was released before heating when products were kept in the refrigerator for a long time.

They found the microplastics varied dramatically, but all samples contained high amounts of plastic. One container, for example, that simulated food refrigerated for six months released approximately 580,000 bits of microplastics, ranging in size from 1 to 14 micrometres. The same container released another 4 million particles when heated in a microwave oven.