A recent study conducted by the University of Milan, in collaboration with the Eos company and the University of Milan-Bicocca, found that food containers heated in the microwave can release microplastics in the environment. The research, published in the international journal Particles and Particle Systems Characterizationhighlights the risks associated with the improper use of plastic containers when heating food.
Microplastics are now present everywhere, from mountain peaks to the ocean depths, and their impact on the environment and human health is still unclear, but potentially harmful.
These microscopic fragments are inhaled daily and ingested with water and food. Some research indicates that every week we consume an amount of plastic equal to the weight of a credit card. One way to reduce exposure may be to avoid heating food in plastic containers in the microwave.
The “schiscetta” and the environment
Bringing your lunch to the office in the so-called “packet” and heating it in the microwave without following the correct instructions can contribute to the release of microplastics into food. This phenomenon was observed thanks to Spes, Single Particle Extinction and Scattering technology, developed in the Physics laboratories of the University of Milan and used by Eos to optically characterize dust.
The research protocol
The idea of checking whether plastic food containers heated in the microwave released micro and nanoplastics came from Eos. Using “Spes” technology, the formation of plastic nano and microspheres during the heating of pure water was highlighted, simulating the heating of food.
“Spes is an innovative method that allows you to classify nano and microparticles in a very precise and complete way”, explains Marco Pallavera, Research and Development director of Eos and first author of the article.
Search results
Research has shown that heating pure water in food containers releases nano- and micro-spheres of polypropylenethe material of which the containers themselves are made.
Polypropylene, biocompatible, melts between 90 and 110 degrees. By bringing the water to a boil, a small portion of the polypropylene melts and then solidifies back into the water. This process is similar to that used industrially to produce polymer nanospheres.
The results, also analyzed in detail by Llorenç Cremonesi and Claudio Artoni of the EuroCold laboratory at the University of Milan-Bicocca, were accompanied by electron microscope images taken by Andrea Falqui of the State University of Milan.
Tiziano Sanvito, administrator of Eos, underlines the importance of following the manufacturers' instructions: “Several manufacturers specify not to bring the containers above 90 °C, or not to heat them for too long in the microwave, or not to use the appliance at maximum power. Following these indications, the effect does not occur.”
Impact on the environment
Marco Potenza, professor of Optics at the “Aldo Pontremoli” Physics Department of the State University of Milan, concludes: “The nano- and micro-particles produced contribute to the dispersion of plastic in the environment, a growing problem in the modern world”.
Confirmation from an American study
Also a recent study published in the journal Environmental Science & Technologyconducted by the University of Nebraska-Lincoln, concluded that plastic containers approved for food use can contaminate food with microplastics when heated in the microwave.
The study analyzed the release of microplastics (particles between 100 nanometers and 5 millimeters) and nanoplastics (between 1 and 100 nanometers) from plastic bags and containers to foods based on use.
The effects of microplastics on human health are still poorly understood. Researchers at the University of Nebraska-Lincoln simulated the consequences on kidney cells, exposing them to concentrations of microplastics similar to those detected in the experiments. 77% of cells exposed to the highest concentrations died. However, researchers admit that it is unclear how many microplastics actually reach the kidneys and what happens inside the human body.
