September 8, 2023 – Results from recent laboratory experiments show that heating water- and milk-based drinks in conventional baby food containers within the microwave releases levels of microplastics and nanoplastics that would potentially be toxic over time.
The experiments weren't carried out on humans. Instead, human cells in a laboratory were exposed to the tiny plastic particles released during microwave treatment. The Insights were published within the magazine earlier this summer Environmental Science and Technology.
Researchers on the University of Nebraska-Lincoln conducted experiments with three kinds of commonly sold baby food packaging: two different polypropylene baby food containers and a reusable polyethylene baby food bag. The container types are FDA-approved, the authors noted.
One set of containers was stuffed with water and one other set of containers with an acidic liquid to mimic the properties of common baby foods and drinks similar to fruits, vegetables or dairy products.
The filled containers were heated in a 1,000 watt microwave at full power for 3 minutes. The researchers then analyzed the liquids to see whether or not they contained micro- or nanoplastic particles.
Microplastic particles are particles with a size of at the least 1/1000Th The size is about one millimeter, nanoplastic particles are smaller than this size.
The researchers concluded that probably the most concentrated consumption of the tiny plastic particles would occur when infants drank products containing microwaved water or when toddlers consumed microwaved dairy products.
Study writer Kazi Albab Hussain, a graduate student in civil and environmental engineering on the University of Nebraska-Lincoln, recently became a father, which inspired the research.
“I couldn’t completely avoid using plastic for my baby,” Hussain said in a single opinion. “But I was able to avoid those (scenarios) that led to greater release of micro- and nanoplastics. People also deserve to know these and they should choose wisely.”
The researchers conducted a further laboratory experiment by which human embryonic kidney cells were exposed to the microplastics and nanoplastics discovered after heating the newborn food containers within the microwave.
They exposed the kidney cells to many more particles than could be released in a single microwave-and-drink session. The amount of particles utilized in the experiment corresponded to the researchers' estimated concentration of particles that collected over many days or from multiple sources.
Within two to 3 days, about 75% of the kidney cells within the laboratory experiment died, indicating potentially high levels of toxicity.
“When we eat certain foods, we are generally informed or have an idea about their calorie content, sugar content, [and] other nutrients. I think it is equally important that we are aware of the number of plastic particles in our food,” said Hussain. “Just as we understand the impact of calories and nutrients on our health, it is crucial to understand the extent of plastic particle ingestion to understand the potential harm they can cause. Many studies, including ours, show that the toxicity of micro- and nanoplastics is strongly related to the level of exposure.”