A research team from the University of Nebraska–Lincoln studied the release of microplastics and nanoplastics from plastic baby food containers and pouches under various conditions. Their findings, published in 2023 in Environmental Science & Technology, revealed that refrigeration and room temperature can release millions to billions of microplastics and nanoplastics over six months. Heating in a 1,000-watt microwave for just three minutes released more than 4 million microplastic and 2 billion nanoplastic particles per square centimeter of plastic. Polyethylene-based food pouches emitted more particles than polypropylene containers. A laboratory study showed that the extracted microplastics and nanoplastics killed three-quarters of cultured embryonic kidney cells after 48 hours of exposure.