Microwaving food containers can release billions of nanoplastics; may harm kidney cells – research
Food is meant to be safe to heat in microwaveable containers. However, a study from the University of Nebraska – Lincoln discovered that certain containers, particularly those used for baby food, can pose health dangers when heated in the microwave.
According to a new Nebraska study, microwaving containers releases billions of nanoplastics, and this exposure to particles can destroy up to 75% of cultured kidney cells.
Their experiments revealed that microwaving plastic baby food containers found on supermarket shelves in the United States can release massive amounts of plastic particles – in certain cases, more than 2 billion nanoplastics and 4 million microplastics per square centimeter of container.
Though the health implications of consuming micro- and nanoplastics are unknown, the Nebraska team discovered that three-quarters of cultivated embryonic kidney cells died after being exposed to the same particles for two days.
In 2021, the team began its research. While previous research has looked at the emission of plastic particles from baby bottles, the researchers discovered that no studies had looked into the types of plastic containers and pouches that are commonly found in stores and supermarkets.
The researchers conducted tests with two baby food containers made of polypropylene (PP) and a reusable pouch made of polyethylene (PE), both of which are FDA-approved plastics. In one experiment, the researchers filled the containers with either deionized water or 3% acetic acid (the latter to replicate dairy products, fruits, vegetables, and other relatively acidic consumables), then microwaved them for three minutes at maximum power in a 1,000-watt microwave.
After that, they examined for micro- and nanoplastics in the liquids, with micro particles being larger than 1/1,000th of a millimeter in diameter and nano being particles smaller than that.
The number of particles produced by microwaving was determined by a variety of parameters, including the plastic container and the liquid contained within it. However, based on a model that took into account particle release, body weight, and per-capita ingestion of various food and drink, the team estimated that infants drinking products containing microwaved water and toddlers consuming microwaved dairy products have the highest relative concentrations of plastic. Experiments that simulated the refrigeration and room-temperature preservation of food or drink over a six-month period also revealed that both could result in the release of micro- and nanoplastics.
The researchers next cultured and exposed embryonic kidney cells to the actual plastic particles released from the containers. The cells were subjected to particle quantities that infants and toddlers might accumulate over time or from several sources.
Only 23% of kidney cells exposed to the highest concentrations survived after two days, a substantially greater mortality rate than seen in previous studies of micro- and nanoplastic toxicity. The researchers assume that kidney cells are more vulnerable to the particles than other cell types studied previously. However, previous research tended to focus on the impacts of bigger PP particles, some of which were perhaps too large to penetrate cells. According to the study, PP containers and PE pouches often emit 1,000 times more nanoplastics than microplastics.
The researchers published their findings in the journal Environmental Science & Technology. The National Science Foundation and the Buffett Early Childhood Institute provided funding for the study.
SOURCE: University of Nebraska-Lincoln
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