by Ally Hirschlag and Martha Henriques
BBC
(Part 2 of 2)
Microplastics gush out of our taps and flake off cookware. They find their way into the yolks of eggs, and deep into meat and vegetables. But if we take certain steps, we can eat less of them.
Kitchen utensils
The starting point for many dishes is the chopping board. One study looked at individual slices made on a chopping board, and estimated that between 199 and 300 microplastic or nanoplastic particles could be generated per millimeter of cut.
A 2023 study found that one type of board, made from polyethylene, was estimated to release between 7.4-50.7g (7.4-1.8oz) of microplastics a year. Another type, made of polypropylene, would release around 49.5g (1.7oz) per year. For context, 50g (1.7oz) is roughly the weight of a generous serving of breakfast cereal.
It’s worth noting though that this was a small study, and microplastic release varied between different people’s chopping styles as well as between board types – a release of that much plastic would leave your chopping board in tatters after a few years of use.
“You start looking and it’s like, yes of course, I can see [the grooves] there,” said Vilde Snekkevik, a marine biologist and microplastics researcher at the Norwegian Institute for Water Research, who published a 2024 review on sources of microplastics in the kitchen. “So, where did the plastic go? It must have gone somewhere.”
Sometimes, it goes straight into the food chopped on it. In the UAE, researchers reported in 2022 that meat bought at a butcher and at a supermarket contained microplastics originating from plastic chopping boards. These microplastics melted when the meat was cooked, and then solidified again as the meal cooled. Washing meat thoroughly for three minutes reduced but did not eliminate the microplastics inside it, the researchers found. Analysis of one used butcher’s board estimated that 875g (30oz) had been lost from it by the end of its lifetime.
Scratched non-stick cookware can an also release an estimated thousands to millions of microplastic particles per use, making them another overlooked source within the kitchen. Even brand-new non-stick cookware used with a soft silicone whisk releases significant numbers of microplastics. Likewise, plastic mixing bowls and blenders release particles with each use. Blending ice around for 30 seconds, for example, releases hundreds of thousands of pieces of microplastic.
Silicone is sometimes suggested as a safer alternative to plastic utensils, but there isn’t concrete evidence that it sheds fewer microplastics, said Annelise Adrian, a senior program officer with the plastics and material science team at World Wildlife Fund.
“While silicone is technically more stable and withstands higher temperatures than single-use plastics, the issues of leaching and microplastics aren’t fully avoided,” Adrian said.
That said, considering its stability, she does use some silicone in her own kitchen.
Snekkevik notes that silicone does indeed degrade under very high heat. “So, it’s definitely a good alternative, and would require a bit more [than plastic] to fragment. But I wouldn’t feel comfortable saying, yep, go for silicone all the way,” Snekkevik said. Other alternatives for some kitchen items are glass and stainless steel, she notes.
There are also green-chemistry-based bioplastics which are designed to biodegrade (unlike traditional plastic) in both the environment and the body.
Green chemistry allows us to create plastic materials with fewer risks, said Paul Anastas, professor in the practice of chemistry for the environment at Yale University. “It’s benign by design,” he said.
However, many plastics, such as polylactic acid PLA straws, have been touted as biodegradable but turned out not to be. Sometimes these plastics simply fragment quicker into microplastics, Snekkevik said. “They’re not, you know, the golden, perfect alternative yet.”
Heat
As far as heat is concerned, hotter plastics get, the more microplastics they tend to release. One study found that plastic containers warmed in the microwave for three minutes could release up to 4.22 million microplastic and 2.11 billion nanoplastic particles from a single square centimeter of plastic. Using similar containers in the refrigerator can also release “millions to billions” of microplastics and nanoplastics – albeit over a much longer period of six months, the study found.
Putting a hot drink in a disposable plastic cup also generates microplastics. One study tested several varieties and found that cups made from polypropylene holding hot water at 50C (122F) released the most microplastics – for all types of cup, there was less contamination when the contents were cold. Examining the cups afterwards, the researchers found the hot contents had damaged the plastic surface. The team estimated that someone using disposable plastic cups once or twice a week might drink between 18,720-73,840 pieces of microplastic a year.
There’s a rule of thumb that happens to follow the famous cookbook Salt, Fat, Acid, Heat, written by chef and food writer Samin Nosrat. Adrian says that these four components can break plastic down into microplastics faster. In a plastic mixing bowl, water and salt releases threefold more microplastics than salt-free water, as the salt crystals rubbed against the bowl surface.
In addition, high fat foods also contain higher concentrations of certain additives from plastic that can be harmful to health, said Sheela Sathyanarayana, a professor of pediatrics and adjunct professor of environmental and occupational health sciences at the University of Washington and Seattle Children’s Research Institute.
Cleaning up
Disposable kitchen sponges are yet another source of micro- and nanoplastics. For those that had a harder and a softer surface, it was the former that came with a higher risk of shedding microplastics. As they wear down, kitchen sponges can release up to 6.5 million pieces of microplastics per gram.
Adding detergents and other cleaning products to a sponge may make the sponge release even more microplastics.
For other common plastic cleaning products, there’s still very little research on their microplastic release. Whether microfiber cloths release microplastics during cleaning was a much-overlooked topic of research at the time Snekkevik and her colleagues published their review in 2024.
However, synthetic textiles are well known to shed large quantities of microplastics, and they are thought to be a primary source of plastic pollution in the ocean.
What to do about a kitchen full of plastic
Snekkevik urges against a knee-jerk reaction of throwing away all your plastic kitchen utensils and appliances. “Even after writing this paper, I do still have certain items in my kitchen that are plastic,” she said. “I’m not going to just throw everything out and be like, that’s it.”
One strategy is to focus on items that show obvious signs of damage – such as anything obviously scraped, cut up, flaking or melted. When it appears to be time to change the item anyway, Snekkevik says she’ll generally choose a plastic-free replacement. “But I wouldn’t go through my kitchen and throw everything out right now, because that’s also not necessarily the environmentally friendly way to do it.”
Beyond your plate
Food and drink may be the most direct way microplastics get into our digestive systems, but it’s still far from clear what effect it has on us. The research to date on the health effects of microplastics in our guts is inconclusive and few studies have been done in humans. Some scientists have suggested it might disrupt the microbes that live in our guts or that some of the smaller particles may even pass into our blood stream. Some of this foreign material may simply become lodged inside our bodies.
“Fossil-based plastics, in their micro- and nano- forms, have been detected in virtually every organ in our bodies that have been studied, including arteries, brain, blood, placenta and testicles,” Anastas said..
It’s possible that much of the plastic inside us might not cause health issues, Sathyanarayana said. “The argument could be made that the particles can be lodged in a place and be inert in that area,” she says.
Adrian adds that there’s also no consensus on how long plastic stays in the body, or whether it accumulates over time. So the microplastics you’ve already eaten and drunk today might not be destined to stay in your body forever.
Indeed, at least some of the microplastics we regularly eat have been observed passing straight out the other end.
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