by Ally Hirschlag and Martha Henriques
BBC
(Part 1 of 2)
You can’t see them, but they are there, hundreds of miniscule particles of plastic lurking in your steak. As it cooks in a hot pan, these unwelcome guests liquify, oozing into the meat before solidifying again as it cools down on your plate.
And they’re not just in steak. Unwittingly, you are eating them all the time.
These interlopers in our food are microplastics and nanoplastics, particles of less than 5mm or between 1 and 1,000 nanometres respectively. But how do they get into our food? And, in a world infused with bits of plastic, what can we do to reduce exposure in our diets?
If you take a closer look around your kitchen, you’ll start to recognize where microplastics enter our meals: they flake off the spatula you use to cook breakfast, leak from the plastic water bottle you put in your child’s backpack and float in the cup of tea on your desk. They’re also buried deep within the foods we eat, from hamburgers to honey.
Once you start looking for them, the exposure points for microplastics can quickly feel overwhelming. But, importantly, it is also possible to make changes to reduce the amount of microplastics we are exposed to in our kitchens.
“There’s a lot of low-hanging fruit in your house that’s really easy to address,” 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.
“I do feel like it gives people a sense of control over their own lives, and we do have that a little bit more than we might think.”
Food
Microplastics are in fruit and vegetables, honey, bread, dairy, fish and meat from hamburgers to chicken. They are inside the yolks of eggs (and in the whites too).
One study of 109 countries found the amount of these plastics people typically consumed in 2018 was more than six times what it was in 1990. Microplastics can get into our food when plants take them in by the roots, or animals consume them in feed.
“If you farm on a piece of land that was previously industrial and the soil is contaminated, [there is] potential for those plants to accumulate the contaminants in the soil,” Sathyanarayana said. Once that the crops are harvested, there are many more opportunities for contamination during processing. “Factories use a huge amount of plastic to be effective and to have high throughput for their products.”
For some foods, it is possible to get rid of some of the microplastics before you eat them. One study in Australia found that people were typically consuming 3-4mg of plastic per serving of home-cooked rice, and up to 13mg per serving of pre-cooked rice. The microplastics were just as present in rice that was packaged in paper, as in rice that came in plastic packaging. However, the researchers found that rinsing the rice reduced the microplastics served up by 20-40 percent. Washing meat and fish can also reduce microplastics – but will not eliminate them.
For other foods, rinsing is impossible. Salt often contains microplastics due to contamination at mining and processing points. A 2018 study found that 36 out of the 39 salt brands analyzed contained microplastics. Sea salt had the highest levels of microplastics, likely due to the high levels of microplastic pollution in the world’s lakes, reservoirs, rivers and oceans.
Both Sathyanarayana and Annelise Adrian, a senior program officer with the plastics and material science team at World Wildlife Fund, are proponents of switching to fresh, whole foods or, at the very least, avoiding ultra-processed foods whenever possible.
“The more ultra-processed a food is, the more likely it is to have high plastic contamination, because there are so many touch points in a factory making that food,” Sathyanarayana said.
Reducing the amount of plastic in the food chain will take more than changes within our individual kitchens. Globally, if the amount of plastic debris polluting the environment were cut by 90 percent, it could halve the amount of plastics consumed by people in the most affected countries.
“Plastic is a cheap, great material,” said Vilde Snekkevik, a marine biologist and microplastics researcher at the Norwegian Institute for Water Research. “The problem is just that we’re overusing it. It’s everywhere.”
Water
Whether it comes from a tap or from a bottle, water is another notable point of exposure to microplastics. One study found the simple act of screwing a plastic bottle cap on and off dramatically increased the amount of microplastics found in the water it carried. With each twist on or off, it generated 553 microplastic particles per liter of water.
“Studies are coming out showing that there are way more micro- and nanoplastics in bottled water than previously thought,” Adrian said.
The plastic inside us
The physical presence of microplastics in the body is of particular interest due to their sheer prevalence in our bodies – including one recent study finding there’s up to a spoonful-sized amount in an average human brain.
Microplastics are also commonly found in tap water. One UK study found them in all 177 samples of tap water tested, with no distinguishable difference in microplastics concentration with bottled water. Similar findings in China, Europe Japan, Saudi Arabia and the US suggest this is a worldwide problem.
But if given the option, drinking tap water may be a better way to reduce microplastic exposure, where supplies are safe to do so. Adrian says investing in a decent filter makes a noticeable difference. Even a simple carbon filter, such as the one found in a water filter pitcher, can remove up to 90 percent of microplastics.
However, even if your water is low in microplastics, if you’re planning to add a plastic-containing tea bag to make a cup of tea, it can release around 11.6 billion pieces of microplastic and 3.1 billion pieces of nanoplastic into your cup. Plastic is often used in small quantities to help seal bags that are otherwise made of paper. Some manufacturers have moved to plastic-free bags.
Packaging and containers
Then there’s the plastic that much of our food comes packaged in. “Food stored in plastic inevitably will contain microplastics,” Adrian said. “That can also include plastic-lined aluminum cans, like a can of beans.”
Simply opening plastic packaging releases a burst of microplastics. Whether you use scissors, tear a packet open with your hands, cut it with a knife or twist a lid off, it can generate up to 250 bits of microplastic per centimeter, an Australian study found. “Needless to say, repeated scissoring/cutting/sliding processes at the same position are akin to sawing to generate mulch,” the study authors note.
The age of a plastic container can also make a difference. A study in Malaysia looked at reusable melamine bowls, to find that after 100 washes the microplastic release was an order of magnitude higher than after the first time the bowl was washed. (Other materials, such as silicone, may behave differently as they age.)
Even if food is only in a container for a short time, there is still ample opportunity for contamination. In China, a study of microplastics from several different types of takeaway food containers estimated that people who have five to 10 takeaways per month might be consuming 145.5-520 pieces of microplastic from the containers their meals come in.
Silicone is a different type of polymer you can find in the kitchen, but this too can break down at high temperatures.
Tomorrow: what to do about a kitchen full of microplastics.
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