Tuesday, October 21, 2025

Microplastics Are Everywhere

You can do one simple thing to avoid them.

If you are concerned about microplastics, the world starts to look like a minefield. The tiny particles can slough off polyester clothing and swirl around in the air inside your home; they can scrape off of food packaging into your take-out food.

But as scientists zero in on the sources of microplastics — and how they get into human bodies — one factor stands out.

Microplastics, studies increasingly show, are released from exposure to heat.

“Heat probably plays the most crucial role in generating these micro- and nanoplastics,” said Kazi Albab Hussain, a postdoctoral researcher at the University of Nebraska at Lincoln.

Pour coffee into a plastic foam cup, and pieces of the cup will leach out into the coffee itself. Brew tea, and millions of microplastics and even tinier nanoplastics will spill from the tea bag into your cup. Wash your polyester clothing on high heat, and the textiles can start to break apart, sending microplastics spinning through the water supply.

In one recent study by researchers at the University of Birmingham in England, scientists analyzed 31 beverages for sale on the British market — from fruit juices and sodas to coffee and tea. They looked at particles bigger than 10 micrometers in diameter, or roughly one-fifth the width of a human hair. While all the drinks had at least a dozen microplastic particles in them on average, by far the highest numbers were in hot drinks. Hot tea, for example, had an average of 60 particles per liter, while iced tea had 31 particles. Hot coffee had 43 particles per liter, while iced coffee had closer to 37.

These particles, according to Mohamed Abdallah, a professor of geography and emerging contaminants at the university and one of the authors of the study, are coming from a range of sources — the plastic lid on a to-go cup of coffee, the small bits of plastic lining a tea bag. But when hot water is added to the mix, the rate of microplastic release increases.

“Heat makes it easier for microplastics to leach out from packaging materials,” Abdallah said.

The effect was even stronger in plastics that are older and degraded. Hot coffee prepared in an eight-year-old home coffee machine with plastic components had twice as many microplastics as coffee prepared in a machine that was only six months old.

Other research has found the same results with even smaller nanoplastics, defined as plastic particles less than one micrometer in diameter.

Scientists at the University of Nebraska, including Hussain, analyzed small plastic jars and tubs used for storing baby food and found that the containers could release more than 2 billion nanoplastics per square centimeter when heated in the microwave — significantly more than when stored at room temperature or in a refrigerator.

The same effect has been shown in studies looking at how laundry produces microplastics: Higher washing temperatures, scientists have found, lead to more tiny plastics released from synthetic clothing.

Heat, Hussain explained, is simply bad for plastic, especially plastic used to store food and drinks.

by Shannon Osaka, Washington Post |  Read more:
Image: Yaroslav Litun/iStock