Humans inhale a credit card's worth of microplastics every week. Here's where it ends up.

A fanned stack of credit cards. Researchers estimate that humans inhale a credit card's worth of microplastics a week.
A fanned stack of credit cards. Researchers estimate that humans inhale a credit card's worth of microplastics a week. (Image credit: Peter Dazeley via Getty Imagescr)

Humans may be inhaling a credit card’s worth of toxic microplastics every week, and for the first time scientists have worked out where it ends up in your body. 

In 2019, a team of scientists estimated that up to 16.2 bits of microplastic enter our airways every hour — adding up to a credit card’s worth each week. Now, researchers have built on these findings to figure out how the plastic moves around our respiratory systems. 

Microplastics are tiny chunks of plastic debris measuring less than 0.2 inch (5 millimeters) long, according to the National Oceanic and Atmospheric Administration (NOAA). These broken-down remnants of industrial waste and consumer goods are impossible to avoid; they can be found across the ocean and the atmosphere, inside bottled water and even in human poop.

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There have been few studies into how toxic microplastics impact human health, especially respiratory health. However, recent studies suggest these tiny particles could pose serious health problems. Now, researchers have used a computer model to find the regions of our airways most impacted by breathing in microplastics. The scientists published their findings June 13 in the journal Physics of Fluids.

"For the first time, in 2022, studies found microplastics deep in human airways, which raises the concern of serious respiratory health hazards,” first author Mohammad S. Islam, a senior research fellow at the University of New South Wales, Sydney, said in a statement

The scientists built a computer model to analyze where the tiny chunks tend to travel inside our airways, and where they get deposited. 

By analyzing this circulation under slow- and fast-breathing conditions with three possible plastic shapes (spherical, tetrahedral, and cylindrical), the researchers found that the biggest chunks of microplastic — those measuring about 5.56 microns (one-seventieth the breadth of a human hair) — were the ones most likely to get lodged. The places these larger chunks tended to go were in the upper airways, such as in the nasal cavity and the back of the throat.

The full health impacts of microplastics on the human body are still unknown. However, microplastics have been shown to kill human cells, and cause bowel inflammation and reductions to fertility in mice.

Microplastics can also carry viruses, bacteria and other hazardous chemicals, which hitchhike on the plastic’s microscopic surfaces.

The researchers say their next steps will be to investigate how the plastics are deposited inside human lungs, taking into account factors such as humidity and temperature. They noted that microplastics are becoming increasingly ubiquitous.

"Millions of tons of these microplastic particles have been found in water, air and soil. Global microplastic production is surging, and the density of microplastics in the air is increasing significantly," Islam said.

Ben Turner
Staff Writer

Ben Turner is a U.K. based staff writer at Live Science. He covers physics and astronomy, among other topics like tech and climate change. He graduated from University College London with a degree in particle physics before training as a journalist. When he's not writing, Ben enjoys reading literature, playing the guitar and embarrassing himself with chess.

  • bolide2
    "the biggest chunks of microplastic — those measuring about 5.56 microns" --is a thousand times smaller than the "tiny chunks of plastic debris measuring less than 0.2 inch (5 millimeters) long" that was given as the size of the problem earlier in the article.

    I seriously doubt that I would fail to notice if I was inhaling pieces of plastic a fifth of an inch long.

    Please can somebody there do some editing?
  • Christophersullivan
    Hello, It appears that there might be an inconsistency or error in the article regarding the size of microplastic particles. The statement you provided states that the "biggest chunks of microplastic" are about 5.56 microns, which is indeed significantly smaller than the previously mentioned "tiny chunks of plastic debris measuring less than 0.2 inch (5 millimeters) long."
    If you have concerns about the accuracy or clarity of the information, it is recommended to reach out to the publisher or author of the article to address the issue and request clarification or correction. Editing or fact-checking the article would require access to the original source and context, which is not available here.