You do not inhale a credit card’s worth of microplastic every week

We inhale a credit card's worth of microplastics each week

A video from BBC Reel, a commercial organisation owned by the BBC, and an article on BBC Future claimed that people inhale a credit card’s worth of microplastic every week. This is a common claim that has been shared many times all over the world in recent months, including on social media—but it isn’t true.

Microplastics are tiny particles of man-made plastic that have spread into the environment. We can’t say quite how much microplastic people do inhale over an average week, but the idea that it’s a credit card’s worth seems to come from a blog that wrongly linked it to an article in the scientific journal Nature, which never made the claim in the first place.

The author of that paper told Full Fact that the true amount inhaled in a typical week is likely to be much, much less. Although his article didn’t describe the mass of microplastic inhaled, he told us that at the highest rate he recorded, inhaling a credit card’s worth would take thousands of years.

Publishers, including scientific publishers, should take care not to share information that could mislead people about the risks to their health. When mistakes happen, they should be corrected right away.

BBC Future removed the reference from its article and published a correction note after we got in touch, as did the Independent, Science Daily, LiveScience and Yahoo News, and Cordis deleted the article from its website. The Daily Mail and IFL Science told us that a correction was under way. The scientific publisher AIP also corrected a press release.

Where did the claim come from?

When we approached BBC Reel to ask about the claim, it told us that the source was a paper published in June 2023 in a scientific journal called Physics of Fluids.

And it’s true that the paper in question says in its introduction: “Research shows humans might inhale about 16.2 bits of plastic every hour, which is equivalent to plastics used to make a credit card in an entire week.” This claim was also used in the first line of a press release from the journal’s publisher, AIP.

To substantiate the claim, the Physics of Fluids article cited a blog on the website of IQAir, an air purification company.

But this blog in turn cited a 2019 research article in Nature, which did not substantiate the claim at all. Both the IQAir blog and the AIP press release have been corrected to remove this claim, after we got in touch. The AIP correction says that the statistic “was determined to be an overestimate, the actual amount is much lower”. It also told us that it is looking into the claim made in the Physics of Fluids paper.

A breathing thermal ‘manikin’

The Nature article describes an experiment with a breathing thermal ‘manikin’, essentially a device in the shape of a person designed to simulate human breathing and measure what it inhales.

The research team, who were based in Denmark, set up the manikin to collect samples in three different apartments. As the article says: “Synthetic fragments and fibres accounted, on average, for 4% of the total identified particles, while nonsynthetic particles of protein and cellulose constituted 91% and 4%, respectively.” The study suggested that the cellulose particles mostly came from paper and cotton, whereas the protein “most likely almost entirely came from shed skin”.

All three samples contained microplastic particles, with the highest concentration in one sample reaching 16.2 particles per cubic metre. (This did not mean it inhaled 16.2 particles per hour. The real hourly rate would have been about 11 particles.)

The article did not include an estimate of the mass of the synthetic plastic particles that would allow a comparison with credit cards. Nor did the article mention credit cards at any point.

Associate Professor Alvise Vianello, the lead author on the study, told us: “I don't know how this thing got stuck to this publication because there is not a single reference to mass estimation in it.”

Using data recorded during the research, however, Associate Professor Vianello told Full Fact he estimated that in the scenario with the highest concentration of microplastics, the manikin would have inhaled about 33,094 nanograms [billionths of a gram] per week. At this rate, he estimated that inhaling a 5g credit card’s worth would take about 3,000 years.  

“So I think we are very far from the 5g per week inhaled,” he said. “To be honest, this credit card thing sounds a bit like a joke to us.”

It’s important to remember that the Nature article is just one study. Other studies have found different rates, but none we can find comes close to a credit card per week.

Inhaling vs ingesting

It’s possible the confusion may have come from a similar statistic about ingesting—not inhaling—plastic, which has been widely quoted since it appeared in a report from the conservation charity WWF in 2019. That report claimed that “on average people could be ingesting approximately 5 grams of plastic every week”.

The report was based on different research, subsequently published in 2021, which produced several estimates for the amount of microplastic that might be found in various types of food and drink—and therefore how much someone might consume in a week.

The highest of the mean weekly estimates was 5.5g, which as WWF said, is roughly the mass of a credit card.

Other scientists have disputed this research, which they say may substantially overstate the amount of microplastic people would consume. (We have not attempted to assess these criticisms or the research ourselves.)

That said, the original study only attempted to quantify the amount of microplastics consumed by looking at those found in water, shellfish, fish, salt, beer, honey and sugar. It therefore doesn’t measure all the microplastics that people might consume in other types of food or drink, or in other ways.

Are microplastics harmful?

While there is general agreement that microplastics are present in the environment, and that they do sometimes get into people’s bodies, we still do not have clear answers to many important questions about them.

These questions include how much microplastic people consume, of what sizes and types, and how much they excrete or exhale afterwards. Crucially, we also don’t yet know how much harm they cause people.

Image courtesy of FlyD