Americans inhale the equivalent of a credit card’s worth of microplastics every week, study suggests

The average person in the West inhales the equivalent of a credit card’s worth of plastic every week, according to a study.

Microplastics, minuscule pieces of the man-made material, are shed by single-use plastics such as bottles and food packaging, which are then released into the air, water and food around us. 

Scientists have previously discovered microplastics in the lungs, brains and blood of living and deceased people, but how much plastic gets into our bodies is still debated. 

Researchers in Australia built a computer model to simulate how microplastics move through and settle in the airways when someone breathes. They found these toxic pollutants tend to collect in hotspots in the nasal cavity or the back of the throat, where they can easily travel deep in the airways.

They also found the average person breathed in 16.2 bits of microplastics every 24 hours, which the academics said was the equivalent to a bank card worth of the material each week.

Researchers say that we breathe in the equivalent of a credit card of microplastics every week (stock image)

Microplastics have been linked to the development of cancer, heart disease and dementia, as well as fertility problems. And there are fears they cause babies to be born dangerously underweight.

Dr Mohammad Islam, a data expert at the University of Technology Sydney who led the latest research, said: ‘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.

‘For the first time, in 2022, studies found microplastics deep in human airways, which raises the concern of serious respiratory health hazards.’

Researchers built a computer model that simulated the movement of ambient air through the human nasal cavity and trachea.

They included microplastic particles of three different shapes — spherical, tetrahedral and cylindrical. 

All were sized at less than six micrometers (microns). For comparison, human cells measure from six to eight microns across on average.

The particles were moved through the respiratory system at a slow speed, to represent standard breathing, and a rapid speed, to represent sharp intakes of air during strenuous exercise.

Results showed that the largest microplastics were more likely to become lodged in the airways than the smaller ones.

The nasal cavity was the place they were most likely to become lodged in.

But when someone was breathing more rapidly, it was less likely that microplastics of any size would become lodged.

The research could not show whether microplastics in the nasal cavity or trachea could then pass into the bloodstream.

But separate evidence has found that they can do this in the intestines after being ingested by humans.

There are concerns that microplastics lodged in the nasal cavity could lead to inflammation in the area or provide a surface on which bacteria may grow, raising the risk of infection.

Once in the bloodstream, they could travel to other areas inside the body where they may disrupt the functioning of cells and trigger inflammation.

Studies have suggested that they could raise the risk of DNA damage to cells and, as a result, the risk of someone developing cancer. 

The study was published on Tuesday in the journal Physics of Fluids.