The amount we absorb is only increasing as ocean pollution worsens...
If you're a seafood fan, you've been absorbing tiny pieces of plastic into your bloodstream that could impact your health.
The plastic fragments, measuring less than a millimetre across, are widely found in mussels, oysters and other shellfish.
A comprehensive, scientific risk assessment seen by Sky News has revealed that more than 99% of the microplastics pass through the human body – but the rest are taken up by body tissues.
Europeans are currently consuming as much as 11,000 pieces of plastic in their food every single year, according to researchers fro the University of Ghent in Belgium.
Fewer than 60 of these are likely to be absorbed, but they will accumulate in the body over time. The amount of plastic absorbed in food will only increase as plastic pollution in the world's oceans gets worse.
Dr Colin Janssen, who led the research, told Sky News the presence of plastic particles in the body was "a concern".
"Now we've established that they do enter our body and can stay there for quite a while, we do need to know the fate of the plastics.
"Where do they go? Are they encapsulated by tissue and forgotten about by the body, or are they causing inflammation or doing other things?
"Are chemicals leaching out of these plastics and then causing toxicity? We don't know and actually we do need to know."
Mussels feed by filtering around 20 litres of seawater a day, ingesting microplastics by accident.
Most are excreted, but on average each mussel contains one tiny fragment lodged in its body tissue. As plastic pollution builds up in the ocean that will increase. By the end of the century people who regularly eat seafood could be consuming 780,000 pieces of plastic a year, absorbing 4,000 of them from their digestive systems.
Dr Janssen said:
"The next generation or two generations might say they left us a rotten plastic legacy because now we are suffering in various ways from that legacy.
"We have to do something about it. We have to act now."
There are more than five trillion pieces of microplastic in the world's oceans and the equivalent of one rubbish truck of plastic waste is being added to the sea every minute. By 2050 that will increase to four trucks every minute.
The plastic in the ocean will take decades or even centuries to break down into small pieces, but many scientists believe it will never completely disappear.
Professor Richard Thompson, a marine biologist at Exeter University, said:
"Hundreds of marine organisms encounter plastic at the sea surface or in the water column, and many of those encounters are harmful if not fatal.
"The scale has passed the critical point. There is enough evidence that we need to take action now."
A documentary on the extent of the dangers posed by plastics in oceans, A Plastic Tide, airs on Sky Atlantic at 8pm tonight or on Sky News at 8pm on Wednesday.
Additional reporting by IRN