The latest development in this area comes from scientists in the Netherlands who have used novel analytical tools to produce the first evidence of plastic particles being absorbed into the bloodstream.

When plastic waste like bags and bottles enter the environment, natural forces like ocean currents, wind and UV light cause them to break down into smaller fragments called microplastics. And these are incredibly troublesome, both because they make it hard for scientists to track their path through the environment and because they can be taken up by living organisms.

We've seen the detrimental impacts on marine creatures, with microplastics found to cause aneurysms in fish and cognitive impairment in hermit crabs. We also now know that they make their way into the human body, with studies on human tissue and stool finding plastic particles in every sample.

The research team behind this new study sought to build on this by investigating the potential presence of plastics in human blood. To do so, the scientists came up with a novel method involving the use of mass spectrometry to inspect human blood for tiny plastic particles.

This technique was applied to samples from 22 healthy donors with the scientists on the lookout for five different polymers that are considered the building blocks of plastic. Three quarters of the subjects were found to have plastic particles in the blood, serving as the first evidence that the material can end up in the human bloodstream. The average concentration was 1.6 micrograms per milliliter, around a teaspoon of plastic to every 1,000 liters of water.

"We have now proven that our bloodstream, our river of life as it were, has plastic in it," said Heather Leslie from Vrije Universiteit Amsterdam.