Many of us have plastic dust flowing through our veins.

The results of the latest study looking for microplastic pollutants in human tissues shouldn't come as a surprise by now. Virtually no place on Earth is free of the polymer fog, after all, from the highest of mountains down to our most intimate organs.

Yet knowing it permeates our very blood brings a new awareness of just how much plastic waste has become an expanding ecological issue.

Researchers from the Vrije Universiteit Amsterdam and the Amsterdam University Medical Center analyzed blood samples taken from 22 healthy anonymous donors for traces of common synthetic polymers larger than 700 nanometers across.

After the team went to great lengths to keep their equipment free of contaminants and test for background levels of plastics, two different methods for identifying the chemical make-up and masses of particles uncovered evidence of several plastic species across 17 of the samples.

Though the exact combinations varied between samples, the microplastics included polyethylene terephthalate (PET) – commonly used in clothing and drink bottles – and polymers of styrene, often used in vehicle parts, carpets, and food containers.

On average, 1.6 micrograms of plastic material were measured for every milliliter of blood, with the highest concentration being just over 7 micrograms.

The researchers couldn't give a precise breakdown of the particle sizes due to the limitations of the testing methods. It's safe to presume, however, that smaller particles closer to the 700 nanometer limit of the analysis would be easier for the body to take in than larger particles exceeding 100 micrometers.

Precisely what all of this means for our health and wellbeing in the long term isn't fully clear.

On one hand, there's still so much we just don't know about the chemical and physical effects of tiny plastic materials nestled among our cells. Animal studies hint at some seriously concerning effects, but interpreting their results within a human health context is far from straight forward.

Nonetheless, the problem is a growing one, with plastic waste entering our oceans set to double by 2040. As all of those discarded shoes, forks, bread tags, steering wheels and chocolate wrappers break up, a greater concentration of microplastics will gradually find its way into our bloodstream.

If it's the dose that makes a poison, it's possible we might cross a line at some point where relatively harmless traces of styrene and PET could start to have some alarming effects on the way our cells grow. Especially during development.

"We also know in general that babies and young children are more vulnerable to chemical and particle exposure," Dick Vethaak, an ecotoxicologist at Vrije Universiteit Amsterdam, told The Guardian's Damian Carrington.

"That worries me a lot."

Keeping the small number of volunteers in mind, it's further evidence that the dust produced by our synthetic world isn't completely filtered by our lungs and gut.

There's also the question of whether the plastics are free-floating in the plasma, or have been gobbled up by white blood cells. Each scenario would have ramifications on how particles move about and what bodily systems they might affect most.

A lot more research will be needed on larger, more diverse groups to map just how and where microplastics spread and accumulate in humans, and how our body eventually discards them.

This research was published in Environment International.