A new study by researchers at the University of Bayreuth in Germany reveals how microplastics hide in a cloak of biomolecules to enter the cells of living animals.
Published Wednesday in the journal Science Advances, the study shows how a piece of microplastic becomes increasingly efficient at attaching itself to and entering body cells within 2 to 4 weeks of being in an ocean or freshwater environment.
Testing the waters
The study found that older microplastic particles are internalized approximately 10 times more often" than newer particles. This essentially means that the longer microplastic beads are in the water, the more biomolecules they attach to.
As Inverse reports, the researchers used freshwater from an artificial pond, saltwater from a small aquarium, and water devoid of microorganism or other particles as a control.
In order to measure the change in microplastics in each of the three types of water, the researchers put samples of tiny particles — 3 micrometers in length — into the water and analyzed them after 2 hours, 2 weeks, and finally 4 weeks.
After 2 weeks, microplastics in both salt and freshwater showed substantial changes to their surface: the freshwater particles showed differences in the surface morphology of the beads, while the saltwater particles showed evidence of salts clustering on their surface.
The role of eco-coronas on microplastics
The scientists call these changes "eco-coronas." These form when a layer of biomolecules coats the microplastics, essentially hiding the artificial material in a cloak of natural material.
"Once biomolecules adsorb onto microplastic particle surfaces, they may function as a chemical stimulus for the attachment and internalization of those particles into cells," the authors write.
In tests with cultures mouse cells, this eco-corona "enhanced the cellular internalization of microplastic" particles into the mouse cells, the authors say.
The study highlights that the longer microplastics are in water, the more biomolecules they attract, leading to this harmful cloaking device. The biomolecules essentially allow microplastics to infiltrate animal cells by "tricking" them into thinking they are natural cells.
The researchers want to follow up on their work to look for further insight into the world of microplastics. However, in a world where there is so much plastic waster floating in our ocean that some of it almost has nation-status, this study already has wide-ranging implications for the environment and humanity.