A CONCERN FOR HUMAN HEALTH
The fact that microplastics can accumulate in body tissues could also mean that more plastic particles are transferred further up the food chain to top predators like humans than is currently thought.
It’s generally believed that only very small microplastics (particles less than 100 microns) can move from the gut or respiratory system into the bloodstream. This would limit the amount of microplastics that are consumed when eating marine vertebrates.
But the US study has found the presence of larger microplastic particles in non-digestive tissues, suggesting this assumption might not hold true. Separate studies in the Persian Gulf and Black Sea have also revealed a variety of microplastic sizes present in non-digestive tissues of commercial fish.
Together, these findings could have implications for human health. Marine mammal meat and blubber are an important food source within certain Indigenous communities. And many people consume fish as part of their diets.
The risk of ingesting microplastics from a seafood meal is, at present, lower than that from drinking bottled water. But the prevalence of microplastics in the marine environment is rapidly increasing, and it is now evident that these particles can enter the bloodstream of animals and humans too. Research has found microplastic particles in human blood samples and in human placenta.
Laboratory studies have managed to highlight the generally negative impacts of microplastic exposure on small fish and invertebrates. However, we still lack a full understanding of the consequences of microplastic ingestion for larger mammals such as whales, dolphins, and humans.
What we are certain of is the escalating abundance of microplastics in the marine environment – our oceans are now filled with more than 170 trillion plastic particles. Efforts to stop the flow of plastic into the marine environment are urgently required.
Samantha Garrard is Senior Marine Ecosystem Services Researcher, Plymouth Marine Laboratory. This commentary first appeared on The Conversation.