Did you know global primary production of plastics exceeds 311 million tonnes per year, with 10 to 20 million tonnes finding its way to the oceans?
Once there, currents transport plastics around the ocean, meaning they can be found in coastal waters, estuaries, beaches and in deep-sea sediment. In fact, a study by the National Oceanography Centre estimates there is at least 10 times more plastic in the Atlantic than previously thought. Of course, plastics don’t just disappear once there are in marine environment. Larger pieces of plastics are broken down into smaller pieces by external forces such as UV radiation, wind, waves, or animals. These tiny fragments which are less than 5mm across, are called microplastics.
These microplastics are carried around by seafloor currents or bottom currents. The continuous, directed movement of sea water basically acts like conveyor belts, transporting these tiny plastic fragments and fibres across the seafloor. These currents can concentrate the microplastics within huge sediment accumulations, which they termed ‘microplastic hotspots‘. An international research project has revealed the highest levels of microplastic ever recorded on the seafloor, with up to 1.9 million pieces in a thin layer covering just one square metre!
Researchers at the Scottish Association for Marine Science found microscopic traces of plastic in 48 per cent of the sea starfish and sea snails they sampled from the Rockall Trough which is >2200 m deep. A range of plastics were identified with polyester being the most abundant plastic identified.
But microplastics also form floating layers in the oceans which looks like food for different specifies. Corals, zooplankton, invertebrates, fishes, seabirds and whales either ingest microplastics or are exposed to them indirectly as predators in food webs. Tests on anchovies show that when plastic is mixed with salt water and begins to disintegrate, it releases an odour which is similar to krill.
With marine life having a a diet of microplastics, it is inevitable for these plastics to end up in our own food chain.
In fact, according to the University of Ghent, the annual dietary exposure for European shellfish consumers can amount to 11,000 microplastics per year! But if you think that avoiding seafood will stop microplastics entering your body, think again! Honey, sugar, salt and drinking water distributed in plastic bottles all contain microplastics.
So what exactly are the effects on the human body?
While studies into how microplastics effect us is still in its infancy, there is evidence, at least in animals, that microplastics can cross the hardy membrane protecting the brain from many foreign bodies that get into the bloodstream.
There is also evidence that chemicals such as polychlorinated biphenyls (PCBs), and other chemicals are linked to harmful health effects, including various cancers, a weakened immune system, reproductive problems and more.
One way to reduce microplastics in our seafood is to spread awareness and tackle the problem of littering. At GreenSeas Trust we do just that. Read more about our BinForGreenSeas project to find out how.