Millions of tons of plastic refuse have entered our oceans annually since about 1950, forming what is known as the Great Pacific Garbage Patch (GPGP). The GPGP isn’t a landfill-like continent made of plastic, but it’s true that, due to current convergence, there is a higher concentration of plastic there than other parts of the ocean. These seem to originate from Asia, North America, and South America. Other collections of debris exist in the South Pacific, the Indian Ocean, and the North and South Atlantic.
Within the GPGP, several areas contain more visible plastic than others. There’s an Eastern Patch, a Western Patch, and a convergence zone of plastic waste that, perhaps, hasn’t yet decided where it will end up. Wherever it goes, there’s a negative effect on wildlife from sea turtles to ocean-going birds to whales.
You might be shocked to know that, despite millions of tons of debris floating in the water, there should be much more, given the amount that is sent there. Huge amounts of plastic wind up in the ocean every year. Where did it all go?
The answer is that the visible trash isn’t the only plastic in the ocean. Some may be on the sea floor, but it’s the tiny bits of plastic smaller than 5 mm, known as microplastics, suspended in the water column that are most hazardous to your health. Think of it as flecks of pepper floating in a bowl of soup. Much of the missing plastic may be such particles. Even smaller ones, microscopic in size, exist in the ocean known as nanoplastics.
All these may have originated from larger floating plastics that have broken up over time. Exposed to UV sunlight for long enough, plastic becomes brittle and breaks into fragments. The resulting microplastic particles are dispersed at all depths.
The concern about these particles is the fact that they tend to end up in our seafood. A new study in collaboration with the UK’s University of Exeter and Australia’s University of Queensland analyzed seafood for the presence of plastics. They found microplastics in every item of seafood sampled. The five types of plastics most commonly identified:
- polyvinyl chloride
- polymethyl methacrylate
These plastics are commonly found in packaging and manufactured synthetic textiles.
The lead researcher of the study, published in the journal Environmental Science and Technology, said: “Considering an average serving, a seafood eater could be exposed to approximately 0.7 milligrams (mg) of plastic when ingesting an average serving of oysters or squid, and up to 30 mg of plastic when eating sardines.”
Despite washing each sample to remove any plastic associated with packaging, the study found:
-0.04 mg of plastic per gram of tissue in squid
-0.07 mg per gram in shrimp
-0.1 mg per gram in oysters
-0.3 mg per gram in crabs
-2.9 mg per gram in sardines.
Every item contained some polyvinyl chloride. The highest amounts came from polyethylene. Each sample, however, varied in the quantity and type of plastic found.
It appears that plastics ingested by seafood progresses to edible parts. Other ways that microplastics may end up in food could be airborne particles, machinery, and handling during the processing phase.
As about 17% of the protein consumed by humans consists of seafood, the findings suggest that those who regularly eat seafood are also eating plastic. It’s possible that humans may be consuming 39,000-52,000 microplastic particles every year. It’s not only in seafood; micro- and nanoplastics have been found in beer, honey, sea salt, and even bottled water.
It’s uncertain how toxic the ingestion of microplastics is, but it’s very unlikely that there’s any benefit. Since we can test for the presence of microplastics in food, we should consider making it part of labeling so that the public knows just what it’s consuming. The answer to the problem, however, is preventing plastics from making it to the open ocean before they break down into microplastics. How do you think we can best decrease plastic pollution?
Joe Alton MD
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