There's Plastic in Your Favorite Shellfish

CC BY 2.0. Lachlan Hardy

Researchers in British Columbia find an average of 8 plastic microfibers per delicious bivalve.

That yummy-looking bowl of oysters or clams may become less appetizing once you realize what is in them. As discovered by researchers on Canada's west coast, most shellfish contain plastic microfibers, regardless of whether they're wild or farmed.

The study was led by professor Sarah Dudas from Vancouver Island University and funded by the Canadian government and the British Columbia shellfish trade association, which is concerned about the use of plastics in its own industry. NPR writes: "The project aimed to learn whether the shellfish aquaculture industry may be contaminating its own crop by using plastic infrastructure like nets, buoys and ropes."

In 2016 Dudas and her students planted thousands of oysters and clams along the coastline of B.C.'s Strait of Georgia. The shellfish were left to soak in the seawater for three months, where they absorbed whatever was in their surroundings. Then they were collected, dissolved in chemicals, and filtered. An average of 8 plastic microfibers were found in each bivalve and the residual plastic particles were gathered for further analysis.

It should not come as a surprise that there is abundant plastic in the ocean; indeed, this is one of the hottest environmental topics of the day, with terrifying predictions being made of more plastic in the ocean than fish by weight by 2050. But less well understood is where it's all coming from and how much is there now.

Another B.C. researcher, Peter Ross, director of the Vancouver Aquarium's Ocean Pollution Research Program, found up to 9,200 microplastic particles per cubic meter of seawater in 2013. NPR describes it as equivalent to emptying a salt shaker into moving boxes -- a significant amount.

While all sorts of plastic particles are found in seawater, from tiny polystyrene beads (used to fill bean bag chairs) to nurdles (raw material used to make plastic products) to microbeads (found in cosmetics and toothpaste), it is microfibers that appear most commonly in shellfish. These are analyzed using a forensic machine called the "Fourier-transform infrared spectroscopy." NPR explains how it works:

"The machine scans individual particles with infrared light and generates a line graph on a nearby computer. Then the program cross-references that graph with a global database of other squiggly lines. One piece of fabric pulls up a list of probable matches — fibers with names like Zeftron 500 and Wonder Thread. They're types of nylon. Other fibers bring up generic and commercial names for olefin and polyester. The data can't pinpoint a fiber's exact source, but taken in aggregate can point to larger trends about the presence of microplastic pollution in the ocean."

A significant source of these microplastics appears to be laundry. Every load of synthetic clothing empties an estimated 1.7 grams of microfibers into the water stream, and these are not filtered out at treatment plants. As marine creatures ingest these fibers, there is concern about the longterm effects of eating them. (One might say this is a good argument for veganism!) There are additional concerns, too:

"There are some indications that those plastics can act as vectors for chemical pollutants and pathogens, and other researchers are studying whether plastics leave the human body after being eaten."

So far, Dudas isn't too worried, since the quantities of microplastic in shellfish to date aren't exceedingly high; but still, it's unsettling to think of what's there -- and was never meant to be.