You guys don’t regularly consult the Monterey Bay Seafood Watch Consumer Guides to determine which seafood is ecologically best to consume? Couldn’t be me. Maybe you’ve been out here thinking all ocean critters are created equal, but you’re dead wrong. Not only are some of the easily-available filets, crustaceans and shellfish on the market actually an environmental disaster, many of them are also potentially filling you with microplastic. And according to new research from the University of York and the University of Hull, mollusks like oysters, mussels and scallops may actually be the worst offenders of all.
Scientists at Hull York Medical School analyzed more than 50 studies conducted between 2014 and 2020 for global plastic contamination in fish and shellfish. They found that mollusks contained the most plastic — up to 10.5 pieces of microplastic per gram. Fish, meanwhile, contained 2.9 pieces of microplastic per gram at their highest, and crustaceans contained 8.6.
Per the data, not all mollusks, fish or crustaceans contained that level of microplastic, and levels varied dramatically depending on region. In some samples, there was no microplastic present at all. The mollusks with the highest amount of microplastic were collected off the coast of Asia, according to the study, potentially from areas with a significant amount of plastic pollution overall.
What’s particularly concerning about the elevated levels of microplastic in mollusks is that, unlike a fish, we tend to eat the entirety of the creature. In fish, the microplastics tend to be concentrated within the intestines and the liver, which we can avoid eating should we choose to. In something like an oyster, however, we’re tossing back the creature whole. Though we may consume fewer grams of mollusks overall than we do fish, we might still be taking in a lot more plastic, anyway.
Currently, we have no concrete idea what consuming all this plastic actually does to the human body. Odds are… it’s not great. Some potential theories include that the plastic may be tainting our bloodstream and cardiovascular system, infusing our body with toxins and pollutants the plastic absorbed prior to being ingested, triggering a systemic inflammatory response and disrupting all of our hormones.
So, until we know for sure, it’s probably best to avoid eating plastic where we can. Farmed seafood tends to have fewer microplastics than wild-caught, though they may still contain some. Given the ability to control the conditions of farmed seafood and the shorter lifespans of seafood raised on farms compared to wild-caught, it is likely a safer choice. More than that, though, it’s actually a more ecologically-sound one. Seafood Watch lists farmed scallops, oysters and mussels as a “best choice” for well-managed and responsibly-farmed seafood. If you insist upon wild-caught, they recommend Canadian oysters. For a full list of their recommendations, I highly recommend downloading their guide. Seriously, I keep it in my wallet!