In a recent study, a team analyzed five different kinds of seafood and found traces of plastic in each sample tested. Plastic frequently ends up in waterways and oceans, where they eventually break down into microplastics that are consumed by marine creatures of all types and sizes. Plankton absorb microplastics, which bioaccumulate as they move up the food chain, and eventually, we are buying it from the market or a restaurant, and it ends up on our plates.
Researchers from the University of Queensland (UQ) and the University of Exeter, purchased raw samples of seafood from a market in Australia, including ten wild squids, ten farmed tiger prawns, ten oysters, ten wild sardines, and five wild blue crabs. Trace levels of plastic contamination were identified in each sample, with the highest amount found in sardines.
To better understand the potential harm microplastics could have on human health, the team used a new technique to pinpoint and measure five different kinds of plastic within the tissues of each sample simultaneously. The study, published by in Environmental Science & Technology, found greatly varying quantities of plastic in each of the different seafood types tested, as well as in the individual species.
Francisca Ribeiro, the lead author of the study, said in a UQ press release:
From the edible marine species tested, sardines had the highest plastic content, which was a surprising result. Another interesting aspect was the diversity of microplastic types found among species, with polyethylene predominant in fish and polyvinyl chloride, the only plastic detected in oysters. Considering an average serving, a seafood eater could be exposed to approximately 0.7mg of plastic when ingesting an average serving of oysters or squid, and up to 30mg of plastic when eating sardines, respectively. For comparison, 30mg is the average weight of a grain of rice.
Since this new technique allows results to be reported in a mass unit, which wasn’t possible before, it’s a significant step forward towards plastic quantification methods in seafood. “We can now define what microplastic levels can be considered harmful to human health,” Ribeiro added.
The plastic found in the samples is commonly used in synthetic fabric and plastic packaging, including polyvinyl chloride, polypropylene, poly (methyl methacrylate), polyethylene, and polystyrene. The plastic found in the highest levels was the world’s most famous plastic – polyethylene, while polyvinyl chloride was found in each sample.
Tamara Galloway, a co-author of the study, said:
We do not fully understand the risks to human health of ingesting plastic, but this new method will make it easier for us to find out.
According to UQ, the next steps of the research include identifying the origin of the plastic contamination found in the seafood tested.
