Researchers at Hull York Medical School analyzed more than 50 studies conducted between 2014 and 2020 to investigate the amount of microplastics in fish and shellfish. The analysis revealed that mollusks such as oysters and clams have the highest levels of microplastic contamination.
“No-one yet fully understands the full impact of microplastics on the human body, but early evidence from other studies suggest they do cause harm,” said study co-author Evangelos Danopoulos.
“A critical step in understanding the full impact on human consumption is in first fully establishing what levels of microplastics humans are ingesting. We can start to do this by looking at how much seafood and fish is eaten and measuring the amount of MPs in these creatures.”
The researchers determined that microplastic content was as high as 10.5 microplastics per gram (MPs/g) in mollusks, 8.6 MPs/g in crustaceans, and up to 2.9 MPs/g in fish.
Consumption data shows that China, Australia, Canada, Japan and the United States are the largest consumers of mollusks, followed by Europe and the UK.
Among the mollusks examined for the study, those collected off the coast of Asia were the most heavily contaminated. This indicates that waters surrounding Asia are more heavily polluted by plastic.
“Microplastics have been found in various parts of organisms such as the intestines and the liver,” said Danopoulos. “Seafood species like oysters, mussels and scallops are consumed whole whereas in larger fish and mammals only parts are consumed. Therefore, understanding the microplastic contamination of specific body parts, and their consumption by humans, is key.”
By 2060, the amount of plastic waste produced annually is expected to triple to up to 265 million metric tons per year. Once the plastic makes its way into the ocean, it has the potential to be consumed by fish and marine mammals.
According to the researchers, more data is needed from different parts of the world to understand how the issue varies between different oceans, seas, and waterways.
The study is published in the journal Environmental Health Perspectives.