Since the beginning of the third millennium, the amount of plastic waste has tripled, with the oceans receiving approximately 8 million tons of plastic annually. If humanity continues to adopt current behaviors of using plastic and dumping it into the water, the oceans could contain more plastic waste than fish by 2050, according to a UN Environment report.
Microplastics, known as microplastics (MPs), pose a threat to human health, and studies have identified their contamination of seafood as a threat to global food security.
What are MPs?
Once plastics reach water sources, they are degraded by ultraviolet radiation, high temperatures, photo-oxidation, and ocean waves, turning into microplastic particles called MPs.
These particles are environmental pollutants that are widespread in all aquatic environments. They are plastic fragments less than 5 mm in size, including plastic debris that can reach very fine particles.
Humans can be exposed to these substances through the consumption of contaminated foods, including seafood, table salt, and drinking water, as well as agricultural products such as fruits and vegetables that are exposed to water contaminated with microplastics.
MPs are made from a combination of chemicals, and the transport of these chemicals into body tissues, after ingestion, can lead to intestinal damage or poisoning.
There is currently no comprehensive data on the presence of microplastics in fish tissue, their quantities, and the routes through which they are transmitted to humans. Recent studies aim to detect and quantify the amount of microplastics present in seafood consumed by humans.
Pacific Northwest Study
A recent study conducted by Portland State University in Oregon, on the US West Coast, found widespread contamination of microplastics in popular fish and seafood in the Pacific Northwest.
Oregon boasts numerous fisheries, a significant part of the state's coastal economy and fishing culture. Therefore, there is growing interest in scientific research related to seafood, which recently revealed the presence of plastic particles within the tissues of six economically and culturally important fish species, including salmon, one of the healthiest natural wild foods and deeply rooted in the diet of the region's indigenous peoples.
The research team collected 182 fish samples, including 122 finfish and 60 crustaceans and mollusks, from the state's coast and retail markets. After microscopic examination, the team found plastic particles in the muscle tissue of 180 fish, representing approximately 99% of the total sample.
According to the study, pink shrimp had the highest concentrations of plastic waste accumulated within their tissues, due to their proximity to the water surface, where floating waste is concentrated.
When comparing fresh shrimp to store-bought samples, researchers found that store-bought shrimp contained more fiber and plastic film, which they attributed to the plastic wrap around the fish.
The American study, published in the journal Frontiers in Toxicology, highlighted the colors of the plastic fragments found within the fish sample. The most common colors were: Blue, then black, followed by clear and white plastic, she said, stressing that the variety of sizes and colors indicates the different sources of pollution in aquatic environments and the difficulty of identifying them.
Environmental scientist Susan Brander of Portland State University says that it's concerning that microplastic fibers are moving from the gut into other tissues like muscle, and this has broad implications for other organisms, including humans.
Scientists have recently observed that people who eat more seafood have more microplastics in their bodies, especially those who consume shellfish such as oysters or mussels. However, the health effects of these plastics on the body and how long they remain in living organs are still unknown, requiring urgent research.
The analysis conducted in Oregon is considered the first of its kind in the Pacific Northwest, but it joins other studies that have found microplastics in seafood fillets in various parts of the world, including the Mediterranean basin, which borders several Arab countries.
The Mediterranean sea
A research collaboration between the University of Catania in Italy and the Universities of Sousse and Monastir in Tunisia has revealed the presence of microplastic particles (MPs) in the edible muscles of five species of fish from the southern Mediterranean coast.
The Tunisian-Italian team began collecting samples from the Tunisian coast and the local markets of Sousse. The species under investigation were:
- European pilchard sardine
- Sea bream
- Red striped bourbon
- Mediterranean mussels
- Sole fish
The analysis revealed the presence of microplastic particles in abundant quantities in all five fish meat samples from the southern Mediterranean coast, with particle sizes varying. Plastic fragments tend to bioaccumulate in organisms and within muscle tissue.
The research team found the highest levels of microparticles (MPs) in red mullet, which is most exposed to plastic waste because it lives in shallow waters, followed by sole fish.
Scientists aren't saying people should stop eating seafood altogether, but it's important for consumers and scientists to understand their exposure to fine particles, because these pollutants are ubiquitous—in the air, water, and many foods other than seafood—because what humans put out into the environment comes back into the environment.
Some researchers are currently working on ways to stop the discharge of plastic waste into the sea, but the only effective way to stop the flow of plastic is to not use plastic.
