Do we eat the plastic that fish eat? Yes, and also its contaminants

The crisis generated by the dumping of pellets off the coast of Portugal and Galicia (Spain) these days returned the informative focus to one of the main environmental problems of the planethe plastic that floods the oceans. The fish eat it, but does it reach the consumer?

Recent scientific studies show that yes, with fish we can ingest plastic particles and contaminants that these materials carry from the factory and also others that they have acquired during their drift in the sea.

In scientific journals there are dozens of articles that explain how pellets – and the rest of the microplastics and synthetic fibers present in the sea – enter the food chain, because various marine organisms ingest them, either by accident or because they confuse them with the zooplankton on which they usually feed.

In the well-known sequence “the big fish eats the small one”, These fragments climb the food chain in the oceans, but do they reach our table? Do we ingest them, or do they remain confined in the digestive system of the fish, which is not normally consumed?

The Research Institute for Sustainable Aquaculture and Marine Ecosystems (Ecoaqua) of the Spanish University of Las Palmas de Gran Canaria (ULPGC) has been working on the project for years. “Microtrophic”which has made it one of the scientific references on marine microplastics, their contaminants and their potential effects on fauna and, at the end of the chain, on humans.

And this is because the Spanish archipelago of the Canary Islands receives tons of microplastics from all over the world on its beaches every year, which float for decades dragged by currents and large ocean gyres until they hit land.

In this movement, plastics not only fragment into smaller and therefore more dangerous pieces, but they also become loaded with persistent organic pollutants that exist in all oceans, which literally stick to them and can be toxic to humans. from certain levels of intake and concentration.

In the particles of this type collected on the coast of the Canary Islands – and also in the pellets, which for example represent a 40% of the plastic garbage on Famara beach, on the Canary island of Lanzarote, Ecoaqua found 80 different contaminants, from ultraviolet filters in sun creams to remains of pesticides that have been banned for years, but that are still in the environment, such as DDT, passing flame retardants (María Camacho and Alicia Herrera, in Science of The Total Environment, April 2019).

These last ones, the retardants, many plastics already have in their original composition, also the pellets, they do not need to adhere to them in the sea.

But is it general or just specific that commonly consumed fish ingest plastics? This scientific group from the University of Las Palmas de Gran Canaria published works that give an idea of ​​the extent of the problem: 80% of wild mackerel caught on the islands have plastic in their stomach (A. Herrera and A. Stindlova in Marine Pollution Bulletin, February 2019) and the same 65% of farmed sea bass from offshore farms (S. Reinold and A. Herrera, Marine Pollution Bulletin, July 2021).

That these fragments and fibers can pass into the tissues (the ‘meat’ what the consumer eats) was already known, but one of the most recent works of this team demonstrated for the first time that its contaminants (those from the factory and those absorbed from the sea) accumulate in the liver of fish. That is, they entered your metabolism.

To do this, Ecoaqua fed fish in its laboratories with pellets fresh from the factory (made of low-density polyethylene, one of the most common) and with pellets collected from Las Canteras beach, in Las Palmas de Gran Canaria, loaded ‘natural’ from other environmental pollutants as they travel through the ocean.

For 60 days, the fish ate a diet composed of a 10% of these plastics, in a percentage similar to what fish can find in places contaminated by microplastics.

Both in the liver of sea bass that ate factory pellets and those that ate ‘beach’ pellets, organic contaminants were found, with higher concentrations in specimens baited with pellets collected from the marine environment (A. Herrera and A. Acosta-Dacal , Science of The Total Environment, May 2022).

“It is important to continue studying microplastics present in the environment to understand both the physical effect of ingestion and the trophic transfer of contaminants that could cause long-term health effects. “Studies over longer periods of time are needed to evaluate the effect of chronic exposure to environmental microplastics on fish,” concludes this last study.