Featured Image Caption: Microplastics range in diverse shapes and forms, but they all have two things in common: they’re humanmade (directly or indirectly) and are particularly small (between 1μm—the size of a human hair— and 5mm—the size of a pencil-top eraser). (Image Source: “Microplastics in the Chesapeake Bay Watershed” by Chesapeake Bay Program, licensed under CC BY-NC 2.0).
Reference: Uddin Mahamud, A.G.M.S., Saha Anu, M., Baroi, A., Datta, A., Uddine Khan, M.S., Rahman, M., Tabassum, T., Tasnim Tanwin, J., & Rahman, T. (2022). Microplastics in fishmeal: A threatening issue for sustainable aquaculture and human health. Aquaculture Reports. https://doi.org/10.1016/j.aqrep.2022.101205
Microplastics are small plastic pieces that were either produced to be small (like microbeads, which are added to health and beauty products like toothpaste and face exfoliants) or are formed through the chipping down of bigger pieces of plastic (like plastic bottles being broken down by waves). First defined in 2004, microplastics have been a hot topic for scientific research for the past decade, especially for the health implications they could have both for human and animal health.
Recently, researchers have found that microplastics have made their way onto our plates through practices in aquaculture. Aquaculture is the breeding, rearing, and harvesting of fish and other marine mammals and is an essential part of the world economy. Researchers have found that the fishmeal that aquacultural companies are feeding their fish is contaminated with microplastics, which then enter the body of the fishes before being passed to our plates.
But Why Is This Happening?
In recent years, fishmeal has been produced using many nutritional components, including small marine fishes that eat waste and are usually part of bycatch. What researchers had not considered before is that these small fishes also inadvertently consume microplastics, which then enter the fish feed and fishmeal that are used in aquacultural systems. Through time, the fish being fed this fishmeal bioaccumulate microplastics in their muscles, which humans then consume. This can all be seen in the image below.
How Is This Affecting Aquaculture and Farmed Fish Physiology?
The insertion of microplastics into fishmeal isn’t just a hypothetical problem; it is actually something that is affecting the fish that consume it physiologically in more ways than one would think. We already mentioned how microplastics bioaccumulate on the muscles and tissues of fish, but this isn’t the only way in which these fish are affected by what they’re being fed. The ingestion of microplastics by fish can lead to changes in behavior, starvation from false hunger satisfaction, digestive backups, energy costs, stunted growth, and internal injuries.
And How Could This Affect Human Health?
The concern then lies with how this could affect us. Research has found that microplastics could have some serious effects on our metabolism and body as a whole. For example, accumulating considerable amounts of microplastics in our bodies could lead to neurotoxicity, genotoxicity, metabolic syndromes, chronic diseases, endothelial dysfunction, inflammation, amongst other secondary effects.
Plastics were not made to be ingested or accumulated in our bodies. It is of utmost importance that we keep this rising problem at bay by being aware that this is happening and making sure the fish we eat are sustainably sourced and responsibly fed.