Plastic pellets are small granules generally with shape of a cylinder or a disk with a diameter of a few mm. These plastic particles are industrial raw material transported to manufacturing sites where “user plastics” are made by re-melting and molding into the final products. Plastic pellets can be unintentionally released to the environment, both during manufacturing and transport.
The plastic pellets are made from petroleum products. The pellets are lipophilic which means that they readily adsorb chemicals from the surrounding seawater which bond on its surface.
It is known that common chemicals that accumulate on the pellets can be highly toxic with concentrations on the pellets up to a million times the level of the surrounding seawater. These chemicals are known as Persistent Organic Pollutants (POPs) and include Poly Chlorinated Bromide (PCBs) which are chemicals such as flame retardants, DDT an insecticide that was banned in the 1970s after it was routinely used worldwide and Polycyclic Aromatic Hydrocarbon (PAH) which are created when products like coal, oil, gas, and garbage are burned.
Plastic pellets can also have chemicals added to them during the manufacturing process, chemicals such as Nonylphenol (NP) is used as an antioxidant and plasticizer in some plastic products and has known endocrine-disrupting potential.
Not only do the pellets adsorb POPs to their surface but they can also desorb or release these chemicals. Studies have shown transference of PCBs from plastic to birds. There is no published research yet showing the desorption of POPs from plastic to fish. It is not known at present the full consequences of this process in the food chain.
Plastic pellets can cause harm in several ways. If they are ingested by fish and marine life they can block digestive systems leading to starvation. They can cause the fish to be more buoyant as well which makes it difficult for them to swim below the surface leading to stress and extra energy usage in a fish that is already consuming less food as a result of the plastic consumption.
In recent years, researchers have reported that seabirds, turtles, and fish are ingesting small plastic items. Most of these plastics are used consumer items that have been carelessly discarded. However, some of this litter consists of resin pellets that sometimes cannot pass through sea creatures’ digestive tracts, which may contribute to malnutrition and starvation.
While consumers need to properly dispose of the products they use, companies throughout the plastics supply chain also must do their part to help keep pellets out of the environment.