Microplastics are small plastic particles with dimensions ranging from one nanometer (to give you an idea: a human hair is about 60,000 nanometers thick) to five millimeters (a long grain of rice is 6 millimeters). And yes, different categories fit into this definition. We classify them according to their origin or their physical properties, size, shape or composition.
If we look at its origin, there are two types: primary and secondary. First and foremost, these are those designed and manufactured for such a small size, that is, they were already designed to be microplastics. This category includes, for example, the small plastic beads that were stuck into the bushes, or the 2 to 4 millimeter plastic beads or cylinders that are made as raw material for the production of large plastic objects and are called pellets. The secondary damage occurs from the decomposition of larger objects: containers, bags, bottles, etc. These occur in the environment due to the physical or chemical degradation of plastic caused by ultraviolet rays from the sun, wind, waves and other environmental factors.
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Due to the size, we have the smallest microplastics, which include, for example, the microspheres of peelings, and the largest, which can reach a diameter of 5 millimeters. Based on their shape, they can be classified into spheres, cylinders or more irregular fragments such as: B. those that are created when larger objects disintegrate, the textile fibers that are released by the washing machine when washing clothes, the fibers that are created by fishing nets. or Styrofoam foam.
Another classification is the one we make according to the type of plastic: the type of polymer from which it is made and the additives added to make the plastic have certain properties, such as: B. greater flexibility, greater resistance, higher temperature resistance, etc. We have many of them there: polyethylene used in plastic bags, polypropylene for packaging and textiles, polystyrene, which is this foam for wrapping things, PVC for pipes, etc. In addition to all of them possible additives that are added. And they are the really polluting substances.
Once the plastic enters the environment, these additives can be transferred to the system, which can cause toxicity since the polymer itself is not harmful to the environment. What we call microplastics is the combination of polymer with additives, which is why we consider microplastics to be toxic pollutants.
The wake-up call about microplastics arose from research into environmental pollution. The researchers observed that when they took the sample, they found many plastic particles in enormous quantities and that they were also very resistant particles that accumulated. The term is very new and comes from an article by British researcher Richard Thompson published in the journal Science in 2004.
Microplastics cause different problems. I work in oceanography and study the movement of these particles and their transport, so I have a better understanding of the risks to marine organisms. They pose physical and chemical risks, such as strangulation if swallowed, but behavior, reproduction and growth can also be affected by ingestion. And depending on the type and type of plastic, it can be more or less serious. But in addition to this biological and ecological risk, they have sociological and economic impacts. For example, think of a beach full of microplastic trash, which can deter tourism.
Isabel Jalon She is a researcher at the EPOC Center (Environnements et Paléoenvironnements Océaniques et Continentaux) at the University of Bordeaux (France).
Question emailed from Pia Inaraja
Coordination and writing:Victoria Toro
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