Environment contamination with plastic debris is one of today’s major environmental problems affecting society. Plastic debris is man-made polymeric waste that has been deliberately or accidentally released into the environment. This waste can consist of extremely varied material, composed of many different polymers in different states of atmospheric alteration and of various shapes and sizes.
Based on their size, plastics can be classified into: macroplastics (> 25 mm), mesoplastics (5–25 mm), microplastics (<5 mm) and nanoplastics (<0.1 μm).
There are two ways of fragmentation of plastics into smaller particles once released into the environment: abiotic and biotic. These processes can also take place simultaneously.
Abiotic degradation is the mechanical degradation of plastics through time and climate change (e.g., freezing, thawing, pressure changes, water turbulence, and damage caused by animal activities). However, the molecular bonds of the plastic are not affected; only morphological changes occur.
Biotic degradation is the degradation resulting from the activity of living organisms. These organisms produce enzymes that break down plastic polymer chains through hydrolytic processes, resulting in a reduction of their molecular weight. The loss of molecular weight then triggers further microbial degradation, enhanced by exposure to water and oxygen, which leads to the continuous loss of the molecule’s structure over time. The biotic degradation of plastic ultimately results in water-soluble oligomers and monomers, which can then mineralize and be assimilated as sources of carbon and nitrogen by microorganisms. Mineralization is precisely that process in which an organic substance, such as a polymer, is converted into an inorganic substance, such as carbon dioxide.
According to their origin, microplastics are classified into two different groups, primary and secondary microplastics. Primary nano and microplastics are microscopic pieces of plastic that are specially manufactured by extrusion or grinding for specific applications, as precursors to other products (eg. Plastic pellets) or for direct use (eg. Abrasives in cosmetic or cleaning products, or roto-milling). Secondary nano and microplastics are those that form in the environment from the fragmentation of larger plastic material into smaller and smaller pieces.
Over the past 70 years we have fostered a growing increase in the world production of plastics, which consequently has spread into the environment to such an extent that we can say we live in a world of plastics. In fact, we know very well that there are 5 “plastic islands” in the world in addition to the more famous Great Pacific Garbage Patch, which are found in the Indian Ocean, the North Atlantic, the South Pacific, the South Atlantic and the Mediterranean Sea. These islands seriously threaten our oceans, and it is estimated that by 2050 there will be as much plastic as fish in ocean waters.
Furthermore, these synthetic polymers are not only environmental pollutants themselves, they also act as carriers for the transport of various types of chemicals and harmful to ecosystems.
Plastics are also considered valid indicators of the recent and contemporary period. Nowadays, microplastic particles have been detected everywhere in a wide range of shapes, polymers, sizes and concentrations in seawater, freshwater, agroecosystems, atmosphere, food and drinking water environments. They can be thin like little veils and blown away by the wind, or they can be hard and compact like rocks.
Their worldwide distribution is so vast that many scientists use it as a key geological indicator of the Anthropocene (a geological era proposed to succeed the Holocene, in which the human being with his activities has managed with territorial, structural and climatic changes to affect on geological processes). Plastics can be used as stratigraphic markers in the archaeological field and have recently been used as precise indicators of earth deposits.
The European Union (EU) has long been at the forefront of environmental sustainability and reducing plastic pollution. A circular economy model, implemented in the EU in 2018, stipulates that all plastic products will be designed for increased durability, effective reuse and recycling, and that all packaging materials within the EU market will be reusable and / or recyclable by 2030. The European Commission has requested that industries involved in the production or recycling of plastics submit “an ambitious and concrete series of voluntary commitments to support the strategy and its vision for 2030”. In other words, it is up to designers and manufacturers to produce reusable and recyclable plastic products for consumers and eliminate their current single-use plastic business model. In the meantime, however, without a strict regulation against these companies, which obliges them to gradually change their production and convert it into biodegradable plastic (or even better, other more natural materials) supply chains, it is only stalling, it is only a way to take time – which is not there – and push further away from that “uncomfortable” deadline to continue doing “business as usual” to the detriment of the planet.
It is not just the institutions that have to face this problem. There is also a lot that we can all do to help reduce the use of plastics, thinking not only of the environment but also of our health, because it is essential to live in a clean and healthy environment, to have an equally healthy life. What we can all do is become aware and more demanding consumers: a very simple thing to start from is to try to make purchases and reasoned choices in our everyday life; for example, it is important to stop an extra minute to reflect on what I am about to put in the cart when there is the possibility to choose, for the same product, between a plastic package and one in paper / tetrapak / glass or other, opt for the one that contains as little plastic as possible. In this way, we will give a message to manufacturing companies, that seeing the increase in purchases of a certain type of product, they will tend to increase the offer.
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