The amount of plastics and microplastics in the oceans is steadily increasing. An estimate published in March 2023 in Plos One, for example, indicates that the amount of plastic waste spread over the surface of our oceans is around 2.3 million tons. What is most worrying, beyond the numbers, are microplastics, which are particles smaller than 5 millimeters that pollute the oceans and alter the balance of marine ecosystems, even ending up in the human food chain, endangering our health. Primary microplastics come from synthetic clothing, tires and even body care products. Why does plastic take so long to break down? There is no one answer for all products, because there are so many plastics and they’re also very different from each other in terms of chemical composition: in some cases, it has been calculated that they can be hundreds of years old. One thing is certain, however: the materials that make up plastic are very resilient, they’re not attacked by microorganisms and are inert – that means they don’t participate in any chemical reaction. To give you some examples, it takes a plastic bottle around 450 years to break down, while for a non-biodegradable plastic bag, it takes about 20 years. Other apparently similar materials, such as organic waste or natural fibers (cellulose), decompose much more quickly thanks to the role of the microorganisms that attack them. The spread of plastic is an urgent problem that has grown dramatically in recent decades due to the massive use of plastic. As a report published in Nature explains, there are between 15 thousand and 51 trillion microplastics floating on the world's surface waters. And these particles tend to unite, forming so-called islands of plastic, with catastrophic consequences for marine fauna and flora. Bioplastics: what are they? A material is a bioplastic if it is composed at least in part of an organic component, if it is biodegradable or if it has both of these properties. Bioplastics can potentially be obtained from any agricultural or food waste, but for now they mainly derive from corn, sugar cane or cellulose. In short, the term ‘bioplastic’ is very broad, so it isn’t enough for a product to fall into this category for us to be sure it’s completely biodegradable. Advantages and disadvantages of bioplastics The main advantage of bioplastics is its lower environmental impact. Decomposition times vary according to the materials and environmental conditions: in humid environments, for example, they break down much more quickly than in dry environments. Degradation times are not always so different from those of traditional plastics, but the use of specific organic compounds can reduce them. The materials that make up bioplastics can also be produced with processes that use renewable sources, reducing the use of fossil materials and greenhouse gas emissions. Bioplastics still have quite high production costs compared to conventional plastics, but the prospects are promising. For both plastics and bioplastics, however, it’s important to avoid throwing them away in nature so that they end up in rivers and seas. Bioplastic, in particular, decomposes more easily if thrown in the organic waste container.
