Microplastics: the state of research

In recent years, attention toward microplastics has grown considerably. But what are they, and why do they raise so much concern? 

Dr. Claudia Cusan, European Registered Toxicologist, S&C BEST Srl

The European Chemicals Agency (ECHA) defines microplastics as small solid or semi-solid plastic particles measuring 5 millimeters or less. Due to their tiny size, they are invisible to the naked eye and can spread virtually everywhere — in water, air, soil, and even inside the human body.

Microplastics can have two different origins. Some are called primary microplastics: particles intentionally manufactured by humans, once used, for example, in cosmetics, certain pharmaceuticals, or industrial applications. Much more common, however, are secondary microplastics, generated by the fragmentation of larger plastic items — such as bottles, bags, and fishing nets — degraded by the combined action of sunlight, wind, and sea. It is estimated that over 99% of microplastics in circulation originate from this unintentional degradation process.

Microplastics do not easily degrade; instead, they persist for long periods, accumulating in the environment and, consequently, in living organisms. They have been found in fish and shellfish, but also in everyday foods and beverages. This means that by consuming bottled water or contaminated food, we can potentially ingest small amounts of them. Once inside our body, the fate of these particles depends on their size: larger ones tend to be excreted in the feces, while smaller ones (less than 50 micrometers) can cross the intestinal barrier, enter the bloodstream, and reach various organs. Researchers have already detected microplastics in the liver, lungs, intestines, placenta, and even in breast milk.

The concern lies not only in the physical presence of these particles but also in their ability to act as chemical sponges. Due to their hydrophobic nature, they tend to adsorb toxic substances present in the environment, such as pesticides, heavy metals, hydrocarbons, and pharmaceutical residues. Once ingested, they can release these harmful substances into the body.

Animal studies have already shown potentially serious effects, including metabolic disorders, immune system alterations, reproductive problems, and even neurotoxicity. Moreover, microplastics can trigger chronic inflammatory processes and oxidative stress, with outcomes that are still poorly understood but raise further concern.

Research on this topic is still in its early stages, and no conclusive data exist yet on the long-term effects on humans. What is clear, however, is that microplastics have now become part not only of the ecosystem but also of our own bodies. In Europe, the issue began to attract public attention around 2018, leading to the launch of plans and strategies aimed at reducing plastic use, improving recycling, and developing more sustainable products. Nonetheless, tackling this challenge requires a coordinated global effort.

An important contribution in this direction comes from industry associations such as the AIBO-FCE group (Italian Business Operator Association – Food Contact Expert). AIBO members bring together multidisciplinary expertise ranging from chemical analysis to toxicology, from regulatory affairs to materials formulation. This integrated network enables a coordinated approach to addressing the issue of microplastics and other emerging topics related to packaging.