Microplastics in footwear and clothing
Investigating the proliferation of these particles in our environment, the issues they can cause, and how microplastics can be identified and eradicated.
by Lucy Cove
Image © pcess609 | iStockphoto.com
There has been growing concern in recent years over the impact our lifestyles and consumption levels are having on our planet, and one particular worry is our reliance on plastics. Highly versatile and durable materials, plastics are widely used in the footwear and clothing industry. Unfortunately, the durability of plastics which is highly valued by manufacturers and consumers presents significant difficulties in disposal at the end of a product’s life. Because plastic is highly resistant to degradation, it has a propensity to break down into smaller and smaller fragments, eventually forming ‘microplastics’, which can pose severe hazards to the earth’s environment.
Origins of microplastics
Microplastics are defined as ‘particles of plastic with a diameter of less than 5 mm’. They can enter environmental ecosystems through a variety of sources, one of the more well-known being the inclusion of plastic beads as an abrasive agent in the beauty and cosmetics industry. Due to their intended use, these beads inevitably enter domestic water systems and, due to their small size, they are unlikely to be removed by standard filtration processes. This means that they eventually end up in our oceans.
Fortunately, the intentional release of microplastics from such sources is relatively easy to eradicate, and several European Union member states have already imposed bans on the use of microplastics for this purpose. The unintended release of microplastic particles is much harder to address. This can occur through by-products of manufacturing processes or from the breakdown of larger plastic items. Because plastics are highly resistant to chemical or biological degradation, they persist in the environment for a long while and, during this time, physically break down to produce microplastics. This can occur with materials used in the footwear industry following disposal of the shoes – from such sources as outsoles, plasticised uppers, parts of laces or fasteners and even the finishes used on textiles and leathers.
Kosamtu | iStockphoto.com
A less obvious source for microplastics, which accounts for a significant portion of their release, is the shedding of microfibres from textiles. Although we tend to think of textiles and plastics as being different types of materials with different properties, many modern synthetic textiles (such as nylon, polyester and acrylic) are, in fact, produced using plastic fibres.
These types of fabric can shed microfibres through normal wear in day-to-day use, However, this impact is minimal compared to the potential for release during domestic washing. The agitation and detergents used during normal wash cycles accelerate the shedding of fibres from the textile, and these are immediately released into waste water. As is the case for microplastic beads in cosmetics, these microfibres are small enough to evade filtration systems, and so eventually make their way into rivers and oceans where they persist for considerable periods of time.
The dangers they pose
The increasing levels of microplastics being released combined with their persistence has led to their rapid accumulation, particularly in aquatic and marine ecosystems. The small size of microplastics means that they are readily ingested by marine life, where they can accumulate in and eventually block the creature’s digestive tract. This results in a reduced appetite, a decline in feeding capacity and depleted energy levels, all of which inhibit growth. An impact is felt not only upon the species which directly ingest the microplastic particles, but also those that rely heavily upon them within the food chain, such as seabirds and larger marine mammals.
Andriy Nekrasov | iStockphoto.com
Very small fragments of plastic can also be absorbed from the digestion system into fatty tissues, where they remain, leading to bioaccumulation through the food chain. This includes the ingestion of seafood intended for human consumption, and there is increasing concern regarding the potential effects of microplastics upon human health. A recent study detected the presence of microplastics in human blood, and found that out of 22 participants, blood samples of 17 individuals contained microplastics. Subsequent further research showed evidence that these microplastics can latch onto the membrane of red blood cells, limiting their ability to absorb oxygen. Similar studies have also detected microplastic particles in human lungs and in the placentas of pregnant women, meaning that foetuses are being exposed to plastic pollution before they are even born.
Md Babul Hosen | iStockphoto.com
It is not yet fully understood how exposure to microplastics may affect human health, but studies indicate that they could have adverse effects. For example, it has been demonstrated that exposure to microplastics causes allergic reactions and death of human cells, indicating that high levels of exposure could have detrimental consequences. It has also been shown that the presence of microplastics could inhibit the repair of lung tissue following damage from respiratory diseases such as COVID-19. This suggests that exposure to the particles could cause problems to vulnerable people recovering from illnesses, as well as on the development of children’s lungs.
Currently, the only legal restrictions upon microplastics within the EU concern their intentional use in the cosmetics industry. However, growing concern in the scientific community could put pressure upon EU member states to impose further restrictions in the near future. Even without legislative changes, the risks that microplastics pose to both human health and our planet mean that brand owners have a moral responsibility to limit the amount that they release. This is especially important for companies wishing to promote an image of sustainability and environmental awareness – something that is becoming more valued by consumers when they decide which products to buy.
Zarina Lukashv | iStockphoto.com
As the discharge of microplastics from consumer goods is usually unintentional, preventing it from occurring is not always easy. One of the key things to consider is the source of the microplastics – both during the manufacturing process and from the finished article. By definition, the majority of microplastics are very small particles which cannot always be seen with the naked eye and which, by their very nature, are very difficult to capture using standard filtration techniques. Despite these challenges, the growing interest within the scientific community has led to innovations aimed at detecting the presence of microplastics, with a view to helping companies to understand and reduce their impact.
One recent development in this area is the use of Pyrolytic GC-MS (gas chromatography with mass spectrometry) to detect the presence of microplastic particles in water, which can be used by brand owners to monitor their discharge from manufacturing processes. This technique involves thermal decomposition of a sample followed by analysis using GC-MS, which quantifies the amount of microplastic particles present and also identifies the type of polymer from which they are derived. As a result, the method can help to determine the specific process from which pollution originates, allowing measures to be implemented in order to address the issue.
There are also test methods available for assessing the shedding of microfibres from textile garments during washing. This involves washing the material under specified conditions, based on either domestic or industrial processes, depending upon the intended use of the item. The waste water is collected and passed through a specialised filter which is capable of retaining shed fibres. The collected fibres are then dried and weighed to quantify the amount discharged. Further analytical techniques can be used to identify the specific fibre types shed, which provides invaluable information to brand owners looking to reduce their emissions.
To summarise – over recent years, our reliance upon plastic materials has led to a rapid increase in the generation of microplastic particles. While we tend to think of single-use items and packaging as being the main source, many different industries contribute to this plastic pollution, including the fashion and footwear industries.
The detrimental effects of microplastics upon aquatic ecosystems has been well documented, and new studies suggest that they can also be hazardous to human health. Our exposure to these potentially harmful particles will continue to increase unless steps are taken to reduce the release of microplastics and, although this presents difficulties, new innovations in the scientific community are helping to address this issue. It is possible that future legislation will impose restrictions upon the unintended release of microplastics from manufacturing processes and this, combined with the growing consumer interest in sustainable products, is likely to drive further innovations in this field.
How can we help?
Please contact SATRA's chemistry team (email@example.com) for further information on the topic discussed in this article.
This article was originally published on page 10 of the January 2023 issue of SATRA Bulletin.