Microplastics: tiny particles causing huge problems

Although small in size, microplastics are a big issue.

Microplastics, generally categorised as plastic objects being less than five millimetres in length, have diverse origins. Some are deliberately designed that way to be added to products, such as microbeads incorporated into toiletries or cosmetics to perform abrasive functions or contribute to cleaning performance. Others are less intentional, resulting from the breakdown of larger plastic objects when natural wear and tear or local conditions cause degradation. Examples of these kinds of microplastics include microfibres breaking off from fishing nets, or from tyres when tyres abrade against the road. A similar process causes microfibres to break off synthetic clothing during washing. For example, a single polyester fleece jacket can shed as many as 250,000 plastic fibres into the wastewater during a single wash.

Unfortunately, most microplastics are too small to be caught by filters at wastewater treatment facilities. This means that, eventually, many of these microplastics are washed into rivers and subsequently into the sea. An estimated 30,000 tonnes of microplastics from consumer products ends up in the oceans each year and some areas of the ocean have been shown to have concentrations of microplastic exceeding 10⁶ pieces per square kilometre.

Given current trends and the long natural breakdown times typical for plastic materials, it seems almost certain that the microplastics concentration in the ocean will continue to increase.

Microplastics present a critical problem in the marine environment. One difficulty lies in the fact that they are ingested by a range of marine organisms, where they can block intestinal tracts, or potentially trick the organism into thinking that eating is unnecessary and thereby causing starvation. There is also growing concern about the chemical impact of microplastics following ingestion by wildlife, as these microparticles may act like sponges to soak up toxic pollutants (e.g. plastic additives from the manufacturing process or chemicals from the surrounding environment). Some microplastics have even been shown to contain carcinogens and mutagens.

All this means that the consumption of microplastics can have a severe influence on marine organisms. Studies have shown that zooplankton grow more slowly and reproduce less successfully in the presence of microplastics. The animals’ eggs are also smaller and less likely to hatch. Experiments demonstrate that this is a result of the zooplankton not eating enough food. This can not only disrupt populations of zooplankton but can also have implications higher up the food-chain.

Although microplastics often enter the food-chain at low levels, higher organisms such as marine mammals and even humans can end up consuming large quantities of microplastics, simply by eating fish from lower down the food-chain. In fact microplastics have recently been found in human stool samples!

The effect of consuming marine organisms containing high concentrations of microplastics on humans is still relatively unexplored. It is not yet clear whether the potentially toxic chemicals which result from the breakdown of microplastics are hazardous to human health in the levels found in seafood.

Miniaturising the microplastics crisis

Innovators worldwide are under pressure to stop the problematic impact of microplastics on our environment. A variety of efforts are underway to tackle the challenge.

Some organisations are focusing their attention on in-situ clean-up of microplastics which are already in the natural environment. For example, Hoola One - originally developed by a group of Master’s students at the University of Sherbrooke in Canada - works like a vacuum cleaner on the beach allowing microplastic particles to be sucked up. The machine then makes use of a density filtration system, which separates plastic from sand using buoyancy (the plastic tends to float, whereas sand sinks). This means that the sand can be returned to the natural environment, whilst the machine retains the plastic particles. This machine can clean up to 17 kg of sand per minute and can collect plastics particles ranging in size from 0.05 to 50 mm. After testing on beaches in Hawaii, the makers of Hoola One are now working to increase capacity and material throughput.

To date, however, the major focus for many groups has been to prevent further microplastics from entering the environment and compounding the already-present issues. Perhaps unsurprisingly, different sectors have devised different solutions.

Tidying up toiletries

Removal of microplastics presents challenges for companies who rely on the properties of the microplastics in their products. Replacement of the microplastics with alternative, biodegradable materials, is currently being explored.

A candidate undergoing extensive research is cellulose, the most abundant organic polymer on earth. It is a main structural component of the cell walls of green plants and a natural polymer, so it is also able to biodegrade under natural conditions. Therefore, once cellulose-based materials reach the ocean the idea is that they will naturally biodegrade and not cause problems for marine life.

One company who have been active in developing alternatives to plastic-based microbeads in cosmetics are naturbeads, a spin-out company from the University of Bath. They produce biodegradable microbeads made from cellulose and have recently filed a UK patent application covering this technology.

Scientists at the Frauenhofer Institute for Microstructure of Active Agents and Systems IMWS in Halle Germany have also been researching methods for manufacturing biodegradable cellulose particles cheaply from raw materials such as beechwood, oats, wheat and corn. They have demonstrated that their biodegradable microbeads have similar cleaning performance to standard non-biodegradable microplastics. A further advantage of these cellulose particles is that they are able to absorb oil and water, which is useful for moisturising creams. The researchers envisage that these products could not only be used in skin cosmetic products such as creams and pealing, but also in decorative cosmetics, such as for mascara, powders and lipstick.

Larger companies such as Novamont and Merck have also launched ranges to replace microplastics present in many cosmetics, using other kinds of biodegradable materials. For example, Novamont have developed their CELUS-BI range which use biodegradable microspheres suitable as exfoliating agents for personal care and for use in cosmetic products. The microbeads are made from Mays starch, PVA and Glycerin and are designed to have properties particularly suited to cosmetics. These products are considered to be readily biodegradable, showing 60% biodegradation within 10 days. As another example, Merck have developed their RonaFlair® range including RonaFlair® Flawless, based on silicon dioxide, and RonaFlair® Mica M, based on mica.

Cracking down on clothes

Synthetic garments such as polyester and acrylic fabrics release microplastics as fibres when they are washed. Along with washing less often and at lower temperatures, several solutions are being developed to minimise the amount of microfibres that escape from our clothes into the waterways.

The washing machine industry is moving towards incorporating filters on washing machines to capture microplastics after generation. A range of companies already offer filters which can be retrofitted to washing machines, for example planet care sells a microfibre filter which can be attached to the discharge hose of a domestic washing machine helping to capture microfibres and prevent them from entering the oceans. However, longer term, we can expect washing machine manufacturers to design machines with outlet filtration systems built-in.

In France, legislation has been passed to prevent microplastics from clothing entering the waterways. As of January 2025, all new washing machines sold in France will have to include a filter to catch microfibres shed by synthetic garments and to stop synthetic clothes from polluting waterways. In Australia similar legislation has also been passed meaning that microplastic filters will be phased-in to commercial and residential washing machines by July 2030.

A big player in this field are the Arçelik group, which manufacture Beko and Grundig brand machines. Arçelik say they have developed the world’s first washing machine with a built-in synthetic microfibre filtration system. The filter is said to be able to block 90 percent of microfibres from entering the water sources and is situated in the detergent draw to allow easy cleaning. These machines are now on sale in the UK.

However, a problem with filters is that they can become blocked and must be manually cleaned.

Inheriting earth ltd have developed a range of solutions to this problem. According to a recent patent application inheriting earth have developed a washing machine filter system, which includes a compactor meaning that microplastics removed from waste water streams are filtered and then compacted meaning that they can be automatically removed from the washing machine without needing to manually clean a filter. An alternative solution involves a filter with a “wash apparatus” which washes the microplastics off the filter after the wash cycle meaning that they can be collected as a slurry at the bottom of the filter container and easily disposed of.

An alternative solution to inbuilt filters is to use a special wash bag. The Guppyfriend Washing Bag is designed to contain clothes during washing. It is made entirely of polyamide 6.6 monofilaments - which don’t shed or lose any fibres themselves - and acts like a filter, filtering the water which has been used to wash the garment before it is drained from the washing machine. Tests by the Frauenhofer Institute in Germany showed that the Guppyfriend dramatically reduced synthetic fibre break off, with 79% less break off with partly synthetic clothes and 86% with completely synthetic clothing. Furthermore, at least 90% of plastic fibres that did break off during washing were retained in the bag, meaning that the bag dramatically reduced the flow of microparticles into the natural environment.

Another avenue that is being explored is modifying the textiles themselves by laminating synthetic fabrics in a pectin coating. Yarn producer Sympatex is conducting research in this area and have reported improvements of from 50 to 70 percent when the yarn is laminated versus non laminated yarn. Interestingly, their research demonstrated that the lamination process was just as effective for yarns derived from recycled materials as for yarns made from virgin plastic.

Elimination elsewhere

Tyres are thought to be the second largest source of microplastic particulates in the UK. One group working to address this problem are the Tyre Collective. They have developed a method to capture tyre particulates at the source. The Tyre Collective’s system makes use of an electrostatic array to attract and capture the positively charged tyre particulate produced during use (for more information see our recent blog Tyres: the secret polluter).

Fishing nets comprise almost half of the plastic floating in the Great Pacific Garbage Patch. Breakdown of nets is also known to be a significant contributor to microplastics present in the ocean. The Ocean Cleanup Technologies BV organisation is looking to develop methods of removing these fishing nets from the ocean before they are able to break down into microplastic particles. As described in a recent patent application, they have developed a system for concentrating plastic waste, which can then be removed from the ocean by a boat. The system consists of a long “floater” (think of a massive version of a swimming pool noodle) with a skirt attached below it. To capture the plastic, the system takes advantage of three natural forces found in the ocean, the wind, the waves and currents. Whilst the current affects the plastic particles in the ocean and the floater, the wind and waves propel only the floater so that the system moves faster than the plastic and thereby allowing the plastic to be captured. Due to the action of the current, the system naturally adopts a U shape concentrating the plastic in a funnel. Once the system is full a support vessel comes to remove the concentrated plastic, which is brought back to land. The intention behind removing large pieces of plastic from the ocean in this way is to prevent shearing of the large pieces of plastic into microparticles.

Micro-management?

Many believe that inventors and companies cannot – or will not - make the necessary progress on addressing the microplastics problem without governmental backing or incentives.

With the Microbead-Free Waters Act of 2015 the US paved the way for banning the use of microplastics in “rinse-off” products such as toothpastes or face wash. Closer to home, a similar ban was enacted in 2017 in the UK and came into force in 2018.

Critics argue that loopholes in these laws can mean that environmentally damaging substitutes can be included into products instead of microplastics. In addition, the UK laws do not ban microbeads in leave-on products such as sunscreens or lipsticks, meaning that large amounts of microplastics are still entering the environment from cosmetics and toiletries in the UK.

In Japan the upper house passed a bill in 2018 to reduce microparticles, which calls on companies to cease the use of microplastics in their products, in particular in face washes and toothpaste. Following the G7 summit, Japan has also been working towards standardization and harmonization of monitoring procedures for microplastics in the ocean.

In the European Union the European Chemicals Agency has submitted a restriction proposal for microplastics which are intentionally added to consumer products. It is estimated that if this restriction is adopted it could reduce the amount of microplastics released into the environment in the EU by 400,000 tonnes over 20 years.

The states of California and Connecticut in the US have also proposed legislation which would mean that polyester garments must bear labels warning of their potential to shed microfibres during domestic washing cycles. This legislation is, however, yet to be made law.

From 1 May 2021 the EU has adopted new rules for labelling tyres (Regulation (EU) 2020/740). The requirement to list abrasion was included in the tyre labelling regulation adopted in February 2020, however, technical questions on how to measure the rate of shedding of microparticles from tyres meant that this requirement was removed. It is, nevertheless, hoped that a definitive test method will be established by 2023. This will allow consumers in the EU to make a choice about the types of tyres which they opt for on their vehicles, as well as opening the door for restricting the use of tyres which shed high amounts of microplastics over their useful lifetime.

It is to be hoped that other governments follow suit in the pursuit of reducing microplastics in due course.

Do microplastics have a future

At the moment, microplastics are subject to increased restrictions on their use, as well as a desire from consumers to choose items which do not contain or shed microplastics. Evidently, there is great scope for innovation in finding alternatives and solutions to the microplastic problem.

Due to the harmful effects of microplastics on aquatic life, both consumers and legislators around the world are keen to reduce the amount of microplastics entering the natural environment. This has led to a range of innovative solutions from biodegradable alternatives to microbeads and yarns which shed fewer microfibres to in-situ systems for hoovering up microplastics on beaches. However, stricter legislation and more research is needed if we want to limit the effects of microplastics on the marine environment and preserve the oceans for futures generations.