ocean plastic sources: microfibres

Up to 31% of the microplastics found in the ocean belong to the category of primary microplastics, which means that they already enter the ocean in this minute size and form. Particles with a diameter of less than 100μm (so 0.1 mm or about the thickness of a human hair) are lost both during manufacture and use of paint, car tyres and textiles, and are carried to the ocean either in runoff, by the wind, or through wastewater systems. 

Paint, which consists of nearly 40% polymers, is now considered the greatest culprit when it comes to shedding microplastics, making up an estimated 58% of ocean primary microplastics. Recent research reveals that the total leakage of paint is somewhere around 2.25 million tonnes a year, with 63% of this leakage in the form of microplastics emitted during application, maintenance and wear and tear and the remaining 37% from unused paint or associated with the end-of-life of painted objects.

Used by a variety of sectors, for example for construction, ship building, road marking or the car industry, most leakage occurs on land but the wear and tear or maintenance of ships and offshore rigs accounts for 18% of the microplastics leaked, obviously directly into the ocean. Microplastics stemming from paint used on houses, bridges, roads or cars have a longer journey to the ocean, transported there by wind, rain or groundwater. According to the report, the construction industry is by far the largest contributor to the total leakage (48%) while road markings are the smallest contributor (2%).

It is thought that about 200,000 tonnes of tiny plastic tyre and brake wear particles are blown or washed from roads into the ocean every year. Caused predominantly by the friction of tyres on road surfaces, the abrasive effect leads to the release of a mixture of tyre and road surface particles. When shed during a journey, the tiny particles of natural rubber and synthetic polymers are either caught by rainwater and enter the ocean through runoff or are carried there by the wind, which spreads them widely - research shows that smaller particles can remain airborne for up to 37 days, with about 43% of their total mass ending up on land, and 57% in the ocean. About 2.7 billion tyres are currently manufactured each year. With an average tyre losing 4 kg during its lifetime, the scale of the problem is immense. 

The shedding of microfibres from textiles poses a similar problem in its sheer magnitude. Not only is the fashion industry one of the greatest polluters during the production phase of textiles in terms of emissions but the microfibre waste created during the course of their manufacture, use and end of life is significant. An estimated 35% of the microplastics found in the ocean come from textiles and each and every one of us contributes to this every time we wash our clothes: each washing cycle releases an average of 700,000, sometimes as much as 1.5 million fibres which pass through wastewater systems that simply aren’t equipped to filter them out, releasing them into rivers and ultimately the ocean. 

Synthetic materials are the worst offenders. The first micro-denier products were created in the 1970s, paving the way for the fashion industry to develop in a whole new direction. Production of synthetic fibres such as polyamide, polyester and acrylic from crude oil and natural gas was embraced by the industry in the 1980s and 1990s so that synthetic fibres now make up as much as 70% of our clothes either on their own or as a cotton/wool/viscose mix. The textiles tick many boxes: they are cheap and flexible, soft and light-weight while strong and durable, they dry quickly and have higher thermal insulation properties than natural fibres, making them particularly useful for sports and outdoor clothing. 

The environmental impact of synthetic materials however far outweighs their advantages: thousands of microfibres are shed during their life cycle, these detach from textiles during the washing cycle and are released into the wastewater system, where somewhere between 65 and 92% of them are filtered out but the remainder released into the environment. With an estimated number of 840 million domestic washing machines in use around the globe, we can expect more than 500,000 tonnes of additional microfibres to enter the ocean every year. 

To make matters worse, research is now showing that this is not just a problem connected with synthetic materials. Natural materials such as cotton or wool also shed fibres when washed. These usually degrade without adverse effects unless they are altered by a chemical process such as the use of additives to give textiles desired properties such as a specific colour or enhanced durability. Anything added to the material, whether a dye or pigment to colour it or a chemical finish such as a flame retardant or antimicrobial agent, reduces its biodegradability. Anthropogenically-modified natural fibres impact the marine environment just as synthetic fibres do.

dive in deeper

A Poison Like No Other: How Microplastics Corrupted Our Planet and Our Bodies

NOAA & EPA Report on Microfiber Pollution

TMC Progress Update 2021/2022

Paint particles in the marine environment: An overlooked component of microplastics