How hazardous carpet waste ends up in horse riding arenas

The horses in the arena trot on an unusual surface. Under their hooves is a layer of sand and shredded car seat covers.

 

Throughout the Netherlands, the ground surface of the arenas is strengthened with various materials such as coconut fibre, wood chips, felt, rubber granules, shredded textile waste and waste carpet offcuts. Weather and environmental factors would otherwise make the arenas too wet, too dry, too loose or too packed for the horses. To avoid the horses sinking beyond their fetlocks into the ground, the sand is mixed with synthetic fibres that absorb water and slowly release it into the ground. A good, ridable surface in all weather conditions may sound desirable, but it still has its risks.

 

Surface strengtheners made of waste textiles are the most popular and, within this, synthetic materials are the material of choice as they do not disintegrate. Wool rots and smells, but carpet fibres (shredded carpet offcuts, polyflakes [residues from the textile industry]), or geopad (shredded weighing cloth), remain good for years. However, these residues or waste products are often made of polyester and are frequently treated with chemicals that are toxic for humans, animals and the environment.

This is a problem, especially for the environment. Research conducted by Anthesis demonstrated that European carpets are made from a complex mix of synthetic materials such as polyester, polyamides and polypropylene. Carpets are made of several layers of different materials that are then coated with chemicals to make them flame retardant and stain-resistant. More than 59 hazardous substances have been found in European carpets, including toxic substances such as lead, phthalates, PFAS, fluorine compounds and metals. These substances pose various health risks, including developmental disorders, endocrine disruptors, asthma, reproductive disorders and cancer.

 

Europe is the second-largest carpet market worldwide and the Netherlands, the United Kingdom and Belgium account for 65% of the demand. While the carpet industry in Europe is growing every year, recycling lags behind, in part due to the complex composition of the material. Every year sees 1.6 million tons – or 1,600,000,000 kilograms – of carpet waste. Of this, about 60% ends up in landfills, 19% to 37% is incinerated, and only 1% to 3% is reused, some of which is used by stables.

 

The Netherlands is the third-largest carpet supplier in the world. Its 12 carpet manufacturers produce about 180 million square metres of carpet every year, reports Routekaart Tapijt 2030. Of this, 85% is exported to other European countries. A recent report by Utrecht University shows that there is still a way to go in the Dutch carpet industry. Little is done in carpet design in terms of circularity, and carpets are made of such complex compositions that they are “non-renewable, non-reusable or can even be dangerous”, says the report.

Dick Vethaak, toxicologist and professor at the Vrije University of Amsterdam, warns that synthetic textile fibres are a major source of microplastic pollution. “These fibres are also released indoors when carpets and clothing wear out and release plastic fibres into the air. Sometimes these fibres contain dangerous additives that can be released into the environment. These could be certain types of flame retardants that keep carpets from catching fire easily but could also be biocides. Fabric fibres also absorb chemicals and our surroundings thus act like sponges that absorb chemicals”.

 

How do synthetic fibres end up in stables? There is no data in the Netherlands about the usage, quantity, or effects of carpet fibres, geopads or polyflakes. However, research by Carpet Recycling UK (CRUK), reports that 400,000 tonnes of carpet waste is generated every year. Of the carpet waste that is not discarded, 22% is used for equestrian activities and amounts to about 40,000 tonnes of carpet waste that disappear every year into stables in the United Kingdom. Zero Waste Europe condemned these figures in a press release in which it asserted that shredded carpet used in stables should not count as recycled on the grounds that “shredded carpet cannot be reused and ultimately pollutes the environment”.

 

On average, three kilos of synthetic soil strengtheners are needed for every square metre of riding arena in equestrian centres. This is mixed with the sand in the top layer of the ground surface. The standard arena size is 20 x 40 metres (800 m2) so a standard arena will usually have 2,400 kilos of carpet fibres. The Netherlands has more than 1,000 equestrian centres, many of which have more than one indoor and outdoor schooling arena. This does not include private arenas.

Interviews with more than 20 equestrian centres in the Netherlands revealed that half have synthetic products in their arenas. In theory, the use and reuse of synthetic fibres is viewed as wonderfully circular – a new material for a new purpose is created from discarded material. Legally, the raw material made from these flakes and fibres are viewed as waste, but because it is used to manufacture a new product, it is not treated as waste under Dutch and European legislation. Because of this, synthetic stiffeners are sometimes supplied with a certificate that labels them as a “clean” product and they can remain in the ground for eternity without being classified as chemical waste. The aforementioned Anthesis research confirms that biocides, flame retardants and other chemicals in the carpet can be released through wear and tear, and spread by attaching to dust particles. The body is thus exposed to their toxic effects through the digestive or respiratory tracts. If the material is not thoroughly washed and shredded, or if it decomposes, microfibres or fine dust form and these contain toxic substances. This is making the hazard all the greater, “particularly when it disperses into the environment in riding stables, for example”, states the research.

 

A concerned equestrian centre owner, who deliberately did not opt for polyflakes, shares these concerns. “When I was riding at another equestrian centre that had polyflakes in the arena, I drew my finger over the partition. It was full of fibres. I can’t imagine that they do not end up in the airways of riders and equestrian centre staff”.

40,000 tonnes of carpet waste per year

Europe’s capital of carpets is Genemuiden, a city in the Netherlands. Almost all the carpet waste in the Netherlands ends up at one of the processors that, logically, are located here too. Van Dijk Containers alone process about 50,000 tonnes of waste, of which 40,000 tonnes is carpet waste and 10,000 tonnes comes from other waste streams such as PET, bottles, films and labels. “The industry in Genemuiden creates a lot of offcuts, primarily from the cleaning textile industry. We use them to make polyflakes. Our carpet fibre stream is made of shredded carpet waste,” says Gerjan van Dijk. His company supplies about 5,000 tonnes – 5,000,000 kilos – of polyflakes and carpet fibres a year.

 

Van Dijk Containers gets most of the discarded carpets from waste separation facilities, where it has its own containers, and from private individuals or companies that drop them off. The recycling process consists of sorting, shredding, sifting and checking the product. “The problem is that used carpets are hard to separate as they usually contain a lot of dirt and other rubbish. It’s a challenge”.

 

Cees Haaksman is the General Manager of Agterberg, a company known for fitting real “Agterberg” surfaces. He let it be known that the Agterberg surfaces only use the residual material of geotextiles. In 2000, Agterberg had this product assessed by the Netherlands Organisation for Applied Scientific Research (TNO). It appeared that it is unlikely that particles of inhalable size are released and therefore any hazardous consequences for humans and horses can be ruled out.

 

The researchers that compiled the report at the time no longer work at TNO. Dr Jan Harm Urbanus, senior researcher at TNO, explains that TNO has small projects that are looking into the possibility of diluting the polyamides, a basic component of carpets, and in so doing, filtering out the rest of the components in the raw materials. This would create pure, clean fibres that could be used to weave new carpets. “At present, it is hard to separate the additives from the polyamides,” explains Urbanus, “so there is no real recycling”.

Research published last year in the Journal of Equine Veterinary Science compared the amount of fine particles that three surface types (sand, sand and wood chips, and sand and synthetic fibres) released. It appeared that the surface made of sand and synthetic fibres released significantly higher amounts of fine particulate matter. Research in the Netherlands thus seems outdated. Apart from the TNO report 20 years ago, only one other piece of research has been carried out in the Netherlands, and that was in 1994. At the time, the RIVM (The National Institute for Public Health and the Environment) only looked at the presence of antimony trioxide, a flame retardant, in shredded car upholstery. The study showed that the safe limits of the flame retardant in the offcuts examined were significantly exceeded. But because leaching into the ground and air remained within safe limits, the product was deemed environmentally clean at the same.

 

Professor Dick Vethaak is part of a research consortium that measures the concentration of synthetic polymers in humans. He explains that the larger plastic particles that humans ingest often leave the body through coughing or excrement. The danger is primarily in the minute particles and fibres. “These nanoplastic particles are even smaller than a bacteria or virus and can work their way deep into the body and pass through the membranes of the lungs and intestines. They then enter the bloodstream and could accumulate in certain organs. If you are continuously exposed to a lot of plastic dust, this could affect your immune system’s ability to fight diseases. We breathe it in, especially textile fibres, eat it and swallow it without knowing enough about the consequences”.

“Not many people are aware that if you fill a riding arena with synthetic textiles, you will generate microplastics,” warns Vethaak. “The horses tread all over it and this releases fibres and hazardous additives in the form of dust. This can pose a risk if the stables, and especially the indoor arenas, are not well ventilated. Horse lovers are thus regularly in contact with relatively high concentrations of plastic dust. Occupational epidemiology has shown us that textile factory workers who are exposed to very high concentrations of nylon and polyester dust particles run a greater risk of disease, including lung disease. People in stables must be careful that they do not have the same issues”.

 

Scientific research into equine health shows that horses, which have sensitive lungs just like humans, have problems with dust and allergens in their surroundings, says Cornélie Westermann, a veterinarian and Dutch and European Specialist in Equine Internal Medicine, about the clinical profile of common equine asthma. “The symptoms vary from mild to severe. If we compare this to humans, it would range from bronchitis to COPD and everything in between”. In stables, the straw, hay, sand, dryness of the ground and ventilation all affect the dust levels. The exact part played by synthetic fibres in lung disease is unknown.

 

Friction causes the flakes and the sand to “wear and tear” and the ground surface needs to be topped up with a new layer every few years. This pushes the small polyester particles deeper into the ground. Should anyone wish to stop using synthetic fibres in the arena, for example, if they sell the surface or place a new surface, they only have two options: either sell the sand mix secondhand on an internet marketplace or have it removed professionally. The latter is very expensive and is thus seldom done, said a stable owner who also named illegal dumping as a third alternative.

 

As the production and usage of polyflakes, carpet offcuts and geopad are not subject to much regulation, they can remain in equestrian arenas for decades. Direct contact with the natural ground surface is not mandatory. On Bokt, the Dutch online equestrian forum, many horse owners share their experiences with these products. Most are happy with the springy ground created by the flakes and fibres. But there are also some concerns expressed about whether these products are chemical waste or not, complaints about shreds and flakes in the manure, and descriptions of how the fibres fly around the arena in the wind.

 

The International Federation for Equestrian Sports (FEI) said that there is a lack of epidemiological data on ground stiffeners and for this reason, there are no guidelines for building and regulating equestrian centres and riding arenas. “In our industry, we are trying to understand the effects of synthetic materials in arenas on both the environment and on the health of humans and horses. The FEI is a great promoter of equine welfare in harmony with sustainability, but we are also aware that these can sometimes be contradictory priorities,” says a spokesperson.

The synthetic fibres in riding arenas should be on the list of potentially hazardous products such as rubber granules on sports fields and the microplastics that are released through wear and tear on tyres, vacuuming carpets and washing clothing in washing machines. This is the opinion of Bernard Merkx, co-founder of Waste Free Oceans. “Each of these products is a hidden cause of the accumulation of microplastics in the environment”. Merkx foresees European legislation and far-reaching manufacturer responsibility for relevant industries such as the carpet and textile industries. “Manufacturers must then be required to work towards making their product circular and create a regular market for high-value uses of the recyclates. In the wider context, collaboration must be sought for better uses and this entails both significant investment and improved legislation”.

 

For the more than 1,000 equestrian centres in the Netherlands, and the even higher number of arenas, synthetic fibres seem to be a good, environmentally friendly choice because they are recycled products that are often delivered with a recognizable certificate. But up until now, there is little policy in the Netherlands covering potential hazards. Checking this at research institutes delivers little information, there are very few inspections, and there is a lack of scientific research. A concerned stable owner warns that “The advantage of polyflakes is that they are comfortable for horses to walk on, but as the stable owner or trainer, we could be tripping up”.

 

– Laura Hoogenraad