The scattering of tiny black particles regularly patterns our floor – by the door where my sons take their football boots off, under the sofa where they lounge in post-match socks, or here and there, where the granules have rained from clothing.

Even when I first recognised what they were, I didn’t know what their real provenance was – that they are, in fact, tiny pieces of ground-down end-of-life tyres. The use of this so-called “rubber crumb”, also known as SBR (styrene butadiene rubber), might seem a clever recycling, but in a world of increasing microplastic pollution, it’s one that should be viewed with scepticism.

I've always found fake grass depressing, whether it is inching its way across the gardens of the UK or our 3G pitches. Of course, I understand why such pitches are so popular, particularly on weeks when the grass playing fields are rained off and they are a refuge where it's still possible to get a training night in, or even a game. But that trail of microplastics that arrives through my door, more frequent than mud, has made me feel it’s time for a proper turf war.

Vicky Allan: Greta spat reminds us what’s bad for women is bad for planet

I'm also aware that the controversy around plastic-based artificial pitches isn’t new. Players have long debated its virtues and flaws – with calls made to banish synthetic pitches from the Scottish Premiership. But a great deal of the discussion has revolved around health. Fears, for instance, were raised in 2018, when goalkeeper Lewis Maguire died of cancer at the age of 20.

Parents have worried over potential toxic effects on children. A key voice throughout, calling attention to the presence of polycyclic aromatic hydrocarbons (PAH), chemicals linked to cancer, has been Professor Andrew Watterson of the University of Stirling, who still now campaigns to have rubber crumb pitches phased out completely.

Many studies however have delivered reassurance. In 2017, the European Chemicals Agency stated that there was a 'very low level of concern' that these will negatively impact human health and, in 2020, a European risk assessment study found “no health concerns” for synthetic turfs with end-of-life tyre-derived infill material.

But there was still enough alarm that last year, following advice from the European Chemicals Agency, EU rules were put in place limiting infill material in synthetic pitches and playgrounds to less than 20mg/kg for eight specific PAHs.

Such regulations do not yet exist here. The UK government currently says that it sees no need for new regulation, since, a public consultation “indicated that at least 95% of the material in use within the UK" falls within the limit set in 2022 under EU REACH. Most pitches in the UK, it said, are already compliant with the restriction.

But is "most" enough? Holland, it's worth noting, plans to phase out all rubber crumb pitches by 2030. Meanwhile, in the United States, the focus of concern has shifted from the PAHs in the crumb to possible PFAs, so-called “forever chemicals” in the grass blades and fabric of sports pitches and other artificial turfs.

Increasingly too, there is the environmental worry about microplastic leakage into our soils, waters and the wider environment. In a world in which we are finding microplastics in the Arctic, our food, our soil, our blood and even human breast milk, this is a concern. Are we breaking down old tyres to make them more pervasive pollutants than they already were?

The Herald: Microplastics have been found in the Arctic and even in human breast milkMicroplastics have been found in the Arctic and even in human breast milk (Image: Newsquest)

Among those campaigning for governments to “ban the use of crumb rubber infill on artificial sports surfaces, as the European Chemical Agency Recommends” is the Scottish environmental NGO, Fidra. It notes that 1,800 tonnes of these rubber crumb granules are estimated to be lost from pitches in Scotland each year.

From there, they leak out into nearby soils, local waters, or, via drains, to the sea. “Microplastics,” Fidra states, “have been found in the stomachs of fish in rivers near 3G pitches and can leach harmful chemicals and toxic heavy metals into the environment.”

The charity is calling for more natural grass pitches, or for use of organic infills when building or refurbishing a pitch and also has a campaign, Pitch In, created with Kimo International, which gives advice on the management of rubber crumb pitches.

Kimo notes, “Manufacturers grind up old tyres to make SBR. As a result, it can contain small quantities of harmful chemicals and heavy metals that wash out into the environment over time. Studies show that zinc, in particular, leaches out from the granulate in sufficiently high concentrations to harm soil biota and aquatic life.”

Meanwhile, the debate over human safety has not concluded. A recently published international review of policy regulations, looking at artificial turf and crumb rubber raised a number of concerns, including the fact that “insufficient research” had been conducted to assess the potential effects of exposure of artificial turf field users to the numerous chemicals.

Vicky Allan: Can we really protect 30% of our land and seas and feed the nation?

The report also observed: “The Scottish Government has not shown any interest in regulating the crumb rubber infill chemical situation beyond their acknowledgement that artificial turf infill is a microplastic with harmful effects when spread to the environment outside playing fields.”

May the turf wars begin. In a world that is aiming to tackle both a biodiversity crisis and a plastic pollution crisis, can there be any place for plastic grass?