Alarm has been raised over fake pebbles washing up on UK beaches that look just like the real thing.
Litter cleaners often miss them because they are similar to real pebbles and rocks.
But beach environmentalists say the ‘pebbles’ can be easily missed, NorthWalesLive reports.
Hilary Rowlands, a founding member of Tywyn Beach Guardians in Gwynedd , Wales says: “It’s only when you pick them up, and feel how light they are, that you realise they are not stones at all,”
They are in fact “fake” plastic pebbles and there’s anecdotal evidence they are washing up from the Irish Sea in ever greater numbers.
Environmentalists say this newest and most curious form of plastic pollution could enter food chains as they break down into microplastics.
Known as pyroplastics, the “stones” are thought to form when pieces of plastic are melted or burnt and thrown into the sea, where they are slowly weathered grey and smooth as they float on long ocean voyages.
Hilary said they are commonplace around the mouth of the Dyfi estuary, disgorged onto beaches by storms.
She’s also found variants, termed plastiglomerates, which are created when burnt plastic fuses with rock, commonly when people light fires on beaches.
“There’s not a single beach I’ve combed where I haven’t come across them,” she said.
“Sometimes they are covered in oil or impregnated with the toxins that come from burning plastic.
“It’s all dangerous, both to the environment and the marine life.
“The longer-term concern is that they will break down into microplastics and threaten marine food chains.”
Dr Andrew Turner, an environmental scientist at the University of Plymouth was first to describe pyroplastics in Britain.
And some beachcombers in Cornwall have been uncovering thousands of plastic rocks and pebbles.
Using X-ray and infrared spectroscopy, Dr Turner discovered they comprised of polyethylene and polyproplyene, two of the most common forms of plastic.
More analysis showed they contained lead and, usually, chromium.
He surmised these were the traces of lead chromate, a compound once added to plastics to colour them red or yellow.
But the scientist was surprised just well the plastic impostors blended in with their surroundings.
He said: “When we have university open days, I show visitors 15 boxes of stones and ask them to pick out the one that contains plastic stones,
“Without touching them, very few people get it right.”
It is for this reason that identifying the scale of the problem is fraught with difficulty.
Given that Dr Turner has received samples from around the world, it’s likely to be a global problem.
And despite recent discoveries, it’s probable many pyroplastics are decades old, perhaps originating from the now banned practise of burning plastic at sea.
“But in some countries plastic is still burnt and cast into the sea to get rid of it,” he said.
Even harder to spot on beaches are another, more insidious form of plastic pollution.
These are nurdles, the tiny lentil-shaped pellets that are the raw material for almost all plastic products.
As they weigh a fraction of a gram, they are easily spilled, quickly entering watercourses and marine systems.
Dawn Thomas, Living Seas awareness officer at North Wales Wildlife Trust said pyroplastics and nurdles both present long-term threats, yet tackling the problem is not easy.
“We have been seeing it (pyroplastic) looking just like pebbles and stones on beaches and that’s part of the problem, as it can get overlooked on a beach clean,” she said.
“Nurdles are smaller and bite-sized for our wildlife – some have even been found to be attracted to the bacterial coating they collect.
“Again, they are difficult to collect as they’re so small and often translucent.”
While the idea of Wales’ beaches turning artificial sounds fanciful, some people worry about the long-term impact on tourism if plastic pebbles keep rolling onto shorelines.
However Hilary Rowlands notes that beaches are already littered with so much plastic that fake stones are not the real threat.
Some litter is washed up by the sea, other items are left by careless visitors or blown there by off-shore winds.
“Having watched last year’s shocking scenes from Southend, when the beach there was strewn with rubbish after the first lockdown, I’m not sure people will worry too much about a few pieces of burnt plastic,” she said.
Natural Resources Wales (NRW) said it has not received any reports about pyroplastics washing up on beaches in Gwynedd.
But it wants to hear from anyone who finds examples.
Katherine Griffith, NRW’s senior marine advisor, said: “Whilst we have seen occasional incidences of burnt plastic on beaches, these were linked to people lighting a fire on the beach and burning plastic on it, rather than the debris having been washed up on the beach.
“If anyone is concerned about the amount of burnt plastic washing up on the coast anywhere in Wales, please report it to us so that our local officers can investigate further.”