The next time you’re enjoying a trip to the seaside, turn your mind away from the ice-cream vans and sand dunes for a moment and spend a few minutes looking beneath your feet.

If you’re on a touristy beach such as Bournemouth, swept clean every morning by teams of litter pickers, you may have to look hard. But even on the tidiest beach, among the shells, seaweed and stones, you will inevitably find plastic.

Sometimes the plastic will be recognisable — perhaps a fragment of a crisp packet or bottle tops.

Often you will just find weird looking coloured blobs, tiny microbeads from cosmetics or blobs of ‘microplastic’.

Every single beach and every stretch of coastline in the world, from Great Yarmouth to Hawaii, is now washed by a tide of this all pervasive, harmful plastic soup.

There are five trillion particles of plastic measuring less than 5mm floating around the seas — collectively weighing nearly 270,000 tonnes.

Around 1 to 4 per cent come from microbeads added to shower gels, facial scrubs, toothpaste and other cosmetics and then washed down the plug hole into the seas. The rest are remnants of plastic bags, discarded fishing lines or old tyres — all worn down into balls by the crashing of the waves and beating sun.

Plastic is supposed to be inert and benign. But in the seas, microplastic pollution is anything but harmless.

According to many marine pollution experts, plastic may be more of a threat to wildlife than oil slicks.

That’s a big claim. The worst oil slick of recent times was caused by the explosion on BP’s Deepwater Horizon rig in the Gulf of Mexico in 2010. It led to a staggering 4.9 million barrels of crude oil — or 668,000 tonnes — gushing into the Gulf of Mexico for 87 days.

The spill stretched across 68,000 square miles of ocean — an area more than eight times the size of Wales — and coated 500 miles of coastline with thick, noxious oil.

The impact on wildlife was horrendous. Coral reefs were wrecked, three times the usual number of dolphins washed up dead or stranded on American beaches, while sea turtle strandings went up. Four years after the accident, 14 species showed symptoms of oil exposure, according to the U.S. National Wildlife Federation.
And yet incredibly the impact of plastic soup could be even worse in the long run.

Daniel Steadman, marine plastics project manager of Fauna and Flora International, says: ‘The trouble with plastic pollution is that it doesn’t go away. It might move around but it is not broken down.

‘And once it is in the oceans it is far harder to clean up than oil. Oil is an organic product and so is broken down eventually by microbes. But plastic doesn’t.’

Dr Erik van Sebille, oceanographer at Imperial College, London, agrees.
‘Both oil and plastic have grave environmental impacts,’ he says. ‘But oil is less harmful in the long run because there are bacteria that eat it away. It doesn’t stay in the ocean for more than a few months compared to the hundreds of years that plastic can linger.’

And the damage the plastic is doing is incalculable. As the Daily Mail has reported for the past few days, there is compelling evidence that tiny plastic particles stunt the growth of animals that ingest it — particularly the tiny creatures near the bottom of the food chain such as worms, plankton, mussels and oysters.

‘It seems smaller creatures spend too much energy trying to digest indigestible plastics and so they don’t put on as much weight as they should,’ says Professor Tamara Galloway, of Exeter University, one of the UK’s leading experts in marine pollution.

The health, size and number of these tiny creatures matters because the web of marine life depends on them. If plankton eat plastic, the creatures that feed on plankton ingest plastic, too. Concentrations of plastic build up the higher up the food chain.

The effects could ripple through the food chain — to fish, jellyfish, birds, turtles, dolphins, whales and even us.

Studies have shown that 30 per cent of fish caught in the English Channel have microplastics in their guts, while as much as 83 per cent of scampi sold in Britain contains these plastics.

It is estimated that each plateful of mussels on a dinner table contains between 20 and 50 microbeads.

But the direct harm from a plastic diet is only part of the problem.

Microbeads and other microplastics turn out to be excellent at absorbing the toxic pollutants that people have pumped into the atmosphere and seas since the Industrial Revolution.

Many of these toxins are called POPs — or persistent organic pollutants — by-products of factories, power stations and farming that hang around for decades, if not longer, and accumulate in the bodies of animals.

They include PCBs, once used in electrical wire, flame retardants called PBDEs and the pesticide DDT. These are horrendous chemicals — long since banned — which have been shown to cause cancer or to mimic sex hormones, contributing to infertility and birth deformities.

Others are toxic metals, such as mercury, which is spewed into the air from coal-burning power stations and factories and which poison the nervous system and kidneys.

Not only are these pollutants long lived, they are hydrophobic — or repelled by water. If they come across plastic in the ocean they are drawn to it like a magnet.

‘In 2001, a group of researchers collected polypropylene pellets, used in plastic manufacturing, from coastal waters in Japan,’ says Prof Galloway. ‘They discovered that over time, these pellets had accumulated toxins at concentrations up to one million times that found in surrounding seawater.’

Scientists know that these POP toxins pass from seawater into the bodies of animals. What they don’t know yet is whether toxins pass from plastics to animals — and if so, what the impact is on their health.

And they don’t know whether exposure to these toxins in seafood could harm us by increasing the risks of cancer, infertility and birth defects.

An Act of Parliament could — and should — ban microbeads from cosmetics. But it can’t miraculously clear up the mess we’ve already put out there.

‘It will be virtually impossible to filter out microplastics from the ocean,’ says Dr van Sebille. ‘They are so small that there is no way to capture the plastic while leaving behind the plankton and fish larvae which are crucial to all life in the ocean.

‘I hope the current attention on microbeads makes people realise that we as humanity need to take care of our waste. It’s not the plastic itself that’s the problem, it’s the way we discard it once we’ve used it.’

Prof Galloway agrees. ‘The growing proliferation of plastic in the sea is the result of our ultra-consumerist, throwaway society, where so many products, especially cosmetics and packaging, are disposed of without a second thought,’ she says.

‘Every time you use a shower gel containing these beads, you will be washing 100,000 tiny microplastics down the plug. ‘Yet it is a rich irony that these goods, so often specifically and deliberately designed to be used only once, can last for centuries.’

And as a result, for centuries, the health of our oceans — and ourselves — could be in peril.