Millions of tons of tiny debris from plastic bags, bottles and clothes in the world’s oceans present a serious threat to human health and marine ecosystems.
This is the stark warning issued by the United Nations in a report on the most dangerous environmental problems facing the world today.
Global plastic production has increased dramatically in recent years. Between 2004 and 2014, the amount of plastic produced rose by 38 per cent, the report said.
And poor waste disposal means when we have finished with our takeaway containers, cigarette butts and party balloons, they are worn down into trillions of ever-smaller particles by the waves.
There is a growing presence of these microplastics, particles of under 5mm in length, in the world’s oceans.
In 2010, between 4.8 million and 12.7 million tons of plastic was washed into the seas and has since shown up in the stomachs of whales, plankton and other marine life.
“There is some evidence that microplastics can cause harm [to organisms],” Richard Thompson, professor of marine biology at Plymouth University, told The Independent.
Dr Thompson said that in laboratory experiments, replacing one per cent of the sediment in a worm tank with plastic had a negative effect on the worms' ability to store energy.
"If we carry on with business as usual – it’s not uncomparable – then we are going to reach those thresholds," he said, adding that there may be places in the world's oceans that have not yet been discovered where microplastics are particularly concentrated.
More than a quarter of all fish now contain plastic, according to a recent study which analysed the guts of fish sold at markets in Indonesia and California.
The United Nations Environment Project report will be presented at the UN Environment Assembly in Nairobi, which starts on Monday.
Scientists fear that chemicals in plastics and also chemicals which attach themselves to plastic in the natural environment could cause poisoning, infertility and genetic disruption in marine life, and potentially in humans if ingested in high quantities.
"The presence of microplastic in foodstuffs could potentially increase direct exposure of plastic-associated chemicals to humans and may present an attributable risk to human health," the UN report, called Frontiers, said.
People could even be breathing in plastic microparticles suspended in the air, with the risk of a noxious effect on the lungs similar to car fumes.