A single plastic bag can result in almost 2 million microscopic pieces of plastic littering the ocean, new research has found.
Microplastics - generally any piece smaller than 5mm across - are easily ingested by marine life, which can be then transferred up the food chain to humans and other animals. Microbeads are a particular kind of microplastic that are set to be banned from next year in New Zealand.
But while phasing out plastic bags is Green Party policy, there are still no concrete plans to ban them.
Researchers at the University of Plymouth fed plastic bags to Orchestia gammarellus, a small amphipod commonly found in the waters around Europe and Scandinavia.
They were surprised at how quickly the tiny crustaceans broke the plastic bags down, but it was to no avail - their rapid consumption didn't eliminate the plastic bag from the environment it all. Instead, each bag was turned into 1.75 million tiny pieces, all of it still polluting the environment.
"An estimated 120 million tonnes of single-use plastic items - such as carrier bags - are produced each year and they are one of the main sources of plastic pollution," said professor of marine biology Richard Thompson.
"They already represent a potential hazard to marine life, but this research shows species might also be contributing to the spread of such debris. It further demonstrates that marine litter is not only an aesthetic problem but has the potential to cause more serious and persistent environmental damage."
Last month Kiwi scientist Trisa Farrelly of Massey University proposed banning glitter for similar reasons.
Microplastics make up a large part of what's known as the Great Pacific Garbage Patch - an area of the north Pacific where plastic seems to congregate.
The latest research was published in journal Marine Pollution Bulletin.