Up to a third of plastic exported from Europe for recycling is being dumped on land or in the sea or incinerated, a new study has found.
And the study by NUI Galway (NUIG) and the University of Limerick (UL) found up to 7pc of all European polyethylene - the most common type of plastic shipped abroad for reuse - actually ends up in the ocean.
In Ireland's case, an average of 3.15pc of plastic exported for recycling in 2017 became ocean debris.
The tracking study by the NUIG and UL researchers quantified the volume of plastic exported for re-use from 30 European countries, including Norway and Switzerland, drawing on data for 2017 when China banned imports of all but the cleanest materials.
Some 46pc of European separated plastic waste is exported outside the country of origin, with a large share shipped to south-east Asia where there are overstretched local waste management systems, the researchers note.
The study - which was published in the scientific journal 'Environment International' - estimates best-case, average, and worst-case scenarios for the amount that became ocean litter.
Lead author George Bishop, a PhD researcher at NUI, said that they calculated that between 32,115 tonnes and 180,558 tonnes found its way to the sea three years ago.
This was equivalent to between 1pc and 7pc of all exported European polyethylene, one of the most common types of plastic in Europe.
UL lecturer and co-author of the paper Dr David Styles said that the study "suggests that 'true' recycling rates may deviate significantly from rates reported by municipalities and countries where the waste originates".
The research was part of a Science Foundation Ireland project on innovative energy technologies for bioenergy, biofuels and a sustainable Irish bioeconomy, led by Prof Piet Lens of NUIG.
European municipalities and waste management companies need to be held accountable for the final fate of "recycled" waste, Prof Lens said, if a move is to be made towards a circular economy.
Organised crime has also risen in some areas most exposed to flood of new waste imports.
The NUIG and UL researchers say their findings "should not discourage people to recycle" as "it remains the best waste management treatment, environmentally speaking".