The world generated 2.3 billion tonnes of municipal waste last year and the pile of trash is set to grow another two-thirds by 2050, the UN said Wednesday, warning of devastating costs for health, economies and the environment. 

Pollution is set to escalate, according to new research by the UN Environment Programme (UNEP), with projections suggesting the greatest growth in rubbish will be in regions that currently rely on open dumping and burning -- practices that emit greenhouse gases, and leach toxic chemicals into soils, waterways and the air.

Without urgent action, the waste mountain is expected to grow to 3.8 billion tonnes by the middle of the century, according to the estimate, which exceeds previous forecasts. 

It also suggests the economic burden will almost double when the "hidden costs" linked to poor waste disposal from pollution, poor health and climate change are taken into account, reaching some $640 billion a year by 2050, from around $361 billion in 2020.   

"Waste generation is intrinsically tied to GDP, and many fast-growing economies are struggling under the burden of rapid waste growth," said Inger Andersen, UNEP's Executive Director.

She said the report could help governments in their efforts to "create more sustainable societies and to secure a liveable planet for future generations". 

The report by UNEP and the International Solid Waste Association (ISWA) was launched at the UN's Environment Assembly being held this week in Nairobi. 

It follows a 2018 a report by the World Bank, which estimated that the world would generate 3.4 billion tons of waste annually by 2050.

'Zero waste'

ISWA said the new report and estimates were both a "guide and call for action" to come up with solutions. 

Those include preventing the rubbish being generated in the first place, as well as better disposal and treatment methods, which could limit net annual costs by 2050 to around $270 billion, the report found. 

But it is possible to do even better, moving to a more circular economic model where increased prosperity is not automatically linked to increased waste. 

The report said this could see a net economic gain of more than $100 billion a year.

"The findings of this report demonstrate that the world urgently needs to shift to a zero waste approach, while improving waste management to prevent significant pollution, greenhouse gas emissions and negative impacts to human health," said the report's lead author Zoe Lenkiewicz, of UNEP.

The world's landfills are a major source of emissions of the potent greenhouse gas methane, which is released when organic waste like food scraps decompose, while transporting and processing rubbish also generates planet-heating carbon dioxide. 

"Indiscriminate waste disposal practices can introduce hazardous chemicals into soil, water bodies and the air, causing long-term, potentially irreversible damage to local flora and fauna, negatively impacting biodiversity, harming entire ecosystems, and entering the human food chain," the report said. 

It said burning trash can release so-called "forever chemicals" into the air, with the potential for significant harmful effects on human health and the environment. 

The report added that research suggested up to a million people die every year as a result of illness related to waste mismanagement, including diarrhoea, malaria, heart disease and cancer.