A quarter of all premature deaths and diseases worldwide are due to man-made pollution and environmental damage, the United Nations has stated in a landmark report on the planet's precarious state.

Deadly smog-inducing emissions, chemicals polluting drinking water, and the accelerating destruction of ecosystems crucial to the livelihoods of billions of people are driving a worldwide epidemic that hampers the global economy, it has warned.

The report six years in the making compiled by 250 scientists from 70 nations depicts a growing chasm between rich and poor countries as rampant over-consumption, pollution and food waste in the developed world leads to hunger, poverty and disease elsewhere.

As greenhouse gas emissions continue to rise amid a preponderance of droughts, floods and superstorms, there is a growing political consensus that climate change poses a future risk to billions.

Health impacts of pollution, deforestation and the mechanised food-chain are less well understood.

World leaders in 2015 came up with the Paris climate deal, which saw each nation promise action to cut emissions in a bid to limit global temperature rises to 1.5 degrees Celsius.

But the health impacts of pollution, deforestation and the mechanised food-chain are less well understood.

Nor is there any international agreement for the environment close to covering what the Paris accord does for climate. 

It said that poor environmental conditions "cause approximately 25% of global disease and mortality" - around 9 million deaths in 2015 alone.

The report says air pollution causes 6-7 million early deaths annually.

Lacking access to clean drinking supplies, 1.4m people die each year from preventable diseases such as diarrhoea and parasites linked to pathogen-riddled water and poor sanitation.

Chemicals pumped into the seas cause "potentially multi-generational" adverse health effects, and land degradation through mega-farming and deforestation occurs in areas of Earth that are home to 3.2bn people.

The report says air pollution causes 6-7 million early deaths annually.

And the way Earth is set, unchecked use of antibiotics in food production will see drug-resistant superbugs become one of the largest causes of premature death by mid-century.

The report has called for a root-and-branch detoxifying of human behaviour while insisting that the situation is not unassailable.

Everyone is saying that by 2050 we have to feed 10bn people, but that doesn't mean we have to double production.

Food waste for instance, which accounts for 9% of global greenhouse gas emissions, could be slashed. The world currently throws away a third of all food produced. That figure is fuelled by 56% in richer nations going to waste.

According to Joyeeta Gupta, Global Environment Outlook co-chair, we can reduce the problem of food waste but it will require changes in the way we live. 

"Everyone is saying that by 2050 we have to feed 10bn people, but that doesn't mean we have to double production," she said.

The unveiling of the report at UN Environment Assembly in the Kenyan capital Nairobi is likely to add to the debate over who bears the greatest responsibility for the damage already borne by Earth.

Some developed nations, led by the US, had threatened not to "welcome" the report - a procedural but nonetheless significant hurdle if nations are to agree on the necessary cuts in waste, over-consumption and pollution.