UNITED NATIONS — The most worrying environmental threats facing the world today range from the rise in diseases transmitted from animals to humans to the increasing accumulation of toxic chemicals in food crops as a result of drought and high temperatures, according to a U.N. report released Friday.

The U.N. Environment Agency’s Frontiers report also highlighted the threat to human health posed by the alarming amount of plastic waste in the oceans, and scientific evidence suggesting that losses and damage from climate change are inevitable, with “profound consequences” for ecosystems, people, assets and economies.

The report emphasizes “the critical relationship between a healthy environment and healthy people,” and stresses the importance of combating global warming by moving to a low-carbon future.

According to the report, the 20th century saw dramatic reductions in ecosystems and biodiversity – and equally dramatic increases in the numbers of people and domestic animals inhabiting the Earth.

This increased the opportunity for viruses, bacteria and other pathogenic agents to pass from wild and domestic animals through the environment to cause diseases in people, the report said.

These diseases – called “zoonotic” or “zoonoses” diseases – include Ebola, bird flu, Middle East respiratory syndrome (MERS), sudden acute respiratory syndrome (SARS), Rift Valley fever, West Nile virus and Zika virus, it said.

According to the report, “around 60 per cent of all infectious diseases in humans are zoonotic as are 75 per cent of all emerging infectious diseases.”

As for toxic chemicals in crops, normally plants convert nitrate into amino acids and protein but drought slows the conversion causing nitrates to accumulate and become toxic to animals, the report said.