The legacy of a 7,000-year-old metal-mining and smelting centre is still polluting the neighbouring environment.
A team of British researchers has found that copper mining in southern Jordan, which began 7,000 years ago, still poses a serious health risk.
John Grattan from the University of Wales, Aberystwyth, said: "The persistence of pollution from the ancient world for thousands of years is a lesson to us in the need to manage pollution today."
He said that vestiges of ancient mining in low-rainfall areas of Africa, the Middle East and South America could pose similar risks.
Archaeologists uncovered complex mines and processing sites in Khirbet Faynan, which still has 100,000 tons of black toxic copper slag. The area's rocks are rich in copper and lead.
Dr Grattan, with F. Brian Pyatt of the department of life sciences, Nottingham Trent University, took soil samples from inside modern Bedouin tents near Khirbet Faynan. They also analysed wood and faeces used for fuel, homemade Bedouin bread and samples from the spoil heaps.
They found that environmental levels of copper around the Wadi Faynan area were dangerously high, exposing the Bedouin to copper poisoning. The metal accumulates in the blood, liver and kidneys, which can be fatal.
Contaminated soil meant plants were contaminated. These were eaten by livestock, whose faeces became contamina-ted. Burning contaminated plants or dung released accumulated copper and increased levels of the metal in the tent. Bedouin bread contained 20 times more copper than a loaf bought in Amman.
But the team does not support a clean-up operation.
Dr Grattan said: "The area is best left undisturbed. The most responsible action on our part would be to map the pollution in order to allow the Bedouin to avoid contamination."
The research was published in Ecotoxicology and Environmental Safety .