Scientists have come across a fern that sucks up arsenic, holding out the prospect of a fast, cheap and safe way of cleaning up contaminated mines and industrial sites.

The plant could also be a potential boon for helping Bangladesh, which is facing a health crisis caused

by arsenic in its drinking water, they hope.

The remarkable plant, called brake fern, is native to Africa, Asia and Australia, and is now widely naturalised in warm parts of the Americas.

A team led by University of Florida soil expert Lena Ma analysed fern found at an abandoned wood-

preservation site in central Florida where there were high concentrations of arsenic compounds.

Brake ferns growing in uncontaminated soil at the site were found to have arsenic levels ranging from 11.8 to 64.0 parts per million.

But those growing in contaminated soil were found to have an he ^afty ^tar

astonishing fondness for the poison, flourishing as they extracted it from the soil. They had arsenic levels of between 1,442 and 7,526 parts per million, most of which was found in the plant's long-fingered green leaves.

In addition, the arsenic-absorbing trick is done quickly. Lab tests showed that within two weeks, the levels of arsenic in ferns rose by a factor of 126 when they were transplanted to contaminated soil.

"Brake fern has great potential to remediate arsenic-contaminated soils cheaply," the researchers report in Thursday's issue of Nature, the British science weekly.

"It has considerable bio-mass and is fast-growing, easy to propagate and perennial."

Arsenic is used in several industrial processes, notably to remove impurities in glassmaking, and in the manufacture of semiconductor wafers.

Research is now underway for devising a way of disposing of arsenic-enriched fern by burning it in ovens, which would provide a source of energy, and enable the element to be recovered in the form of a gas.

Ma, a native of north-eastern China, said that brake fern held out promise for helping Bangladesh, where between 35 and 77 million people out of a population of 125 million are at risk of being exposed to arsenic in their drinking water.

The peril stems from the creation over the past two decades of water pipes that have been drilled into shallow rock containing naturally occurring arsenic.

"Conceptually, the water in Bangladesh could flow through reservoirs planted with brake fern to filter out the arsenic," Ma told AFP, stressing however that further tests would be needed to check out this suggestion.