With dioxins and other poison wastes recently highlighted in New Zealand US scientists report they have come across a fern that sucks up arsenic from contaminated soil. John Howard reports.

A remarkable plant, called brake fern, has the potential as a fast, cheap and safe way of cleaning up contaminated mines and industrial sites. The plant is native to Africa, Asia, and Australia and has become naturalised in other warm parts of the world.

A team of scientists led by University of Florida soil expert, Lena Ma, analysed brake fern found at an abandoned wood-preservation site where there were high concentrations of arsenic compounds. The ferns were found to have astonishing fondness for the poison most of which was found in the long-fingered green fronds.

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

But those in contaminated areas had arsenic levels between 1,422 and 7,526 parts per million showing that the fern was gobbling up the poison waste.

And it is done very quickly. Lab tests showed that within two weeks, the level of arsenic in the ferns rose by a factor of 126 when they were transplanted into contaminated soil.

Lena Ma says "Brake fern has great potential to remediate contaminated soils cheaply, it has considerable biomass, is fast growing, easy to propagate and is perennial."

Ma, a native of China, said the brake fern held out promise to help people who are at risk of being exposed to arsenic in their drinking water.

Arsenic occurs naturally in the soil but not in sufficient quantities to cause harm. But it is also used in several industrial processes which can leach into the environment.

A plan is now being considered to determine whether brake fern has the potential to gobble-up a range of industrial pollutants and poisons. Research is urgently needed.