Rooting out land mines

April 12, 2004

CAN A PLANT protect the world? Or at least mine-pocked sections of it?

Danish scientists reported in the journal Nature that they have developed a strain of thale cress whose leaves change color from green to red if it detects nitrogen dioxide in the soil. That's what leaches out of land mines and some cluster bombs when they are in the ground. Should the plant hold up in field tests, it would be a giant step in restoring lands and countries decimated by wars.

Up to 110 million unexploded land mines in more than 70 countries kill and injure 26,000 people every year, according to the International Red Cross. And they take a heavy economic toll, rendering unusable large areas of crop-worthy land (40 percent of Cambodia's fertile land, 90 percent of Angola's, according to the United Nations) as well as straining medical systems. Governments pay $200 million to $300 million for cleanup each year.

Current best practices for detecting unexploded bombs are walking through the suspected minefield using metal detectors and bomb-sniffing dogs to point out likely spots, then prodding a stick into the ground to find the mine. It's a dangerous, tedious and seemingly endless process. On average, one mine removal crew member dies and two are injured for every 5,000 bombs they detect and explode. Worldwide, mine removers destroy about 10,000 bombs a year, and they aren't keeping up. More bombs are still going into the ground than are being taken out year after year.

Using a sprayer, workers could seed fields and roadsides with the weedy thale cress strain (which is modified not to reproduce), and two months later see the results. It wouldn't replace the dogs or the humans, but it could radically speed up the process, as well as signal caution in fields until mine removers can get to them.

Thale cress is the kind of flowering weed that sprouts up in cracks in the sidewalk, the kind despised by fancy gardeners. But since its relatively simple genome sequence was fully mapped in 2000, it has become a pet test subject. Variations also have shown promise in detecting excess radiation in the soil and perhaps such pathogens as anthrax.

Such speeded-up evolution carries its own dangers, and it's prudent to be cautious before loosing new plants into the ecosystem. But it is a sign of hope that humans -- who are clever enough to build cheap, lasting, deadly devices -- also are clever enough to find better ways of cleaning up the time bombs they leave behind.

Baltimore Sun Articles
Please note the green-lined linked article text has been applied commercially without any involvement from our newsroom editors, reporters or any other editorial staff.