Bees used in search for hidden landmines

Foraging honeybees, handheld electronic "sniffers" and devices that can rival the nose of a trained bloodhound are all being used to help overcome the nightmare of landmines and the tragic maimings and deaths they cause.

Science is playing a big part in finding new and more powerful methods to unearth these devices and a variety of new techniques were described yesterday at the American Association meeting in Washington DC.

Hundreds of thousands of acres of usable land are off-limits to human use because of the 100 to 120 million landmines they conceal. These are joined by an estimated 40,000 new landmines each week and, while they are used by battling military forces, all too frequently their victims are children and other civilians.

Prof Jerry Bromenshenk, of the University of Montant-Missoula, described ongoing work at his institution, which has studied the use of foraging bees to detect plastic and metal landmines. The bees pick up pollen, but also dust and chemical residues leached by explosives into the soil. The dust brought back to the hive by the bees can be analysed for minute traces of TNT, the main explosive used in these devices.

A variety of hand-held chemical sniffers have been developed that sample the air above suspected landmines. They can detect traces of TNT given off by the landmines and speed up their discovery. One of the latest techniques involves using nuclear quadrupole resonance (NQR), a method developed by Dr Allen Garroway and colleagues at the US Naval Research Laboratory. NQR is similar to the magnetic resonance imaging used in hospitals and overcomes the greatest impediment to rapid landmine detection, false alarms.

Conventional metal detectors can detect tiny firing mechanisms used in small, largely plastic antipersonnel mines, but they can't differentiate between landmines and other scraps of metal.