Hand-Held Device Locates Hot Spots of Lead Contamination Using a hand-held scanner to map hot spots where the soil is full of lead could protect children in mining towns against brain damage, scientists at Columbia University concluded in a new study. Touched to the ground, the device, an X-ray fluorescence scanner, can measure the soil's lead content in less than a minute, said Alexander van Geen, a geochemist at Columbia's Lamont-Doherty Earth Observatory and an author of the study, which is in the current issue of the Bulletin of the World Health Organization. The "XRF guns," which are often used by scrap-metal sorters, cost between $15,000 and $40,000. His team tested the scanners in Cerro de Pasco, Peru, a town in the high Andes with mines dating back 1,400 years. Samples as close as 100 yards apart showed widely variable lead levels, so it is possible to find and mark off the areas most dangerous to young children, who get fine lead dust on their hands while playing and then put their fingers in their mouths. "People assume the contamination is everywhere, and it's not," Dr. van Geen said. It could be in one backyard and not in another. Or, he said, in an untested playground, schoolyard, or any place where children gather. The technology could be useful anywhere families live close to mines or smelters, which is common in Latin America and Africa, he said. Lead is a byproduct not just of lead mines, but of mining for gold, silver, copper and other metals.