People of numerous pre-Columbian civilizations in northern Chile, including the Incas and the Chinchorro culture, suffered from chronic arsenic poisoning due to their consumption of contaminated water, new research suggests.

Previous analyses showed high concentrations of arsenic in the hair samples of mummies from both highland and coastal cultures in the region. However, researchers weren't able to determine whether the people had ingested arsenic or if the toxic element in the soil had diffused into the mummies' hair after they were buried.

In the new study, scientists used a range of high-tech methods to analyze hair samples from a 1,000- to 1,500-year-old mummy from the Tarapacá Valley in Chile's Atacama Desert. They determined the high concentration of arsenic in the mummy's hair came from drinking arsenic-laced water and, possibly, eating plants irrigated with the toxic water. [See Photos of the Mummy and Excavation Site]