Exposure to geogenic lithium in ancient Andeans: Unraveling lithium in mummy hair using LA-ICP-MS

The ancient Andeans, who lived along the coastal region of the arid Atacama Desert in present day Chile had access to scarce freshwater via a few small rivers originating from the Andean Altiplano. Due to volcanic-derived lithium minerals and their solubility in water, the surface water in the Atacama Desert region is rich with lithium (Li); often many orders of magnitude higher than that of other rivers in the world. The goal of this study was to examine whether ancient Andean mummy individuals (n = 145) from four burial areas in northern Chile (Azapa, Camarones, Lluta and Morro) were exposed to geogenic lithium by conducting laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) on a single strand of hair per individual. The resulting concentrations for Li in mummy hair [Site, Median, Range (μg/g), n: Azapa, 0.38, 0.04–2.91 μg/g, n = 98; Morro, 0.33, 0.03–0.65 μg/g, n = 14; Camarones, 0.61, 0.07–12.8 μg/g, n = 31; Lluta, 2.9, 2.7–3.1 μg/g, n = 2] had the following order: Lluta > Camarones > Azapa > Morro. Hair-Li concentration of the Andean mummies were nearly 20 times elevated when compared to concentrations of Li in the hair of contemporary populations in other regions. Exposure to Li as revealed in hair appears to be depend in part on where ancient Andeans were buried, and generally correlates well with dissolved Li in associated rivers.