14 Feb 2017

Scientists develop tool for studying ancient civilizations

Canadian Light Source scientists have discovered a way to determine if lead found in bones is the result of contamination after burial or because of exposure during a person’s lifetime.

“We are very excited to be working on this because we see it as a way to add a new tool to the toolkit of a researcher,” said Dr. Ian Coulthard, a scientist at the CLS.

Dr. Ian Coulthard
Dr. Ian Coulthard

“This opens the possibility of going back and re-examining bone samples that other researchers dismissed as being too contaminated to study. We can now pull useful information about biological exposure to toxic metals out of those samples.”

Lead oxides were a primary ingredient in many paints and putties in the 18th and 19th centuries. The lead oxide paints rendered wooden warships waterproof and resistant to damage from insects. Lead is also malleable and easy to form, which was useful for construction. Archeologists and anthropologists will now be able to revisit history to learn more about exposure to toxic metals such as lead. They could also better understand the practices of ancient civilizations, such as the Incas, that left no written record.

“Without the written record, the human remains become more important. There are still the artifacts but there are things that the human remains can tell you that the artifacts cannot,” said Dr. Coulthard.

Prior to this discovery, researchers examining exhumed bones were unable to determine if the lead they were seeing in the bone had leached into the bone from the soil because they would see traces of lead contamination throughout the sample.

During their study, the scientists were able to pinpoint specific lead contamination by manipulating a beam of light and making it the same size or smaller than the structural features of the bone. Such a high spatial resolution can localize traces of lead to an area as small as 0.002 millimetres.

“Where you see the red or yellow that is brighter, that’s where the lead is,” said Dr. Coulthard as he pointed enthusiastically to his computer screen showing images from the study.

Images from the JAAS front cover
Images from JAAS front cover

The findings of the team, which included researchers from the University of Saskatchewan, Lakehead University, and Cornell University, is the cover story of the most recent issue of the Journal of Analytical Atomic Spectrometry. The group conducted its investigation at the Sector 20 US Department of Energy and CLS beamlines at the Advanced Photon Source, Argonne, Ill.

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Choudhury, Sanjukta, David Nana Agyeman-Budu, Arthur R. Woll, Treena Marie Swanston, Tamara Varney, David ML Cooper, Emil Hallin, Graham George, Ingrid Pickering, and Ian Coulthard. "Superior Spatial Resolution in Confocal X-ray Techniques Using Collimating Channel Array Optics: Elemental Mapping and Speciation in Archaeological Human Bone." Journal of Analytical Atomic Spectrometry (2017). DOI: 10.1039/C6JA00297H

Story by Lana Haight

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