Further evidence of lead contamination of Omaha skeletons.

A previous analysis of Omaha skeletons dating between A.D. 1780 and 1820 revealed the presence of lead in all skeletons with high concentrations in children and adult males (Reinhard and Ghazi [1992] Am. J. Phys. Anthropol. 89:183-195). Two likely explanations for the high lead levels were presented: 1) metabolic absorption of lead and 2) diagenetic uptake of lead by the bones from postmortem application of pigments to the corpse. Two types of lead were available to the Omaha tribe: 1) Mississippi Valley type, and 2) non-Mississippi Valley type. It has been suggested that red-lead pigment mixed with mercury sulphide (cinnabar) applied to the corpse may have been one of the sources of lead found in bones. Further isotopic analyses of samples of pigment and metallic lead artifacts associated with the skeletons revealed that non-Mississippi Valley type lead is present in the pigment while Mississippi Valley type lead comes from metallic artifacts. Both lead and mercury were found in the pigment samples, verifying that a lead-based pigment mixed with cinnabar-based pigment was used as a cosmetic by the Omaha. Isotopic analysis of lead in skeletons indicates that the pigment contributed most to lead content of bone. This new evidence clarifies the previous study and suggests specific mechanisms by which lead became incorporated into bone.