Comparison of the distributions of bromine, lead, and zinc in tooth and bone from an ancient Peruvian burial site by X-ray fluorescence 1 Ronald R. Martin, Steven J. Naftel, Andrew J. Nelson, and William D. Sapp III Abstract: Synchrotron micro X-ray fluorescence was used to study the distribution of selected trace elements (Zn, Pb, and Br) in tooth and bone samples obtained from an individual from a pre-Columbian archaeological site (Cabur) lo- cated on the north coast of Peru. The results show that Zn, Pb, and Br are present in both the teeth and bone samples and that the Zn and Pb seem to be confined to similar regions (cementum and periostium), while Br shows a novel distribution with enrichment close to the Haversian canals and (or) in regions that appear to be Ca deficient. Key words: teeth, bone, metals, XRF, Br, Zn, and Pb. Résumé : On a fait appel à la fluorescence de micro rayons X (FRX) à synchrotron pour étudier la distribution d’éléments choisis (Zn, Pb et Br) qui sont présents à l’état de trace dans des échantillons de dents et d’os obtenus à partir des restes d’un individu retrouvé sur un site archéologique précolombien (Cabur) situé sur la côte Nord du Pérou. Les résultats montrent que le Zn, le Pb et le Br sont présents dans les échantillons d’os ainsi que de dents et que le Zn et le Pb semblent confiner dans des régions similaires (cementum et periostium) alors que le Br présente une distribution nouvelle comportant un enrichissement aux abords des canaux haversiens et/ou dans les régions qui apparaissent comme déficientes en calcium. Mots-clés : dent, os, métaux, FRX, Br, Zn, Pb. [Traduit par la Rédaction] Martin et al. 836 Introduction Human teeth and bone constitute significant reservoirs of trace elements that are potentially indicative of diet, disease, and (or) environmental exposure (1). Bone is a complex tis- sue, approximately 35% organic (mainly collagen), while the remainder is mineral, principally bioapatite. The outer por- tion of most bone is dense and is termed compact bone. The structure of compact bone is formed around the cylindrical shaped osteons, or Haversian systems, oriented parallel to the long axis of the bone. The Haversian systems are the sites where remodeling of the bone occurs. Bone density de- creases toward the center to yield spongy or trabecular bone (2). The outer surface of bone is covered by a fibrous mem- brane called the periostium. This term is also used to indi- cate the outside surface of the bone itself, while the term endostium indicates the center of the bone. As noted in the preceding, bone is actively remodeled so that the turnover time for any metal deposited in bone repre- sents a confounding factor in the interpretation of bone metal content. In addition, turnover is dependent on bone type. Lead (Pb 2+ ), thought to substitute for Ca 2+ in calcium carbonate and hydroxyapatite in the mineralized component of bone and teeth (3), has a turnover rate estimated at 1% per year in cortical bone and 8% per year in trabecular bone (4). Teeth are more robust than bone and are generally well preserved. However, tooth structure is such that the individ- ual component tissues (enamel, dentine, cementum) of teeth have unique potentials as metal reservoirs. Enamel, the hard- est structure in the human body, constitutes the tooth crown and is generally believed to be free of remodeling effects and is resistant to diagenesis. Naturally, much analytical ef- fort has been directed at the enamel. In mammals (and hence humans) there are two sets of dentition, which form at different times in an individual’s life. Deciduous teeth begin formation within 14–19 weeks of fertilization and enamel mineralization is complete shortly after birth (5, 6). Thus, analysis of the metal content of de- ciduous enamel reveals details of a brief period in an indi- vidual’s life. The permanent dentition is formed from early childhood to approximately 16 years of age. Therefore, anal- ysis of the enamel of permanent teeth reveals details of a much longer period during an individual’s development. The Can. J. Chem. 85: 831–836 (2007) doi:10.1139/V07-100 © 2007 NRC Canada 831 Received 29 March 2007. Accepted 1 August 2007. Published on the NRC Research Press Web site at canjchem.nrc.ca on 6 September 2007. R.R. Martin, S.J. Naftel. 2 Department of Chemistry, University of Western Ontario, London, ON N6A 5B7, Canada. A.J. Nelson. Department of Anthropology, University of Western Ontario, London, ON N6A 5B7, Canada. W.D. Sapp III. Cotsen Institute of Archaeology, UCLA, Los Angeles, CA 90024, USA. 1 This article is part of a Special Issue dedicated to Professor G. Michael Bancroft. 2 Corresponding author (e-mail: snaftel@uwo.ca).