Distribution of Ca in human hair and its relation to oxidative damage examined by X-ray contact spectromicroscopy and X-ray fluorescence mapping

Introduction We have been studying the relation between Ca accumulation and oxidative damage in human hair [1], intended to provide the possible explanation between Ca content and the incidence of human breast cancer [2]. Xray spectromicroscopy using a contact microscope with an electronic zooming tube is a powerful tool for the observation at sub-micron resolution of the distribution of cysteic acid, an oxidation product of cystine used for an index of oxidation state of hair, at the S-K absorption edge [3] and for Ca mapping at the Ca-K absorption edge [1]. Alternatively for Ca distribution X-ray fluorescence mapping provides a more sensitive method but rather lower spatial resolution compared with the electronic zooming system. In the previous report, we investigated the induction of oxidative damage controlled by the treatment time of an oxidative agent in relation to the accumulation of Ca, and found that Ca accumulation in the peripheral part (cuticle) and the major part (cortex) followed the increase of oxidative damage, while in the central part (medulla) seemed to be independent of oxidation [4]. In the present study we focused on the accumulation of Ca in the medulla region by selecting hair specimen having medulla, because all hair specimens do not always possess medulla structure.