Quantitative analysis of untreated hair samples for monitoring human exposure to heavy metals

The method of quantitative analysis for untreated hair samples, which we developed three years ago, has proved to be quite useful for investigating environments contaminated by certain toxic elements. In the present work, the experimental conditions are improved. Loss of certain elements owing to irradiation damage, which has remained as one of the experimental uncertainties, was examined. It was found that the concentration of sulfur decreases gradually throughout the irradiation, while for the other elements, including arsenic and mercury, no changes occur under our measuring conditions. Furthermore, the degree of alteration of elemental concentration depending on the position along the hair was investigated. As a result, concentrations of some elements at different positions on a 14-cm-length hair, which was taken from a small-scale miner in the Philippines, showed some dependence on the distance from the root reflecting her history as a miner, while mercury does not show large deviation from a main trend. It was also found that concentration of mercury in hairs taken from different parts of a body does not show large difference. These results demonstrate that mercury and arsenic concentration in hairs, obtained by the present method, become a good index for an estimation of human exposure to these toxic elements. Changes of concentration of some elements depending on the way of cleaning before irradiation are studied in detail and the optimum way of washing is established