Epidemiological Assessment of Significance for Hair Minerals Measured by PIXE Method

Many metabolic disorders, such as atopic dermatitis, are suspected to be associated with alterations in the concentration of some trace elements caused by the intake of bio-accumulated toxic foods. The U.S. Environmental Protection Agency suggests that human hair be considered an important indicator for worldwide biological monitoring of toxic trace elements. In the epidemiological risk assessment of trace elements accumulated in the human body, it is crucial to be able to estimate the body burden of these toxic elements for each individual. However, the quantitative assessment of this burden for infants is hardly possible through questionnaires or even with Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES), since the amount of hair available from them may only be a few strands. Only the particle induced X-ray emission (PIXE) method seems readily applicable in this situation. Since risk estimates may be biased if an uncertainty in PIXE measurements is simply ignored, we have studied the statistical nature of some PIXE measurements in healthy mothers and infants. This paper develops a method of assessing the usefulness of the PIXE measurements for use in epidemiological risk assessment. The method is described and illustrated using PIXE measurements of the hair samples of 842 pairs of mothers and infants at the national one-month and 10- month medical checkup.