STUDY OF TRACE-ELEMENT CONCENTRATIONS IN HUMAN TISSUES BY EDXRF SPECTROMETRY

Human tissues (bone, hair, liver and kidney) from 61 individuals, coll ected post-mortem, were analyzed by energy-dispersive x-ray fluorescen ce (EDXRF) spectrometry. All samples were analyzed without any chemica l treatment. The soft tissues (liver and kidney) were lyophilized and ground in an agate mortar whereas the hard tissues (bone and hair), af ter being lyophilized, were dried in an oven for 24 h at 200 degrees C prior to grinding. The samples were prepared by pressing the powder i nto pellets 2.0 cm in diameter. To investigate any possible contaminat ion in the grinding procedure or loss of some elements due to the dryi ng process, a few samples were analyzed by total reflection x-ray fluo rescence. Levels of contamination of 1% for Fe and 3% for Cu and a los s of 19% for Se were introduced. To establish the accuracy and reprodu cibility of the technique, five targets of a standard reference materi al, NBS 1577a Bovine Liver, were examined. Each sample was studied for its content of Mn, Fe, Cu, Zn, Se, As, Sr, Rb and Pb in order to dete rmine possible correlations between these elements in the different ti ssues. Variations in the concentrations of these elements with age and sex were also investigated in hard tissues. The elemental concentrati ons obtained for the studied elements are in reasonable agreement with those reported in the literature. Correlations among the elements for the different tissues were examined. For hair, a significant differen ce between male and female was found only for Zn. The Pearson correlat ion matrix, calculated to investigate the correlation between elementa l concentrations and the dependence of these concentrations on age, sh owed that there is a negative correlation with age for Cu and Sr, alth ough very weak. No significant correlations exist among the studied el ements in hair, except for Fe and Cu. For bone samples, Zn, Sr and Pb present a significant positive correlation with age. The correlation a mong elements in bone is significant only for Fe and Cu. The results o f the Pearson correlation matrix coefficients for elemental concentrat ions in hair and bone showed a significant correlation for Fe. The Pea rson correlation matrix for soft tissues showed a positive correlation between Fe and Pb and a negative correlation between Zn and Pb in liv er samples. The same test showed a strong positive correlation between Fe and Zn and between Cu and Zn and a weak significant correlation be tween Mn and Cu and between Rb and Pb in kidney. (C) 1998 John Wiley & Sons, Ltd.