A study of the characteristics of trace elements in the hair of Japanese. Reference values and element patterns for determining normal levels

Abstract

Twenty-one elements in hair were analyzed from 1, 008 Japanese men and 891 women who were living in the Tokyo area and considered healthy. Cold vapor atomic absorption spectrometry was used for Hg, and the ICAP method for Ca, Mg, P, Na, K, Fe, Cu, Mo, Mn, Zn, Cr, Se, Li, Ni, Co, V, Pb, Cd, Al and As. The results are as follows.(1) Goodness-of-fit tests conducted for each element indicated no true normal or log-normal distributions at the 0.1% significant level for any element. However, P and Zn were similar to normal distributions, and Ca, Mg, Na, K and Mn to log-normal distributions.(2) The relationship between each element and age was examined. No element required reference values on the basis of age. However, eight elements, P, Na, K and Hg (higher in men), and Ca, Mg, Cu, and Zn (higher in women) showed sex differences for both parametric and nonparametric tests.(3) By investigating correlations and partial correlations and performing factor analyses, patterns in certain elements and differences between these patterns were found among men and women. The combinations of Ca-Mg (r: _??_ 0.674, _??_ 0.750) and Na-K (r: _??_ 0.586, _??_ 0.616) showed high correlations in both men and women. In such pairs, the ratio between the two seems to be important in determining the amount of each.(4) On the basis of the above, trace element reference values, appropriate as screening levels, could be based by the Herrera's percentile method. These values may also be useful as basic levels in specifying the presence of disease and to provide data for interracial or intercultural comparisons.