Analysis of Trace Elements in Hair of Pregnant Women Using XRF Spectrometry

Trace element changes in the hair during pregnancy have recently attracted some attention. Briggs et al.' were among the first investigators to observe lower hair zinc levels in pregnant women. It was assumed that this decrease in zinc concentration during pregnancy probably demonstrated some depletion of the zinc content of the body. A similar effect was observed by Hambidge and Dorgemueller.' In their studies, both zinc and iron levels in the last month of pregnancy were lower than those in early pregnancy. These lower levels appear to correspond to observations in studies involving the hair levels of chromium in women following p r e g n a n ~ y .S~i.m~i lar results for zinc concentrations in hair have also been reported by Bergmann et al.' In addition, Ashurbekov6 found a significant increase in sodium, and a decrease in iron concentration in hair during pregnancy.

A number of methods have been used to determine trace element concentrations in human hair.' Very useful data for the study of trace element metabolism in hair were obtained by measuring cross-sectional and longitudinal concentration profiles using a proton mi~roprobe'*~(m icro-PIXE). Because of the small range of low-energy protons, PIXE is not the most suitable technique when information on the mean concentration of an element in human hair is required. In contrast, excitation of hair samples by x-rays (from an x-ray tube or synchrotron radiation) permits information on average concentrations of elements present in the sample to be obtained directly. In this work, the concentrations of several elements in the hair of women during pregnancy and immediately after delivery were determined. All women belonged to the same population group, lived in the same area, were of similar age (25-35 years) and treated their hair at home with almost the same cosmetics. Concentrations were determined using a slightly modified computer program for quantitative sample analysis described previously." In addition to root-end hair samples, longitudinal concentration profiles were also used. Concentrations of trace elements determined at various distances from the root were corrected using the results of hair analysis for women in a control group. In this group samples were taken periodically, always from the same location on the scalp, and the results of the analysis were compared with those of longitudinal analysis of hair taken from a neighbouring location on the scalp in the previous sampling. Using the known rate of hair growth (2-3 mm per week) it was possible to establish the mean trend of the variation of the trace elements in hair during the course of pregnancy (there was no significant difference in hair growth rate between the pregnant and the non-pregnant women). The influence of hair circle on the results obtained was minimized by analysing a bunch of piles.

S. Tornic, J. Lakato, V. Valkovic (X-Ray Spectrometry, Vol. 18, 73-76 (1989))