Study on trace element determination in human head hair using neutron activation analysis

Trace element determination in human hair has become increasingly popular for monitoring environmental exposure, assessing nutritional status, evaluating intoxication and diagnosing diseases. However, there are controversies of this use due to the difficulty in the removal of only exogenous origin elements from the hair, the small correlation data between elements contents in the hair and other tissues and the poor quality of analytical results for certain elements. In this study, adequate experimental conditions have been established for human scalp hair analysis in order to obtain further reliable reference value ranges. Neutron activation analysis (NAA) was used for the determination of fourteen trace elements. Irradiations were performed at the IEA-R1 nuclear research reactor. Aliquots of samples from three individuals were analyzed and the results presented good reproducibility, indicating the sample homogeneity. The quality control of the results was assessed analyzing certified materials. The relative errors lower than 8% and relative standard deviations varying from 1.2 to 15% were obtained for most of elements in the reference materials analysis. Hair samples from voluntary donors from Sao Paulo State, aged from 15 to 60 years were studied and the results obtained indicate that As, Co, Cr, Cs, La, Sb, Sc and Se are present in the hair at a low level of 7g kg-1 and the elements Br, Ca, Fe, K, Na and Zn, at μg kg-1 level. There is a necessity of obtaining reliable reference values or intervals for hair trace elements for a defined healthy population. (author)