Forensic aspects of trace element variation in the hair of isolated Amazonas Indian tribes

Thermal neutron activation analysis and instrumental gamma-ray spectrometry were used to analyze the elemental constituents in the head hair from sedentary Indian populations in the Venezuelan Amazonas region. Concentration values for 30 elements were determined quantitatively, and the presence of 7 others was detected qualitatively. The remoteness of the area and the primitive ecological conditions of the local population prevents the exposure of their biological systems to industrial and agricultural contamination, either external or metabolic. These conditions are reflected in a marked decrease of the concentration ranges of the trace elements, and a significant reduction or even the total absence of some components. The results demonstrate that closed groups of individuals exposed to similar dietary and environmental conditions exhibit closely similar trace element patterns in their hair and, consequently, in other biological tissue. This fact severely limits the use of trace element patterns in hair for forensic comparisons. The results also indicate that a large part of the constituents found in hair is probably deposited externally from ambient contamination and that any metabolic deposition occurs much more uniformly and probably in lower concentrations. Tables of analytical results in parts per million are presented, together with representative gamma-ray spectra of the hair. Comparison with earlier data in the literature is also shown.