Differences in trace-element concentrations in hair between males and females

Abstract

Hair clippings (from the head) from over a hundred persons in and around Orange County of California were analysed for mercury, gold, zinc, and copper by instrumental neutron activation analysis. The results of the study show significant differences in the trace-element distributions between males and females. For mercury, the mode of the distribution occurs at about 1 to 1,5 ppm for males and 4 to 6 ppm for females. A significant difference between the male and female distribution curves was also found for gold, and a less significant one for zinc and copper. This study indicates the possibility that the high levels of mercury and gold in the hair of females are more likely due to external contamination, because of the more frequent and intense exposure of their hair to cosmetics. Moreover, as females usually have longer hair, their hair strands are exposed to such treatment over a longer period of time. Hair being a good ion-exchange material, trace elements are absorbed easily during the process of washing and setting of hair, and accumulation of these over a long period may cause a very high concentration of these elements. The variability of trace-element concentration as a result of external contamination, and the sometimes marked variation along the length of the hair, pose a serious problem in forensic work. Identification criteria should provide for these variations, especially in the case of mercury and gold. This work also indicates that if the evidence hair from the scene of a crime does not contain the root end, its value as an evidence specimen is considerably reduced.