Lithium, selenium, cobalt and other elements in scalp hair from a group of young Spanish adults

Human scalp hair has been suggested as an appropriate tissue to determine body burden of various metals although this raises controversy in the scientific community due to different factors influencing their content in this matrix. Lithium (Li), selenium (Se) and cobalt (Co) have been linked to mood and brain function, recent reviews have reported an inverse association for these metals in human scalp hair with suicide rates. As a pilot study, we have determined the levels of these metals, including arsenic (As), mercury (Hg) and lead (Pb), in scalp hair from 37 young adults (20 to 24 years-old; 28 female and 9 male) from different towns in the Community of Madrid (Spain). After appropriate pre-treatment of samples following previous methodologies, metals were monitored by ICP-MS. The limits of detection were (in ng/g): Li (1.98), Se (5.14), Co (0.75), As (2.0), Hg (1.0), Pb (1.0). The concentrations were as follows (median and percentiles are provided in ng/g): Li 5.44 (4.45, 7.47), Se 309.04 (255.47, 331.79), Co 7.53 (2.78-17.04); and concentrations for As (0.014), Hg (1.72) and Pb (0.64) are presented as arithmetic means in µg/g. Although our results are not reliable due to the differences in the number of participants by sex, levels of Se and Hg were significantly higher in males, which is in accordance with similar studies and could be related to the higher and significant intake of fish and shellfish previously reported in male participants in this group of population by our team. In general, the presence of these metals in the Spanish group’s hair were within those highlighted in different studies performed in healthy Caucasian young adult populations. However, levels of Li, Co and Se were much lower than reference ranges reported for a Japanese population, which although from a different ethnic background, might suggest that the intake of these essential elements could be compromised in the Spanish group. Our results, although preliminary, might indicate that the intake of Li, Co and Se should be carefully monitored in Spanish young adults, as these have been recognised as essential metals for optimal brain function.