Effect of sex on the levels of aluminium and titanium in hair in a sample of young Spanish adults.

Human hair can be used as a tool to determine environmental exposure to inorganic metal contaminants and to estimate the chemical burden in the individual. However, a series of factors (including sex and age) have been described as confounding factors in the assessment of metals in human hair, factors that make its use controversial. There is a lack of information about the excretion of metals in hair and little is known about how sex can affect the presence of these elements in this matrix. To investigate the possible effect of sex, scalp hair samples were collected in 37 young adults (20 to 24 years-old; 28 female and 9 male) from different towns in the Community of Madrid (Spain) attending the University of Alcalá. Subjects were selected following the inclusion criteria and methods described in previous research. Aluminium (Al) and titanium (Ti) were analysed in these samples by ICP-OES following the methodology previously described. The levels of Ti were significantly higher in male compared to female participants (0.82 vs. 0.68 µg/g; p<0.05). In contrast, the levels for Al were higher in hair in the female group (8.15 vs. 6.62 µg/g; NS) although the results did not show statistical significance. The levels of these metals were consistent with other studies performed in similar age-groups although different trends due to sex have been reported. There is currently no hypothesis that explains our results. Human hair can be invaluable in environmental human health studies and a possible diagnostic tool so it would be useful to perform further studies to have a better understanding of the kinetics of excretion of metals in hair.