“Reference values” of trace elements in the hair of a sample group of Spanish children (aged 6–9 years) – Are urban topsoils a source of contamination?

• Reference values of trace elements in the hair of Spanish children aged 6–9 years.
• Based on a well-defined healthy group of non-exposed children.
• Reference values were computed according to IUPAC criteria.
• Age, gender and place of residence may affect levels of metals in human hair.
• Local soils might not be a potential source of trace elements.

Human hair is used as a biomonitor to evaluate the environmental exposure to contaminants in the individual. However, the use of human hair is controversial, mainly because reference levels for pollutants in hair have not yet been set. In the case of Spain, few biomonitoring studies have involved infants and children. A biomonitoring study was conducted to investigate the possible normal values of trace elements of toxicological concern in children aged 6–9 years from the city of Alcalá de Henares, Community of Madrid (Spain), following the methodology and strict inclusion criteria previously developed by our group. Levels of Al, As, Be, Cd, Cr, Cu, Hg, Mn, Ni, Pb, Sn, Ti, Tl, V and Zn were monitored in scalp–hair from 117 healthy children (47 boys and 70 girls) between April and May of 2001. The levels of trace elements here described could be considered as possible “reference values” for children aged 6–9 years resident in the Community of Madrid. These values might also be selected as a preliminary screening tool to evaluate if a Spanish child has been exposed to any of the contaminants studied here. This study also investigated whether local urban topsoils were a source of metals for this population.