Evaluating the possible effect of area of residence on the levels of mercury in the hair of Spanish children and adolescents.

Human biomonitoring programmes are robust, efficient and practical tools to protect the public health against environmental pollutants. Human hair is a good matrix to measure exposure to mercury (Hg). A monitoring study was performed in Alcalá de Henares, Madrid Region, Spain. Hg was monitored in urban topsoils and in human hair of two well-defined and healthy groups of population by ICP-MS: children (6-9 years) and adolescents (13-16 years) following the methodology described in Peña-Fernández et al. (2014a, 2014b). The city was divided in four areas or zones with different characteristics to assess the possible effect of the area of residence and age on the presence of Hg in soils and hair. Hg was not detected in any sample of soil, indicating that the contaminant levels in the soil were lower than the detection limit of the ICP-MS (0.002 mg kg-1). The range of total Hg determined in the adolescent population of Alcalá (0.09 to 2.41 μg/g) was significantly lower (p<0.001) than that monitored in children (0.16 to 4.86 μg/g). The increased presence of this neurotoxic metal in child could be attributed to the physiological characteristics of this group as children would possibly be more exposed to Hg through dietary and environmental sources. Analysis of the influence of the geographic area on the metal content of hair in biomonitoring studies can be significant and should be considered in environmental studies, as this could be of public health relevance. For example, children that live in zone II and IV (more urban and industrial areas in Alcalá de Henares, respectively) show levels of Hg in hair that exceed the threshold level of 1 μg/g above which cognitive and neurological deficits are thought to arise, risks that are less likely for children living in zone I (with more green areas) where levels of Hg are below the threshold level for health risks.