Presencia y distribución medioambiental de metales pesados y metaloides en Alcalá de Henares, Madrid. Evaluación del riesgo para la población y biomonitorización de la población escolar

Abstract

Nowadays, the metals and metalloids are essential for the economy of most of the countries. Nevertheless, their commercial, industrial and domestic use is the cause of the dispersion of these substances in the environment. That has been producing a series of impacts on the ecosystem and on the whole population. It is accepted that the analysis of the levels of polluting agents in the environment is not suitable, by itself, to categorically establish the danger that they can represent for health. So, biological monitors must be used to complete the studies of evaluation of the risks since it permits to measure the degree of exhibition to the polluting agents. In this way the hair is an important biological indicator of the metal content in the organism. Given the importance that the quality of the environment plays in our health, a great legislative development has been carried out during the last years, which, on the whole, is trying to protect our resources, favoring their sustainable use and guaranteeing the reduction of anthropogenic pollution. In response, different trace elements were monitored in soils of public parks of Alcala de Henares, Madrid (Spain), as well as in an industrial zone near to the University Campus of Alcala University, in July and December 2000, and July 2001. As a result, an estimation of the toxic and carcinogenic risk for the general population has been performed, but also a biomonitorization of children (6 to 9 years) and adolescent (10 to 13 years) population. All the samples have been subjected to an acid digestion, and the levels of Al, As, Be, Cd, Cr, Cu, Hg, Mn, Ni, Pb, Sn, Ti, Tl, V and Zn have been determined by inductively coupled plasma-mass spectrometry (ICP-MS) and by inductively coupled optical emission spectrometry (ICP-OES). Concerning the risks evaluation, the methodology described by US EPA has been followed. The Analysis of Principal Components and the study of the Correlation of Pearson have revealed that the metals are distributed according to their source of main emission, natural, for Al, As, Be, Cd, Cr, Mn, Tl and V, and antropogenic, for Cd, Cu, Pb and Zn. In addition, a increase of these elements in soils has been observed between July 2000 and July 2001, that it could be attributed to the natural features of these substances, that makes them ubiquitous, persistent and non-biodegradable in this matrix. The presence of the trace elements monitored in July 2001, in general, has not meant an increase of the noncancerigenic or toxic risks for population. On the contrary, the As concentration taken by ingestion, and the Cr concentration taken by inhalation are above the established level considered by U.S. EPA, although it has been assumed that the concentration of Cr (VI) is 1/6 of the total Cr determined. On the other hand, it has been observed that the mineral content in hair would be influenced by sex and age, being higher in earlier ages, due to the highest sensitivity to pollution described for this group. In addition, it was observed that levels of these substances have been higher in the hair of girls that could be attributed to differences in the system endocrine between sexes that would occur during the puberty. All the considerations about the obtained results in this work, has revealed that the hair could be a useful biomonitor for the evaluation of the exposure to metals and metalloids. For that reason, it could be said that the presence of trace elements in the urban soils of Alcala de Henares has not been a way of exposure for the studied population. Nevertheless, a constant monitoring of the presence of these substances would be advisable, as well as taking measures to reduce the environmental levels of As and Cr found in the samples.