Evaluating the effect of age and area of residence in the metal and metalloid contents in human hair and urban topsoils.

Monitoring the levels of trace elements in hair can allow estimating the effects of the geographical location and also can provide a notion of the metal body burden. However, the use of human hair is controversial due to the different confounding factors that could affect the presence of trace elements in hair. As a result, a comprehensive monitoring study was performed in Alcalá de Henares, one of the major cities in the Madrid region, Spain. Trace elements have been monitored in urban topsoils and in human hair of two well-defined and healthy groups of population: children (6-9 years) and adolescents (13-16 years). The city was divided into four areas or zones with different characteristics to assess the possible effect of area of residence and age in the presence of Al, As, Be, Cd, Cr, Cu, Hg, Mn, Pb, Sn, Ti, Tl and Zn in soils and hair. There is no current hypothesis that explains the possible effect of the area of monitoring in the distribution of Be, Cr, Ni, Sn and Ti found in these urban soils, maybe because urban soils receive high disturbance, and there are many factors involved. The presence of most of the trace elements monitored was significantly higher in the hair of the children population, except for Sn and Zn. This could be attributed mainly to dietary habits. Other factors influencing metal content in hair such as environmental factors would have had a minimal effect in the population groups here studied. Finally, none of the levels of trace elements studied in hair were significantly correlated with levels measured in the topsoils of public parks in Alcalá de Henares, with the exception of Pb in adolescent participants.

Annual and seasonal variability of metals and metalloids in urban and industrial soils in Alcalá de Henares (Spain).

Contamination of urban and industrial soils with trace metals has been recognized as a major concern at local, regional and global levels due to their implication on human health. In this study, concentrations of aluminum (Al), arsenic (As), beryllium (Be), cadmium (Cd), chromium (Cr), manganese (Mn), nickel (Ni), lead (Pb), tin (Sn), thallium (Tl), vanadium (V) and zinc (Zn) were determined in soil samples collected in Alcalá de Henares (Madrid, Spain) in order to evaluate the annual and seasonal variation in their levels. The results show that the soils of the industrial area have higher metals concentrations than the urban area. Principal component analysis (PCA) revealed that the two principal sources of trace metal contamination, especially Cd, Cu, Pb, and Zn in the urban soils of Alcalá can be attributed to traffic emissions, while As, Ni and Be primarily originated from industrial discharges. The seasonal variation analysis has revealed that the emission sources in the industrial area remain constant with time. However, in urban areas, both emissions and emission pathways significantly increase over time due to ongoing development. Currently, there is no hypothesis that explains the small seasonal fluctuations of trace metals in soils, since there are many factors affecting this. Owing to the fact that urban environments are becoming the human habitat, it would therefore be advisable to monitor metals and metalloids in urban soils because of the potential risks to human health.

"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?

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.

Establishing the importance of human health risk assessment for metals and metalloids in urban environments.

Rapid development, industrialisation, and urbanisation have resulted in serious contamination of soil by metals and metalloids from anthropogenic sources in many areas of the world, either directly or indirectly. Exponential urban and economic development has resulted in human populations settling in urban areas and as a result being exposed to these pollutants. Depending on the nature of the contaminant, contaminated urban soils can have a deleterious effect on the health of exposed populations and may require decontamination, recovery, remediation and restoration. Therefore, human health risk assessments in urban environments are very important. In the case of Spain, there are few studies regarding risk assessment of trace elements in urban soils, and those that exist have been derived mainly from areas potentially exposed to industrial contamination or in the vicinity of point pollution. The present study analysed Al, As, Be, Cd, Cr, Cu, Hg, Mn, Ni, Pb, Sn, Ti, Tl, V and Zn soil concentrations in and around the city of Alcalá de Henares (35 km NE of Madrid). Soil samples were collected in public parks and recreation areas within the city and in an industrial area on the periphery of the city. From these results, an assessment of the health risk for the population was performed following the methodology described by the US EPA (1989). In general, it was observed that there could be a potential increased risk of developing cancer over a lifetime from exposure to arsenic (As) through ingestion of the soils studied (oral intake), as well as an increased risk of cancer due to inhalation of chromium (Cr) present in re-suspended soils from the industrial area. Our group has previously reported (Granero and Domingo, 2002; Peña-Fernández et al., 2003) that there was an increased risk of developing cancer following exposure to As in the same soils in a previous study. Therefore, it is necessary to reduce the levels of contaminants in these soils, especially As and Cr as these have been found to exceed safe levels for human health.

Monitoring lead in hair of children and adolescents of Alcalá de Henares, Spain. A study by gender and residential areas.

In recent years there has been an increased interest from the European Union (EU) in the development of large Human Bio-monitoring (HBM) studies across Europe, especially biomonitoring toxic metals. In Spain, most studies using hair as a biomarker have been conducted to determine occupational or industrial exposures, and have involved adult populations. Few studies have involved adolescents and children, despite these groups being sensitive to environmental contamination and pollutants. Therefore, the objective of the present study was to determine the degree of lead exposure in children and adolescents residing in Alcalá de Henares, Spain. Lead poisoning is the number one toxicological threat in the environment. So, lead (Pb) was selected as it is a persistent environmental contaminant, is measureable and is also a neurotoxin that can affect brain development. The city of Alcalá de Henares was divided into four zones to determine the influence of residence area on Pb levels. A range of other variables including age and gender were also considered within the study. The study comprised 115 children (6-9 years old) and 96 adolescents (13-16 years old). There was a significant difference between the levels of Pb in the hair of adolescents, for different gender and area of residence (p<0.001 and p<0.01 respectively). There was no significant difference in the Pb levels in hair of children, for different gender or area of the city. The levels of Pb were significantly (p<0.001) elevated in children compared to adolescents (1.48 vs. 0.70 µg/g), and there was a significant difference in Pb levels in male and female adolescent hair (0.53 vs. 0.77 µg/g) (p<0.001). The association observed between areas of residence and the Pb level in hair of the adolescent group could be mainly attributed to dietary habits and/or socioeconomic status.