Are children exposed to light rare earth elements in urban environments?

Abstract

BACKGROUND AND AIM: Human biomonitoring can provide invaluable information on exposure of a specific population to chemical pollutants to appropriately manage the threat. The aim was to identify whether children living in Alcalá de Henares, one of the biggest populated cities in the Community of Madrid (Spain), are exposed to rare earth elements (REEs), specifically cerium (Ce) and neodymium (Nd). METHODS: Scalp hair was collected from 120 children (6 to 9-years-old; 50 boys, 70 girls). Ce and Nd were analysed by ICP-MS after appropriate removal of exogenous contamination. Data was processed using different statistical models according to the detection frequency with the support of the ‘NADA’ statistical package. RESULTS:The limits of detection were (in µg/g): Ce (0.0048) and Nd (0.0028). Both REEs were detected in almost all the hair samples monitored (78.8% & 71.7%, respectively), which would suggest a general exposure to these contaminants as they have been poorly detected in scalp hair from other groups of population living in the Comunidad de Madrid. Concentrations are provided as median and interquartile range in µg/g: Ce 0.011 (0.005, 0.017) and Nd 0.004 (0.0028, 0.007). Both REEs did not show sex dependency, but Ce showed statistical significance according to zones of residency (p0.01); the mean concentration of Ce was lower in children’s hair living in areas with a higher density of green areas than in those with higher number of buildings/industrial activities (0.008 vs 0.014 µg/g). CONCLUSIONS:Alcalá’s children population have not been significantly exposed to Ce and Nd, as levels of Ce and Nd in scalp hair were of the same order of magnitude as those reported in the literature in non-exposed children. However, the implementation of interventions to minimise the environmental exposure REEs in Alcalá might be needed, as these can affect the physical growth and development, function of immune system and intelligence in children. KEYWORDS: Cerium, neodymium, human hair, monitoring, Spanish children, exposure.