Health implications of the distribution of arsenic species in airborne particulate matter

Airborne particle samples were taken between 2001 and 2008 at an urban site (Huelva) in southwestern Spain. Arsenic was found in the samples due to the presence of a near-by copper smelter, sometimes at concentrations above the target value of 6 ng m(-3) proposed by EU regulations (annual means from 4.6 to 10.4 ng As m(-3) in PM10, and 3.0 to 9.1 ng As m(-3) in PM2.5). The results obtained by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) showed that arsenic accumulates preferentially (ca. 70-80%) in the particles with smaller diameter (PM2.5 versus PM10), representing a threat to human health due to the higher capacity of the finer particles to enter the organism through the respiratory system. Moreover, the toxicity of the inorganic arsenic species depends also on the oxidation state, As(III) being more toxic that As(V). The speciation analysis performed with High Performance Liquid Chromatography-Hydride Generation- Atomic Fluorescence Spectrometry (HPLC-HG-AFS) with samples collected between 2006 and 2008, showed that As(V) represented the main arsenic species, but As(III) was also found at significant concentration, representing a 5-10% of the total arsenic content. The results also indicate that the more toxic As(III) tends to concentrate preferentially in the finer fraction PM2.5 in comparison with As(V), thus representing an added health risk for the local population.