Geochemistry, mineralogy and oral bioaccessibility of lead, zin and antimony in house dust collected from households in the city of Estarreja

A pilot survey, focusing on potentially toxic elements (PTE) in house dust collected from nineteen households from the industrial city of Estarreja, was carried out for purposes of human exposure assessment studies. This study aims at investigating the influence of the dust mineralogy and geochemistry on the oral bioaccessibility of chosen PTEs, as estimated by the Unified BARGE method Pseudo-total and bioaccessible concentrations of major and trace elements were determined by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The mineral composition of indoor and paired outdoor dust samples was determined by means of X-ray diffraction analysis. The results show that the chemical composition of the dust samples discriminates completely between indoor and outdoor dust samples. The stepwise multiple discriminant analysis model obtained indicates that sodium, magnesium, cadmium, and iron are the most important variables in the discrimination. The mineralogy is dominated by calcite, quartz, and feldspars, with minor phyllosilicates, comprising a set of phases that occur in most samples. Minerals of the serpentine group (e.g., lizardite), soluble salts and oxides-hydroxides were identified in some samples, usually in trace amounts. The Enrichment Factors indicate that zinc and antimony are the PTEs of the greatest concern. However, due to a few anomalous concentrations found in some house dust samples, lead was further included in the study. The results of the bioaccessibility testing vary between PTEs. While lead and zinc are markedly bioaccessible, antimony mostly occurs in insoluble forms, which can be explained by the distinct solid phase distribution of the three elements. Although Sb is highly enriched in the indoor dust, a potential exposure through dust ingestion is significantly decreased by the low oral bioaccessibility shown by the PTE.