Detection and quantification of anthropogenic titanium-, cerium-, and lanthanum-bearing home dust particles

Abstract

Home dust samples were collected from the surface of heating, ventilation, and air conditioning (HVAC) filters from eleven homes at different locations in Columbia, South Carolina, USA. Bulk metal concentrations in the dusts were measured using inductively coupled plasma-mass spectrometry (ICP-MS). Size-based elemental distributions in the <450 nm particles were determined by asymmetrical flow-field flow fractionation (AF4) coupled to ICP-MS. The bulk Ti/Nb ratios are generally higher (up to 5609) than the natural background ratios (e.g., 320), indicating contamination of home dusts with TiO₂-engineered particles. Size-based Ti/Nb ratios in the <450 nm fraction are similar to the natural background ratio, indicating a natural origin of Ti-bearing particles in this size fraction, and subsequently that anthropogenic Ti-bearing particles (TiO₂) are associated with particles >450 nm either due to aggregation or to their release as large particles. The concentrations of TiO₂-engineered particles were estimated by mass balance calculations using total Ti concentrations and increases in Ti/Nb ratios above the natural background ratio. They vary between 0 and 13 300 mg TiO₂ kg⁻¹. The upper crustal-normalized rare earth element pattern indicates a positive La and Ce anomaly. The size of the cerium and lanthanum anomalies varies from 0.8 to 1.6 and 0.7 to 3.95, respectively, indicating contamination of several home dusts with Ce and La. The concentrations of bulk anthropogenic Ce and La were estimated based on mass balance calculations and anomaly size and varied between 0 and 5.7 ± 2.2 mg Ce kg⁻¹ and 0 and 21.1 ± 7.4 mg La kg⁻¹, respectively. Size-based Ce/La ratios in the <450 nm fraction are lower than the natural background ratio, indicating contamination of this size fraction with nanosized La-bearing particles. Anthropogenic Ti and La concentrations in home dust are attributed to releases from paint during home renovation. This implies that exposure of construction workers to Ti- and La-bearing particles during home renovation may potentially pose human health risks.