Rare earth elements and select actinoids in the Canadian house dust study
Pat E Rasmussen, Christine Levesque, Marc Chénier, H David Gardner
Indoor Air 2017 March 17
Nationally representative baseline data are presented for rare earth elements (REE), plus thorium (Th) and uranium (U) in house dust sampled from 1025 urban homes, in units of concentrations (μg g(-1) ), loadings (μg m(-2) ) and loading rates (ng m(-2) day(-1) ). Spearman rank correlations indicate that, in addition to outdoor sources, consumer products and building materials can influence indoor dust concentrations of REE, Th and U. Correlations (p <0.01) with numbers of occupants, dogs and cats suggest soil track-in. Correlations (p <0.01) with hardwood floors suggest release of REE additives used in pigments and coatings during daily wear-and-tear. Concentrations of light REE are elevated in smokers' homes compared to non-smokers' homes (p <0.001), suggesting that a key source is "mischmetal", the REE alloy used in cigarette lighter flints. Indoor sources include geological impurities in raw materials used in consumer products, such as U and Th impurities in bentonite clay used in cat litter, and REE impurities in phosphates used for a variety of applications including dog food and building materials. Median gastric bioaccessibility (pH 1.5) of most REE in dust ranges from about 20% to 29%. Household vacuum samples correlate with fresh dust samples from the same homes (p <0.001 for all investigated elements) This article is protected by copyright. All rights reserved.
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