Characterization of Antimony Species Using Micro-Analytical Synchrotron Techniques on Household Dust Samples From Ottawa, Canada
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Rasmussen et al. (2001) observed that Sb concentrations were enriched in household dust relative to outdoor garden soil samples and suspected the enrichment may be due to anthropogenic internal sources. Antimony trioxide (Sb2O3) is commonly found in various halogen flame-retardants and is a suspected carcinogen (IARC, 1989). North Americans spend a significant proportion of their time indoors, and are frequently exposed to dust. Therefore, characterizing potentially harmful metal(loid)s (i.e. Sb2O3) has become of increasing priority to various governmental agencies. A combination of micro-analytical synchrotron techniques (micro X-ray fluorescence (µXRF), micro X-ray diffraction (µXRD), micro X-ray absorption near-edge spectroscopy (µXANES)) and environmental scanning electron microscopy (ESEM) were used to characterize five archived samples provided by Health Canada. Two samples were in the 90th percentile for Sb content in household dust from a suite of 50 houses studied by Rasmussen et al. (2001). The corresponding garden soils of these houses were also analysed. The fifth sample was a children’s bedroom from a house studied in detail by Walker et al. (2010). Synchrotron microanalysis of Sb presents many challenges, given its high absorption energy (31 KeV), and the relatively low concentrations and small particles in house dust. An appropriate experimental set-up was optimized after several trials. Antimony within household dust is currently not of toxicological concern (EU, 2008). Micro-XRF maps of household dust samples and corresponding garden soils from sample to sample displayed distinct element correlations of Sb with other elements. This suggests that Sb species present within homes are not restricted to a single source. Potential sources are Pb based or Sb containing pigments (Naples Yellow), metal alloys and possibly flame-retardants. The lack of correlation between Sb hot spots in the garden soil sample compared to the household dust suggests the source of interior Sb may not be external. A collaborative project with another student in the Environmental Studies Masters program was conducted to examine the potential for interdisciplinary work. Effective communication was the greatest barrier but there was success in the creation of a forum where people could critically think about the various nuances of household dust.