es5018587_si_001.pdf (3.77 MB)
Zinc in House Dust: Speciation, Bioaccessibility, and Impact of Humidity
journal contribution
posted on 2014-08-19, 00:00 authored by Suzanne Beauchemin, Pat E. Rasmussen, Ted MacKinnon, Marc Chénier, Kristina BorosIndoor
exposures to metals arise from a wide variety of indoor
and outdoor sources. This study investigates the impact of humid indoor
conditions on the bioaccessibility of Zn in dust, and the transformation
of Zn species during weathering. House dust samples were subjected
to an oxygenated, highly humid atmosphere in a closed chamber for
4 to 5 months. Zinc bioaccessibility before and after the experiment
was determined using a simulated gastric acid extraction. Bulk and
micro X-ray absorption structure (XAS) spectroscopy was used to speciate
Zn in dust. Exposure to humid conditions led to a significant increase
in Zn bioaccessibility in all samples, which was due to a redistribution
of Zn from inorganic forms toward the organic pools such as Zn adsorbed
on humates. ZnO readily dissolved under humid conditions, whereas
ZnS persisted in the dust. Elevated humidity in indoor microenvironments
may sustain higher Zn bioaccessibility in settled dust compared to
drier conditions, and part of this change may be related to fungal
growth in humid dust. These results help to explain the greater bioaccessibility
of certain metals in house dust compared to soils.