title: Zinc in house dust: speciation, bioaccessibility, and impact of humidity.
abstract: Indoor 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.
authors.affiliation: Natural Resources Canada , CanmetMINING, 555 Booth Street, Ottawa, Ontario Canada , K1A 0G1.
authors.forename: Suzanne
authors.initials: S
authors.lastname: Beauchemin
authors.forename: Pat E
authors.initials: PE
authors.lastname: Rasmussen
authors.forename: Ted
authors.initials: T
authors.lastname: MacKinnon
authors.forename: Marc
authors.initials: M
authors.lastname: Chénier
authors.forename: Kristina
authors.initials: K
authors.lastname: Boros
mesh_terms: D016902:Air Pollution, Indoor / Q000032:analysis*; D004391:Dust / Q000032:analysis*; D004784:Environmental Monitoring; D005744:Gastric Acid / Q000737:chemistry; D006813:Humidity; D013440:Sulfides / Q000032:analysis; D056928:X-Ray Absorption Spectroscopy; D015032:Zinc / Q000032:analysis* / Q000737:chemistry; D017967:Zinc Compounds / Q000032:analysis; D015034:Zinc Oxide / Q000032:analysis
chemical_list: D004391:Dust; D013440:Sulfides; D017967:Zinc Compounds; D015032:Zinc; C031238:zinc sulfide; D015034:Zinc Oxide