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In Vitro, in Vivo, and Spectroscopic Assessment of Lead Exposure Reduction via Ingestion and Inhalation Pathways Using Phosphate and Iron Amendments
journal contribution
posted on 2019-08-13, 16:34 authored by Farzana Kastury, Euan Smith, Emmanuel Doelsch, Enzo Lombi, Martin Donnelley, Patricia L. Cmielewski, David W. Parsons, Kirk G. Scheckel, David Paterson, Martin D. de Jonge, Carina Herde, Albert L. JuhaszThis
study compared lead (Pb) immobilization efficacies in mining/smelting
impacted soil using phosphate and iron amendments via ingestion and
inhalation pathways using in vitro and in
vivo assays, in conjunction with investigating the dynamics
of dust particles in the lungs and gastro-intestinal tract via X-ray
fluorescence (XRF) microscopy. Phosphate amendments [phosphoric acid
(PA), hydroxyapatite, monoammonium phosphate (MAP), triple super phosphate
(TSP), and bone meal biochar] and hematite were applied at a molar
ratio of Pb:Fe/P = 1:5. Pb phosphate formation was investigated in
the soil/post-in vitro bioaccessibility (IVBA) residuals
and in mouse lung via extended X-ray absorption fine structure (EXAFS)
and X-ray absorption near edge structures (XANES) spectroscopy, respectively.
EXAFS analysis revealed that anglesite was the dominant phase in the
ingestible (<250 μm) and inhalable (<10 μm) particle
fractions. Pb IVBA was significantly reduced (p <
0.05) by phosphate amendments in the <250 μm fraction (solubility
bioaccessibility research consortium assay) and by PA, MAP, and TSP
in the <10 μm fraction (inhalation–ingestion bioaccessibility
assay). A 21.1% reduction in Pb RBA (<250 μm fraction) and
56.4% reduction in blood Pb concentration (<10 μm fraction)
were observed via the ingestion and inhalation pathways, respectively.
XRF microscopy detected Pb in the stomach within 4 h, presumably via
mucociliary clearance.