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In Vitro, in Vivo, and spectroscopic assessment of lead exposure reduction via ingestion and inhalation pathways following immobilization using phosphorus and iron amendments

Kastury F., Smith E., Doelsch E., Lombi E., Donnelly M.J., Cmielewski P.L., Parsons D.W., Scheckel K.G., Paterson D., de Jonge M.D., Herde C., Juhasz A.L.. 2019. Environmental Science and Technology, 53 (17) : p. 10329-10341.

This 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 ?m) and inhalable (<10 ?m) particle fractions. Pb IVBA was significantly reduced (p < 0.05) by phosphate amendments in the <250 ?m fraction (solubility bioaccessibility research consortium assay) and by PA, MAP, and TSP in the <10 ?m fraction (inhalation¿ingestion bioaccessibility assay). A 21.1% reduction in Pb RBA (<250 ?m fraction) and 56.4% reduction in blood Pb concentration (<10 ?m fraction) were observed via the ingestion and inhalation pathways, respectively. XRF microscopy detected Pb in the stomach within 4 h, presumably via mucociliary clearance.

Mots-clés : santé publique; toxicité du sol

Thématique : Autres thèmes; Maladies et risques professionnelles; Chimie et physique du sol

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