Citation:

Kastury, F., E. Smith, E. Lombi, M. Donnelley, P. Cmielewski, D. Parsons, M. Noerpel, Kirk G. Scheckel, A. Kingston, G. Myers, D. Paterson, M. de Jonge, AND A. Juhasz. Dynamics of Lead Bioavailability and Speciation in Indoor Dust and X-ray Spectroscopic Investigation of the Link between Ingestion and Inhalation Pathways. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 53(19):11486-11495, (2019). https://doi.org/10.1021/acs.est.9b03249

Impact/Purpose:

Exposure to lead (Pb) presents social, economic and environmental burden on families, communities and society as a whole. When inhaled, Pb particles may have prolonged lung residence time, potentially causing chronic toxicity and neurological impairment in children. However, absorption of Pb via the inhalation of Pb contaminated dust is not well studied. This study investigated the uptake of Pb into blood from indoor dust, clearance of particles from the lungs to the gastro-intestinal tract, and the influence of mineralogy on Pb absorption and particle retention. This study lends fundamental insight to our knowledge of Pb exposure from dust via the inhalation pathway and identifies X-ray based spectroscopy as a valuable tool for future research into metal exposure assessment. Pb bioavailability and retention/clearance with mining/smelting impacted dust, and the link between Pb inhalation and ingestion scenarios are currently not well understood. Consequently, this study investigated the dynamics of Pb absorption from Pb contaminated house dust following instillation into C57BL/6 mouse lungs. Changes in blood Pb concentration were monitored over a 24 h exposure period. X-ray Fluorescence (XRF) microscopy of whole organs was then utilized to visualize particle distribution and clearance from the lungs into the GI tract. Changes in Pb speciation in vivo were also assessed using X-ray Absorption Near Edge Spectroscopy (XANES).

Description:

Lead (Pb) exposure from household dust is a major childhood health concern because of its adverse impact on cognitive development. This study investigated the absorption kinetics of Pb from indoor dust following a single dose instillation into C57BL/6 mice. Blood Pb concentration (PbB) was assessed over 24 h, and the dynamics of particles in the lung and gastro-intestinal (GI) tract were visualized using X-ray fluorescence (XRF) microscopy. The influence of mineralogy on Pb absorption and particle retention was investigated using X-ray absorption near-edge structure spectroscopy. A rapid rise in PbB was observed between 0.25 and 4 h after instillation, peaking at 8 h and slowly declining during a period of 24 h. Following clearance from the lungs, Pb particles were detected in the stomach and small intestine at 4 and 8 h, respectively. Analysis of Pb mineralogy in the residual particles in tissues at 8 h showed that mineral-sorbed Pb and Pb-phosphates dominated the lung, while organic-bound Pb and galena were the main phases in the small intestines. This is the first study to visualize Pb dynamics in the lung and GI tract using XRF microscopy and link the inhalation and ingestion pathways for metal exposure assessment from dust.

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