Lead speciation in artificial human digestive fluid

For children, soil ingestion via hand-to-mouth behavior can be a main route of exposure to contaminants such as lead. The ingested lead can be mobilized from the soil and form new species during the digestion process. Speciation is known to affect the availability of metals for transport across biol...

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Bibliographic Details
Published in:Archives of environmental contamination and toxicology 2003, Vol.44 (1), p.107-115
Main Authors: OOMEN, A. G, TOLLS, J, SIPS, A. J. A. M, VAN DEN HOOP, M. A. G. T
Format: Article
Language:English
Subjects:
Administration, Oral
Biological and medical sciences
Biological membranes
Chemical and industrial products toxicology. Toxic occupational diseases
Child
Contaminants
Digestive System - chemistry
Electrophysiology
Humans
Ingestion
Intestinal Mucosa - physiology
Ions
Lead
Lead - chemistry
Lead - pharmacokinetics
Medical sciences
Metal ions
Metals and various inorganic compounds
Soil Pollutants - pharmacokinetics
Speciation
Toxicology
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Summary:For children, soil ingestion via hand-to-mouth behavior can be a main route of exposure to contaminants such as lead. The ingested lead can be mobilized from the soil and form new species during the digestion process. Speciation is known to affect the availability of metals for transport across biological membranes. In the present study, in vitro digestions were performed with (artificially contaminated) standard soil. Lead speciation was investigated in the artificial human intestinal fluid, i.e., chyme, to gain insight into the lead species and lead fractions that may be available for transport across the intestinal epithelium. To that end, both a lead ion selective electrode (Pb-ISE) and a voltammetric technique (differential pulse anodic stripping voltammetry, DPASV) were used. The results indicate that in chyme only a negligible lead fraction is present as free Pb(2+), whereas lead phosphate and lead bile complexes are important fractions. The lead phosphate complexes appear to be voltammetrically labile, i.e., in dynamic equilibrium with Pb(2+). Labile complexes can dissociate and the produced metal ions can subsequently be transported across the intestinal epithelium. Lead bile complexes may behave in a similar manner, or this organometal complex may be able to traverse the intestinal membrane. Therefore, substantially more than only the free metal ion should be considered available for transport across the intestinal epithelium.
ISSN:0090-4341
1432-0703
DOI:10.1007/s00244-002-1225-0