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Lead speciation in artificial human digestive fluid
A G Oomen1, J Tolls, A J A M Sips
1RITOX, Environmental Toxicology and Chemistry, Utrecht University, The Netherlands. agnes.oomen@rivm.nl
Archives of Environmental Contamination and Toxicology
|November 16, 2002
Summary
Children ingest soil contaminants like lead through hand-to-mouth behaviors. Lead speciation in the intestines reveals that lead phosphate and bile complexes, not just free lead ions, are available for absorption.
Area of Science:
- Environmental Health
- Toxicology
- Analytical Chemistry
Background:
- Soil ingestion is a primary exposure route for lead in children.
- Lead speciation during digestion influences its bioavailability and absorption across biological membranes.
Purpose of the Study:
- To investigate lead speciation in artificial human intestinal fluid (chyme).
- To determine lead fractions available for intestinal transport after in vitro digestion.
Main Methods:
- In vitro digestion of artificially lead-contaminated soil.
- Analysis of lead speciation using a lead ion selective electrode (Pb-ISE).
- Voltammetric analysis with differential pulse anodic stripping voltammetry (DPASV).
Main Results:
- In chyme, free Pb(2+) ions represent a negligible fraction of total lead.
- Lead primarily exists as lead phosphate and lead bile complexes.
- Lead phosphate complexes are labile, existing in equilibrium with Pb(2+).
Conclusions:
- Lead bioavailability in the intestines is underestimated when considering only free metal ions.
- Both labile lead phosphate and lead bile complexes may contribute to lead transport across the intestinal epithelium.
- Further research should consider these complexed forms when assessing lead exposure risks.