Title
In vitro intestinal lead uptake and transport in relation to speciation
Author
Oomen, A.G.
Tolls, J.
Sips, A.J.A.M.
Groten, J.P.
Publication year
2003
Abstract
Children might be exposed substantially to contaminants such as lead via soil ingestion. In risk assessment of soil contaminants there is a need for information on oral bioavailability of soilborne lead. Oral bioavailability can be seen as the result of four steps: (1) soil ingestion; (2) mobilization from soil during digestion, i.e., bioaccessibility; (3) transport across the intestinal epithelium; and (4) first-pass effect. Lead bioaccessibility and speciation in artificial human small intestinal fluid, i.e., chyme, have been investigated in previous studies. In the present study, transport of bioaccessible lead across the intestinal epithelium was investigated using the Caco-2 cell line. Cell monolayers were exposed to (diluted) artificial chyme. In 24 h, approximately 27% of the lead were associated to the cells and 3% were transported across the cell monolayer, without signs of approaching equilibrium. Lead associated to the cells showed a linear relationship with the total amount of lead in the system. Bile levels did not affect the fraction of lead associated to Caco-2 cells. Extrapolation of the lead flux across the Caco-2 monolayer to the in vivo situation indicates that only a fraction of the bioaccessible lead is transported across the intestinal epithelium. Furthermore, the results indicate that as the free Pb2+ concentration in chyme was negligible, lead species other than the free metal ion must have contributed to the lead flux toward the cells. On the basis of lead speciation in chyme, this can be attributed to dissociation of labile lead species, such as lead phosphate and lead bile complexes, and subsequent transport of the released free metal ions toward the intestinal membrane.
Subject
Biology Health
Physiological Sciences
lead
pollution exposure
article
bioavailability
cell strain CACO 2
controlled study
first pass effect
human
human cell
intestine absorption
lead poisoning
membrane permeability
metal metabolism
priority journal
risk assessment
soil pollution
tissue level
Administration, Oral
Biological Availability
Caco-2 Cells
Digestive System
Humans
Intestinal Mucosa
Ions
Lead
Soil Pollutants
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DOI
https://doi.org/10.1007/s00244-002-1226-z
TNO identifier
236930
ISSN
0090-4341
Source
Archives of Environmental Contamination and Toxicology, 44 (1), 116-124
Document type
article