Air Quality Criteria for Lead Volume II of II - (NEPIS)(EPA) - US ...

AX5-182
Table AX5-10.8 (cont’d). Lead and Intestinal Uptake—Effect on Ultrastructure, Motility, Transport, and Miscellaneous
Compound and
Concentration Duration Species Blood Lead Effects a Authors
OECD
(Organisation for
Economic Co-operation
and Development)
medium was artificially
contaminated at 1, 3, 5, or
10 times the Dutch
intervention value of
530 mg/Pb/kg dry wt. Pb
containing medium was
presented at the apical
surface of the cells in 2
mL DMEM/chyme.
Neutral red uptake
studies had
DMEM/chime with low
5 µM and high 50 µM Pb
content
44 mg/kg/d Pb as
53 mmol/L Pb acetate
2.5 mg/mL Pb acetate in
drinking water
100 µM Pb nitrate,
in vitro
Cell viability
studies—24 h
incubation.
Pb transport studies,
1, 3, 5, and 24 h
— Transport of bioaccessible Pb across the intestinal epithelium—In Coco-2
cells exposed to artificial chime, with in 24 hrs. App. 27% of the Pb was
associated with the cells and 3% were transported across the cell
monolayer. Pb associated with cells showed a linear relationship with the
Pb available in the system.
Results indicate that only a fraction of the bioavailable Pb is transported
across the intestinal epithelium.
On the basis of Pb speciation in chime, It could be attributed that
dissociation of labile Pb species, such as Pb phosphate, and Pb bile
complexes and subsequent transport of the released free metal ions flow
toward the intestinal membrane.
4 wks Rat — Pb exposure significantly decreases the amplitude of contraction in rat
duodenum.
55 days Colonic segments
taken from
chronically
exposed guinea
pigs
Duration not
specified
Muscle–myenteric
plexus
preparations of
distal ileum of
controlled animals
Exposed:
80 µg/dL
Colonic propulsive activity as measured by the velocity of the
displacement of the balloon, from the oral to the aboral end, did not get
affected significantly by Pb treatment. In longitudinal muscle-myenteric
plexus preparations of distal ileum, addition of Pb nitrate (100 µm) caused
slight increase in cholinergic contractions.
— Moderate decrease of electrically induced cholinergic contractions.
Oomen et al. (2003)
Karmakar and
Anand (1989)
Rizzi et al. (1989)