ERE596

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ERE596 Special Topics in Environmental Modeling
Toxicokinetics Models Problem Set 5 SUNY College
of Environmental Science and Forestry Gary
Diamond (diamond_at_syrres.com) October 2004
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IEUBK Model for Lead in Children(birth to 84
months)
Plasma - Extracellular Fluid
RBC
Tr. Bone
Cr. Bone
Other
Kidney
Liver
Urine
Feces
Other
Blood Lead
3
(2,3)
Plasma ECF
C1
C3
C2
IEUBK Model
Plasma ECF 2 x plasma volume
4
(4)
k1 10 d-1 (at low MRBC)
k2 0.1 d-1
5
(5)
2) Capacity-limited
1) Capacity-unlimited
1) Capacity-unlimited
2) Capacity-limited
PAF 0.2 AV 1 UPMax age-specific
ABSsoil/dust 0.3 ABSfood/water 0.5
6
(5)
Medium-specific, Capacity-limited GI absorption
Constant age (24 months)
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Medium-specific, Capacity-limited GI absorption
(5)
UPMax varies with age UPMax 100 ug (24
mo) UPMax 187ug (84 mo)
Diet and water - Capacity-limited - AF0.5 (at
low intakes)
Soil and dust - Capacity-limited - AF0.35 (at
low intakes)
8
(5)
Comparison of AF Values for Various Models
EPA IEUBK, diet and water
9
(6)
0.08 d-1
Trabecular Bone
Trabecular Bone
Cortical Bone (80)
20 d-1
Cortical Bone (80)
TPLCORT/TPLTRAB
Plasma ECF
WTCORT/WTTRAB
0.08 d-1
80 d-1

• Transfer rates set to establish uptakes in
  proportion to relative masses of cortical and
  trabecular bone

10
(7)
11
(8)
Average for age range 25-48 mo
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GM 4.6 ug/dL GSDi 1.6 95th percentile 10
ug/dL P10 0.05
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Models, models, and more models...
Rabinowitz et al. 1976
Bert, 1989
Carlisle and Wade,1992
Leggett, 1993
OFlaherty, 1993
Bowers et al. 1994
Stern,1994
U.S. EPA et al. 1994
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Its like 4-day-old babies in the maternity
ward. Most of the models are only attractive to
the person who created them.
Science 2841451, 1999