231
as 60 μg L
−1
. Evidently, the uranium concentration in all, or nearly all, groundwater
samples is much above the maximum acceptable values of WHO, USEPA, ICRP,
UNSCEAR and AERB, India.
5.4 Biokinetic Behaviour
The biokinetic behaviour in the human body following chronic intake for 60 years
via the drinking water pathway has been estimated using Li’s hair compartment
model, and results are summarized in Table 3.
Uranium Burden in Different Compartments in Human Body
GI Tract
The gastrointestinal tract comprising of the stomach, small intestine (SI), upper
large intestine (ULI) and lower large intestine (LLI) is the first recipient of ingested
uranium. The range of uranium retention in GI tract was 0.47 to 5.39 μg. Significant
absorption of uranium begins in the small intestine. Absorption appears to be maximum for uranium ingested in the chemical form of UO 2 (NO 3 ) 2 ·6H 2 O, UO 2 F 2 , or
Na 2 U 2 O 7 , roughly half as great for UO 4 or UO 3 and 1–2 orders of magnitude lower
for UCl 4 , U 3 O 8 , UO 2 and UF 4 (Leggett and Harrison 1995).
Blood
The least significant retention of uranium in the human body takes place in the
plasma, as is proved by average value of 0.09 μg U following 60 years of chronic
water intake. A secular equilibrium exists between ionic uranyl hydrogen carbonate
complex and uranyl-albumin complex in the blood plasma (Moss et al. 1983).
Plasma acts as a transport medium for soluble uranium complexes with citrate,
bicarbonates and transferrin (protein) among the tissues and organs of deposition
(Chevari and Likhner 1968; Stevens et al. 1980; Cooper et al. 1982).
Liver
The liver is classified into two compartments—Liver1 and Liver2—on the basis of
their biological removal half-times of 7 days and 10 years, respectively. The range
of uranium retained in both liver compartments combined is 2.02–23.21 μg with an
average of 7.40 μg, which accounts for 2.33% of the whole body retention.
Biokinetic Modelling and Risk Assessment of Uranium in Humans
as 60 μg L
−1
. Evidently, the uranium concentration in all, or nearly all, groundwater
samples is much above the maximum acceptable values of WHO, USEPA, ICRP,
UNSCEAR and AERB, India.
5.4 Biokinetic Behaviour
The biokinetic behaviour in the human body following chronic intake for 60 years
via the drinking water pathway has been estimated using Li’s hair compartment
model, and results are summarized in Table 3.
Uranium Burden in Different Compartments in Human Body
GI Tract
The gastrointestinal tract comprising of the stomach, small intestine (SI), upper
large intestine (ULI) and lower large intestine (LLI) is the first recipient of ingested
uranium. The range of uranium retention in GI tract was 0.47 to 5.39 μg. Significant
absorption of uranium begins in the small intestine. Absorption appears to be maximum for uranium ingested in the chemical form of UO 2 (NO 3 ) 2 ·6H 2 O, UO 2 F 2 , or
Na 2 U 2 O 7 , roughly half as great for UO 4 or UO 3 and 1–2 orders of magnitude lower
for UCl 4 , U 3 O 8 , UO 2 and UF 4 (Leggett and Harrison 1995).
Blood
The least significant retention of uranium in the human body takes place in the
plasma, as is proved by average value of 0.09 μg U following 60 years of chronic
water intake. A secular equilibrium exists between ionic uranyl hydrogen carbonate
complex and uranyl-albumin complex in the blood plasma (Moss et al. 1983).
Plasma acts as a transport medium for soluble uranium complexes with citrate,
bicarbonates and transferrin (protein) among the tissues and organs of deposition
(Chevari and Likhner 1968; Stevens et al. 1980; Cooper et al. 1982).
Liver
The liver is classified into two compartments—Liver1 and Liver2—on the basis of
their biological removal half-times of 7 days and 10 years, respectively. The range
of uranium retained in both liver compartments combined is 2.02–23.21 μg with an
average of 7.40 μg, which accounts for 2.33% of the whole body retention.
Biokinetic Modelling and Risk Assessment of Uranium in Humans