Table 2 -9. Uranium Levels for Various Effects

DOE-STD-1136-2004

Guide of Good Practices for Occupational Radiological Protection in Uranium Facilities

Table 2 -9. Uranium Levels for Various Effects

Uranium Absorbed

Corresponding Class

Corresponding

D Uranium Intake in

Kidney Burden

into Bloodstream, g

Effect

Standard Man, mg

g U/g Kidney

U per g body weight

No effect

0.04

5.9

1.1

Maximal Nonlethal

0.08

11.6

2.2

LD50

2.0

294

54.8

The values for "standard man" are based on the ICRP Publication 30 model for uranium metabolism

(47.6% of inhaled Class D uranium is taken up into the bloodstream, and 12% of that goes to the kidneys).

For example, the "no effect" value in Table 2.9 corresponds to a kidney burden of (5.9)(.476)(.12) = 0.337

mg. The mass of kidney tissue in standard man is 310 g, so this kidney burden represents 1.1 g uranium

per gram of kidney tissue.

An airborne contamination limit from this "no effect" kidney burden can be derived by calculating

the airborne uranium concentration at which chronic exposure would result in a kidney burden that just

equals the "no effect" burden. In the illustrative analyses below, the 1500-day component of ICRP

Publication 30's kidney retention function is neglected, since this contribution is neglig ible.

For chronic exposure to a constant concentration, the maximum kidney burden will occur at the

equilibrium condition--when the amount of uranium entering the kidney each day equals the amount

being removed from the kidney. The daily kidney uptake rate and removal rate are calculated from the

following formulas:

K = Br x Ca x fb x fk

where

K = kidney uptake rate (mg/day)

Br = breathing rate (m3/day)

Ca = air concentration (mg/m3)

fb = inhaled fraction entering bloodstream (0.476)

fk = bloodstream fraction entering kidneys (0.12) and

R = λKb

where

R = kidney removal rate (mg/day)

λ= 0.693/T1/2 (day-1)

Kb = amount in the kidney (mg)

T1/2= biological half- life of U in kidney = 6 days

To calculate the concentration at which chronic exposure would result in a kidney burden of 0.337

mg, the uptake rate in kidney is set equal to the removal rate for a 0.337-mg kidney burden:

R = (0.337) x 0.693/6 = 0.039 mg/day

K = Br (m3/day) x Ca(mg/m3) x (0.476) x (0.12)

K= R = 0.039 mg/day

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