206
Table 7 Minimal risk levels for uranium [based on ATSDR 2013]
Route
Form
Duration
MRL
Basis
Uncertainty
factor
Inhaled Soluble
Intermediate 1 × 10
−4
 mg [U] m
−3
LOAEL of 0.15 mg
[U] m
−3 for minimal
renal lesions in dogs.
Adjusted for
intermittent exposure
resulting in an
adjusted LOAEL of
0.032 mg [U] m
−3
300
Chronic
4 × 10
−5
 mg[U] m
−3
One-year dog study
involving exposure to
UCl 4 . A BMCL 10 of
0.019 mg [U] m
−3
was selected. This
BMCL 10 was adjusted
for intermittent
exposure resulting in
an adjusted BMCL 10
of 0.0037 mg [U] m
−3
100
Insoluble Intermediate 2 × 10
−3
 mg [U] m
−3
A NOAEL of
1.1 mg [U] m
−3 in
dogs was used (based
on renal effects). This
value was adjusted
for intermittent
exposure resulting in
an adjusted NOAEL
of 0.24 mg [U] m
−3
100
Chronic
8 × 10
−4
 mg[U] m
−3
A LOAEL of
5.1 mg [U] m
−3 for
lung fibrosis and
metaplasia in rhesus
monkeys was
selected. This
LOAEL was adjusted
for intermittent
exposure resulting in
an adjusted LOAEL
of 0.82 mg [U] m
−3
1000
(continued)
M. C. Thorne