25
PLUTONIUM
3. HEALTH EFFECTS
Table 3-1. Selected Exposure Details from the ITRI and PNL Dog Studies and
Conversion Procedures Used to Compare Initial Lung Burden in Common
Units of kBq/kg Body Weight
Exposure and conversion information
Study references
ITRI evaluated single exposure of juvenile male and female dogs (3 months
of age) at an AMAD particle size of 1.5 µm. The dogs were placed into one
of eight groups based
on intended ILB, resulting in mean ILBs of 0, 0.018,
0.11, 0.37, 1.1, 2.3, 3.7, 7.0, or 19 kBq/kg body weight.
ITRI evaluated single exposure of aged male and female dogs (7–10 years of
age) at an AMAD of 3.0 µm. The dogs were placed into one of five groups
based on intended ILB. The reported mean ILBs of 0, 0.033, 0.091, 0.18,
and 0.37 μCi/kg body weight were converted
to 0, 1.22, 3.37, 6.6, and
13.7
kBq/kg, respectively (1 μCi = 37 kBq).
ITRI evaluated single inhalation exposures of beagle dogs (n=108 exposed
and 18 controls for each sex) using three separate particle sizes (0.75, 1.5,
and 3.0 µm AMAD with individual particle activities from 0.048 to 7.4 mBq),
and four to eight graded exposure levels for each particle size (with median
ILBs of 0.16, 0.63, 1.6, 3.7, 6.4, 14, and 29 kBq/kg lung). ILB was
measured after allowing time for mucociliary clearance using
169
Yb
incorporated into the
239
Pu particles as a tracer. Animals were followed until
death. Information was collected
on retention, distribution, respiratory
function, and pathology. Data by time after exposure and particle size
include percent activity retention, activity distribution and retention in five
types of lymph nodes, lymphocyte counts, surviving fraction, lung dose,
lung tumor probability, occurrence of radiation pneumonitis and its impact
on respiratory function, malignant and benign
tumors by organ system and
type, causes of death, and competition between pneumonitis and lung
cancer, Particle size was converted to activity, with 0.75 and 3.0 µm
AMAD particles containing 0.048 and 7.4 mBq of
239
Pu, respectively.
239
Pu(NO
3
)
4
:
PNL evaluated single exposure of young adult male and female dogs (17–
22 months of age) at an AMAD particle size of 0.81 µm. Mean ILBs of 0, 0,
2±2; 8±4; 56±17; 295±67; 1,709±639; and 5,445±1,841 nCi were reported
for unexposed controls, vehicle controls, and exposed groups 1–6,
respectively, and were converted to mean ILBs of 0, 0, 0.0069, 0.030,
0.207, 1.02, 5.91, and 18.83 kBq/kg body weight by converting nCi to kBq
(1 nCi = 0.037 kBq), which were then divided
by a mean body weight of
10.7 kg (the reported mean body weight for the
239
PuO
2
-exposed PNL
dogs, which was assumed to represent the
239
Pu(NO
3
)
4
-exposed PNL dogs
as well since body weight data for these dogs were not located in available
study reports).
DOE 1989, 1994b
DOE 1988d, 1989
Muggenburg et al.
2008
Dagle et al. 1996;
DOE 1986b;1988b,
1989, 1994a; Park et
al. 1995
μCi = microCurie; AMAD = activity median aerodynamic diameter; ILB = initial lung burden; ITRI = Inhalation
Toxicology Research
Institute; kBq = kiloBequerel; PNL = Pacific Northwest Laboratory
26
PLUTONIUM
3. HEALTH EFFECTS
239
Pu(NO
3
)
4
data from the dog studies consist of interim and annual reports and more recent publications
that focus on selected end points of toxicity. The presentation of health effects in the dog studies from
ITRI and PNL in this Toxicological Profile for Plutonium focuses primarily on results of the available
comprehensive reports and secondarily on results of interim data.
Inhalation exposures in the dog studies were quantified using radiological measurements to estimate
initial plutonium burdens (activity or activity-per-body weight or activity-per-organ weight), rather than
aerosol concentrations of plutonium.
In the ITRI and PNL studies, exposure groups were defined as
ranges or group means based on initial plutonium burdens. However, over the 30-year time span of
publications, initial plutonium burdens were quantified using several different units (e.g., µCi, µCi/kg
lung weight, kBq, kBq/kg body weight, total kBq deposited in the lung); thus, data obtained from a single
study may have been reported in several different publications over a span of time during which changes
may have been made in conventions for reporting initial lung burdens. The convention of kBq/kg body
weight has been selected to express initial lung burden for the ITRI and PNL dog studies summarized in
this toxicological profile for plutonium. Table 3-1 summarizes reported initial lung burden
data from
each of these studies, as well as any additional data used for conversions to the convention of kBq/kg
body weight. Selected interim and final reports and all publicly-available comprehensive reports were
consulted for relevant exposure and health effects data. It should be noted that for a particular study,
various reports may vary slightly in estimated initial lung burdens. In this toxicological profile for
plutonium, the most recent publications typically served as the definitive source of initial lung burden
data.
As discussed in Section 3.5, Mechanisms of Toxicity, plutonium-induced health effects are
considered to
be the result of energy deposited by alpha particle emissions in tissues that retain plutonium for extended
periods (i.e., lung, bone, liver following inhalation exposure). Similar health effects would be expected
from any alpha-emitting source that would result in similar cumulative tissue-specific radiation dose and
dose rate.
3.2.1.1 Death
Epidemiological Studies in Humans.
Possible associations between exposure to plutonium and
mortality
have been examined in studies of workers at the U.S. plutonium production and/or processing facilities
(Hanford, Los Alamos, Rocky Flats), as wells as facilities in Russia (Mayak) and the United Kingdom
(e.g., Sellafield). The most recent findings from these studies are summarized in Table 3-2. Collectively,