PLUTONIUM
144
3. HEALTH EFFECTS
Studies conducted in animals have shown that exposures to plutonium that occur in
young animals result
in greater distribution of plutonium to skeletal tissues and that neonates absorb a substantially larger
fraction of an ingested dose of plutonium than adults. These observations suggest that infants and
children may have a higher, or altered, susceptibility to plutonium toxicity. Studies on toxicokinetics and
health effects for exposures that occur during postnatal development would improve our understanding of
potential vulnerabilities of children to plutonium.
In adults, approximately 50% of the plutonium body burden resides in bone.
The potential effects of
increased mobilization of bone mineral during pregnancy, to support the development of the fetal
skeleton, on maternal-fetal transfer of plutonium has not been examined. Studies of plutonium levels in
offspring of mothers who carry a bone burden of plutonium would improve our understanding of potential
pre- and postnatal exposures the might emanate from maternal-fetal transfer.
Child health data needs relating to exposure are discussed in Section 6.8.1, Identification of Data Needs:
Exposures of Children.
3.12.3 Ongoing Studies
Dr. Charles Watson, from Washington State University, and several active or retired Pacific Northwest
National Laboratory scientists are finishing a comprehensive report on the biological effects of inhaled
239
PuO
2
in beagle dogs; the completed report will be submitted to Radiation Research.
The following ongoing studies were identified in the Federal Research In Progress database (FEDRIP
2007).
Dr.
Richard Day, from the University of Pittsburgh, Pittsburgh, Pennsylvania, is continuing longitudinal
follow-up health effects assessment of radiation exposures in a cohort of workers from the Mayak
facilities in Russia. Dr. Martha Linet, from the Division of Cancer Epidemiology and Genetics,
National
Cancer Institute, is studying populations exposed to occupational radiation, which includes a cohort of
26,000 Mayak nuclear facility workers (in the former Soviet Union) exposed to particularly high doses of
external radiation and alpha radiation from internalized plutonium. Dr.
Ray Lloyd, from the University of
Utah, Salt Lake City, Utah, is testing recently-developed plutonium biokinetic models to human data from
Russian nuclear workers to extend
current biokinetic, dosimetric, and risk models to the human.
PLUTONIUM
145
4. CHEMICAL, PHYSICAL, AND RADIOLOGICAL INFORMATION
4.1 CHEMICAL IDENTITY
Information regarding the chemical identity of plutonium and selected plutonium compounds is located in
Table 4-1.
4.2 PHYSICAL, CHEMICAL, AND RADIOLOGICAL PROPERTIES
Information regarding the physical and chemical properties of plutonium and selected plutonium
compounds is located in Table 4-2. Information regarding the radiological properties of selected
plutonium isotopes is located in Table 4-3. The decay schemes for
239
Pu and
241
Pu are summarized in
Figures 4-1 and 4-2, respectively.
Plutonium is a member of the actinide series and is a human-made element (atomic number 94).
Actinides are the 15 elements starting with actinium, atomic number 89, and extending to lawrencium,
atomic number 103. All of the isotopes of the actinide elements are radioactive.
Plutonium was the first
human-made element to be synthesized in weighable amounts.
238
Pu was discovered in 1940 by Seaborg
and co-workers; it was synthesized by the bombardment of uranium with deuterons (
2
H). Isotopes with
mass numbers 228–247 have been identified for plutonium; all are radioactive.
The most important
isotope is
239
Pu, which has a half-life that is sufficiently long (24,100 years) to permit its preparation in
large amounts, making it possible to perform chemical studies. Metallic plutonium exists in six allotropic
modifications under ordinary pressure; a seventh phase exists under high pressure. Five oxidation states,
Pu(III), Pu(IV), Pu(V), Pu(VI), and Pu(VII), are known to exist in compounds and solution (Clark et al.
2006). Plutonium(III) and plutonium(IV) are considered to be the reduced forms of plutonium, while
plutonium(V) and plutonium(VI) are the oxidized forms (DOE 1987a). While the atomic mass of
plutonium depends on the isotope, 244 is frequently listed as the mass of plutonium on periodic tables.
244
Pu is the isotope with the longest half-life.
PLUTONIUM
146
4. CHEMICAL AND PHYSICAL INFORMATION
Table 4-1. Chemical Identity of Plutonium and Selected Plutonium Compounds
Characteristic
Information
a
Chemical name
Plutonium
Plutonium(IV) dioxide Plutonium nitride
Synonym(s)
No data
Plutonium dioxide
No data
Registered trade name(s)
No data
No data
No data
Chemical formula
Pu
PuO
2
PuN
Identification numbers:
CAS registry
7440-07-5
b
12059-95-9
12033-54-4
NIOSH RTECS
No data
No data
No data
EPA hazardous waste
No data
No data
No data
OHM/TADS
No data
No data
No data
DOT/UN/NA/IMDG shipping No data
No data
No data
EINECS
231-117-7
235-037-3
No data
HSDB
6465
No data
No data
NCI
No data
No data
No data