Actinides
391
Chernobyl accident (Skwarzec 1997). Annual discharge of 239+240 Pu with water of the
Vistula river system to the Baltic Sea is estimated to be 130 MBq (Kabat et al. 2013).
The contents of 239+240 Pu in fish and shellfish sampled in the Irish Sea were
reported to be up to 2pCi/g (ATSDR 2002b). Mesoplankton collected from about
200  m depth contain this radionuclide up to 452  mBq/kg, whereas the content of
238 Pu was much smaller, 13 mBq/kg. Mesoplankton from deeper layer contain much
less of these elements (Sanchez-Cabeza et al. 2003).
Concentration of both Pu radionuclides, 239+240 Pu, in air near Heildelberg,
Germany, during the period 1954–1975 varied from 0.086 to 0.75 fCi/m 3 , and their
total cumulative deposition was calculated to range between 0.054 and 2.10 mCi/km 2
(Jabick vide Kabata-Pendias 2011). Volcanic eruptions are significant sources of Pu.
58.4.3 HUMANS
Humans may be exposed to Pu by breathing air, drinking water, and eating food containing Pu. However, the levels of Pu in the environment are generally very low and
of little health consequence. Exposure to its higher levels could occur from an accidental release during its use. Workers at nuclear facilities using Pu may be exposed
to its higher levels.
Little Pu (about 0.05%) is absorbed from the gastrointestinal tract after ingestion,
and little is absorbed through the skin following dermal contact. When it is inhaled,
a significant fraction can move from the lungs through the blood to other organs,
depending on the solubility of Pu compounds. After leaving the intestine or lung,
about 10% of Pu clears the body. The rest of Pu compounds enter the bloodstream
deposits, about equally in the liver and skeleton, where it remains for long time, with
biological retention half-lives of about 20 and 50 years. Plutonium metabolism in
physiological systems consists, primarily, of hydrolytic reactions and formation of
complexes with proteins and nonprotein ligands.
The Pu amounts deposited in the liver and skeleton increase with age. However, it
is possible that the bones of children could be more severely affected by Pu than the
bones of adults. Most of the body burden of Pu resides in the skeleton and liver, and
following inhalation exposures, in the lung and lung-associated lymph nodes. Risks
for adverse outcomes of Pu exposures are strongly dependent on radiation doses
received by specific tissues and organ systems.
The main health effect of exposure to Pu is cancer (mainly the lung, bones, and
liver), which may occur years after the exposure. Especially workers exposed to Pu
in air at high levels are at risk. The IARC classified 239 Pu and its decay products
( 240 Pu and other isotopes) in Group 1 as carcinogenic to humans (IARC 2001, 2013).
As for other radionuclides, the risk coefficients for tap water are about 80% of those
for dietary ingestion (Argonne 2007).
Plutonium generally poses a health hazard only if it is taken into the body because
all isotopes, except 241 Pu, decay by emitting the α particles, whereas the β particles
emitted by 241 Pu are of low energy. Inhaling airborne Pu is the primary concern for all
isotopes, and cancer resulting from the ionizing radiation is the health effect of concern. The ingestion hazard associated with common forms of Pu is much lower than
the inhalation hazard, because absorption into the body after ingestion is quite low.