CESIUM, RADIOACTIVE: Nuclear Power Plant Emissions
Effluent
Concentrations :
Radioactive isotopes of cesium (e.g., cesium-137 and cesium-134) have been
released to the atmosphere from atmospheric weapons testing, accidents from nuclear
reactors, and nuclear-powered satellites burning up in the
atmosphere upon re-entry(1). The total amount of cesium-137 released from
weapons testing through 1980 was estimated as 2.6X10+7 Ci, 76% of which was
released in the northern hemisphere and 24% in the southern hemisphere(2). On
April 26, 1986, a steam buildup caused an explosion and fire at a nuclear
power generating plant in Chernobyl, Ukraine,
releasing an estimated 5.4X10+5 Ci of cesium-134 and 1.1X10+6 Ci of cesium-137
into the atmosphere over Europe(3). Long-range transport spread the
radionuclides through the Northern Hemisphere; no airborne activity from
Chernobyl has been reported south of the equator(4). By early May 1986, these
radionuclides were readily detectable in environmental samples collected in
North America(5). More recent estimates have put the total activity of
cesium-137 released from the Chernobyl power plant
as 2.3X10+6 Ci and 1.2X10+6 Ci for cesium-134(6). On January 24, 1978, the
Soviet nuclear-powered satellite Cosmos 954 re-entered earth's
atmosphere over the Canadian Arctic, releasing an estimated 86 Ci of
cesium-137(7). In October 1957, an accident at the Windscale nuclear
weapons plant at Sellafield in the United Kingdom resulted in a
release of 595 Ci of cesium-137(8). Routine activities at nuclear
power plants and fuel-reprocessing stations
also release cesium-137 and cesium-134 to the environment on a regular basis.
Radiocesium released in airborne effluents from the normal operation of nuclear
power plants is considered low in comparison
to releases from atmospheric weapons testing and the major releases following
accidents at nuclear power plants.
In 1998, it was reported that 1.3X10-4 Ci of cesium-134 and 5.1X10-3 Ci of
cesium-137 were released to the atmosphere from the Savannah River plutonium
processing site in South Carolina(9). In 1993, the Nuclear
Regulatory Commission estimated that 0.013 Ci of 134Ci and 0.023 Ci of
cesium-137 were released in airborne effluents from 30 pressurize water reactor nuclear
power plants operating in the United
States(10). It was also estimated that 4.6X10-4 Ci of cesium-134 and 3.3X10-3 Ci
of cesium-137 were released in airborne effluents from 28 boiling water reactors
nuclear power plants(10).
Sediment/Soil Concentrations :
SEDIMENT: The concns of cesium-137 in eight sediment cores of the Danube River,
Austria were about 540 pCi/kg in April 1985, but increased to approx
27,000-81,000 pCi/kg in October 1986, following the accident at the Chernobyl nuclear
power plant(1). The deposition of cesium-137
attributed to the accident at the Chernobyl nuclear power
plant in sediment at five different sites in Lake Constance,
Germany ranged from 2.7X10-7 to 2.1X10-6 Ci/sq m, while the fallout from nuclear
weapons testing since 1963 ranged from 1.4X10-7 to 5.4X10-7 Ci/sq m(2). It was
estimated that 2,973 Ci of cesium-137 and 1,622 Ci of cesium-134 were released
to the sediments in the cooling and surrounding the Chernobyl nuclear
power plant following the accident in 1986(3).
Surface sediment samples collected from the Spanish Mediterranean coast near the
Vandellos nuclear power plant
in 1989 contained cesium-137 and cesium-134 concentration ranges of 0.47-16.7 Bq/kg
and <0.05-1.14 Bq/kg, respectively(4). Twenty-seven surface sediment samples
(upper 3 cm) collected from the Pechora Sea in July 1994 had concentration
values for cesium-137 ranging from below the detection limit to 10.4 Bq/kg, with
a mean of 3.13 Bq/kg(5).
Effluent Concentrations :
The dumping of high and low level radioactive wastes into the Arctic waters by
the former Soviet Union has also led to the release of cesium-137 and cesium-134
as well as other radioactive nuclides into these waters(1). In the past, the
majority of radioactive cesium released to water surfaces in North America arose
from deposition following atmospheric nuclear weapons testing
conducted by the United States, primarily during the 1960s(1). Radioactive
cesium can be introduced to water from nuclear power
plants (during accidents and normal operation) and at
facilities that produce weapons grade plutonium and uranium. During the period
of 1961-1973, it was estimated that about 514 Ci of cesium-137 was emitted to
the Savannah River, SC watershed due to activities at the Savannah River
Plutonium Processing Plant(2). It was further noted that about
18% of this total (92 Ci) drained directly into the Savannah River(2). In 1998,
it was reported that 1.0X10-4 Ci of cesium-134 and 0.19 Ci of cesium-137 were
released in liquid effluents from the Savannah River plutonium processing site
in South Carolina(3). In 1993, the NRC estimated that 1.88 Ci of cesium-134 and
2.85 Ci of cesium-137 were released in liquid effluents from 30 pressurized
water reactor nuclear power plants
operating in the United States(4). It was estimated that 0.12 Ci of cesium-134
and 0.58 Ci of cesium-137 were released in liquid effluents from 28 boiling
water reactor nuclear power plants(4).
EPA reported that the total on-site discharges of cesium-137 from containment
ponds at the Nevada Test Site was 0.0017 Ci in 1997(5). It was estimated that
1,622 Ci of cesium-137 and 811 Ci of cesium-134 were released to the cooling
pond surrounding the Chernobyl, Ukraine nuclear power
plant following the accident in 1986(6).
Sediment/Soil Concentrations :
SOIL: Radioactive cesium has been released to soil surfaces by underground nuclear
weapons testing, fallout from the accident at the Chernobyl power
plant and fallout from atmospheric weapons testing. About 1,400
underground test have been performed worldwide, with a total explosive yield of
about 90 megatons(1). Small amounts of cesium-137 and cesium-134 are also
released to soil from the normal operation of nuclear power
plants and the storage of spent fuel rods. Not including the
30-km exclusionary zone, an area of approximately 2.4X10+4 sq km near the
Chernobyl nuclear power plant
was contaminated with cesium-137 at a deposition density >5.4X10-5 Ci/sq m
following the accident in 1986(2). Within the exclusionary zone, the
contamination density may have been 2 orders of magnitude greater in limited
areas(2). The mean deposition density of cesium-137 and cesium-134 in four
different soils in Devoke, United Kingdom for May 1986 were reported as 3.7X10-5
to 5.4X10-7 Ci/sq m and 1.0X10-7 to 1.8X10-7 Ci/sq m, respectively(3). The
deposition density of cesium-137 in 123 soil core collected at the Idaho
National Engineering and Environmental Laboratory ranged from 1.6X10-8 to
3.4X10-7 Ci/sq m(6). The deposition density of cesium-137 in soils from Idaho,
Montana, and Wyoming ranged from 3.0X10-9 to 1.1X10-7 Ci/sq m, and it was
assumed that its origin was fallout from the Nevada Test Site(4). The mean
deposition density of cesium-137 in the top layer (0-8 cm) of soils near the
Chernobyl nuclear power plant
in 1988 was 8.6X10-5 Ci/sq m and the mean deposition density of cesium-134 was
1.9X10-5 Ci/sq m(5).
Artificial Pollution Sources :
Radioactive cesium is released to the environment during the normal operation of
nuclear power plants,
explosion of nuclear weapons, and accidents involving nuclear
power plants or nuclear
powered satellites or submarines. High levels of cesium-134 and cesium-137 have
been released to the environment, as a result of atmospheric nuclear
weapons testing (which has been discontinued for many years) or underground
weapons testing and the accident at the Chernobyl, Ukraine nuclear
reactor site in 1986. There have only been two major reactor accidents at nuclear
plants where radiocesium was released in significant amounts.
The two accidents occurred in Windscale, England in 1957 and Chernobyl, Russia
in 1986(1).
Fish/Seafood Concentrations :
The concn of cesium-137 in bullhead catfish inhabiting an abandoned nuclear
reservoir at the Savannah River site in South Carolina were as high as 1.54X10+5
pCi/kg(1), but concns in various freshwater species of fish in the Ottawa River
ranged from 54 to 351 pCi/kg(2). After the accident at the Chernobyl nuclear
power plant, the avg concns of cesium-137 in
perch and pike obtained from 52 freshwater lakes in Finland were 55,811 and
66,297 pCi/kg, respectively, in 1988. By contrast, in 1992, the mean concns of
cesium-137 in perch and pike had fallen to 14,324 and 18,567 pCi/kg,
respectively(3). Mussels (Mytilus edulis (L.)) collected from 11 estuaries
around the Irish coastline in August 1988 contained cesium-137 and cesium-134
concentration ranges of <0.5-9.8 and <0.4-<0.7 Bq/kg (dry weight),
respectively(4). The mean activity concentrations of cesium-137 detected in the
edible portion of 34 crabs and 37 lobsters caught commercially in the Sellafield
coastal area offshore from the Sellafield nuclear fuel
reprocessing plant in the northeast Irish Sea between May 25
and June 5, 1997 were 3.1 and 5.0 Bq/kg (wet), respectively(5).
Sediment/Soil Concentrations :
SOIL: The concn of cesium-137 in soils of Thessaloniki, Greece ranged from 1,440
to 35,324 pCi/kg (avg 8,154 pCi/kg) and the concn of cesium-134 ranged from
about 270 to 5,676 pCi/kg during the period of August 1986 to February 1989,
with most of the fallout attributed to the accident at the Chernobyl nuclear
power plant(1). The concn of cesium-137 in 10
uncultivated fields from southern England ranged from 0 to 946 pCi/kg, with the
highest levels contained in the top 10 cm of the soil surface(2). The concn of
cesium-137 in five cultivated fields ranged from 0 to 540 pCi/kg, and the concns
were well distributed from the surface to the plough layer(2). The concn of
cesium-137 in three soils in Hong Kong receiving a large amount of rainfall
ranged from 32 to 201 pCi/kg(3). The avg concn of cesium-137 in uncultivated
soils in northern Poland ranged between 616 and 4,170 pCi/kg from 1988-1991(4).
The mean concn of cesium-137 in surface soils from the Los Alamos nuclear
laboratory test site during the period of 1974-1996 was 611 pCi/kg(5). Concn of
cesium-137 around the perimeter of the site and background concns off the site
were 589 and 419 pCi/kg, respectively. The concn of cesium-137 and cesium-134 in
soils and sediments at 18 US DOE facilities ranged from 20 to 4.69X10+7 pCi/kg(6).
The mean concn of cesium-137 in soils taken from two high-elevation sites in
northern Colorado ranged from 4,054 to 7,027 pCi/kg(7). Soil samples collected
in 1994 and 1995 from the industrial area and residential area surrounding a plant
for the utilization and repair of nuclear-powered submarines in
the coastal area of Cut Bay in Olenjya Bay in the Kolsky Gulf, Russia contained
cesium-137 in concentrations of 1-15 Bq/kg of air dry sample and 8-19 Bq/kg of
air dry sample, respectively(8).
Methods of Manufacturing :
Radioactive isotopes of cesium such as cesium-134 and cesium-137 are produced by
nuclear fission in fuel rods in nuclear power
plants. Radiocesium can be recovered from fission products by
digestion with nitric acid. After filtration to remove the waste, the
radioactive cesium phosphotungstate is precipitated using phosphotungstic acid.
Other processes for the removal of cesium-134 and cesium-137 from radioactive
waste involve solvent extraction using macrocyclic polyethers, or crown ethers
and coprecipitation with sodium tetraphenylboron.
Environmental Fate/Exposure Summary :
Radioactive isotopes of cesium (cesium-134 and cesium-137) have been released to
the environment by human activities such as the atmospheric testing of nuclear
weapons (from 1945 to 1980) and accidents at nuclear power
plants (e.g., at Chernobyl, Ukraine in 1986). There are no
naturally-occurring radioactive forms of cesium. The environmental fate of the
radioactive forms of cesium is expected to be similar to those of the stable
(non-radioactive) form. Current exposure of the general population of the US to
radioactive cesium-134 and cesium-137 is expected to be low since atmospheric
testing of nuclear weapons has been discontinued for many years
and Chernobyl-related fallout was low in the US. However, exposure is possible
from contaminated ground/surface waters at US Dept of Energy (DOE) sites,
resulting from past defense related efforts at these sites. (SRC)
Toxicity Summary :
TOXICITY SUMMARY: The element cesium exists in several forms known as isotopes.
In nature, cesium exists only as a non-radioactive (or stable) isotope known as
cesium-133 (Cs-133); however, there exist several cesium isotopes that are
radioactive. The radioactive isotopes of cesium are formed during nuclear
fission, in commercial applications such as the generation of electricity at nuclear
power plants. The most important cesium
isotopes in terms of their potential effects on human health are cesium-134
(Cs-134) and cesium-137 (Cs-137). In this summary, the most pertinent
information on the radiation toxicity of Cs-134 and Cs-137 are presented. Both
Cs-137 and Cs-134 emit beta radiation and gamma radiation. Beta radiation
travels short distances and can penetrate the skin and superficial body tissues
while gamma radiation can travel great distances and penetrate the entire body.
The radiation dose from these radionuclides can be classified as either external
(if the radiation source is outside the body) or internal (if the radiation
source is inside the body). Beta radiation emitted outside the body is normally
of little health concern unless the radioactive material contacts the skin. Skin
contact can allow the beta radiation to pass through the epidermis to live
dermal tissue where it becomes a major contributor to the radiation dose to the
skin. Beta and gamma radiation may induce tissue damage and disruption of
cellular function. The half-lives of Cs-134 and Cs-137 are approximately 2 years
and 30 years, respectively. Because of the continual emission
of radiation, people could be exposed to radiation from Cs-137 or Cs-134
released to the environment. High levels of Cs-134 and Cs-137 have been released
to the environment from nuclear weapons testing and incidents
such as the 1986 accident at the Chernobyl nuclear reactor in
Ukraine. In these cases, cesium was one of many radionuclides present in the
release. It is, thus, not possible to ascribe any of the observed health effects
to radioactive cesium specifically. There are, however, documented reports of
health effects in humans exposed to radioactive cesium. These reports arise from
the accidental exposure of civilians to Cs-137 sources in Goiania, Brazil, in
1987 and Tammiku, Estonia, in 1994 and from the exposure of military personnel
to Cs-137 during 1996 and 1997 in Lilo, Republic of Georgia. External and
internal exposures of humans to radiocesium have resulted in a spectrum of
adverse health effects that range from nausea to death. In 1987, approximately
250 persons, including children, were exposed externally and internally to
radiation from a scavenged medical source with an activity of 50.9 TBq (1,375 Ci)
137-CsCl. Some of the exposed individuals showed signs of acute radiation
syndrome, such as nausea, vomiting, and diarrhea. A large number of the
individuals with acute radiation syndrome developed bone marrow failure and 4 of
these died. Dermal injuries observed among the exposed individuals ranged from
radiation dermatitis to severe radiation injuries leading to an amputation.
Ocular and reproductive effects were also reported. Two incidents of external
exposure to radiation from Cs-137 have demonstrated that serious adverse effects
may also be expected when individuals are exposed only externally to high levels
of radiation from Cs-137. In 1997 it was discovered that military recruits had
been accidentally exposed to several sealed Cs-137 radioactive sources at a
training facility in Lilo, Republic of Georgia. Nausea, weakness, headaches, and
loss of appetite were the most commonly reported symptoms among the exposed
recruits. Vomiting was reported by three of the patients, two of whom received
the highest estimated doses. The exposures of the recruits occurred over several
months. Although accurate information on the duration of the exposure was not
available, doses were estimated by scoring unstable chromosome aberrations in
peripheral blood lymphocytes and by electron spin resonance dosimetry of teeth
of the exposed individuals. The estimated mean doses ranged from 0.2 to 5.9 Gy
(The radiological event at Lilo. International Atomic Energy Agency (2000).
Vienna). In 1994, several individuals (aged 13 to 78) were exposed to a sealed
Cs-137 source stolen from a waste repository in Tammiku, Estonia. The observed
health effects in the exposed individuals ranged from a relatively mild case of
radiation sickness to death. Solid state dosimetry techniques were applied for
reconstruction of the doses of several individuals exposed in the house where
the stolen Cs-137 source was kept. The estimated whole body radiation doses
ranged from 0.1 Gy to 4 Gy. The individual with the highest estimated whole body
dose also had an estimated localized radiation exposure to the thigh of 1,830 Gy.
The latter individual died 12 days after the initial exposure event. The
survivors showed dermal effects and effects in blood. A 13-year old male was the
most exposed among the survivors (estimated whole-body dose of 1.5-5.5 Gy). He
suffered severe and prolonged bone marrow aplasia and radiation burns. (The
Radiological Accident in Tammiku (1998). The International Atomic Energy Agency,
Vienna. 4 November 1998). (SRC)
Artificial Pollution Sources :
The radioactive isotopes of cesium are formed during nuclear
fission, in commercial applications such as the generation of electricity at nuclear
power plants. The most abundant radioisotopes
that are formed in this manner are cesium-137 and cesium-134(1).
Environmental Bioconcentration :
Daphnids (250 individuals/L) placed in 0.45 um filtered river water (Vienne
River, France; downstream from Civaux nuclear power
plant) with a cesium-137 concentration of 6X10-2 ug/L (7X10+4
Bq/L) had an observed steady state concentration factor of 30 mL/g (wet weight)
cesium-137(1). During the depuration phase, the half-life of cesium-137 from
daphnids was very fast, 0.3 days, indicating that radionuclide absorption to the
surface was the major process involved in the contamination of daphnids(1).
Environmental Water Concentrations :
GROUNDWATER: The concn of cesium-137 and cesium-134 in groundwater at 18 DOE
facilities was reported in the range of 2.7X10-3 to 1.83X10+3 pCi/L(1). The
concn of cesium-137 measured in groundwater wells at Carlsbad, NM (the site of
project GNOME) ranged from 99 to 6.8X10+5 pCi/L in 1997(2). The concn of
cesium-137 in groundwater at the Chernobyl nuclear power
plant was in the range of 40.5 to 1,100 pCi/L in 1988 and 29.7
to 129.7 pCi/L in 1989(3).
Environmental Water Concentrations :
SURFACE WATER: High and low level radioactive wastes have been dumped by the
former Soviet Union into remote Arctic waters, leading to the release of
radioactive cesium into the Kara and Barents Seas(1). The level of cesium-137 in
the surface water of the Barents Sea and Kara Sea was 0.14 and 0.16 pCi/L,
respectively(1). Cesium-137 was also detected in deep water of the Barents Sea a
concn of 0.15 pCi/L(1). The concn of cesium-137 in the Black Sea was in the
range of 2.7 to 8.1 pCi/L for the period 1991-1996, with the exception of the
spring of 1992, when concns as high as 43 pCi/L were observed(2). From 1988 to
1991, the mean concns of cesium-137 and cesium-134 along the Spanish coast of
the Mediterranean Sea were 0.13 and 0.0072 pCi/L, respectively(3). Due to its
shorter half-life, cesium-134 was detected in all 14 samples collected in 1988
and 1989, but only in 3 samples collected in 1990 and 1991, suggesting that the
cesium-134 levels observed in the surface Mediterranean waters were due
exclusively to Chernobyl-related deposition. The 137Cs concn incorporated into
the Mediterranean Sea near the Spanish coast from the post-Chernobyl fallout was
about 0.032 pCi/L, which was approx a 33% increase over previous levels(3). Max
cesium-137 and cesium-134 levels in the immediate vicinity of nuclear
power plants located on the southern Catalan
shore of the Mediterranean were 0.57 and 0.059 pCi/L, respectively(3). The concn
of cesium-137 in lakes and streams in Devoke, UK decreased exponentially from a
max concn of about 8.1 pCi/L on May 6, 1986 to about 0.027 pCi/L, 1,200 days
later(4). The mean concn of cesium-137 in six lakes located in central Finland
ranged from 111 pCi/L in 1987 to 8.1 pCi/L in 1989(5).
Atmospheric Concentrations :
URBAN/SUBURBAN: Radioactive cesium-134 and cesium-137 were detected at various
concns in the atmosphere following the accident at the Chernobyl nuclear
power plant on April 26, 1986(1). The avg
concns of cesium-134 and cesium-137 in eastern Canada were reported as 0.024 and
0.046 pCi/cu m, respectively, during May 10-24, 1986 (2). The max atmospheric
concn of cesium-137 measured in New York City in May 1986 was 0.26 pCi/cu m (3).
In 1975, the max concn of cesium-137 in the atmosphere, in Poland, was 1.89 pCi/cu
m (4). The concn of cesium-137 in the atmosphere of Thessaloniki, Greece ranged
from 8.1X10-4 to 0.044 pCi/cu m from July 1987 to Dec 1988(5). The concn of
cesium-137 in Tsukuba, Japan during May 1986 ranged from about 0.054 to 1.6 pCi/cu
m(6).
Disposal Methods :
Low-level radioactive waste (LLW) is a general term for a wide range of wastes.
Industries, hospitals and medical, educational, or research institutions;
private or government laboratories; and nuclear fuel cycle
facilities (e.g., nuclear power reactors and
fuel fabrication plants) using radioactive materials generate
low-level wastes as part of their normal operations. These wastes are generated
in many physical and chemical forms and levels of contamination.
General Manufacturing Information :
The materials cycle for cesium-137, a low-level radioactive material of interest
from a security perspective ... as well as for its extensive industrial and
medical uses, has been characterized for the United States for the year 2000.
The focus is on products utilizing the isotope rather than on isotope production
and subsequent disposal as a result of nuclear power
generation. The results indicate that, during 2000, of the 1.5 PBq of cesium-137
that entered use, 94% was contained in sources in imported devices; the amounts
in domestic source material recycling (4%) or as imported source materials (2%)
were trivial by comparison. Losses from use were about 0.5 PBq; of this amount
86% was by radioactive decay, 11% was active source material that was recovered
and recycled, and 3% was source material sent to low-level disposal sites. The
current stock of cesium-137 in use is about 20 PBq; this stock is currently
growing by more than 1 PBq per year (the difference between inputs to and losses
from use).
Prior History of Accidents :
/Windscale, United Kingdom Radiation Incident/ In October 1957, the first
substantially publicized release of radioactive material from a nuclear
reactor accident occurred at the Windscale nuclear weapons plant
at Sellafield in the United Kingdom. During a routine release of stored energy
from the graphite core of a carbon dioxide-cooled, graphite-moderated reactor,
operator error allowed the fuel to overheat. This led to uranium oxidation and a
subsequent graphite fire. Attempts to extinguish the fire with carbon dioxide
were ineffective. In the end, water was applied directly to the fuel channels
but not before the fire had burned for 3 days, resulting in the release of
iodine-131 (740 terrabecquerel; 20 kCi), cesium-137 (22 terrabecquerel; 0.6 kCi),
polonium-210 (8.8 terrabecquerel; 0.2 kCi), ruthenium-106 (3 terrabecquerel;
0.08 kCi), and xenon-133 (1.2 petabecquerel; 32.4 kCi). The fire consumed much
of the uranium fuel, and some of the resulting fallout was in the form of
flake-like uranium oxide varying in size from 1 to 25 cm. The contamination of
pastureland was widespread; for those in close proximity to the accident, the
greatest threat of exposure was considered to be from iodine-131 via
contaminated cow's milk. Those living farther from the accident were exposed to
significant amounts of iodine-131 via milk consumption and air inhalation. The
consumption of cow's milk was quickly banned; this lessened the exposure to
iodine-131. The highest individual doses (approximately 100 milligray) were to
the thyroids of children living near the accident site. The collective dose
equivalent received in the United Kingdom and the rest of Europe was estimated
to be 2,000 man-sieverts, of which 900 man-sieverts was from inhalation, 800
man-sieverts was from ingestion, and 300 man-sieverts was from external
exposure. The main radionuclides contributing to the exposures were iodine-131
(37%), polonium-210 (37%), and cesium-137 (15%). There has been no detected
impact on the health of the public from this accident.
Ecotoxicity Excerpts :
/BIRDS and MAMMALS/ Liver and muscle tissue from dead seals and porpoises found
stranded around the UK coast have been analysed for the following radionuclides:
cesium-134, cesium-137, plutonium-238, plutonium 239+240. Multifactor analysis
of variance indicated that, for radiocesium, there was no significant difference
for harbour seals, grey seals or porpoises in terms of species or gender;
however, the tissue activity concentration increased with body weight and
decreased with distance from Sellafield, the major nuclear
reprocessing plant in the UK. The levels of radiocesium in
muscle were higher than those in liver, while there appeared to be a
concentration factor of approximately 3-4 for muscle radiocesium when compared
to radiocesium levels reported for fish, the main food source of the marine
mammals under study. Approximate radiation dose calculations indicated that the
average dose from radiocesium was less than 10% of the dose from the naturally
occurring radioisotope of potassium, 40-K. ...The marine mammals concentrated
radiocesium from their environment by a factor of 300 relative to the
concentration in seawater indicating the value of using marine mammal tissue to
measure radiocesium contamination in the marine environment. The maximum
radiation dose to the marine mammals from radiocesium was higher than doses
previously assessed for critical groups of humans living near Sellafield, while
the maximum dose from plutonium was comparable to the doses for humans.
/Cesium-134, cesium-137, plutonium-238, -239+240/
Plant Concentrations :
Lichens and mosses have been shown to trap and retain cesium-137 and cesium-134
more so than vascular plants, due to their relatively large
surface area. Lichens and mosses from northern Greece contained cesium-137
levels of 6.6X10+4 to 5.1X10+5 pCi/kg during the period of 1989-1991(1) and moss
samples from Finland collected in 1988-1989 contained 4.3X10+4 to 9.7X10+5 pCi/kg(2).
The mean concn of cesium-137 in three species of lichens collected in August
1986 from Megalopolis, Greece were 2.6X10+4 to 3.3X10+4 pCi/kg, while the mean
concns for the same three species of lichens collected in October 1996 had
fallen to 3,324 to 7,892 pCi/kg(3). Mushrooms, lichens, and mosses obtained near
Manitoba, Canada in August 1986 contained cesium-137 at mean concns of 6.4X10+5,
8.6X10+4, and 8.4X10+4 pCi/kg, respectively(4). Vegetation samples collected in
1994 and 1995 from the industrial area and residential area of a plant
for the utilization and repair of nuclear-powered submarines in
the coastal area of Cut Bay in Olenjya Bay in the Kolsky Gulf, Russia contained
cesium-137 concentrations of 10 to 210 Bq/kg of air dry sample and 20 to 530 Bq/kg
of air dry sample, respectively(5). Seaweeds collected from the water area of
Cut Bay had a cesium-137 concentrations of 0.1 to 1.1 Bq/kg of moist sample(5).
Soil Adsorption/Mobility :
The vertical migration patterns of cesium-137 produced from the atomic bomb that
exploded in Nagasaki, Japan were studied over a 40-year period(1). Over this
period, 95% of the cesium remained in the top 10 cm of the soil surface and no
cesium was detected below a depth of 40 cm(1). The migration rate of cesim-137
was 0.10 cm/yr(1). Cesium-137 had the largest median distribution coefficient (Kd)
of five radionuclides (manganese-54, cobalt-60, zinc-65, strontium-85, and
cesium-137), and a positive correlation was observed between the adsorption
coefficient and exchangeable potassium content in soil(2). In all 25 soil and
sediment samples collected from a variety of contrasting locations in the Esk
estuary on the Cumbrian coast in the United Kingdom (10 km south of the British Nuclear
Fuels Ltd plant at Sellafield) in May 1990, >50% of
cesium-137 appeared to be firmly bound within a residual phase(3). Four sediment
samples (cesium-137 concentrations ranging from 1470 to 5680 kBq/kg)collected
from Reservoir 10 in the Techa river near the Mayak Production Association in
the Urals mountains were tested to determine the remobilization of cesium-137
using freshwater and seawater extractions(4). The total apparent distribution
coefficient (Kd) values of cesium-137 in the four samples in a
sediment-freshwater system ranged from 4,100 to 156,000 ml/g. In the seawater
sediment system, the mean apparent Kd values decreased by 94% and remobilization
in seawater was 5% of total activities (i.e. releases of 165 kBq/kg dry weight)
for cesium-137(4).
Environmental Water Concentrations :
SEAWATER: Seawater samples collected in 1994 and 1995 from the Cut Bay water
area surrounding a plant for the utilization and repair of nuclear-powered
submarines in Olenjya Bay in the Kolsky Gulf, Russia contained a cesium-137
concentration of 0.04 Bq/l(1). Cesium-137 concentrations in large volume water
samples collected from the Catalan Sea in the Northwestern Mediterranean in 1991
at depths of 2-3 m (surface), 100 m, 500 m, and 1000 m were 4.4, 4.1, 3.2, and
1.80 Bq/cu m, respectively(2).
Food Survey Values :
Levels of cesium-137 were below detection limits for all foods analyzed in the
US FDA Total Diet Study in 1991-1996, with the exception of honey(1). The concn
of cesium-137 in honey from the 1995 Market Basket Survey was 181.1 pCi/kg. The
avg concn of total cesium-137 and cesium-134 in milk powder, infant milk powder,
infant cereal, meat, lentil, wheat, and macaroni samples from Saudi Arabia were
514, 351, 486, 162, 270, 676, and 351 pCi/kg, respectively(2). For the month of
June 1986, the avg concn of total cesium-137 and cesium-134 in milk, green
vegetables, fruit, lamb, and beef were reported as 3,243, 2,703, 2,703, 8,108,
and 1,622 pCi/kg in high deposition areas of the United Kingdom(3). It was also
estimated that the concn of total cesium-137 and cesium-134 was <676 pCi/kg
in each of these food sources in areas of low deposition during this time frame.
The max concn of cesium-137 in pasteurized milk from 65 cities in the US was 14
pCi/L in May 1989(4). The concn of cesium-137 in fresh milk from Chester, NY and
pasteurized milk samples from New York City in May 1986 ranged from about 5.4 to
18.9 pCi/L(5). Using radiological surveys from 1978 and 1985-1986, the concn of
cesium-137 in 44 adult food groups from the Rongelap Island and Rongelap Atoll
was in the range of 0.52-13,000 pCi/kg(6). The mean activity concentrations of
cesium-137 detected in the edible portion of 34 crabs and 37 lobsters caught
commercially in the Sellafield coastal area offshore from the Sellafield nuclear
fuel reprocessing plant in the northeast Irish Sea between May
25 and June 5, 1997 were 3.1 and 5.0 Bq/kg (wet), respectively(7).
Prior History of Accidents :
The Chelyabinsk region of the southern Ural Mountains was one of the main
military production centers of the former USSR and included the Mayak nuclear
materials production complex in the closed city of Ozersk. Accidents, nuclear
waste disposal and day-to-day operation of the Mayak reactor and radiochemical plant
contaminated the nearby Techa River. The period of most releases of radioactive
material was 1949-56, with a peak in 1950-51. During the first years of the
releases, 39 settlements were located along the banks of the Techa River, and
the total population was about 28,000. Technical flaws and lack of expertise in
radioactive waste management led to contamination of vast areas, and the
population was not informed about the releases. The protective measures that
were implemented (evacuations, restrictions on the use of flood lands and river
water in agricultural production and for domestic purposes) proved to be
ineffective, since they were implemented too late. Approximately 7,500 people
were evacuated from villages near the River between 1953 and 1960. ... During
1949-56, 7.6x10+7 cubic meters of liquid wastes with a total radioactivity of
100 PBq were released into the Techa-Isset-Tobol river system. ... Large
populations were exposed over long periods to external gamma radiation, due
largely to cesium-137 but also to other gamma-emitting radionuclides such as
zirconium-95, niobium-95 and ruthenium-106 present in the water and on the banks
of the Techa River. The internal radiation dose was from ingestion of
strontium-90 and cesium-137 over long periods... . Systematic follow up of a
cohort of almost 30,000 individuals who received significant exposure from the
releases was begun in 1967. ... The preliminary results of follow-up from 1950
through 1989, which were analyzed in linear dose-response models for excess
relative risk, indicate an increased rate of mortality from leukemia and solid
tumors related to internal and external doses of ionizing radiation.
Other Chemical/Physical Properties :
There are several radioactive isotopes of cesium ranging from cesium-114 to
cesium-145. The radioactive isotopes have a wide range of half-lives ranging
from about 0.57 seconds (cesium-114) to about 3X10+6 years (cesium-135). The
radioactive isotopes cesium-137 and cesium-134 are significant fission products
because of their high fission yield, their long half-lives, and their
biochemical similarity to potassium. The fission yield of cesium-137 in nuclear
reactions is relatively high, about 6 atoms of cesium-137 are produced per 100
fission events. Cesium-137 has a radioactive half-life of about 30 years and
decays by beta decay either to stable barium-137 or a meta-stable form of barium
(barium-137m). The metastable isotope (barium-137m) is rapidly converted to
stable barium-137 (half-life of about 2 minutes) accompanied by gamma ray emission
whose energy is 0.662 MeV. The first beta decay mode that forms barium-137m
accounts for roughly 95% of the total intensity, while the second mode accounts
for about 5%. Radioactive cesium-134 primarily decays to stable barium-134 by
beta decay accompanied by gamma ray emissions or less
frequently to stable xenon-134 by electron capture (EC) accompanied by a single
gamma ray emission. The energy of the various gamma rays are in
the range of 0.24-1.4 MeV.
Other Chemical/Physical Properties :
DECAY PATHWAY: Cesium-137, half-life 30.07 years, 5.6% decays via beta(-) emission
(5.6%, 1176 keV maximum, 416.3 keV average energy) to barium-137, half-life
stable; 94.4% decays via beta(-) emission (514 keV maximum, 174
keV average energy) to barium-137m, half-life 2.55 min, decays via isomeric
transition (gamma emission, 661.6 keV) to barium-137, half-life
stable
Radiation Limits & Potential :
DECAY PATHWAY: Cesium-137, half-life 30.07 years, 5.6% decays via beta(-) emission
(5.6%, 1176 keV maximum, 416.3 keV average energy) to barium-137, half-life
stable; 94.4% decays via beta(-) emission (514 keV maximum, 174
keV average energy) to barium-137m, half-life 2.55 min, decays via isomeric
transition (gamma emission, 661.6 keV) to barium-137, half-life
stable
Other Chemical/Physical Properties :
DECAY PATHWAY: Cesium-134, half-life 2.065 years, decays via beta(-) emission
(27% ,88.6 keV maximum, 23.1 keV average energy; 70% ,668 keV maximum, 210 keV
average energy) and gamma emission (abs intensities: 97.6% 605
keV; 85.5% 796 keV; 15.4% 569 keV) to barium-134, half-life stable
Radiation Limits & Potential :
DECAY PATHWAY: Cesium-134, half-life 2.065 years, decays via beta(-) emission
(27% ,88.6 keV maximum, 23.1 keV average energy; 70% ,668 keV maximum, 210 keV
average energy) and gamma emission (abs intensities: 97.6% 605
keV; 85.5% 796 keV; 15.4% 569 keV) to barium-134, half-life stable
Atmospheric Standards :
The following values may be used for determining if facilities are in compliance
with the national emission standards for hazardous air
pollutants for Cs-134 and Cs-137 in the gaseous form: 5.2X-05 and 2.3X-05 Ci/yr;
in the liquid/powder form: 5.2X-02 and 2.3X-02 Ci/yr; and in the solid form:
5.2X+01 and 2.3X+01 Ci/yr, respectively. Radionuclides with a boiling point at
100 deg C or less, or exposed to a temperature of 100 deg C, must be considered
a gas. Capsules containing radionuclides in liquid or powder form can be
considered to be solids. Concentration levels for environmental compliance
include dose levels to members of the general public from emissions
of radionuclides to the atmosphere for Cs-134 and Cs-137 are 2.7X-14 and 1.9X-14
Ci/cu m, respectively(1).
Soil Adsorption/Mobility :
In soil, cesium has low mobility and usually does not migrate below a depth of
40 cm. The majority of cesium ions are retained in the upper 20 cm of the soil
surface(1-3). For example, vertical migration patterns of cesium-137 in four
agricultural soils from southern Chile indicated that approx 90% of the applied
cesium was retained in the top 40 cm of soil(4). In one soil, essentially 100%
was bound in the upper 10 cm(4). Migration rates of radiocesium were derived
from depth distribution profiles and were in the range of 0.11 to 0.29 cm/yr(4).
No correlations were observed for other soil properties such as pH, water
content, cation exchange capacity, and exchangeable calcium. Other studies
report that clay and zeolite minerals strongly bind cesium cations and therefore
reduce the bioavailability of cesium and the uptake in plants
by irreversibly binding cesium in interlayer positions of the clay particles(5).
Experiments conducted by growing plants in a peat soil showed
that the introduction of zeolites into the soil-plant system
decreased the uptake of cesium-134 in plants by a factor of
eight(6). The low hydration energy of cesium cations is primarily responsible
for their selective sorption and fixation by clays and zeolites(7). Soils rich
in organic matter adsorb cesium(8). However, the cesium adsorbed in the organic
fraction is readily exchangeable and highly available for plant
uptake(8). Regions in Venezuela, Brazil, and Russia where the soils are peaty or
podzolic, the mobility of cesium is considerably greater than in other
soils(9,10).
Ecotoxicity Excerpts :
/BIRDS AND MAMMALS/ Transfer of cesium-137 in the soil-plant/lichen-reindeer
food chain was studied in central (Ostre Namdal) and southern Norway (Vaga)
during 2000-2003. Reindeer from these areas have been continuously subjected to
countermeasure application since the 1986 Chernobyl accident. In both areas no
decline in cesium-137concentrations was detectable in reindeer slaughtered in
autumn since 1995, or in reindeer slaughtered in winter since 1998-1999.
Seasonal differences in cesium-137 concentrations in reindeer have been less
pronounced in recent years, with cesium-137 concentrations occasionally higher
in autumn than in winter. Soil-to-plant cesium-137 transfer was
significantly higher in Ostre Namdal than in Vaga. Climatic influences on lichen
growth and abundance, and on soil properties that influence the availability of
cesium-137 for plant uptake, are hypothesized to have a larger
impact on long-term transfer of radiocesium in the soil-plant/lichen-reindeer
food chain than has been previously observed. /Cesium-137
Other Chemical/Physical Properties :
DECAY PATHWAY: Cesium-131, half-life 9.69 days, decays via electron capture (352
keV) to xenon-131, half-life stable; 1.95% decays via electron capture to
xenon-131m which decays via isomeric transition (16.4 keV, gamma emission)
to xenon-131
Radiation Limits & Potential :
DECAY PATHWAY: Cesium-131, half-life 9.69 days, decays via electron capture (352
keV) to xenon-131, half-life stable; 1.95% decays via electron capture to
xenon-131m which decays via isomeric transition (16.4 keV, gamma emission)
to xenon-131
Prior History of Accidents :
/Chernobyl Radiation Incident/ The accident at the Chernobyl reactor happened
during an experimental test of the electrical control system as the reactor was
being shut down for routine maintenance. The operators, in violation of safety
regulations, had switched off important control systems and allowed the reactor
to reach unstable, low-power conditions. A sudden power
surge caused a steam explosion that ruptured the reactor vessel, allowing
further violent fuel-steam interactions that destroyed the reactor core and
severely damaged the reactor building. The radioactive gases and particles
released in the accident were initially carried by the wind in westerly and
northerly directions. On subsequent days, the winds came from all directions.
The deposition of radionuclides was governed primarily by precipitation
occurring during the passage of the radioactive cloud, leading to a complex and
variable exposure pattern throughout the affected region. The radionuclides
released from the reactor that caused exposure of individual were mainly
iodine-131, cesium-134 and cesium-137. Iodine-131 has a short radioactive
half-life, but it can be transferred to humans relatively rapidly from the air
and through milk and leafy vegetables. Iodine becomes localized in the thyroid
gland. The isotopes of cesium have relatively longer half-lives. These
radionuclides cause longer-term exposures through the ingestion pathway and
through external exposure from their deposition on the ground. Average doses to
those persons most affected by the accident were about 100 mSv for 240,000
recovery operation workers, 30 mSv for 116,000 evacuated persons and 10 mSv
during the first decade after the accident to those who continued to reside in
contaminated areas. Outside Belarus, the Russian Federation and Ukraine, other
European countries were affected by the accident. Doses there were at most 1 mSv
in the first year after the accident with the dose over a lifetime estimated to
be 2-5 times the first year doses. The exposures were much higher for those
involved in mitigating the effects of the accident and those who resided nearby.
The Chernobyl accident caused many severe radiation effects almost immediately.
Of 600 workers present on the site, 134 suffered from radiation sickness. Of
these, 28 died in the first three months and another 2 soon afterwards. In
addition, during 1986 and 1987, about 200,000 recovery operation workers
received doses of between 0.01 Gy and 0.5 Gy. That cohort is at potential risk
of late consequences such as cancer and other diseases. The Chernobyl accident
also resulted in widespread radioactive contamination in areas of Belarus, the
Russian Federation and Ukraine inhabited by several million people. In addition
to causing radiation exposure, the accident caused long-term changes in the
lives of the people living in the contaminated districts. For the last 14 years,
attention has been focused on investigating the association between exposure
caused by the radionuclides released in the Chernobyl accident and late effects,
in particular thyroid cancer in children. The number of thyroid cancers (about
1,800) in individuals exposed in childhood is considerably greater than expected
based on previous knowledge. Apart from the increase in thyroid cancer after
childhood exposure, no increases in overall cancer incidence or mortality have
been observed that could be attributed to ionizing radiation.
Ecotoxicity Excerpts :
/PLANTS/ The present study was designed to compare the
effectiveness of three plant bioassays to assess DNA damage
induced by low doses of cesium-137: Vicia-micronucleus test (Vicia-MCN),
Tradescantia-micronucleus test (Trad-MCN) and Tradescantia-stamen-hair mutation
test (Trad-SH) were used. Vicia faba (broad bean) and Tradescantia clone 4430
(spiderwort) were exposed to cesium-137 according to different scenarios:
external and internal (contamination) irradiations. Experiments were conducted
with various levels of radioactivity in solution or in soil, using solid or
liquid cesium-137 sources. The three bioassays showed different sensitivities to
the treatments. Trad-MCN appeared to be the most sensitive test (significant
response from 1.5 kBq/200 mL after 30 hr of contamination). Moreover, at
comparable doses, internal irradiations led to larger effects for the three
bioassays. These bioassays are effective tests for assessing the genotoxic
effects of radioactive cesium-137 pollution. /Cesium-137/
Biological Half-Life :
Biological half-lives for radiocesium in specific organisms/environments were
reported as follows: moss, 4-5 years; lichen, 5-8 years; grass, 14 days; plant
surface, 14 days; hen, 1-5 days; cow, 3 days; fish, 70-300 days; child, 57 days;
woman, 84 days; and man, 105 days. /Radiocesium/
General Manufacturing Information :
Cesium isotopes of mass number 112 to 148 have been identified. Cesium-133 is
the only stable isotope. Cesium-134, 136Cs and 137Cs are the only isotopes of
significance from an environmental perspective. They are formed from the nuclear
fission process. Their half-lives are 2.06 years, 13.2 days, and 30.17 years,
respectively. Cesium-135 also is formed as a result of the fission process.
However, it is not a significant isotope, because it is a low-energy (0.21 MeV)
beta-only emitter with a long half-life (2.2ױ06 years). /Cesium isotopes/
General Manufacturing Information :
Cesium-137 is produced in nuclear fission and occurs in
atmospheric debris from weapons tests and accidents. It is a very important
component of radioactive fallout; and because of its moderately long half-life
and high solubility, it is a major source of long-lived external gamma radiation
from fallout. It accounts for 30 percent of the gamma activity of fission
products stored for one year, 70 percent in two years, and 100 percent after
five years.
Disposal Methods :
Nuclear Regulatory Commission regulations separate low-level
waste into three classes: A, B and C. The classification of the waste depends on
the concentration, half-life and types of the various radionuclides it contains.
The NRC sets requirements for packaging and disposal of each class of waste.
Class A low-level waste contains radionuclides with the lowest concentrations
and the shortest half-lives. About 95% of all low-level waste is categorized as
Class A.
Disposal Methods :
Low-level waste disposal occurs at commercially operated low-level waste
disposal facilities that must be licensed by either the Nuclear
Regulatory Commission or Agreement States. The facilities must be designed,
constructed, and operated to meet safety standards. The operator of the facility
must also extensively characterize the site on which the facility is located and
analyze how the facility will perform for thousands of years into the future.
There are three existing low-level waste disposal facilities in the United
States /Barnwell, SC, Richland, WA, Envirocare in Utah/ that accept... low-level
waste. All are in Agreement States. The Low-level Radioactive Waste Policy
Amendments Act of 1985 gave the states responsibility for the disposal of their
low-level radioactive waste. The Act encouraged the states to enter into
compacts that would allow them to dispose of waste at a common disposal
facility. Most states have entered into compacts; however, no new disposal
facilities have been built since the Act was passed.
Human Toxicity Excerpts :
/EPIDEMIOLOGY STUDIES/ More than 25,000 residents were exposed to external gamma
radiation as well as internally from fission products (primarily from
cesium-137, strontium-90, ruthenium-106, and zirconium-95) released into the
Techa river from the nearby Mayak plutonium production facility, predominately
in the early 1950s. Studies have been conducted of cancer mortality in residents
and their offspring, as well as pregnancy outcomes. Initial dose estimates were
based on average doses reconstructed for settlements. Efforts are ongoing to
estimate individual doses for members of this resident cohort. To date, there is
no evidence of a decrease in birth rate or fertility in the exposed population
and no increased incidence of spontaneous abortions or stillbirths. There is
some evidence of a statistically significant increase in total cancer mortality.
Current estimates of the excess absolute risk (EAR) of leukemia in this cohort
is 0.85 per 10,000 person-year Gy (95% confidence interval 0.2, 1.5), and for
solid tumors the relative risk estimate is 0.65 per Gy (95% confidence interval
-0.3, 1.0). Median dose estimates for soft tissue in this cohort are 7 mSv
(maximum 456 mSv), and for bone marrow are 253 mSv (maximum 2021 mSv). Estimates
of the relative risk for cancer of the esophagus, stomach and lung are similar
to those reported for atomic bomb survivors. There is no evidence of an increase
in cancer mortality in the offspring of exposed residents. There has also been
one study of persons living in the town of Ozyorsk exposed to fallout from the
nearby Mayak nuclear facility. An excess of thyroid cancer 3-4
times expected relative to rates for all of Russia has been observed. The excess
is somewhat lower (1.5-2-fold higher) based on a comparison with Chelyabinsk
Oblast rates. No estimates of radiation dose were included in this study.
/Cesium-137, strontium-90, ruthenium-106, and zirconium-95 contamination/
Human Toxicity Excerpts :
/BIOMONITORING/ /GENOTOXICITY/ The results of... three post-Chernobyl studies
(two in Belarus and one in Ukraine) and for the one conducted on the populations
in the vicinity of the nuclear test site in Semipalatinsk
(Kazakhstan) provide evidence that mutations at minisatellite loci can be
induced by radiation in human germ cells. The dose-response relationships,
however, remain uncertain because of considerable difficulties in the estimation
of parental gonadal doses. For example, in the first Belarus study the level of
surface contamination by cesium-137 was used as a broad dose measure, and the
children of parents inhabiting heavily contaminate areas (>250 kBq/sq m) were
found to have twice the frequency of mutations compared to those of parents from
less contaminated areas (<250 kBq/sq m). In the second Belarus study (with
more exposed families and more loci sampled), based on estimates of individual
doses, two groups were defined <20 mSv and >20 mSv. The mutation frequency
in the children from the latter group was 1.35 times that in the former and that
from both groups was about 2-fold higher than in the unexposed U.K. controls. In
the Ukraine study, a 1.6-fold increase in mutation rate in the exposed fathers
but not in exposed mothers (both relative to unexposed controls) was found, but
again, the dose-response relationship is uncertain. The authors noted that the
dose from external chronic irradiation and internal exposures together were of
the order of approx. 100 mSv (excluding short-lived isotopes). In the
Semipalatinsk study, again, there was a 1.8-fold increase in the first
generation progeny of parents receiving relatively high doses of radiation
(cited as >1.0 Sv, but could have been lower or higher). In this study,
through the use of three-generation families, the authors obtained evidence for
a decline in mutation frequency as population doses decreased. /Cesium-137
fallout/
Absorption, Distribution & Excretion :
Placental transfer: The concentrations of cesium-137 arising from exposure to
fall-out from nuclear weapons were measured in nine newborn
children within three days of birth and in their mothers. The concentrations
were similar. After an accident in Brazil in which a woman in her fourth month
of pregnancy was contaminated with cesium-137, both the mother and her newborn
child were monitored one week after birth. The concentration of cesium-137 in
the mother (0.91 kBq/kg bw) was similar to that in her newborn child (0.97 kBq/kg
bw), and the concentration in the placenta was the same as that in the whole
maternal body and the fetus./Cesium-137/
Biological Half-Life :
After the Chernobyl accident, increased cesium-137 body burdens were measured
for 22 Japanese male adults. An average biological half-time of 101 days was
estimated. In the 1960s, an average Cs biological half-time of 86 days was
reported for 23 Japanese male adults under quasi-equilibrium conditions in
regard to cesium-137 from atmospheric nuclear weapon tests.
Comparing the present data with the 1960s results, the difference in the
biological half-time of cesium at a confidence level of 90% was not significant
but had an increasing tendency. When the two groups of data were combined, the
biological half-time for cesium was 9327 days for the 45 individuals. Thus, the
reference biological half-time should be 90 days for Japanese male adults. Four
subjects were studied in both the 1960s and the 1980s. A clear relationship was
observed between the increase in half-time and increase in age. /Cesium-137/
Plant Concentrations :
Eight species of mushrooms collected in 1993 from the area around the Nuclear
Center of Mexico (average cesium-137 soil concentration of 1.112 kBq/sq m) were
determined to have the following cesium-137 activities (Bq/kg dry weight) and
Aggregated Transfer Coefficients (sq m/kg): Agaricus campestre, 2 and 0.002;
Clitocybe gibba, 14 and 0.018; Lactarius salmonicolor, 9 and 0.029; Psathyrella
spadicea, 16 and 0.12; Russula delicata, 11 and 0.011; Clavariadelphus truncatus,
12 and 1; Gomphus flocosus, 16 and 0.28; and Helvella lacunosa, 7 and 0.016(1).
Animal Concentrations :
In 1986, the concn of cesium-134 in animal muscle tissues taken from Ireland was
as follows: woodcock (N=24; range, 3.9-206.4 Bq/kg), duck (N=5; range, 2.2-14.3
Bq/kg), and snipe (N=5; range, 1.0-5.4 Bq/kg); the concn of cesium-137 was as
follows: woodcock (N=24; range, 6.2-565.5 Bq/kg), duck (N=5; range, 6.4-18.0 Bq/kg),
and snipe (N=5; range, 3.6-16.9 Bq/kg)(1). The mean concn of cesium-137 in the
reindeer muscle tissue was 900 Bq/kg between 1986-1987 in Northern Sweden(2).
Between 1991-1998, the mean concn of cesium-137 in deer muscle and bone (N=11)
from Los Alamos were 2,516 Bq/kg and 888 Bq/kg, respectively(3). The mean concn
of cesium-137 in bone, liver, muscle, and kidney tissue from caribou (N=18)
taken from Saskatchewan in 1995 were 58, 228, 367, and 553 Bq/kg,
respectively(4). The concn of cesium-137 in neck, shoulder, and back tissue from
caribou (N=36) taken from Alaska in 1987 ranged from 26-232, 28.4-204.1, and
30.2-166.5 Bq/kg, respectively(5). Cesium-137 was detected in four of eight
reindeer bone samples collected from before 1989 to 1993 from Archipelago Novaya
Zemlya, Russia, a nuclear testing site, in concentrations of
<0.005, 0.08, 0.08, and 0.09 Bq/g(6).
Probable Routes of Human Exposure :
Exposure to radioactive cesium is more important from a health perspective than
exposure to stable cesium(1). Current exposure of the general US population to
cesium-134 and cesium-137 is expected to be low since atmospheric testing nuclear
weapons has been discontinued for many years and Chernobyl-related fallout was
low in the US(1).
Threshold Limit Values :
The Physical Agents TLV Committee accepts the occupational exposure guidance of
the International Commission on Radiological Protection (ICRP). Ionizing
radiation includes particulate radiation (e.g., alpha particles and beta
particles emitted from radioactive materials, and neutrons from nuclear
reactors and accelerators) and electromagnetic radiation (e.g., gamma rays
emitted from radioactive materials and x-rays from electron accelerators and
x-ray machines) with energy greater than 12.4 electron-volts (eV) ... The
guiding principle of radiation protection is to avoid all unnecessary exposures.
ICRP has established principles of radiological protection. There are (1) the
justification of a work practice: No work practice involving exposure to
ionizing radiation should be adopted unless it produces sufficient benefit to
the exposed individuals or the society to offset the detriment it causes. (2)
The optimization of a workpractice: All radiation exposures must be kept as low
as reasonably achievable (ALARA), economic and social factors being taken into
account. (3) The individual dose limits: The radiation dose from all relevant
sources should not exceed the /ICRP/ prescribed dose limits.
Other Occupational Permissible Levels :
The recommendations in the American National Standards Institute standard, ANSI
Z88.2-1992, "American National Standard For Respiratory Protection,"
are endorsed by the U.S. Nuclear Regulatory Commission and may
be used by licensees in establishing a respiratory protection program with the
/several/exceptions /including limitations that do not permit or greatly
restrict the use of quarter-facepiece respirators and supplied air respirators
and self-contained breathing apparatus (SCBA) that operate in the demand mode./
Soil Standards :
Environmental radiation protection standards for management and disposal of
spent nuclear fuel, high-level, and transuranic radioactive
wastes include release limits for containment requirements (cumulative releases
to the accessible soil environment for 10,000 years after disposal) per 1,000
metric tons of heavy metal or other unit of waste for Cs-137 is 1,000 curies(1).
Special Reports :
U.S. Nuclear Regulatory Commission; Regulatory Guide 8.34 -
Monitoring Criteria and Methods to Calculate Occupational Radiation Doses. 1992/
Available at http://www.nrc.gov/reading-rm/doc-collections/reg-guides/occupational-health/active/8-34/index.html
as of September 25, 2006
Prior History of Accidents :
In 1957, a nuclear waste storage facility in the Chelyabinsk
region, near the town of Kyshtym, exploded (the Kyshtym accident) due to a
chemical reaction, producing contamination referred to as the East Urals
Radiation Trace (EURT). About 273, 000 people lived in the contaminated area.
Ten years later, in 1967, after an exceptionally dry summer, the water of the
Karachay Lake, an open depot of liquid radioactive waste, evaporated, and a
storm transported radionuclides from the dry shores. Eleven thousand individuals
were resettled as a result of the Kyshtym accident, of whom 1,500 had previously
been resettled from the Techa River.
MORE ABOUT HEALTH EFFECTS
CESIUM,
RADIOACTIVE
CASRN: NO CAS RN
Toxicity Summary:
TOXICITY SUMMARY: The element cesium exists in several forms known as isotopes.
In nature, cesium exists only as a non-radioactive (or stable) isotope known as
cesium-133 (Cs-133); however, there exist several cesium isotopes that are
radioactive. The radioactive isotopes of cesium are formed during nuclear
fission, in commercial applications such as the generation of electricity at
nuclear power plants. The most important cesium isotopes in terms of their
potential effects on human health are cesium-134 (Cs-134) and cesium-137
(Cs-137). In this summary, the most pertinent information on the radiation
toxicity of Cs-134 and Cs-137 are presented. Both Cs-137 and Cs-134 emit beta
radiation and gamma radiation. Beta radiation travels short distances and can
penetrate the skin and superficial body tissues while gamma radiation can travel
great distances and penetrate the entire body. The radiation dose from these
radionuclides can be classified as either external (if the radiation source is
outside the body) or internal (if the radiation source is inside the body). Beta
radiation emitted outside the body is normally of little health concern unless
the radioactive material contacts the skin. Skin contact can allow the beta
radiation to pass through the epidermis to live dermal tissue where it becomes a
major contributor to the radiation dose to the skin. Beta and gamma radiation
may induce tissue damage and disruption of cellular function. The half-lives of
Cs-134 and Cs-137 are approximately 2 years and 30 years, respectively. Because
of the continual emission of radiation, people could be exposed to radiation
from Cs-137 or Cs-134 released to the environment. High levels of Cs-134 and
Cs-137 have been released to the environment from nuclear weapons testing and
incidents such as the 1986 accident at the Chernobyl nuclear reactor in Ukraine.
In these cases, cesium was one of many radionuclides present in the release. It
is, thus, not possible to ascribe any of the observed health effects to
radioactive cesium specifically. There are, however, documented reports of
health effects in humans exposed to radioactive cesium. These reports arise from
the accidental exposure of civilians to Cs-137 sources in Goiania, Brazil, in
1987 and Tammiku, Estonia, in 1994 and from the exposure of military personnel
to Cs-137 during 1996 and 1997 in Lilo, Republic of Georgia. External and
internal exposures of humans to radiocesium have resulted in a spectrum of
adverse health effects that range from nausea to death. In 1987, approximately
250 persons, including children, were exposed externally and internally to
radiation from a scavenged medical source with an activity of 50.9 TBq (1,375 Ci)
137-CsCl. Some of the exposed individuals showed signs of acute radiation
syndrome, such as nausea, vomiting, and diarrhea. A large number of the
individuals with acute radiation syndrome developed bone marrow failure and 4 of
these died. Dermal injuries observed among the exposed individuals ranged from
radiation dermatitis to severe radiation injuries leading to an amputation.
Ocular and reproductive effects were also reported. Two incidents of external
exposure to radiation from Cs-137 have demonstrated that serious adverse effects
may also be expected when individuals are exposed only externally to high levels
of radiation from Cs-137. In 1997 it was discovered that military recruits had
been accidentally exposed to several sealed Cs-137 radioactive sources at a
training facility in Lilo, Republic of Georgia. Nausea, weakness, headaches, and
loss of appetite were the most commonly reported symptoms among the exposed
recruits. Vomiting was reported by three of the patients, two of whom received
the highest estimated doses. The exposures of the recruits occurred over several
months. Although accurate information on the duration of the exposure was not
available, doses were estimated by scoring unstable chromosome aberrations in
peripheral blood lymphocytes and by electron spin resonance dosimetry of teeth
of the exposed individuals. The estimated mean doses ranged from 0.2 to 5.9 Gy
(The radiological event at Lilo. International Atomic Energy Agency (2000).
Vienna). In 1994, several individuals (aged 13 to 78) were exposed to a sealed
Cs-137 source stolen from a waste repository in Tammiku, Estonia. The observed
health effects in the exposed individuals ranged from a relatively mild case of
radiation sickness to death. Solid state dosimetry techniques were applied for
reconstruction of the doses of several individuals exposed in the house where
the stolen Cs-137 source was kept. The estimated whole body radiation doses
ranged from 0.1 Gy to 4 Gy. The individual with the highest estimated whole body
dose also had an estimated localized radiation exposure to the thigh of 1,830 Gy.
The latter individual died 12 days after the initial exposure event. The
survivors showed dermal effects and effects in blood. A 13-year old male was the
most exposed among the survivors (estimated whole-body dose of 1.5-5.5 Gy). He
suffered severe and prolonged bone marrow aplasia and radiation burns. (The
Radiological Accident in Tammiku (1998). The International Atomic Energy Agency,
Vienna. 4 November 1998). (SRC)
Evidence for Carcinogenicity:
There is inadequate evidence in humans for the carcinogenicity of cesium-137.
/Cesium/
There is sufficient evidence in experimental animals for the carcinogenicity of
mixed beta-particle emitters (iodine-131, cesium-137, cerium-144 and
radium-228). /Iodine, Cesium, Cerium, Radium/
Evaluation. There is sufficient evidence in humans for the carcinogenicity of
X-radiation and gamma-radiation. There is sufficient evidence in experimental
animals for the carcinogenicity of X-radiation and gamma-radiation. Overall
evaluation. X-radiation and gamma-radiation are carcinogenic to humans (Group
1).
Human Toxicity Excerpts:
/SIGNS AND SYMPTOMS/ /ACUTE RADIATION SYNDROME/ Fifty persons involved in the
cesium-137 accident in Goiania showed symptoms of whole-body and local acute
irradiation and also external or internal contamination mainly due to ingestion
or absorption of cesium-137. Fourteen of the 50 developed severe bone marrow
depression characterized by neutropenia and thrombocytopenia. Eight of these 14
received GM-CSF intravenously. None were submitted to bone marrow
transplantation. Four of the 14 died due to hemorrhage and infection. For those
with significant internal contamination evaluated by in-vitro and in-vivo
assays, Prussian Blue was administered with doses ranging from 1.5 to 10 g/day.
Besides Prussian Blue, other measures were taken to increase decorporation of
cesium-137, including administration of diuretics, water overload, and
ergometric exercises. From 50 to 100 persons are being followed in a medical
protocol. /Cesium-137/
/SIGNS AND SYMPTOMS/ /ACUTE RADIATION SYNDROME/ Approximately 250 individuals
were exposed externally to an open 50.9 TBq (1,375 Ci) 137-cesium chloride
radioactive source in Goiania, Brazil, in 1987. Many of these individuals also
experienced oral and dermal exposure. The estimated absorbed doses ranged from 1
to 7 Gy (100 to 700 rad). The exposed individuals showed signs and symptoms of
acute radiation syndrome including vomiting, diarrhea, and nausea, as well as
skin lesions from radiation burns, orofacial lesions, ocular injury,
hematological effects (bone marrow aplasia, leukopenia, thrombocytopenia,
lymphopenia, neutropenia), mild elevations of some liver enzymes, and reduced
sperm counts. Twenty individuals developed the acute radiation syndrome, 14
(70%) of whom developed bone marrow failure after having received whole-body
radiation doses ranging from 1 to 7.0 Gy (100 to 700 rad). Four (29%) of these
14 individuals died. The adverse effects were the result of beta and gamma
radiation, not cesium per se. /Cesium-137 chloride/
/CASE REPORTS/ /LIVER/ Mild elevations of aminotransferases (ALT/AST) were seen
in a few patients hospitalized following radiation exposure to an opened
cesium-137 chloride radioactive source in Goiania, Brazil, in 1987. /Cesium-137
chloride/
/CASE REPORTS/ /ACUTE RADIATION SYNDROME/ On 13 September 1987, a radiation
accident occurred in the city of Goiania in Central Brazil. Approximately 250
people were exposed to a cesium-137 source from an abandoned radiotherapy unit.
At least 14 patients showed some degree of bone marrow depression, and eight
developed the classical signs and symptoms of acute radiation syndrome (ARS).
Twenty-eight people presented local radiation injuries ranging from first to
third degree, and 104 individuals showed evidence of internal contamination.
This paper describes the circumstances of the event, the first-aid measures
taken, the criteria adopted for triage of the exposed population, and the
radiation protection procedures used during the clinical management of the
irradiated individuals. /Cesium-137/
/CASE REPORTS/ /SKIN/ A case of child abuse involving industrial radiography
sources has been reported ... . A petroleum engineer had possession of at least
a 37GBq (1Ci) cesium-137 source used for oil and gas well logging. The dose rate
at contact for such a source is approximately 5 Gy/min. One of the engineer's
sons was subjected to various occasions in which "shiny silver
pellets" were in the earpieces of headphones that he was told to wear, in a
pillow he was told to use, and in a sock he found on his bed. It was also
assumed that while under sedation, he was exposed at other times of which he was
unaware. He was first seen by a family physician for what appeared to be bruises
and reddish-brown blisters. These were assumed to be infections, but over
succeeding weeks and months, new lesions appeared on the medial aspects of the
thighs, right ankle, right hand, and left side of his forehead. ... Over the
next 6 months, persistent, ulcerating lesions of the right thigh kept the child
out of school. ... A plastic surgeon recognized the lesions as radiation
necrosis. Both testes had been effectively destroyed, and the boy was
functionally castrated. /Cesium-137/
/CASE REPORTS/ /ACUTE RADIATION SYNDROME/ In Tammiku, Estonia, in 1994, a
cesium-137 source (a few terabecquerels) thought to have been part of an
irradiator was disposed of as scrap metal. It was recovered and stored in a
source store with limited security. The store was broken into and the source
removed. Six people, exposed to varying degrees up to 4 Gy whole body, developed
a variety of lesions. One localized exposure was up to 1,800 Gy and the person
died. /Cesium-137/
/CASE REPORTS/ /SKIN/ Eleven frontier guards were exposed to one or more sources
of cesium-137 with activities up to 150 GBq at the Lilo Training Center near
Tbilisi, Georgia. The incident occurred over a period spanning 1996 and 1997.
The sources were intended for training civil defense specialists or for
calibration. Some of the sources had been removed from their containers, either
still fixed in the source holder or separate from it. Information on the
irradiation is incomplete, but it appears that at least one source was kept in
the pocket of a coat. Each of the guards suffered from one or more acute
localized irradiation lesions of varying seriousness; several suffered from
nausea and vomiting. /Cesium-137/
/CASE REPORTS/ /ACUTE RADIATION SYNDROME/ In an accident involving the stealing
and breaching of a radiotherapy source in Goiania, Brazil, 39 individuals had a
high level of cesium-137 internal contamination. Prussian Blue was used, in
doses that varied from 3-10 g/day for adults, to enhance the elimination of
cesium-137 from the body. The total internal committed doses and the effect of
Prussian Blue treatment for 15 contaminated adults involved in this accident
have been evaluated in this paper. Prussian Blue caused dose reductions in the
range of 51-84%, with an average of 71%. This reduction was shown to be
independent of the dosage of Prussian Blue. ...
/CASE REPORTS/ /ACUTE RADIATION SYNDROME/ In September 1987, the Goiania
radiological accident involving a source of cesium-137 culminated in about 140
victims who presented internal and/or external contamination and/or external
exposure to radiation and/or radiation burns. Internal contamination was
verified through analysis of urine and fecal samples. Internal contamination was
also evaluated by measurements performed at the whole-body counter installed in
Goiania in November 1987. To enhance the decorporation of cesium-137, patients
were treated with the following: 1) Prussian Blue, oral administration, in 46
patients; 2) diuretics, oral administration, in 17 patients; 3) induced
perspiration, increasing cesium-137 elimination. These procedures were done
under rigorous clinical evaluation and considering the data from assay of
excreta and data obtained from the whole-body counter. The doses of Prussian
Blue exceeded about 6.5 times the dose previously indicated in the literature.
It was the first time diuretics were used in humans to treat cesium-137 internal
contamination. The results of these procedures are discussed. /Cesium-137/
/CASE REPORTS/ /REPRODUCTIVE SYSTEM/ Spermatozoa were reduced or absent in the
semen of nine males examined approximately 1 month following presumed acute
radiation doses on the order of several hundred rad from an opened cesium-137
chloride radioactive source in Goiania, Brazil, in 1987. These individuals may
have experienced mixed external, dermal, and oral exposure. /Cesium-137
chloride/
/CASE REPORTS/ /EYE/ Among 20 patients hospitalized following mixed external and
internal exposure to an opened cesium-137 chloride radioactive source in Goiania,
Brazil, in 1987, a few patients complained of lacrimation, hyperemia and edema
of the conjunctiva, and ocular pain. A few cases of protracted reduction in
visual capacity were also reported, among which retinal injury was documented.
In these cases, there was no change in lens transparency. These effects were due
to the radiation, not to cesium per se. /Cesium-137 chloride /
/EPIDEMIOLOGY STUDIES/ More than 25,000 residents were exposed to external gamma
radiation as well as internally from fission products (primarily from
cesium-137, strontium-90, ruthenium-106, and zirconium-95) released into the
Techa river from the nearby Mayak plutonium production facility, predominately
in the early 1950s. Studies have been conducted of cancer mortality in residents
and their offspring, as well as pregnancy outcomes. Initial dose estimates were
based on average doses reconstructed for settlements. Efforts are ongoing to
estimate individual doses for members of this resident cohort. To date, there is
no evidence of a decrease in birth rate or fertility in the exposed population
and no increased incidence of spontaneous abortions or stillbirths. There is
some evidence of a statistically significant increase in total cancer mortality.
Current estimates of the excess absolute risk (EAR) of leukemia in this cohort
is 0.85 per 10,000 person-year Gy (95% confidence interval 0.2, 1.5), and for
solid tumors the relative risk estimate is 0.65 per Gy (95% confidence interval
-0.3, 1.0). Median dose estimates for soft tissue in this cohort are 7 mSv
(maximum 456 mSv), and for bone marrow are 253 mSv (maximum 2021 mSv). Estimates
of the relative risk for cancer of the esophagus, stomach and lung are similar
to those reported for atomic bomb survivors. There is no evidence of an increase
in cancer mortality in the offspring of exposed residents. There has also been
one study of persons living in the town of Ozyorsk exposed to fallout from the
nearby Mayak nuclear facility. An excess of thyroid cancer 3-4 times expected
relative to rates for all of Russia has been observed. The excess is somewhat
lower (1.5-2-fold higher) based on a comparison with Chelyabinsk Oblast rates.
No estimates of radiation dose were included in this study. /Cesium-137,
strontium-90, ruthenium-106, and zirconium-95 contamination/
/EPIDEMIOLOGY STUDIES/ A few studies have investigated adult resident
populations living in highly contaminated areas. ...The incidence of leukemia
and lymphoma in the general population of the Bryansk region of Russia for the
period 1979-1993 /was investigated/ using an ad hoc registry of hematological
diseases established after the Chernobyl accident. The incidence rates in the 6
most contaminated districts (more than 37 kBq/sq m of cesium-137 deposition
density) did not exceed the rates in the rest of the region or in Bryansk city,
where the highest rates were observed. Comparisons of crude incidence rates
before and after the accident (1979-1985 and 1986-1993) showed a significant
increase in the incidence of all leukemia and non-Hodgkin lymphoma, but this was
mainly due to increases in the older age groups in rural areas. The incidence of
childhood leukemia and non-Hodgkin lymphoma was not significantly different in
the 6 most contaminated areas from the incidence in the rest of the region.
Similarly, ... no evidence of an increase in leukemia rates in the most
contaminated areas of the Kaluga district of the Russian Federation /was found/
after the Chernobyl accident. In Ukraine, ...incidence rates for leukemia and
lymphoma in the most highly contaminated areas of the Zhytomir and Kiev
districts /were examined/ before and after the Chernobyl accident. Total
incidence in adults increased from 5.1 per 100,000 during 1980-1985 to 11 per
100,000 person-years during 1992-1996 but there was no excess in contaminated
areas of the regions. Similarly, ...the incidence of leukemia and lymphoma /was
investigated/ in the three most contaminated regions of Ukraine. There was a
steady increase in leukemia and lymphoma rates for both men and women between
1980 and 1993, but there was no evidence of a more pronounced increase after the
accident. /Cesium-137 fallout/
/EPIDEMIOLOGY STUDIES/ ...Reports have focused on changes in childhood leukemia
rates before and after the accident in individual European countries and
elsewhere. Overall, there was little evidence for an increase in rates of
childhood leukemia in Ukraine, Belarus, Russia, Finland, Sweden, Greece, or a
number of other countries from Central, Eastern and Southern Europe after the
Chernobyl accident. Furthermore, there was no association between the extent of
contamination /(primarily cesium-137)/ and the increase in risk in these
countries. However, one Swedish study, reported a nonstatistically significant
increase of /acute lymphoblastic leukemia/ (ALL) after the accident in children
younger than five years old (OR=1.5, 95% confidence interval 0.8, 2.6). A small
study in northern Turkey showed that in one pediatric cancer treatment center,
more patients with ALL were seen after the accident than before, but no
incidence rates were reported. There has been only one analytic (case-control)
study of childhood leukemia reported based on cases identified among residents
of the Rivno and Zhytomir oblasts in Ukraine. Cases were under age 20 at the
time of the accident and were diagnosed between 1987 and 1997. Data were
collected on 272 cases, however, the analysis was based on only 98 cases that
were independently verified and interviewed. Controls were randomly selected fro
the same oblasts, excluding the raion of residence of the case, and matched
according to age at the time of the accident, sex, and type of settlement. The
mean estimated dose to the bone marrow among study subjects was 4.5 mSv and the
maximum was 101 mSv. the study found a statistically significant increased risk
of acute leukemia among males with cumulative doses above 10 mSv and diagnosed
form 1993-1997. A similar association was found for acute myeloid leukemia
diagnosed in the period 1987-1992. Theses results should be interpreted
cautiously, however, as they are based on approximately only one-third of the
cases and a lesser proportion of controls, and it is not clear whether cases and
controls were selected for dose estimation in an unbiased manner. /Cesium-137
fallout/
/EPIDEMIOLOGY STUDIES/ Several studies have investigated the risk of leukemia in
children exposed to Chernobyl fallout /(primarily cesium-137)/ while in utero.
All are ecologic in design, and results are inconsistent. The initial study
compared rates for temporal cohorts born during "exposed" and
"unexposed" periods in Greece and found a 2.6-fold increase in
leukemia risk and elevated rates for those born in regions with higher levels of
radioactive fallout. However, the numbers of cases in each exposure group were
small and the results could not be duplicated when a similar approach comparing
areas with the same categories of contamination (<6 kBq/sq m, 6-10 kBq/sq m,
>10 kBq/sq m) was applied to the analysis of data from the German Childhood
Cancer Registry. In a study in Belarus, where levels of contamination are higher
by a factor of ten or more, the results were similar to the Greed study but the
trend was weaker. Nevertheless, although the findings are based on small number
and are not statistically significant, the highest annual incidence rate was in
1987, the year after the accident, and the largest rate ratio (RR=1.51, 95%
confidence interval 0.63, 3.61) was in the two most contaminated regions: Gomel
and Mogilev. A more recent small study ... compared leukemia incidence during
1986 to 1996 among children born in 1986 and thus exposed in utero in Zhitomir,
a contaminated region with children born in Poltava, a relatively uncontaminated
region. The reported risk ratios based on cumulative incidence show significant
increases for all leukemia (relative risk (RR)=2.7, 95% confidence interval 1.9,
3.8) and for the subtype of acute lymphoblastic leukemia (RR=3.4, 95% confidence
interval 1.1, 10.4). The ongoing European Childhood Leukemia-Lymphoma Incidence
Study (ECLIS) has evaluated the risk of leukemia by age using data from
population-based cancer registries in Europe (including Belarus and Ukraine).
Focusing on the risk of leukemia by age of diagnosis in 6 month intervals in
relation to the estimated doses from the Chernobyl fallout received in utero,
preliminary results suggest a small increase in risk in infant leukemia and
leukemia diagnosed between 24-29 months. /Cesium-137 fallout/
/EPIDEMIOLOGY STUDIES/ Fall-out from weapons testing in the 1950s and from the
Chernobyl accident resulted in the ingestion of cesium-137 by Lapps who breed
reindeer in the northern parts of the Nordic countries and the Russian
Federation. In addition, small amounts of americium and plutonium were ingested
by Lapps from contaminated reindeer. A cohort of 2034 Lapps who bred reindeer in
Sweden or who were members of the households of breeders was assembled in 1960
and followed through mortality registries from 1961 through 1985. The rate of
mortality from all causes was similar to that of the entire Swedish population:
428 deaths occurred, and the SMR was 0.95. A significantly lower mortality rate
than expected was observed for all cancers (SMR, 0.70), and significantly
decreased risks were found for cancers of the colon, respiratory organs, female
breast, male genital organs and kidneys and for malignant lymphomas. The stomach
was the only site for which a significantly increased risk for cancer was found
(SIR, 2.25; 95% CI, 1.46-3.32) when compared with national rates. /Cesium-137
fallout/
/BIOMONITORING/ /GENOTOXICITY/ The results of... three post-Chernobyl studies
(two in Belarus and one in Ukraine) and for the one conducted on the populations
in the vicinity of the nuclear test site in Semipalatinsk (Kazakhstan) provide
evidence that mutations at minisatellite loci can be induced by radiation in
human germ cells. The dose-response relationships, however, remain uncertain
because of considerable difficulties in the estimation of parental gonadal
doses. For example, in the first Belarus study the level of surface
contamination by cesium-137 was used as a broad dose measure, and the children
of parents inhabiting heavily contaminate areas (>250 kBq/sq m) were found to
have twice the frequency of mutations compared to those of parents from less
contaminated areas (<250 kBq/sq m). In the second Belarus study (with more
exposed families and more loci sampled), based on estimates of individual doses,
two groups were defined <20 mSv and >20 mSv. The mutation frequency in the
children from the latter group was 1.35 times that in the former and that from
both groups was about 2-fold higher than in the unexposed U.K. controls. In the
Ukraine study, a 1.6-fold increase in mutation rate in the exposed fathers but
not in exposed mothers (both relative to unexposed controls) was found, but
again, the dose-response relationship is uncertain. The authors noted that the
dose from external chronic irradiation and internal exposures together were of
the order of approx. 100 mSv (excluding short-lived isotopes). In the
Semipalatinsk study, again, there was a 1.8-fold increase in the first
generation progeny of parents receiving relatively high doses of radiation
(cited as >1.0 Sv, but could have been lower or higher). In this study,
through the use of three-generation families, the authors obtained evidence for
a decline in mutation frequency as population doses decreased. /Cesium-137
fallout/
/BIOMONITORING/ /GENOTOXICITY/ Following the Goiania radiation accident,
lymphocytes from 110 exposed or potentially exposed individuals were analyzed
for the frequencies of chromosomal aberrations (dicentrics and centric rings) to
estimate absorbed radiation dose. Dose estimates for 21 subjects exceeded 1.0 Gy,
and for eight subjects they exceeded 4.0 Gy. Four of the subjects died. After
the emergency period, a cytogenetic follow-up of 10 of the highest exposed
patients was started. The results suggest that the average disappearance
half-time of lymphocytes containing dicentric and centric rings was 130 days,
which is shorter than the usually accepted value of 3 yr reported in the
literature. /Cesium-137 chloride/
/BIOMONITORING/ /GENOTOXICITY/ The current study comprises the analysis of
mutations in 10 individuals accidentally exposed to cesium-137 during the 1987
radiological accident in Goiania, Brazil. Their exposures were among the highest
experienced, ranging from 1 to 7 Gy. Peripheral T-lymphocyte samples were
obtained 3.3 years after the original exposure and mutation was studied at the
hprt locus using the 6-thioguanine-resistance selection assay. The mutational
spectrum for the exposed population is comprised of 90 independent mutants.
Based on T-cell receptor analysis, only 5% (5/95) were clonally related. Mutants
were initially studied using RT-PCR and directly sequenced using an automated
laser fluorescent DNA sequencer. Mutants that repeatedly failed to produce cDNAs
were studied using a multiplex PCR assay with genomic DNA. Missense mutations
were the most frequent event recovered, comprising 40% (23/57) of the spectral
sample. An excess of events involving A:T base pairs was observed, exhibiting a
significant difference (chi square = 12.7, P = 0.0004) when compared to the
spontaneous spectrum. This finding may reflect the effect of ionizing
radiation-induced damage, suggesting a potential similarity to radiation effects
in prokaryotes. At the genomic level, 36.7% (33/90) of the mutants exhibited
gross structural alterations, as detected by multiplex PCR. Deletion events were
over-represented in our spectral sample, displaying a twofold increase when
compared to the frequency observed in the spontaneous mutation database.
/Cesium-137 chloride/
/BIOMONITORING/ /GENOTOXICITY/ Five years after the initial exposure to
radioactive fallout from the Chernobyl accident of 1986, slightly greater
frequencies of chromosomal aberrations were observed in peripheral blood
lymphocytes of three groups of Byelorussian children (41 total) living in areas
with ground contamination from cesium-137 fallout than in those of an Italian
control group of 10 children. /Cesium-137 fallout/
/BIOMONITORING/ /GENOTOXICITY/ Results of multiyear cytogenetic study of
children and teenagers living in areas, radioactive by contaminated after
Chernobyl accident, were adduced. Mean density of cesium-137 contamination in
two compared living areas were 111 and 200 kBq/sq m and mean external doses
accumulated for 1986-2001 were 6.7 and 11.4 mGy correspondingly. Averaged
thyroid doses received by subjects of all age groups in the second area were
approximately 1.5 times higher than in the first area; in the youngest group
(0-1 year) the doses were 114.3 and 174.3 mGy. During 17 years cytogenetic
investigation approximately from 30% to 60% of examined persons were observed
the increased level of chromosome aberrations in lymphocytes of peripheral
blood. Average frequency of unstable aberrations (acentrics, dicentrics and
centric rings) constituted about 0.4 per 100 cells (0.22 per 100 cells in
controls) during all period of observation. Level of marker aberrations (dicentrics
and centric rings) was increased almost all times of study and varied within
0.04-0.19 per 100 cell (0.03 in control group). The parallel investigation of
frequency of stable aberrations by FISH method showed up their level about 3
times exceeding observed dicentrics level. Comparably higher indexes of
cytogenetic disturbances were revealed in group exposed in utero during period
of accident. /Cesium-137 fallout/
/BIOMONITORING/ /GENOTOXICITY/ Chromosome analysis of peripheral lymphocytes
from two Norwegian populations (44 reindeer herding South samis from Roros and
Snasa, 12 sheep farmers from Valdres) exposed to fallout from the Chernobyl
accident were made. The doses from cesium through the years 1987-1991 were
calculated based on whole-body measurements of cesium-134 and cesium-137 giving
a total cumulative mean internal dose of 5.54 mSv for the total group of 56
persons. Chromosome aberrations were within the normal range when compared with
historical controls with the exception of dicentrics (0.3% per cell, which is a
10-fold increase) and rings (0.07% per cell). A dose-dependent increase in
dicentrics and rings based on cesium exposure was not observed.
/BIOMONITORING/ /GENOTOXICITY/ Fluorescence in situ hybridization (FISH) is a
powerful method largely used for detecting chromosomal rearrangements,
translocations in particular, which are important biomarkers for dose assessment
in case of human exposure to ionizing radiation. To test the possibility of
using the translocation analysis by FISH-painting method in retrospective dose
assessment, /the authors/ carried out in vitro experiments in irradiated human
lymphocytes, in parallel with the analysis of translocations in lymphocytes from
10 individuals, who were exposed to cesium-137 in the Goiania (Brazil) accident
(samples collected 10 years after exposure). The in vitro dose-response curve
for the genomic translocation frequencies (FGs) fits a linear quadratic model,
according to the equation: Y=0.0243X(2)+0.0556X. The FG values were also
calculated for the individuals exposed to cesium-137, ranging from 0.58 to 5.91
per 100 cells, and the doses were estimated and compared with the results
obtained by dicentric analysis soon after the accident, taking the opportunity
to test the validity of translocation analysis in retrospective biodosimetry. A
tentative of retrospective dosimetry was performed, indicating that the method
is feasible only for low level exposure (below 0.5 Gy), while for higher doses
there is a need to apply appropriate correction factors, which take into
consideration mainly the persistence of chromosomal translocations along with
time, and the influence of endogenous and exogenous factors determining the
inter-individual variability in the cellular responses to radiation.
/OTHER TOXICITY INFORMATION/ /SKIN/ The external dose from cesium radionuclides
arises primarily from the penetrating gamma rays that travel great distances in
air. Beta radiation emitted outside the body is normally of little health
concern unless the radioactive material contacts the skin. Skin contact can
allow the beta radiation to pass through the epidermis to live dermal tissue
where it becomes a major contributor to a radiocesium-generated radiation dose
to the skin. At very high doses, the beta and gamma radiation can cause such
adverse effects as erythema, ulceration, or even tissue necrosis. /Cesium
radionuclides/
/OTHER TOXICITY INFORMATION/ /ENDOCRINE SYSTEM/ ...Relatively little has been
published regarding thyroid outcomes other than thyroid cancer, although one
study has reported an elevated risk of benign thyroid tumors. There have been
reports of increases in autoimmune disease and antithyroid antibodies following
childhood exposure to Chernobyl. However, a study by the Sasakawa Foundation
which screened 114,000 children found no association between a surrogate for
thyroid dose (cesium-137) and thyroid antibodies, hypothyroidism,
hyperthyroidism, or goiter. /Cesium-137/
Populations at Special Risk:
Dose rate, i.e., the time over which a radiation dose is delivered, may
influence risk in a variety of ways. In experimental animals, the risk per unit
dose is usually greater at higher dose rates, for the same cumulative dose of
low-LET radiation.
Probable Routes of Human Exposure:
Exposure to radioactive cesium is more important from a health perspective than
exposure to stable cesium(1). Current exposure of the general US population to
cesium-134 and cesium-137 is expected to be low since atmospheric testing
nuclear weapons has been discontinued for many years and Chernobyl-related
fallout was low in the US(1).
Toxicity Summary:
TOXICITY SUMMARY: The element cesium exists in several forms known as isotopes.
In nature, cesium exists only as a non-radioactive (or stable) isotope known as
cesium-133 (Cs-133); however, there exist several cesium isotopes that are
radioactive. The radioactive isotopes of cesium are formed during nuclear
fission, in commercial applications such as the generation of electricity at
nuclear power plants. The most important cesium isotopes in terms of their
potential effects on human health are cesium-134 (Cs-134) and cesium-137
(Cs-137). In this summary, the most pertinent information on the radiation
toxicity of Cs-134 and Cs-137 are presented. Both Cs-137 and Cs-134 emit beta
radiation and gamma radiation. Beta radiation travels short distances and can
penetrate the skin and superficial body tissues while gamma radiation can travel
great distances and penetrate the entire body. The radiation dose from these
radionuclides can be classified as either external (if the radiation source is
outside the body) or internal (if the radiation source is inside the body). Beta
radiation emitted outside the body is normally of little health concern unless
the radioactive material contacts the skin. Skin contact can allow the beta
radiation to pass through the epidermis to live dermal tissue where it becomes a
major contributor to the radiation dose to the skin. Beta and gamma radiation
may induce tissue damage and disruption of cellular function. The half-lives of
Cs-134 and Cs-137 are approximately 2 years and 30 years, respectively. Because
of the continual emission of radiation, people could be exposed to radiation
from Cs-137 or Cs-134 released to the environment. High levels of Cs-134 and
Cs-137 have been released to the environment from nuclear weapons testing and
incidents such as the 1986 accident at the Chernobyl nuclear reactor in Ukraine.
In these cases, cesium was one of many radionuclides present in the release. It
is, thus, not possible to ascribe any of the observed health effects to
radioactive cesium specifically. There are, however, documented reports of
health effects in humans exposed to radioactive cesium. These reports arise from
the accidental exposure of civilians to Cs-137 sources in Goiania, Brazil, in
1987 and Tammiku, Estonia, in 1994 and from the exposure of military personnel
to Cs-137 during 1996 and 1997 in Lilo, Republic of Georgia. External and
internal exposures of humans to radiocesium have resulted in a spectrum of
adverse health effects that range from nausea to death. In 1987, approximately
250 persons, including children, were exposed externally and internally to
radiation from a scavenged medical source with an activity of 50.9 TBq (1,375 Ci)
137-CsCl. Some of the exposed individuals showed signs of acute radiation
syndrome, such as nausea, vomiting, and diarrhea. A large number of the
individuals with acute radiation syndrome developed bone marrow failure and 4 of
these died. Dermal injuries observed among the exposed individuals ranged from
radiation dermatitis to severe radiation injuries leading to an amputation.
Ocular and reproductive effects were also reported. Two incidents of external
exposure to radiation from Cs-137 have demonstrated that serious adverse effects
may also be expected when individuals are exposed only externally to high levels
of radiation from Cs-137. In 1997 it was discovered that military recruits had
been accidentally exposed to several sealed Cs-137 radioactive sources at a
training facility in Lilo, Republic of Georgia. Nausea, weakness, headaches, and
loss of appetite were the most commonly reported symptoms among the exposed
recruits. Vomiting was reported by three of the patients, two of whom received
the highest estimated doses. The exposures of the recruits occurred over several
months. Although accurate information on the duration of the exposure was not
available, doses were estimated by scoring unstable chromosome aberrations in
peripheral blood lymphocytes and by electron spin resonance dosimetry of teeth
of the exposed individuals. The estimated mean doses ranged from 0.2 to 5.9 Gy
(The radiological event at Lilo. International Atomic Energy Agency (2000).
Vienna). In 1994, several individuals (aged 13 to 78) were exposed to a sealed
Cs-137 source stolen from a waste repository in Tammiku, Estonia. The observed
health effects in the exposed individuals ranged from a relatively mild case of
radiation sickness to death. Solid state dosimetry techniques were applied for
reconstruction of the doses of several individuals exposed in the house where
the stolen Cs-137 source was kept. The estimated whole body radiation doses
ranged from 0.1 Gy to 4 Gy. The individual with the highest estimated whole body
dose also had an estimated localized radiation exposure to the thigh of 1,830 Gy.
The latter individual died 12 days after the initial exposure event. The
survivors showed dermal effects and effects in blood. A 13-year old male was the
most exposed among the survivors (estimated whole-body dose of 1.5-5.5 Gy). He
suffered severe and prolonged bone marrow aplasia and radiation burns. (The
Radiological Accident in Tammiku (1998). The International Atomic Energy Agency,
Vienna. 4 November 1998). (SRC)
Evidence for Carcinogenicity:
There is inadequate evidence in humans for the carcinogenicity of cesium-137.
/Cesium/
There is sufficient evidence in experimental animals for the carcinogenicity of
mixed beta-particle emitters (iodine-131, cesium-137, cerium-144 and
radium-228). /Iodine, Cesium, Cerium, Radium/