COBALT, RADIOACTIVE: Nuclear Power Plant Emissions
General
Manufacturing Information :
Corrosion product radionuclides are created by neutron activation of reactor
components such as piping or fuel element cladding. ... In addition, corrosion
products can be found in workers who have had intakes at other nuclear
facilities, notably nuclear power plants or naval shipyards servicing
nuclear-powered vessels. ... Historically, fresh corrosion product radionuclides,
regardless of origin, were usually a mixture of several radionuclides. The
predominant radionuclide was usually cobalt-60, with cobalt-58, manganese-54,
and iron-59 as the other significant constituents in a fresh mixture. Other
radionuclides were often present in trace amounts, but they were generally of
little dosimetric consequence. The relative abundance of the radionuclides
varied from facility to facility. However, given the time elapsed since
operation of the reactors at Hanford, the short-lived corrosion products have
decayed away, leaving cobalt-60 as the nuclide of concern. ...Corrosion products
are usually oxides. /Cobalt, manganese, and iron oxides/
Environmental Fate/Exposure Summary :
Cobalt-60 is produced by neutron activation of components of nuclear reactors;
these components are made of various alloys of steel that contain metals that
can absorb neutrons and produce cobalt-60. Cobalt-60 can also be produced in a
particle accelerator. Trace amounts of cobalt-60 are present in the environment
worldwide due to fallout from past atmospheric nuclear weapons testing.
Cobalt-60 may be released to the environment from nuclear reactors and
facilities that process spent nuclear fuel, especially hardware associated with
the spent fuel. Cobalt-60 may be release to the environment through discharges
of low-level aqueous radioactive wastes from nuclear power plants. The highest
annual discharge of cobalt-60 from the AEA Witfrith reactor in Dorset, UK was 20
TBq in 1980-81. Between 1986-90 approximately 270 GBq of cobalt-60 was
discharged into the Rhone River in liquid wastes. Total releases of cobalt-60 to
the atmosphere from the Savannah River Site (SRS), South Carolina between
1968-96 were 0.092 Ci. Total releases of cobalt-60 to streams from the SRS
between 1954-95 were 66 Ci. Occupational exposure to cobalt-60 may occur for
workers at nuclear facilities, irradiation facilities, and nuclear waste storage
sites. Cobalt-60 is used in brachytherapy to treat various types of cancer. In
this application, cobalt-60 is contained within a sealed source, and the release
of cobalt-60 to the environment would be expected to be minimal and exposure to
cobalt-60 by cancer patients would be limited to its gamma emission rather than
to the element itself. Individuals may be exposed to cobalt-57 through its use
in diagnostic testing as a radiotracer in radioactive vitamin B12. According to
the US Nuclear Regulatory Commission, the collective intake of cobalt-60 by
ingestion and inhalation at power reactors in 1998 was 352 uCi for 25 intake
records and 27,000 uCi for 281 intake records, respectively. The collective
intake at fuel fabrication facilities was 0.486 uCi for 502 intake records. (SRC)
Artificial Pollution Sources :
Cobalt-60 is produced be neutron activation of components of nuclear reactors;
these components are made of various alloys of steel that contain metals that
can absorb neutrons and produce cobalt-60(1). Cobalt-60 can also be produced in
a particle accelerator(1). Trace amounts of cobalt-60 are present in the
environment worldwide due to fallout from past atmospheric nuclear weapons
testing(1). Cobalt-60 may be released to the environment from nuclear reactors
and facilities that process spent nuclear fuel, especially hardware associated
with the spent fuel(1). Cobalt-60 may be release to the environment through
discharges of low-level aqueous radioactive wastes from nuclear power plants(5).
The highest annual discharge of cobalt-60 from the AEA Witfrith reactor in
Dorset, UK was 20 TBq in 1980-81(2). Between 1986-90 approximately 270 GBq of
cobalt-60 was discharged into the Rhone River in liquid wastes(3). Total
releases of cobalt-60 to the atmosphere from the Savannah River Site (SRS),
South Carolina between 1968 and 1996 were 0.092 Ci(4). Total releases of
cobalt-60 to streams from the SRS between 1954-95 were 66 Ci(4). Cobalt-60 is
used in brachytherapy to treat various types of cancer(1). In this application,
cobalt-60 is contained within a sealed source, and the release of cobalt-60 to
the environment would be expected to be minimal(SRC).
Human Toxicity Excerpts :
/OTHER TOXICITY INFORMATION/ Workers in commercial nuclear power plants are
typically exposed to gamma radiation. The main routes of exposures are from
fission products and activation products. The activation product of greatest
concern is cobalt-60, which emits energetic gamma-rays of 1.15 and 1.33 MeV per
nuclear transformation. The average annual effective dose of monitored workers
in the commercial fuel cycle between 1985 and 1989 was 2.9 mSv and the annual
average collective dose was 2,500 person-Sv. /Cobalt-60/
Effluent Concentrations :
On July 1, 1992, 68 MBq of cobalt-60 was released form the nuclear power plant
of Bugey located on the Rhone River, France; two of the reactors are cooled
using water from the Rhone River(1). Between 1986-90 approximately 270 GBq of
cobalt-60 was discharged into the Rhone River in liquid wastes(1). The highest
annual discharge of cobalt-60 from the AEA Winfrith reactor in Dorset, UK was 20
TBq in 1980-81(2). Concentrations of cobalt-60 in the intertidal mudflat
sediments, seaweed, and marine fauna declined following the closure of the
nuclear reactor at AEA Winfrith in Dorset, UK in 1990(2).
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.
Sediment/Soil Concentrations :
SEDIMENT: Cobalt-60 concentration in surface sediments from 4 sites in one of
the reservoir created in the river Techna near the Mayak Production Association
in the Urals mountains, which produced weapons-grade plutonium, ranged from 42
to 88 kBq/kg dry weight(1). Cobalt-60 concentrations in bottom sediments
collected near the Vandellos Nuclear Plant (Spain) in 1989 ranged from <0.07
to 0.44 Bq/kg(2). Cobalt-60 concentrations in sediment samples from the Peconic
River system, Long Island, NY, downstream from the Brookhaven National
Laboratory (BNL) were 9.6, 6.7, 9.6, and 10.5 Bq/kg dry weight at depth
intervals of 0.00 to 0.06, 0.06 to 0.15, 0.15 to 0.24, and 0.24 to 0.37 meters,
respectively(3). On the BNL property boundary, cobalt-60 concentrations in
sediment were 5.8 Bq/kg dry weight (0.00-0.06 m) and <4 Bq/kg dry weight for
the remaining depth intervals(3). Cobalt-60 concentrations in sediment samples
from two locations from a control river, Connetquot River (Long Island, NY),
were <4 Bq/kg at 0.00 to 0.06 and 0.06 to 0.15 m depths(3).
Plant Concentrations :
Cobalt-60 concentrations in sea grass (Possidonia oceanica) collected near the
Vandellos Nuclear Plant (Spain) collected in 1987 ranged from 0.70 to 7.66 Bq/kg
dry weight, with a mean value of 1.6 Bq/kg dry weight(2).
Probable Routes of Human Exposure :
Occupational exposure to cobalt-60 may occur for workers at nuclear facilities,
irradiation facilities, and nuclear waste storage sites(1). According to the US
Nuclear Regulatory Commission, the collective intake of cobalt-60 by ingestion
and inhalation at power reactors in 1998 was 352 uCi for 25 intake records and
27,000 uCi for 281 intake records, respectively(1). The collective intake at
fuel fabrication facilities was 0.486 uCi for 502 intake records(1). Cobalt-60
is used in brachytherapy to treat various types of cancer(2). In this
application, cobalt-60 is contained within a sealed source(2). Individuals may
be exposed to cobalt-57(SRC) through its use in diagnostic testing as a
radiotracer in radioactive vitamin B12(3).
General Manufacturing Information :
Cobalt-59 is the only naturally occurring isotope of the element. The other
twenty-two isotopes and their metastable states, ranging from mass numbers 50 to
67, are radioactive. Isotopes with mass numbers less than 59 decay by positron
emission or electron capture. Isotopes with mass numbers greater than 59 decay
by beta and gamma emission. Except for cobalt-60, the most important
radionuclide, their half-lives range from milliseconds to days. The principal
isotopes of cobalt (with their half-lives) are cobalt-57 (t 1/2 272 days),
cobalt-58 (t 1/2 71 days), and cobalt-60 (t 1/2 5.27 years). Isotopes 57 and 58
can be determined by X-ray as well as gamma spectrometry. Isotope 60 is easily
determined by gamma spectrometry. /Cobalt isotopes/
Other Chemical/Physical Properties :
DECAY PATHWAY: Cobalt-60, half-life 5.27 years, decays via beta(-) emission
(99.9%, 317.9 keV maximum, 95.8 keV average energy) and gamma emission (abs
intensities: 99% 1173 keV; 100% 1332 keV) to nickel-60, half-life stable
Radiation Limits & Potential :
DECAY PATHWAY: Cobalt-60, half-life 5.27 years, decays via beta(-) emission
(99.9%, 317.9 keV maximum, 95.8 keV average energy) and gamma emission (abs
intensities: 99% 1173 keV; 100% 1332 keV) to nickel-60, half-life stable
Interactions :
Vitexina, a product containing the flavonoid vitexin as the main component, is
derived from a plant, Vigna radiata (L.), that has been traditionally used in
Vietnam for detoxification. This remedy is also used to treat the symptoms of
conditions classified as "hot" in traditional medicine. The present
study is a randomized, placebo-controlled comparative clinical trial for
investigating the radioprotective effects of Vitexina for breast cancer patients
undergoing radiotherapy with cobalt-60. No relevant weight loss, (even weight
gain), occurred in 70% of patients in the Vitexina group, whereas 73% of the
placebo group lost 1 to 2 kg of weight after 6 weeks of radiation therapy. The
administration of Vitexina produced a significantly protective effect in
peripheral blood cells in amount and in lymphocyte blast-transformation
function. Condition of hot was observed in almost all cancer patients in this
study by tongue examination. Hot condition did not change in the Vitexina group,
but the incidence of hot and extreme hot cases were significantly increased in
the placebo group after 6 weeks of radiation therapy. The results suggest that
application of medicinal plants of the "clearing heat and
detoxification" classification as an adjuvant would be a potential solution
in integrative cancer therapy. /Vitexina and Cobalt-60/
Other Chemical/Physical Properties :
Half-life: 271.8 days, gamma emission /Cobalt-57/
Storage Conditions :
The half-life of cobalt-60 (t1/2= 5.2 y), and its gamma emissions make it a
principal contributor to potential dose effects in storage and transport of
radioactive waste. /Cobalt-60/
Radiation Limits & Potential :
Half-life: 271.8 days, gamma emission /Cobalt-57/
Other Chemical/Physical Properties :
In aqueous solution and in the absence of complexing agents, Co+2 is the only
stable oxidation state, existing in water as the pink-red hexaaquo complex ion,
Co(H2O)6 +2. Simple cobalt ions in the +3 oxidation state decompose water in an
oxidization-reduction process that generates Co+2. ... Complexation of Co+3
decreases its oxidizing power and most complex ions of the +3 oxidation state
are stable in solution. ... Chelate complexes are well-known and are used to
extract cobalt from solutions of other ions. /Cobalt compounds/
Therapeutic Uses :
Teletherapy is radiation therapy delivered using an external beam of ionizing
radiation. Options include gamma rays (from a radioactive cobalt-60 source) and
photons or electrons (from an X-ray generator or accelerator). ... Electrons,
which have less power to penetrate tissue, are used to treat skin lesions,
superficial lymph nodes, and other tumors situated near the surface of the
patient. In addition to "conventional" radiation therapy, experts in
radiation oncology have developed several other methods of external beam
therapy. Intraoperative radiation therapy (IORT) uses electrons to treat tumors
that have been surgically exposed. IORT delivers a single high dose of radiation
directly to the tumor after overlying and surrounding tissue have been
temporarily moved out the way. IORT is of greatest use for accessible tumors of
the abdomen and pelvis that cannot be removed surgically. Stereotactic
radiosurgery (SRS) delivers radiation beams to a small target within the skull.
The resulting dose distribution yields a small region of high dose precisely
conforming to the target. ... /Cobalt-60/
Major Uses :
Cobalt is also used in the cobalt bomb, a hydrogen bomb surrounded by a cobalt
metal shell. When the nuclear explosion occurs cobalt-60 is formed from
cobalt-59 by neutron capture. Considered a dirty bomb because of long half-life
and intense beta and gamma radiation.
Major Uses :
Cobalt-57. Used in nuclear medicine to help physicians interpret diagnostic
scans of patients' organs, and to diagnose pernicious anemia.
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 percent 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. ... 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.
Radiation Limits & Potential :
For activities conducted under licenses issued by the Nuclear Regulatory
Commission, the monthly average concentration (uCi/mL) for releases to sewers
for Class W cobalt compounds is as follows: cobalt-55 2x10-4; cobalt-56 6x10-5,
cobalt-57 6x10-4, cobalt-58 2x10-4, cobalt-60 3x10-5.
Radiation Limits & Potential :
The Orphan Sources Initiative is designed to assist states in retrieving and
disposing of radioactive sources that find their way into non-nuclear
facilities, particularly scrap yards, steel mills, and municipal waste disposal
facilities. Specially licensed sources bear identifying markings that can be
used to trace these sources to their original owners. However, some sources do
not have these markings or the markings become obliterated. In these cases, the
sources are referred to as orphan sources because no known owner can be
identified. They are one of the most frequently reported radioactive
contaminants in shipments received by scrap metal facilities. If a steel mill
melts a source, it contaminates the entire batch of metal, the processing
equipment, and the facility. More importantly, it can result in the exposure of
workers to radiation. There have been at least 26 recorded accidental meltings
of radioactive material in the United States since 1983. One such case happened
in Texas in 1996 when a cobalt-60 source was stolen from a storage facility and
sold as scrap metal. Workers and customers of the scrap yard and law enforcement
officers who conducted investigations at the scrap yard were exposed to the
source and may have received dangerous doses of radiation. /Cobalt-60/
Medical Surveillance :
/In nuclear reactor workers/ in vivo and excreta measurements are the bioassay
methods used in monitoring for corrosion product radionuclides /predominently
cobalt-60/. All of these radionuclides are gamma-emitters and can be measured
directly using in vivo techniques. Whole body counting, using either
sodium-iodide or coaxial germanium detectors, is the in vivo technique typically
applied for bioassay of these nuclides. Because the radionuclides are easily
detectable using in vivo measurement, excreta measurements are not required in
most intake situations, unless there is concern for other radionuclides such as
strontium or plutonium, which are not readily measurable by in vivo techniques.
Measurement of radionuclides in early fecal excretion can be used as a means for
establishing the relative radionuclide distribution in a corrosion product
mixture; however, analysis of a nasal or appropriate surface contamination smear
sample is preferred if the elements present may exhibit different absorption
characteristics in the GI tract.
Mechanism of Action :
Apoptosis is a crucial phenomenon for radiation-induced cell death. Since Bax
plays a critical role in inducing apoptosis via p53-dependent and -independent
pathways, /the authors/ analyzed a role of Bax in radiation sensitivity in
esophageal carcinoma cells. Using eight human esophageal carcinoma cell lines,
irradiation was performed with cobalt-60 gamma-rays. Radiation sensitivity was
determined by induction of apoptosis, which was assessed by morphological change
in nuclear condensation of chromatin, DNA ladder formation and apoptosis-related
genes after irradiation. The survival curve was evaluated by clonogenic assay
using a parameter D0 after irradiation, compared to that of the control. After
transfection of the bax gene into low radiation sensitivity, TE-1 cells were
conducted by lipofection method using pSFFV-Neo vector carrying bax cDNA.
Radiation sensitivity of esophageal carcinoma cells was associated with
induction of apoptosis, in a time- and dose-dependent manner. Induction of
apoptosis affects early responsiveness to irradiation rather than the parameter
D0. Radiation-induced apoptosis was associated with an increase in expression of
bax gene, regardless of p53 genetic status. The introduction of the bax gene
into a low radiation sensitivity cell line, TE-1, enhanced radiation sensitivity
in association with increased apoptotic cell death after irradiation. Radiation
sensitivity of esophageal carcinoma cells can be evaluated by induction of
apoptosis, as an early predictive marker for radiation response. The
proapoptotic gene bax plays a critical role in the determination of tumor
response in radiation therapy. /Cobalt-60/
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./
FDA Requirements :
Based on its experience in regulating investigational radioactive
pharmaceuticals, the Nuclear Regulatory Commission has compiled a list of
reactor-produced isotopes for which it considers that applicants may reasonably
be expected to submit adequate evidence of safety and effectiveness for use as
recommended in appropriate labeling. Such use may include ... Isotope: cobalt 58
or cobalt 60; Chemical Form: labeled cyanocobalamin; Use: intestinal absorption
studies.
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
MORE ABOUT HEALTH EFFECTS
Evidence for Carcinogenicity:
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:
/CASE REPORTS/ /ACUTE RADIATION SYNDROME/ The accident occurred in Northern
Italy ... .The source was cobalt-60. The operator entered the room and was not
wearing a film badge. Of particular note was the rapid drop in white blood cells
and lymphocytes and the onset of nausea and vomiting in less than 30 min. ...
After an initial fever, the patient experienced a latent period for
approximately 6 days, after which time fever rapidly rose and the patient died
12 days postexposure. The terminal event was listed as dramatic deregulation of
the cardiac rhythm with extreme tachycardia, very high central temperature
oscillations, and a Cheyne-Stokes rhythm. /Cobalt-60/
/CASE REPORTS/ Electron spin resonance and fluorescence in situ hybridization
were used to evaluate the dose to the finger of a worker who accidentally
touched a radiotherapy cobalt-60 therapy source in November 1995. In September
1999, the middle finger was amputated. /The authors/ estimated the dose to the
bone of the finger to be 6.4+/-0.5 Gy using the electron spin resonance additive
dose method and a corrected dose of about 20+/-3 Gy could be inferred by
translocation analysis in peripheral lymphocytes using the fluorescence in situ
hybridization method. This retrospective dosimetry was performed for the victim
4 years after the accident, but the compatibility of the results obtained by
physical and biological methods reinforce their validity, although in the case
of partial-body exposure the biological method has limitations and demonstrates
the need to find appropriate correction factors. /Cobalt-60/
/CASE REPORTS/ /EYE/ Exposure of a male worker to a whole-body dose of 159 rad
(1.59 Gy) of cobalt-60 radiation resulted in a progressive deterioration of
visual acuity, due to cataract development, in the left eye (which was more
exposed than the right) over time. /Cobalt-60/
/CASE REPORTS/ /ACUTE RADIATION SYNDROME/ A fatal radiation accident with a
2.43pentaBq (65 kCi) cobalt-60 radiation source occurred in Norway in 1982. The
patient was estimated to have received an inhomogeneous whole body dose of
approximately 10-30 Gy and he died on day 13 after the accident. The clinical
features in general were consistent with a hematological syndrome variant of the
acute radiation syndrome (ARS). Gastrointestinal symptoms were modest compared
with the estimated dose. More recent insights cast doubt about the classical
descriptions and interpretation of ARS, which show many similarities to the
multi-organ failure (MOF) of otherwise severely traumatized patients. This
report discusses the features of ARS in this case in relation to commonly
accepted features of MOF, based on clinical and autopsy data. /Cobalt-60/
/CASE REPORTS/ /ACUTE RADIATION SYNDROME/ In 1963, six cases of acute radiation
sickness resulting from an accidental non-uniform cobalt-60 gamma-ray
irradiation of approximately 10 Ci were treated first in Hefei, Anhui province,
and were then transferred to our hospital. The whole body average doses were
estimated to be 2x10+2 cGy to approximately 8x10+3 cGy. Two of patients died of
intestinal acute radiation sickness within 2 weeks. Autopsy findings revealed
findings consistent with multi-organ failure. Four cases survived, and one of
them recovered from septicaemic shock. Loss of hair, systemic infection, high
fever and bleeding occurred in five cases. The essential therapeutic measures
were strict isolation, preventive treatment with anti-infection drugs, fresh
blood transfusion and sometimes infusion of formed blood elements. Among the
survivors, two cases received homologous bone marrow transfusion. The general
conditions of four cases followed-up for a period of 24-40 years are apparently
good, with transparent lens, normal thyroid function and normal immunological
reactions, except one patient who had a low serum immunoglobulin G level. Three
cases showed subnormal adrenocortical activity and impairment of sex gland
function. Patient A died from a car accident 24 years after the radiation
accident. Patient C gave birth to a daughter and a son; the latter had severe
mental retardation. Serial electroencephalographic changes occurred only in
those cases who received high cranial doses. In all the cases, persistence of
chromosome aberrations in peripheral lymphocytes was observed. Owing to local
high doses, the remote regional effects led to amputation of one leg in patient
D and to pathological fracture of the femur in patient A. /Cobalt-60/
/CASE REPORTS/ /ACUTE RADIATION SYNDROME/ On 25 June 1990 in Shanghai, two men
(Shi, a 56-year-old male, and Wan, a 53-year-old male) were accidentally exposed
to homogeneous high dose and high dose rate cobalt-60 irradiation (total
activity 0.85 PBq, at the time of delivery from the manufacturing factory in
June 1960) up to 12 Gy and 11 Gy, respectively. Both suffered from an extremely
severe hematopoietic form of acute radiation sickness. Through energetic salvage
and human leukocyte antigen (HLA) haploidentical bone marrow transplantation,
their survival times were prolonged to 25 days and 90 days, respectively. In the
case of Wan, the implanted bone marrow resided and engrafted completely, and
hematopoiesis was restored. However, the patient died of interstitial pneumonia
90 days after exposure to radiation. The clinical course of multi-organ failure
and the valuable experience obtained from the management of these patients is of
great significance in directing the prevention of multi-organ failure and the
treatment of such patients in the future. Pathological findings from these two
autopsy cases are helpful in elucidating the underlying pathogenesis of clinical
multi-organ failure, the cause of death and especially, the pathogenesis and
morphogenesis of lung fibrosis. /Cobalt-60/
/CASE REPORTS/ /ACUTE RADIATION SYNDROME/ In Istanbul, Turkey in 1998, a 3 TBq
cobalt-60 therapy source inside a shielded transport container was sold as
scrap. The individuals who purchased the source were unaware of the radiation
hazard and proceeded to break open and dismantle the container in a residential
area of Istanbul. A total of 18 persons, including 7 children, were admitted to
hospital. Five exhibited clinical effects of acute radiation exposure, with one
person having signs of radiation-induced skin injuries on the fingers of one
hand. /Cobalt-60/
/CASE REPORTS/ /ACUTE RADIATION SYNDROME/ /A 43 pentaBecquerel (PBq) cobalt-60
source/ remained in the farmer's home for 212 hr and in his pocket for 52 hr.
The source was also kept in the left pocket of his 7 year old brother's trousers
for 18 hr. The average whole-body dose to the farmer and his younger brother was
estimated to be 806 and 40 Gy. Both died on January 23 and 25, respectively, due
to failure to respond to any medical treatment. Four other people, who received
doses of 8, 6, 4, 2 Gy, respectively, survived after medical treatment. Two of
them have not fully recovered from local injuries; the other two are doing well.
A follow up study, together with involved medical treatment, has shown that in
17 years after exposure, they had fully recovered with good physical and mental
condition and memory. Local effects are mainly long-term injuries to the skin
and skeleton. There have been no significant changes in the lenses of their
eyes. /Cobalt-60/
/CASE REPORTS/ /ACUTE RADIATION SYNDROME/ In Bangkok, Thailand in February 2000,
three old radiotherapy heads /were/ taken to a scrap yard. One source, estimated
to be about 15.5 TBq cobalt-60, was removed from its shielding. The resulting
exposure caused 10 persons to be hospitalized, and three of these subsequently
died. /Cobalt-60/
/CASE REPORTS/ /ACUTE RADIATION SYNDROME/ /A/ fatal accident in Israel involved
an irradiator facility (12.6 PBq cobalt-60) used for sterilizing medical
products and spices for the food industry. A distorted carton became jammed on
the conveyor transport system while the source was in the exposed position. The
operator disregarded the warning signal and entered the irradiation room. His
whole-body dose was estimated to be about 10-15 Gy. Despite intensive medical
care, he died of radiation effects 36 days after exposure. /Cobalt-60/
/CASE REPORTS/ /ACUTE RADIATION SYNDROME/ In /a/ fatal accident in Belarus, an
operator was exposed to radiation in an industrial irradiator, following a jam
in the product transport system, with the source (30 PBq cobalt-60) in the
exposed position. A mean whole-body dose of approximately 11Gy, with localized
areas of up to 18 Gy, was estimated. Despite intensive medical treatment, the
operator died 113 days after exposure. /Cobalt-60/
/CASE REPORTS/ /ACUTE RADIATION SYNDROME/ /A/ fatal accident in China involved
an irradiation facility (0.85 PBq cobalt-60) used for sterilizing traditional
Chinese medicines. One of the two doors in the entry route had been out of
commission. Seven workers entered to rearrange the product boxes/and/ two of the
workers received doses of 11 and 12 Gy and subsequently died. /Cobalt-60/
/CASE REPORTS/ /ACUTE RADIATION SYNDROME/ ... /Seven workers were exposed to a
8.5X10+14 Bq cobalt-60 gamma source at a radiological medicine laboratory in
Shanghai/. The seven workers suffered acute external radiation exposure of the
whole body at widely varying degrees at different distances from the source in a
short time. Within 30 min after the accident, one worker felt nauseated and
within 7 hours, the other began vomiting. ... Dose reconstruction was made for
the measurement and estimation of the radiation doses received by the seven
workers, along with biological dose measurements. ... Chromosome aberration
analysis and physical measurements agree within 10%. Two of the seven workers,
who received 12 and 11 Gy radiation exposure, respectively, died after being
treated for 25 and 90 days. The other five workers /who received between 2.0 and
5.2 Gy radiation exposure/ recovered after treatment. /Cobalt-60/
/EPIDEMIOLOGY STUDIES/ Following the observation of increased prostate cancer
mortality related with cumulative external radiation dose in the UK Atomic
Energy Authority... a nested case control study of prostate cancer risk among
employees of the facility /was conducted/. The study showed that exposure to 5
radionuclides (tritium, chromium-51, iron-59, cobalt-60, zinc-65), evaluated
separately, was associated with an increased risk of prostate cancer. Analyses
of the association between external radiation dose and prostate cancer risk were
carried out both for workers with probably exposure to the radionuclides and for
those who had no such exposure. The association between external dose and
prostate cancer was restricted to those with radionuclide exposure. /Tritium,
chromium-51, iron-59, cobalt-60, zinc-65/
/EPIDEMIOLOGY STUDIES/ Children who once resided in radiocontaminated apartments
since early 1983 were examined for height and body weight status from age 1
month to 18 years and before they moved out of the apartments. The physical
heights and body weights of 21,898 age- and sex-matched non-exposed children
from a nationwide school surveillance in 1997-98 were taken as controls. The
physical height data were shown as height percentiles (HP) compared with
reference children and age-specific relative height differences (RHD). RESULTS:
HP and RHD in 48 exposed boys and 37 girls were analysed using generalized
estimating equations (GEE), which accounted for multiple measurements and
correlation between these measurements in the same individuals during this
period. After adjusting for effects from parental heights and body mass index
(BMI), clear dose-related decreases in HP and RHD were observed in the exposed
boys with a cumulative exposure > 60 mSv. CONCLUSIONS: Prolonged low
dose-rate y-radiation exposure was associated with adverse effects on the
physical heights of growing boys, but were less apparent in the exposed girls.
/Low dose gamma radiation/
/BIOMONITORING/ /GENOTOXICITY/ Increased micronucleus frequency, both of single
and multiple nucleates, /was found/ in 48 people who had been exposed to 0.12-16
Gy over a 2 to 10 year period as a result of a building contaminated with
cobalt-60-containing steel. Subjects who lad left the building showed a decrease
in micronucleus formation that correlated with time since cessation of exposure.
/Cobalt-60/
/BIOMONITORING/This ... has been performed with radiation victims who were
accidentally exposed to a cobalt-60 source and its release into the environment.
The aim of the study was to assess the effects of elevated radiation exposures
on plasma level, on erythrocyte thiobarbituric acid reactive substance (TBARS)
level and on erythrocyte glutathione (GSH) levels. Patients were treated in
different hospitals with different symptoms such as nausea, vomiting, dizziness,
along with severe anemia in some patients. Blood samples were collected 3 to 5
days following the radiation accident. Increases in plasma (6.25+/-0.90 nmol/mL))
and erythrocyte TBARS levels (330.5+/-30.5 umol/gHb)) were found in comparison
to a healthy group (3.72+/-0.68 nmol/mL and 150.7+/-20.5 umol/gHb, respectively)
at a significant level (p<0.001). Erythrocyte GSH levels (5.2+/-0.30 umol/gHb)
were found to be decreased among the victims (healthy group: 10.2+/-0.7 umol/gHb)
at the same significance level (p<0.001). These observations confirm a
significant change induced by radiation in the oxidant/antioxidant status among
the victims. It is suggested here that antioxidant supplementation therapy might
be effective in preventing the harmful effects of cobalt-60 radiation among
radiation victims. /Cobalt-60/
/BIOMONITORING/ Many people in Taiwan have been living in buildings constructed
with cobalt-60-contaminated steel rods. To study the biological effects of
chronic low-dose ionising radiation on the residents of one such building,
micronucleus formation in these individuals was compared with that in controls.
... The 73 residents had 77 age-and-sex-matched controls: 31 had 31 close
relatives as controls (group A controls); eight of the 31 had a second set of
close relatives; and the other controls were 38 residents in neighboring
buildings. Two micronucleus assays were used - a cytochalasin B (CBMN) assay and
another involving incubation with cytarabine (CBMNA). Assay results are given as
frequency, or the number of binucleate cells containing one micronucleus per
1000 randomly examined binucleate cells. Findings The CBMN and CBMNA mean (SD)
frequencies for 31 exposed individuals (0.016 +/-0.009 and 0.025 +/-0.013
respectively) were greater than those for their group A controls (0.009 +/-0.004
and 0.016 +/-0.009, respectively) (p=0.0006 and 0.0002, respectively). The mean
CBMN and CBMNA frequencies for all the exposed individuals (0.017+/-0.011 and
0.030 +/-0.014, respectively) were significantly greater than those for all
controls (0.011+/-0.008 and 0.019+/-0.01; p=0?0001 for both comparisons). The
ranges of the differences in CBMN or CBMNA frequencies between 31 exposed
individuals and their group A controls were 0.003 to 0.020 and 0.001 to 0.032,
respectively. After adjustment for age, sex, and cigarette smoking, the adjusted
relative risks of micronucleus formation from radiation exposure in all 73
residents was 1.56 (95% CI 1.42-1.71; p=0?0001) by the CBMN assay and 1.64
(1.53-1.77; p=0?0001) by the CBMNA assay. ... These findings suggest that
chronic low-dose and low-dose-rate gamma-ray environmental exposure may induce
cytogenetic damage in human beings. /Cobalt-60/
/OTHER TOXICITY INFORMATION/ Workers in commercial nuclear power plants are
typically exposed to gamma radiation. The main routes of exposures are from
fission products and activation products. The activation product of greatest
concern is cobalt-60, which emits energetic gamma-rays of 1.15 and 1.33 MeV per
nuclear transformation. The average annual effective dose of monitored workers
in the commercial fuel cycle between 1985 and 1989 was 2.9 mSv and the annual
average collective dose was 2,500 person-Sv. /Cobalt-60/
Medical Surveillance:
/In nuclear reactor workers/ in vivo and excreta measurements are the bioassay
methods used in monitoring for corrosion product radionuclides /predominently
cobalt-60/. All of these radionuclides are gamma-emitters and can be measured
directly using in vivo techniques. Whole body counting, using either
sodium-iodide or coaxial germanium detectors, is the in vivo technique typically
applied for bioassay of these nuclides. Because the radionuclides are easily
detectable using in vivo measurement, excreta measurements are not required in
most intake situations, unless there is concern for other radionuclides such as
strontium or plutonium, which are not readily measurable by in vivo techniques.
Measurement of radionuclides in early fecal excretion can be used as a means for
establishing the relative radionuclide distribution in a corrosion product
mixture; however, analysis of a nasal or appropriate surface contamination smear
sample is preferred if the elements present may exhibit different absorption
characteristics in the GI tract.
Probable Routes of Human Exposure:
Occupational exposure to cobalt-60 may occur for workers at nuclear facilities,
irradiation facilities, and nuclear waste storage sites(1). According to the US
Nuclear Regulatory Commission, the collective intake of cobalt-60 by ingestion
and inhalation at power reactors in 1998 was 352 uCi for 25 intake records and
27,000 uCi for 281 intake records, respectively(1). The collective intake at
fuel fabrication facilities was 0.486 uCi for 502 intake records(1). Cobalt-60
is used in brachytherapy to treat various types of cancer(2). In this
application, cobalt-60 is contained within a sealed source(2). Individuals may
be exposed to cobalt-57(SRC) through its use in diagnostic testing as a
radiotracer in radioactive vitamin B12(3).
Antidote and Emergency Treatment:
Immediate First Aid/ Ensure that adequate decontamination has been carried out
as needed. If patient is not breathing, start artificial respiration, preferably
with a demand valve resuscitator, bag-valve-mask device, or pocket mask, as
trained. Perform CPR if necessary. Immediately flush contaminated eyes with
gently flowing water. Do not induce vomiting. If vomiting occurs, lean patient
forward or place on left side (Head-down position, if possible) to maintain an
open airway and prevent aspiration. Keep patient quiet and maintain normal body
temperature. Obtain medical attention. /Radiological Threats: Radiological
Dispersal Devices or Weapons/
Basic Treatment. Establish a patent airway (oropharyngeal or nasopharyngeal
airway, if needed). Suction if necessary. Watch for signs of respiratory
insufficiency and assist ventilations if necessary. Administer oxygen by
nonrebreather mask at 10 to 15 mL/min. Monitor for shock and treat if necessary.
Anticipate seizures and treat if necessary. Perform routine emergency care for
associated injuries. ... Perform routine basic life support care as necessary. /Radioactives
I, II, and III/
Basic Treatment. Establish a patent airway (oropharyngeal or nasopharyngeal
airway, if needed). Watch for signs of respiratory insufficiency and assist
ventilations if necessary. Administer oxygen by nonrebreather mask at 10 to 15
L/min. Monitor for shock and treat if necessary. Anticipate seizures and treat
if necessary. Perform routine emergency care for associated injuries. For eye
contamination, flush eyes immediately with water. Irrigate each eye continuously
during transport. Do not use emetics. For ingestion, rinse mouth and administer
5 mL/kg up to 200 mL of water for dilution if the patient can swallow, has a
good gag reflex, and does not drool. Perform routine BLS care as necessary.
/Radiological Threats: Radiological Dispersal Devices or Weapons/
Advanced Treatment. Consider orotracheal or nasotracheal intubation for airway
control in the patient who is unconscious or is in severe respiratory distress.
Monitor cardiac rhythm and treat arrhythmias as necessary. Start IV
administration of 0.9% saline (NS) or lactated Ringer's (LR) TKO. For
hypotension with signs of hypovolemia, administer fluid cautiously. Watch for
signs of fluid overload. Treat seizures with diazepam or lorazepam. Perform
routine advanced life support care as needed. Use proparacaine hydrochloride to
assist eye irrigation. /Radioactives I, II, and III/
Advanced Treatment. Consider orotracheal or nasotracheal intubation for airway
control in the patient who is unconscious or is in severe respiratory distress.
Monitor cardiac rhythm and treat arrhythmias as necessary. Start IV
administration of 0.9% saline (NS) or lactated Ringer's (LR). For hypotension
with signs of hypovolemia, administered fluid cautiously. Watch for signs of
fluid overload. Treat seizures with diazepam (Valium) or lorazepam (Ativan).
Perform routine advanced life support care as needed. Use proparacaine
hydrochloride to assist eye irrigation. /Radiological Threats: Radiological
Dispersal Devices or Weapons/
Special Considerations. Most symptoms from radioactive product exposure are
delayed; treat other medical or trauma problems according to normal protocols.
An accurate history of the exposure is essential to determine risk and proper
treatment modalities. The dose of radiation determines the type and clinical
course of exposure: 100 rads: GI symptoms (nausea, vomiting, abdominal cramps,
diarrhea). Symptom onset within a few hours. 600 rads: Several GI symptoms
(necrotic gastroenteritis) may result in dehydration and death within a few
days. Several thousand rads: neurological/cardiovascular symptoms (confusion,
lethargy, ataxia, seizures, coma, cardiovascular collapse) within minutes to
hours. Bone marrow depression, leukopenia, and infections usually follow severe
exposures./Radioactives I, II, and III/
Special Considerations. Radiation monitors should be available to evaluate the
radiation dose rates and compute/verify safe times to remain in contaminated
areas. Experts are needed to review the data and provide specific
recommendations to the Incident Commander as to the hazards present in the
affected areas. Medical radiation experts should be available to guide patient
treatment. Most symptoms from radioactive product exposure are delayed; treat
other medical or trauma problems according to normal protocols. An accurate
history of the exposure is essential to determine risk and proper treatment
modalities. The dose of radiation determines the type and clinical course of
exposure: 100 rads: GI symptoms (nausea, vomiting, abdominal cramps, diarrhea).
Symptom onset within a few hours. 600 rads: Severe GI symptoms (Necrotic
gastroenteritis) may result in dehydration and death within a few days. Several
thousand rads: neurological/cardiovascular symptoms (confusion, lethargy,
ataxia, seizures, coma, cardiovascular collapse) within minutes to hours. Bone
marrow depression, leukopenia, and infections usually follow severe exposures.
Assistance and advice on patient care concerns may be obtained from the Oak
Ridge Radiation Emergency Assistance Center and Training Site 24 hours a day by
calling (615) 576-3131 or (615) 481-1000, ext. 1502 or beeper 241. /Radiological
Threats: Radiological Dispersal Devices or Weapons/
Emergency and Supportive Measures. Treatment of serious medical problems takes
precedence over radiologic concerns. Maintain an open airway and assist
ventilation if necessary. Treat coma and seizures if they occur. Replace fluid
losses from gastroenteritis with intravenous crystalloid solutions. Treat
leukopenia and resulting infections as needed. Immunosuppressed patients require
reverse isolation and appropriate broad-spectrum antibiotic therapy. Bone marrow
stimulants may help selected patients. Specific drugs and antidotes. Chelating
agents or pharmacologic blocking drugs may be useful in some cases of ingestion
or inhalation of certain biologically active radioactive materials, if they are
given before or shortly after exposure. /Radiation (Ionizing)/
Decontamination. 1. Exposure to particle-emitting solids or liquids. The victim
is potentially highly contaminating to rescuers, transport vehicles, and
attending health personnel. 1. Remove victims from exposure, and if their
conditions permit, remove all contaminated clothing and wash the victims with
soap and water. b. All clothing and cleansing water must be saved, evaluated for
radioactivity, and properly disposed of. c. Rescuers should wear protective
clothing and respiratory gear to avoid contamination. At the hospital, measures
must be taken to prevent contamination of facilities and personnel. d. Induce
vomiting or perform gastric lavage if radioactive material has been ingested.
Administer activated charcoal, although its effectiveness is unknown. Certain
other adsorbent materials may also be effective. e. Contact Radiation Emergency
Assistance Center & Training Site (REAC/TS/: telephone (865) 576-3131 or
(865) 481-1000)/ and the state radiologic health department for further advice.
In some exposures, unusually aggressive steps may be needed (eg, lung lavage for
significant inhalation of plutonium). 2. Electromagnetic radiation exposure. The
patient is not radioactive and does not pose a contamination threat. There is no
need for decontamination once the patient has been removed from the source of
exposure, unless electromagnetic radiation emitter fragments are embedded in
body tissues. /Radiation (Ionizing)/
Initial Emergency Department Considerations. Chelating agents or pharmacologic
blocking drugs (potassium iodine, diethylenetriamine pentaacetic acid (DTPA),
dimercaprol (British antilewisite, BAL), sodium bicarbonate, Prussian blue,
calcium gluconate, ammonium chloride, barium sulfate, sodium alginate, D-penicillamine)
may be useful if given before or immediately after exposure. The Oak Ridge
number listed /in Special Considerations/ can be contacted for specific
treatment advice. /Radiological Threats: Radiological Dispersal Devices or
Weapons/ p
Basic Treatment. Establish a patent airway (oropharyngeal or nasopharyngeal
airway, if needed). Suction if necessary. Watch for signs of respiratory
insufficiency and assist ventilations if necessary. Administer oxygen by
nonrebreather mask at 10 to 15 L/min. Monitor for pulmonary edema and treat if
necessary. Monitor for shock and treat if necessary. FOr eye contamination,
flush eyes immediately with water. Irrigate each eye continuously with 0.9%
saline (NS) during transport. Do not use emetics. For ingestion, rinse mouth and
administer 5 mL/kg up to 200 mL of water for dilution if the patient can
swallow, has a strong gag reflex, and does not drool. administer activated
charcoal. /Cobalt and Related Compounds/
Advanced Treatment. Consider orotracheal or nasotracheal intubation for airway
control in the patient who is unconscious, has severe pulmonary edema, or is in
severe respiratory distress. Positive-pressure ventilation techniques with a
bag-valve-mask device may be beneficial. Consider drug therapy for pulmonary
edema. Consider administering a beta agonist such as albuterol for severe
bronchospasm. Monitor cardiac rhythm and treat arrhythmias if necessary. Start
IV administration of D5W TKO. Use o.9% saline (NS) or lactated Ringer's (LR) if
signs of hypovolemia are present. For hypotension with signs of hypovolemia,
administer fluids cautiously. Consider vasopressors if patient is hypotensive
with a normal fluid volume. Watch for signs of fluid overload. Use proparacaine
hydrochloride to assist eye irrigation. /Cobalt and Related Compounds/
Evidence for Carcinogenicity:
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).
Probable Routes of Human Exposure:
Occupational exposure to cobalt-60 may occur for workers at nuclear facilities,
irradiation facilities, and nuclear waste storage sites(1). According to the US
Nuclear Regulatory Commission, the collective intake of cobalt-60 by ingestion
and inhalation at power reactors in 1998 was 352 uCi for 25 intake records and
27,000 uCi for 281 intake records, respectively(1). The collective intake at
fuel fabrication facilities was 0.486 uCi for 502 intake records(1). Cobalt-60
is used in brachytherapy to treat various types of cancer(2). In this
application, cobalt-60 is contained within a sealed source(2). Individuals may
be exposed to cobalt-57(SRC) through its use in diagnostic testing as a
radiotracer in radioactive vitamin B12(3).
All of the above is
directly from http://toxnet.nlm.nih.gov/