TRITIUM,
RADIOACTIVE: Nuclear Power Plant Emissions
CASRN: 10028-17-8
Effluent
Concentrations :
The World Health Organization has estimated the total amount of tritium released
from atmospheric testing of nuclear weapons through 1980 was approximately
1.2X10+20 to 2.4X10+20 Bq(1). The total environmental discharge of tritium in
the effluent of pressurized water reactor (PWR), boiling water reactor (BWR),
heavy water reactor (HWR) and gas cooled reactor (GCR) nuclear power plants
operating worldwide in 1980 was estimated as 4X10+15 Bq(1). The total tritium
activity discharged into the environment by nuclear fuel reprocessing plants
operating in Windscale, UK, La Hague, France and Marcoule, France were 2X10+15
Bq in 1978(1). Annual tritium airborne release rates from the Savannah River
Plant in South Carolina have ranged from 1.4X10+16 Bq to 9.9X10+16 Bq from 1974
to 1977 with an average of 4.1X10+16 Bq(1). An accidental pulse release of
approximately 2X10+13 Bq of tritium from an industrial plant in Northern
Switzerland moved through the sewers, to a sewage treatment plant, and was
ultimately released to the River Glatt(2).
Environmental Fate/Exposure Summary :
There are 6 isotopes of hydrogen /tritium/. Hydrogen-1 and hydrogen-2 are
naturally occurring and stable. Hydrogen-3 is naturally occurring and
radioactive. Hydrogen isotopes with mass numbers 4-6 are artificially produced
and are radioactive. Tritium is the a naturally occuring radioactive isotope of
hydrogen and is produced as a result of the interaction of cosmic radiation with
gasses present in the upper atmosphere. The natural steady-state global
inventory of tritium is about 7.3 kilograms. It is naturally present as a very
small percentage of ordinary hydrogen in water (HTO), both liquid and vapor and
tritium gas (HT). Tritium has also been released to the environment from past
atmospheric testing of nuclear weapons and from discharges from nuclear power
plants. HTO is generally indistinguishable from normal water and is transported
throughout the environment in the same manner as water. Rain and snowfall remove
tritium from the atmosphere and volatilization of HTO from water and soil
surfaces transports tritium back to the troposphere. In soil, tritium is
transported by runoff, erosion and leaching. Tritium is eventually transformed
to He-3 by the natural process of radioactive decay with a half-life of about
12.26 years. Occupational exposure may occur through inhalation and dermal
contact with this compound at workplaces where tritium is produced or used.
Monitoring data indicate that the general population may be exposed to tritium
via ingestion of water and food, and dermal contact with tritium in rainfall and
atmospheric samples. (SRC)
General Manufacturing Information :
The United States has not produced tritium since 1988, when the Department of
Energy's (DOE's) production facility site in South Carolina closed. Immediate
tritium needs are being met by recycling tritium from dismantled U.S. nuclear
weapons. According to DOE, resumption of tritium production is essential for
maintaining the U.S. nuclear weapons stockpile. ... On December 22, 1998, the
DOE Secretary announced that he had chosen the light water reactor technology as
the primary means for tritium production; the accelerator design will be
retained as a backup. He selected the Tennessee Valley Authority's (TVA's) Watts
Bar Nuclear Plant and Sequoyah Nuclear Plant, Units 1 and 2, in Tennessee as the
preferred facilities for producing future supplies of tritium. ... The tritium
will still be shipped to (in the form of tritium producing burnable absorber
rods) and extracted at the Savannah River site.
Non-Human Toxicity Excerpts :
/LABORATORY ANIMALS: Neurotoxicity/ To provide experimental data for evaluating
tritium risk of nuclear-energy plant and instituting safety protection standard
of nuclear effects of low-dose tritiated water(HTO) on the developing central
nerve system, ... Pregnant adult C57BL/6J strain mice and Wistar rats were
irradiated with beta-rays from HTO by a single intraperitoneal injection on the
12.5th and 13th day of gestation. The activity of HTO was (x10+4) Bq/g b.w.)
24.09, 48.18 and 144.54, respectively. Neurobehavior and learning and memory
ability were tested. Ca2+ currents of hippocampal neurons were examined by
patch-clamp. Apoptosis of brain cells was detected morphologically and
biochemically by DNA electrophoresis. SDS-PAGE and Western blotting were used to
detect P53 protein in the cultures. ... After irradiation with beta-rays from
HTO in utero, the offspring showed hyperactivity in their young age period and
then showed depression-hypoactivity in adulthood. The exposed animals had
difficulties in both learning and memory retention and the developing neurons of
the central nerve system showed lower Ca2+ currents, higher number of apoptosis,
a typical ladder pattern DNA and increasing P53 protein. /The authors concluded
that/ Lower Ca2+ currents, higher number of apoptosis of brain cells and
abnormal expression of P53 protein were the substance basis of the damage of
central nerve system caused by tritium.
Ecotoxicity Excerpts :
/PLANTS/ Maize and barley plants were grown from seed for a period of 30 days in
an enclosure in which the soil water and atmospheric vapor contained equilibrium
concentrations of tritiated water. At the end of the experiment the plant water
of the maize and the barley contained 95 and 84%, respectively, of the
environmental concentration of tritium. The tritium-to-hydrogen ratio in plant
dry matter was 60% for maize and 45% for barley of the environmental
tritium-to-hydrogen ratio. The results show a significant isotope effect which
reduces the tritium content of food grown in a continuously contaminated
environment.
Other Chemical/Physical Properties :
DECAY PATHWAY: Hydrogen-3, half-life 12.32 years, decays via beta(-) emission
(18.590 keV) to helium-3, half-life stable
Natural Pollution Sources :
A significant amount of tritium from the sun's surface is believed to be brought
to the earth by solar wind and flare emissions. This tritium is rapidly
incorporated into water molecules and mixed into the water of the atmosphere,
hydrosphere, and biosphere(1).
Clinical Laboratory Methods :
Methods of Analysis. Tritium is collected primarily as/ water vapor/ HTO along
with water (H2O) by distillation and then determined from its beta emission in a
liquid scintillation system. No gamma rays are emitted. The distillation process
is usually performed from a basic solution of potassium permangenate to oxidize
radionuclides and organic compounds, preventing them from distilling over and
subsequently interfering with counting. Charcoal can also be added to the
distillation mixture as an additional measure to remove organic material.
Volatile iodine radionuclides can be precipitated as silver iodide before
distillation. Another distillation technique involves the use of cyclohexane to
form an azeotropic (low boiling point) mixture. This technique is sometimes used
in analysis of biota samples. Tritium may be analyzed, indirectly, by mass
spectrometry of its progeny, 3He.
Major Uses :
Bombarding particle in cyclotrons, activator in self-luminous phosphors, in cold
cathode tubes, tracer in biochemical research and various special problems in
chemical analysis, luminous instrument dials, thermonuclear power research.
Artificial Pollution Sources :
Tritium's use as a radioactive agent in making luminous paints(1-3), bombarding
particle in cyclotrons, activator in self-luminous phosphors, in cold cathode
tubes, tracer in biochemical research and various special problems in chemical
analysis, luminous instrument dials, and thermonuclear power research(2) may
result in its release to the environment through various waste streams(SRC).
General Manufacturing Information :
The principal USA site of production is the Savannah River Plant near Aiken, SC.
/Former/
Plant Concentrations :
Tritium was detected in floral samples of three different species of plants in
the vicinity of radioactive waste lagoons located in Los Alamos, NM at levels of
3.3 to 78.0 pCi/mL(1).
Artificial Pollution Sources :
... Present in effluents from nuclear reactors and weapons. Currently, the
tritium present in the environment and the relative contribution of the sources
have been estimated to be about 0.5 to 1 megacurie from nuclear reactors ... and
about 1X10+3 megacuries from nuclear explosions.
Medical Surveillance :
Tritium is a radionuclide uniformly absorbed by the body. The purpose of
cytomorphological and cytochemical leukocytes examination in tritium-affected
workers was early detection of initial health disorder caused by tritium
contamination. Cytoplasm and nuclear morphological changes were analyzed by
colored blood smear microscopy. The enzyme activity in granulocytes was examined
by cytochemical methods. Morphological changes were found in 47.17% of the
subjects (N=53) and in 2% (N=52) of the controls. Chromosomal aberrations in
lymphocytes were found in 49.05% of the exposed workers and in 2% of the
controls. The granulocytes enzyme activities were significantly diminished in
the exposed workers (p < or =0.001). The average level of beta radiation
found in the urine of those affected by tritium was 3.46 kBq/L, while it was
significantly lower in the others: 0.35 kBq/L. The enzyme activity decreases
after 5 yr of tritium exposure. Nuclear and cytoplasm changes as well as lowered
enzyme activity in granulocytes were found in tritium-contaminated workers.
Interdependence of cytomorphological and cytochemical changes was established.
There was no correlation between cytochemical changes and granulocytes count.
Human Toxicity Excerpts :
/BIOMONITORING/ /GENOTOXICITY/ Tritium is a radionuclide uniformly absorbed by
the body. The purpose of cytomorphological and cytochemical leukocytes
examination in tritium-affected workers was early detection of initial health
disorder caused by tritium contamination. Cytoplasm and nuclear morphological
changes were analyzed by colored blood smear microscopy. The enzyme activity in
granulocytes was examined by cytochemical methods. Morphological changes were
found in 47.17% of the subjects (N=53) and in 2% (N=52) of the controls.
Chromosomal aberrations in lymphocytes were found in 49.05% of the exposed
workers and in 2% of the controls. The granulocytes enzyme activities were
significantly diminished in the exposed workers (p < or =0.001). The average
level of beta radiation found in the urine of those affected by tritium was 3.46
kBq/L, while it was significantly lower in the others: 0.35 kBq/L. The enzyme
activity decreases after 5 yr of tritium exposure. Nuclear and cytoplasm changes
as well as lowered enzyme activity in granulocytes were found in
tritium-contaminated workers. Interdependence of cytomorphological and
cytochemical changes was established. There was no correlation between
cytochemical changes and granulocytes count.
RCRA Requirements :
Under the implementing regulations of the Resource Conservation and Recovery Act
(RCRA) [specifically at 40 CFR 261.4(a)(4)], source, special nuclear and
by-product material as defined by the Atomic Energy Act of 1954 (AEA) is
excluded from the definition of solid waste (and thus, from the RCRA hazardous
waste management requirements). ... Accelerator-produced tritium, on the other
hand, does not qualify for this exclusion (since the tritium is produced by a
linear accelerator, and does not involve the production or utilization of
special nuclear materials or the extraction or concentration of source
material). ... Pursuant to the RCRA regulations, it is the responsibility of the
generator of a waste to determine if that waste is subject to the hazardous
waste requirements [40 CFR 262.11].
Methods of Manufacturing :
Numerous reactions are available for the artificial production of tritium and it
is now made on a large scale by neutron irradiation of enriched lithium-6 in a
nuclear reactor. The lithium is in the form of an alloy with magnesium or
aluminum which retains much of the tritium until it is released by treatment
with acid. Alternatively the tritium can be produced by neutron irradiation of
enriched LiF at 450 degrees in a vacuum and then recovered from the gaseous
products by diffusion through a palladium barrier.
Methods of Manufacturing :
A small quantity of tritium is produced through neutron capture by deuterium in
the heavy water used as moderator in /nuclear/ reactors.
Methods of Manufacturing :
Tritium is produced as a minor product of nuclear fission. The yield of tritium
is 1-2 atoms in 10,000 fissions of natural uranium, enriched uranium, or a
mixture of transuranium nuclides.
Other Chemical/Physical Properties :
Magnetic dipole moment: +2.97896 nuclear magnetons
Other Chemical/Physical Properties :
Reacts with deuterium or protons (at sufficiently high temp) to undergo nuclear
fusion.
Preventive Measures :
Surveys of hood exhausts to unrestricted areas may be necessary to demonstrate
compliance with NRC (Nuclear Regulatory Commission) or state regulations.
Non-Human Toxicity Excerpts :
/LABORATORY ANIMALS: Subchronic or Prechronic Exposure/ Tritium (3-H) may enter
the environment from human activities, particularly at production, processing,
or waste storage sites such as the Department of Energy's Savannah River Site, a
former nuclear production facility in South Carolina. Understanding the dynamics
and potential adverse effects of tritium in exposed organisms is critical to
evaluating risks of tritium releases at such sites. Previous studies estimated
the biological half-life of tritium in mice to be approximately 1.13 days;
however, these laboratory studies were not conducted under environmentally
realistic conditions. In this study, designed to be more representative of
environmental exposure, mice were allowed to drink water containing tritium
(activity about 300 Bq/mL) for a period of 2 wk. The induction of oxidative
stress from tritium exposure was evaluated by comparing the activities of
antioxidant enzymes (catalase, glutathione peroxidase, and superoxide dismutase)
in exposed and control mice. From this experiment, the biological half-life of
tritium was determined to be 2.26+/-0.04 days, almost double previous estimates.
While positive controls (X-ray irradiated mice) showed responses in antioxidant
enzyme activity, there was no indication of oxidative stress induction in mice
exposed to tritium at this concentration.
Natural Pollution Sources :
Tritium occurs naturally to the extent of about 1 atom per 10+18 hydrogen
atoms(1) as a result of nuclear reactions induced by cosmic rays in the upper
atmosphere(1,2).
Natural Pollution Sources :
The principal source of natural tritium is the nuclear reactions induced by
cosmic radiation in the upper atmosphere, where fast neutrons, protons, and
deuterons collide with components of the stratosphere to produce tritium.
Tritium has also been observed in meteorites(1).
Environmental Water Concentrations :
In the prenuclear age, tritium content of rainwater ranged from < 1 to >
100 TUs (Tritium Units), depending mainly on the time between evaporation from
seawater and precipitation of the water mass. Continental river water and
biosphere hydrogen typically contained several TUs. The well mixed surface layer
of the oceans generally had a few tenths of a TU, and the deep sea waters had
undetectable levels. At the height of atmopsheric testing of nuclear weapons in
1963, the tritium content of rainwater attained a maximum of about 1X10+4 TUs in
the northern hemisphere and about a tenth as high in the southern hemisphere.
The content of surface seawater increased to about 5-20 TU. /TU= Tritium Unit= 1
(3)H atom/1X10+18 H atoms, corresponding to a specific radioactivity in water of
about 199 mBq/kg (7.1 dpm/kg)/(1).
Food Survey Values :
Tritium was detected in 4% of 200 portions of foods (raw vegetables, fruits,
fish, and milk) collected near 33 nuclear reactors from October 1986 to
September 1992(1). The maximum concentration observed in these positive
detections was 70 Bq/kg, and most of the positive detections occurred in fish
and vegetables in the vicinity of 4 sites(1).
Federal Drinking Water Standards :
Pursuant to the Atomic Energy Act, discharges and releases of tritium to waters
from DOE facilities are regulated by DOE and those from licensed nuclear
facilities are regulated by NRC or NRC Agreement States. Under the Safe Drinking
Water Act, the Environmental Protection Agency (EPA) has established the
standard for tritium in water from drinking water systems. EPA and States also
use this standard for protection of ground water that may be used as drinking
water. DOE requirements prohibit DOE operations from releasing effluents that
would cause a drinking water system to exceed this standard.
Analytic Laboratory Methods :
Fourier transform NMR can be used to detect (3)H (nuclear spin one-half), which
has an efficiency of detection /of approximately/ 20% greater than that of (1)H.
This technique is useful for ascertaining the position and distribution of
tritium in the labeled compound.
MORE ABOUT HEALTH EFFECTS
TRITIUM,
RADIOACTIVE
CASRN: 10028-17-8
This record contains information for tritium, an isotope of hydrogen. For
general information on radiation, such as transportation, sampling, analytical
methods, regulations, and spill clean-up, refer to the IONIZING
RADIATION record.
For other data, click on the Table of Contents
Human Toxicity Excerpts:
/HUMAN EXPOSURE STUDIES/ The body does not readily absorb H2, HT, HD, D2, DT, or
T2 from inhaled gases or through the skin. If inhaled in elemental form, almost
all tritium in the gas is exhaled. Only a very small fraction is retained in the
lungs. Tritium in the form of water (HTO, DTO, and T2O) is adsorbed through the
skin and in the lungs from inhaled gases. Tritium in water form is readily
retained in the body and remains with a biological half-life of approximately 10
days. Due to the body's ready adsorption of tritium in the form of tritiated
water, exposure to tritiated water in air is on the order of 15,000 to 25,000
times more hazardous than exposure to gaseous tritium (HT, DT, and T2).
/CASE REPORTS/ A woman was accidentally exposed to tritiated gas that escaped
from glass capillary tubes. She incorporated about 35 GBq (1 Ci) of tritiated
water. After several hours of delay, treatment was initiated to reduce the
exposure by enhanced fluid intakes and forced diuresis. She was followed for
chromosomal aberrations for 11 years. The authors monitored the number of
dicentric chromosomes found in lymphocytes, and found that they have fallen over
the years with a half-time of 3.3 years. No other significant clinical
abnormalities were noted.
/CASE REPORTS/ Urine samples from eight male radiation workers who had an
unplanned acute tritiated water intake were measured for tritium-in-urine up to
300 d post-exposure. During the first month or so post-exposure, these
individuals increased their fluid intakes to accelerate the turnover rate of
tritium in the body for dose mitigation. Their daily fluid intakes reverted to
normal levels in the latter period of the study. A non-linear regressional
analysis of the tritium-in-urine data showed that the average biological
half-life of tritium in body water, with standard deviation, was 6.3+/-1.0 days
(range, 5.0-8.1 d) and 8.4+/-2.0 days (range, 6.2-12.8 d) during the respective
periods of increased fluid intake and the later period of normal fluid intake. A
longer term component of tritium excretion was also observed with average
biological half-life of 74+/-18 days (range, 58-104 d), indicating the
incorporation of tritium, and its retention, in the organic fractions of the
body. A mathematical model was developed and used to estimate the dose increase
from the metabolized organically bound tritium on the basis of the kinetics of
tritium-in-urine. The model accounts for a change in the rates of urinary
excretion caused by variable fluid intakes. The average dose to the body, for
the eight male workers, due to the metabolized organically bound tritium was
estimated to be 6.2+/-1.3% (range, 3.5% to 8.9%) of the committed effective dose
due to tritium in the body water. This value for the dose increase from
organically bound tritium is in the range of the current recommendations of the
International Commission on Radiological Protection, i.e., organically bound
tritium incorporated into the body contributes about 10% of the dose to the body
water following tritiated water intakes.
/BIOMONITORING/ For bioassay purposes, urine is normally used for determining
tritium concentrations in body water. Workers who may be or who have been
exposed to tritium are normally required to submit urine samples for bioassay
periodically. The sampling period may be daily, biweekly, or longer, depending
on the potential for significant exposure. Special urine samples are normally
required after an incident or a work assignment with a high potential for
exposure. After a possible exposure, the worker should empty the bladder 1 to 2
hours later. A sample taken after the bladder is emptied should be reasonably
representative of the body water concentration. A sample collected before
equilibrium is established will not be representative because of dilution in the
bladder, or because of initial high concentration in the blood. However, any
early sample may still be useful as a sign of the potential seriousness of the
exposure.
/BIOMONITORING/ /GENOTOXICITY/ Tritium is a radionuclide uniformly absorbed by
the body. The purpose of cytomorphological and cytochemical leukocytes
examination in tritium-affected workers was early detection of initial health
disorder caused by tritium contamination. Cytoplasm and nuclear
morphological changes were analyzed by colored blood smear microscopy. The
enzyme activity in granulocytes was examined by cytochemical methods.
Morphological changes were found in 47.17% of the subjects (N=53) and in 2%
(N=52) of the controls. Chromosomal aberrations in lymphocytes were found in
49.05% of the exposed workers and in 2% of the controls. The granulocytes enzyme
activities were significantly diminished in the exposed workers (p < or
=0.001). The average level of beta radiation found in the urine of those
affected by tritium was 3.46 kBq/L, while it was significantly lower in the
others: 0.35 kBq/L. The enzyme activity decreases after 5 yr of tritium
exposure. Nuclear and cytoplasm
changes as well as lowered enzyme activity in granulocytes were found in
tritium-contaminated workers. Interdependence of cytomorphological and
cytochemical changes was established. There was no correlation between
cytochemical changes and granulocytes count.
/OTHER TOXICITY INFORMATION/ Tritium ... does not constitute an external
radiation hazard. However, tritium presents a serious hazard through ingestion
and subsequent exposure of vital body tissue to internal radiation.
/OTHER TOXICITY INFORMATION/ The median lethal dose (LD50) of tritium
assimilated by the body is estimated to be 370 GBq (10 Ci). Higher doses can be
tolerated with forced fluid intake to reduce the biological half life.
/OTHER TOXICITY INFORMATION/ Risk coefficients for inhalation of radionuclides
are expressed as the probability of radiogenic cancer mortality or mobidity per
unit intake, where the intake is averaged over all ages and both genders.
...Mortality and morbidity risk coefficients for inhalation /of Hydrogen (H-3,
particulate), fast absorption type and gastrointestinal uptake of 1.0 are/
3.61X10-13 Bq-1 and 5.28X10-13 Bq-1, /respectively/. /For medium absorption type
and GI uptake of 0.1 the risk coefficients are/ 4.58X10-12 Bq-1 and 5.38X10-12
Bq-1. /For slow absorption and GI uptake of 0.01 the risk coefficients are/
2.12X10-11 Bq-1 and 2.30X10-11 Bq-1. Mortality and morbidity risk coefficients
for inhalation /of Hydrogen (H-3, water vapor) with GI uptake of 1.0 are/
1.04X10-12 Bq-1 and 1.52X10-12 Bq-1 /respectively/. /For Hydrogen (H-3,
elemental gas) with GI uptake of 1.0 are/ 1.04X10-16 Bq-1 and 1.52X10-16 Bq-1.
/from table/
/OTHER TOXICITY INFORMATION/ Risk coefficients for ingestion of radionuclides in
tap water or food are expressed as the probability of radiogenic cancer
mortality or morbidity per unit intake, where the intake is averaged over all
ages and both genders. ...Mortality and morbidity risk coefficients for
ingestion of water and food /for Hydrogen (H-3, tritiated water) with a
gastrointestinal uptake of 1.0:/ Tap water intakes- 9.44X10-13 Bq-1 and
1.37X10-12 Bq-1 /respectively/; Dietary intakes- 1.20X10-12 Bq-1 and 1.76X10-12
Bq-1. Mortality and morbidiey risk coefficients for ingestion of water and food
/for Hydrogen (H-3, organically bound) with a GI uptake of 1.0:/ Tap water
intakes- 2.09X10-12 Bq-1 and 3.03X10-12 Bq-1, /respectively/; Dietary intakes-
2.66X10-12 Bq-1 and 3.89X10-12 Bq-1. /from table/
Human Toxicity Values:
The median lethal dose (LD50) of tritium assimilated by the body is estimated to
be 370 GBq (10 Ci). Higher doses can be tolerated with forced fluid intake to
reduce the biological half life.
Probable Routes of Human Exposure:
NIOSH (NOES Survey 1981-1983) has statistically estimated that 5,947 workers
(1,110 of these are female) are potentially exposed to tritium in the US(1).
Occupational exposure may occur through inhalation and dermal contact with this
compound at workplaces where tritium is produced or used(SRC). Monitoring data
indicate that the general population may be exposed to tritium via ingestion of
water and food, and dermal contact with tritium in rainfall and atmospheric
samples(SRC). Human exposure to tritium most often occurs in the form of
tritiated water, THO(2).
Probable Routes of Human Exposure:
NIOSH (NOES Survey 1981-1983) has statistically estimated that 5,947 workers
(1,110 of these are female) are potentially exposed to tritium in the US(1).
Occupational exposure may occur through inhalation and dermal contact with this
compound at workplaces where tritium is produced or used(SRC). Monitoring data
indicate that the general population may be exposed to tritium via ingestion of
water and food, and dermal contact with tritium in rainfall and atmospheric
samples(SRC). Human exposure to tritium most often occurs in the form of
tritiated water, THO(2).
All of the above is
directly from http://toxnet.nlm.nih.gov/