EPA Facts about Technetium-99
What is technetium-99?
Technetium-99 (Tc-99) is a radioactive metal.
Most technetium-99 is produced artificially, but
some also occurs naturally in very small
amounts in the earth's crust. Technetium-99
was first obtained from the element
molybdenum, but it is also produced as a
nuclear reactor fission product of uranium and
plutonium. All isotopes of technetium are
radioactive, and the most commonly available
forms are technetium-99 and technetium-99m.
In addition to being produced during nuclear
reactor operation, technetium-99 is produced in
atmospheric nuclear weapons tests. Metastable
technetium-99 (technetium-99m), the shorter-
lived form of technetium-99, is also a
component of gaseous and liquid effluent from
nuclear reactors. Technetium-99m is used
primarily as a medical diagnostic tool, and it can
be found as a component of industrial and
institutional wastes from hospitals and research
laboratories.
What are the uses of technetium-99?
Technetium-99 is an excellent superconductor at
very low temperatures. In addition, technetium-
99 has anti-corrosive properties. Five parts of
technetium per million will protect carbon steels
from corrosion at room temperature.
Technetium-99m is used in medical therapy in
brain, bone, liver, spleen, kidney, and thyroid
scanning and for blood flow studies.
Technetium-99m is the radioisotope most
widely used as a tracer for medical diagnosis.
How does technetium-99 change in the
environment?
Technetium-99 is not a stable isotope. As
technetium-99 decays, it releases beta particles
and eventually forms a stable nucleus. Beta
particles can pass through skin, but they cannot
pass through the entire body. The time required
for a radioactive substance to lose 50 percent of
its radioactivity by decay is known as the half-
life. The half life is 210,000 years for
technetium-99 and 6 hours for technetium-99m.
How are people exposed to technetium-
99?
Man-made technetium-99 has been found in
isolated locations at federal sites in the
groundwater beneath uranium processing
facilities. Technetium-99 contamination at these
selected sites is a concern if individuals are
exposed to technetium-99 by drinking
contaminated water and ingesting contaminated
plants. The potential exposure from external
radiation by technetium-99 is minimal because
the isotope is a weak beta emitter. Technetium-
99m is not a concern at these sites because of its
short half-life. Technetium-99 is also found in
the radioactive waste of nuclear reactors, fuel
cycle facilities, and hospitals.
In the natural environment, technetium-99 is
found at very low concentrations in air, sea
water, soils, plants, and animals. The behavior of
technetium-99 in soils depends on many factors.
Organic matter in soils and sediments plays a
significant role in controlling the mobility of

-------
technetium-99. In soils rich in organic matter,
technetium-99 is retained and does not have
high mobility. Under aerobic conditions,
technetium compounds in soils are readily
transferred to plants. Some plants such as
brown algae living in seawater are able to
concentrate technetium-99. Technetium-99 can
also transfer from seawater to animals.
How does technetium-99 get into the
body?
At radioactively contaminated sites with
technetium-99 contamination, the primary
routes of exposure to an individual are from the
potential use of contaminated drinking water
and ingestion of contaminated plants. Exposure
may occur to persons working in research
laboratories that conduct experiments using
technetium-99 and technetium-99m. Patients
undergoing diagnostic procedures may receive
controlled amounts of technetium-99m, but also
avoid a more invasive diagnostic technique.
Is there a medical test to determine
exposure to technetium-99?
Special tests that measure the level of
radioactivity from technetium-99 or other
technetium isotopes in the urine, feces, hair,
and exhaled air can determine if a person has
been exposed to technetium. These tests are
useful only if administered soon after exposure.
The tests require special equipment and cannot
be done in a doctor's office.
How can technetium-99 affect people's
health?
Once in the human body, technetium-99
concentrates in the thyroid gland and the
gastrointestinal tract. The body, however,
constantly excretes technetium-99 once it is
ingested. As with any other radioactive material,
there is an increased chance that cancer or
other adverse health effects can result from
exposure to radiation.
What recommendations has the U.S.
Environmental Protection Agency made
to protect human health?
Please note that the information in this section
is limited to recommendations EPA has made to
protect human health from exposure to
technetium-99. General recommendations EPA
has made to protect human health at Superfund
sites (the 10~4 to 10"6 cancer risk range), which
cover all radionuclides including technetium-99,
are summarized in the fact sheet "Primer on
Radionuclides Commonly Found at Superfund
Sites."
EPA has established a Maximum Contaminant
Level (MCL) of 4 millirems per year for beta
particle and photon radioactivity from man-
made radionuclides in drinking water.
Technetium-99 is covered under this MCL. The
average concentration of technetium-99 that is
assumed to yield 4 millirems per year is 900
picoCuries per liter (pCi/L). If other radionuclides
that emit beta particles and photon radioactivity
are present in addition to technetium-99, the
sum of the annual dose from all the
radionuclides cannot exceed 4 millirems/year.
For more information about how EPA addresses
technetium-99 at Superfund sites
Contact Stuart Walker of EPA:
(703) 603-8748 or walker.stuart@epa.gov,
or visit EPA's Superfund Radiation Webpage:
http://www.epa.gov/superfund/resources/radiation/

-------