Plutonium is a radioactive element. Pure plutonium is a silvery-white metal.

Most plutonium is found combined with other substances, for example, plutonium dioxide (plutonium with oxygen) or plutonium nitrate (plutonium with nitrogen and oxygen).

Plutonium is usually measured in terms of its radioactivity (curies or becquerels). Both the curie (Ci) and the becquerel (Bq) tell us how much a radioactive material decays every second.

Exists in various forms called isotopes

The most common plutonium isotope is plutonium-239.

Each radioactive isotope of an element constantly gives off radiation, which changes it into an isotope of a different element or a different isotope of the same element. This process is called radioactive decay.

Plutonium-238 and plutonium-239 give off alpha particles (sometimes referred to as alpha radiation) and transform into uranium-234 and uranium‑235, respectively.

The half-life is the time it takes for half of the atoms of a radionuclide to undergo radioactive decay and change it into a different isotope. The half-life of plutonium-238 is 87.7 years. The half-life of plutonium-239 is 24,100 years. The half-life of plutonium-240 is 6,560 years.

Very small amounts of plutonium occur naturally. Plutonium-239 and plutonium-240 are formed in nuclear power plants when uranium-238 captures neutrons. Plutonium is used to produce nuclear weapons.

Plutonium-238 is used as a heat source in nuclear batteries to produce electricity in devices such as unmanned spacecraft and interplanetary probes.

Released during testing of nuclear weapons

Plutonium released during atmospheric testing of nuclear weapons, which ended in 1980, is the source of most of the plutonium in the environment worldwide. The plutonium released during these tests was deposited on land and water. The small amount that remains in the atmosphere continues to be deposited as it slowly settles out.

Plutonium is also released to the environment from research facilities, waste disposal, nuclear fuel reprocessing facilities, nuclear weapons production facilities, and accidents at facilities where plutonium is used.

Deposited in water or soil

Plutonium can be transported in the atmosphere usually when it is attached to particles in the air. It can be deposited on land or water by settling or by rain. Plutonium can stick to particles in soil, sediment, and water.

Plutonium isotopes will undergo radioactive decay in the environment.

Soil

Average plutonium levels in surface soil from fallout range from 0.01 to 0.1 picocuries (pCi) per gram of soil (1 picocurie equals one-trillionth [10-12] of a curie).

Plutonium concentrations in air are generally low. Baseline plutonium-239 concentrations in air ranging from 1.6x10-6 to 3.8x10-6 pCi per cubic meter of air (pCi/m3) have been reported.

Workplace

Persons who work at nuclear fuel and weapons production facilities have a greater chance of being exposed than individuals in the general population.

Accident

You could be exposed to plutonium if there was an accidental release of plutonium during use. It is very unlikely you would be exposed as the result of a traffic accident or disposal. Plutonium transport containers are virtually indestructible by accident or fire. The disposal site is deep underground and away from the public.

Plutonium can enter your body when it is inhaled or swallowed

When you breathe air that contains plutonium, some of it will get trapped in your lungs. Some of the trapped plutonium will move to other parts of your body, mainly your bones and liver. The amount of plutonium that stays in your lungs depends on the solubility of the plutonium that is in the air you breathe.

A small amount of the plutonium you swallow (much less than 1%) will enter other parts of your body (mainly your bones and liver).

If plutonium gets onto your healthy skin, very little, if any, plutonium will enter your body. More plutonium will enter your body if it gets onto injured skin, such as a cut or burn.

Plutonium in your body will remain there for many years

Plutonium leaves your body very slowly in the urine and feces. If plutonium were to enter your lungs today, much of the plutonium would still be in your body 30�50 years later.

Lung, liver, and bone cancer

You may develop cancer depending on how much plutonium is in your body and for how long it remains in your body. The types of cancers you would most likely develop are cancers of the lung, bones, and liver. These types of cancers have occurred in workers who were exposed to plutonium in air at much higher levels than is in the air that most people breathe.

Affect ability to fight infections

In laboratory animals, plutonium affected the animal�s ability to resist disease (immune system).

There are differences between children and adult

Studies in young animals have shown that a larger amount of the plutonium deposited in the lung will move to growing bones. Therefore, it is possible that the bones of children could be more severely affected by plutonium than the bones of adults; however, this has not been shown in humans or tested in laboratory animals.

Studies in animals have also shown that a larger amount of plutonium that enters the gut of newborn animals is absorbed into the body.

Effects in unborn children

We do not know if plutonium causes birth defects or affects the ability to have children, although some plutonium that reaches the blood can be found in ovaries and testes.

A large portion of the plutonium in the body of adults is in bone. It is possible that plutonium in the bones of a pregnant woman may move to the fetus, when the calcium from the mother�s bone is being used to build the bones of the fetus.

Risk for working

People working at facilities using plutonium that is not highly contained will be more highly exposed to plutonium than the general population.

Risk near the home

People do not generally live near facilities that use plutonium in their operations. Some people may be slightly more exposed to plutonium due to releases of plutonium through filtered stack-emissions or waste water. Any releases are to be within regulatory limits. Disposal sites are deep underground and away from the public.

Breathing plutonium-contaminated air is the most dangerous way to be exposed to plutonium. If you know or suspect that plutonium has been released to the air, you should leave the area immediately.

Can be measured in urine and feces

Plutonium can be measured in the urine and feces even at very low levels. These measurements can be used to estimate the total amount of plutonium that has entered the body.

The levels of plutonium in the body can be used to predict the kind of health effects that might develop from that exposure.

Plutonium inside the body can be detected from outside the body

Some sensitive equipment can measure the weak gamma rays that travel to the outside of the body after they are released from plutonium and other radioactive materials inside the body. In the United States, this equipment is only available in a few locations.

General public

0.1 rem/year for the general public and 0.5 rem/year for people who work with patients in nuclear medicine. These regulations are for all forms of radiation combined, so they are not only for plutonium.

Workers

5 rem/year for workers in industries where exposure to radiation may occur and 0.5 rem for the pregnancy period following the declaration of pregnancy by a woman in an industry where exposure to radiation may occur.