Fact Sheet – Radionuclides

Estimated Population At Risk At Identified Sites: 3.3 Million People*

Estimated Global Impact: 5 to 8 Million People*


What Are Radionuclides?

A radionuclide is as an atom with an unstable nucleus. Radionuclides occur naturally in soil and rocks as a consequence of radioactive decay. When materials decay, they emit radiation and eventually disintegrate over time. Radioactive materials cannot be treated, and only lose their harmful effect when they have finished decaying. Because this can take millennia, these materials must be stored appropriately to reduce exposure to humans and prevent migration.


What Are Radionuclides Used For?

Radionuclides occur naturally in the environment, although some of the more harmful types are released through industrial processes. Radionuclides are used for a variety of purposes for both their chemical properties and as sources of radiation. For example, radioisotopes are used in biomedicine in the diagnosis, treatment, and research of diseases. Additionally, in the field of genetics, radionuclides allow scientists to label molecules and study processes such as DNA replication. Other applications include material tests and controls (e.g. in the metalurgical or aviation industry). Radionuclides are also used for energy and weapons production. These latter uses are more commonly the source of problematic environmental releases.


How Are Radionuclides Released Into The Environment?

Radionuclides can either occur naturally (e.g. ores, radon gas in granite) or are released into the environment through accidents, weapon use, or poor waste disposal and abandonment. At some mining sites, ores such as uranium are taken for their radioactive properties and industrial uses. The waste tailings from such mines can contaminate disposal sites and migrate through dust and water. Once unearthed, these ores are often discarded without proper actions to prevent the spread of radiation. This is a particular problem in Eastern Europe and Central Asia.


How Do Radionuclides Reach Humans?

If radionuclides are released into the environment, they can migrate through dust and water to spread from the original source. They can then either irradiate the body from the outside or be incorporated by ingestion or inhalation.


What Health Risks Can Radionuclides Cause?

When ionizing radiation strikes a living organism, it may injure the organism’s cells. The effects of radionuclides depend on the type and exposure level. Different tissues in the human body can be damaged by ionizing radiation in different ways. Sometimes the damage is of a degree that cannot be repaired or is too severe or widespread. Mistakes made in the body’s repair process can lead to cancerous cells. Lung, stomach, and bone cancer have all been associated with exposure to radiation.


*Population estimates are preliminary and based on an ongoing global assessment of polluted sites.

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