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Fact Sheet - Radionuclides

Population at risk: 22 million people*
Estimated DALYs: not available

*Estimate includes 800k to 1 million at risk based on point source exposure to radionuclides derived from 91 identified sites in the Toxic Sites Identification Program.

Radionuclides are so called as they undergo a process known as radioactive decay. Some of them occur naturally in soil and rocks, while man has artificially created others. Radionuclides are atoms with an unstable nucleus. Radioactive decay occurs as a result of the unstable nucleus’s desire to become a stable nucleus. This process primarily occurs through disintegration and releases of excess energy in the form of radioactive particles and radiation. These radioactive elements will decay at a fixed rate, known as a half-life. A half-life is the length of time it will take for half of the unstable material to degrade into a more stable form. The length of the half-life depends upon the element and isotope, which can range from fractions of a second to millions of years. 

The type of radiation emitted from this process also varies with the main categories of radiation that can be emitted including alpha, beta, gamma and neutron radiation. Under normal circumstances, the only way to reduce the radioactivity of a radioactive material and its associated harmfulness is through the natural decay process. As a result, it can take long spans of time for exposure levels to certain radioactive materials to be considered safe, necessitating proper storage and handling precautions during this time.

Radioactive materials are classified into two classes: high-level and low-level.1 High-level materials are primarily the result of fuel used by a reactor to produce electricity or weapons materials, while low-level materials are those with a short half-life or have been contaminated with nuclear materials. Similarly, radionuclides can be divided into the two-categories of “heavy” or “light”. Heavy radionuclides, also known as unstable nuclides, are elements having over 83 protons in their nuclei. Conversely, light nuclides include elements that have fewer than 83 protons in their nuclei.2

Some types of radioactive materials include clothing used in the nuclear industry, medical materials and equipment from inside reactors. The more common, large-volume sources of radioactive wastes, however, are from uranium mining and use of nuclear reactors. Uranium-238, the most common isotope of uranium found in nature, will also naturally decay to radium-225, which has a half-life of 1,600 years.3 The latter will decay to radon gas, which poses an exposure risk in some areas of the world even in well-insulated homes. Other common (artificial and natural) radionuclides are cesium-137, strontium-90, cobalt-60, plutonium, technetium-99 and thorium.4

Radionuclides have been beneficially used in a range of medical and scientific applications. For example, they have been used to diagnose, treat and research diseases in the biomedical industry. Gamma emitting radionuclides have also been use as tracers to monitor organ functions while other radionuclides, such as radium and radon, have been used to treat certain cancers.5 Other radionuclides have been used to label models and study certain biological processes, such as DNA replication. However, the main application of radionuclides today is for their use in energy production and weapons industry.

Pure Earth estimates that between 800,000 and 1 million people are at risk for exposure to radionuclides at 91 sites involving the mining and processing of uranium globally (identified through the Toxic Sites Identification Program (TSIP). As radionuclides are comprised of a heterogeneous set of materials, we do not present a burden of disease estimate. As of 2015, TSIP has confirmed these sites pose a threat to the health of the population exposed.

However, it must be noted that our estimate of the population affected by radionuclides only includes those that may have their physical health impacted at sites identified through the Toxic Sites Identification Program. A study conducted by Green Cross Switzerland, in conjunction with the University of Southern California Institute for Global Health with cooperation from local partners, estimates that the physical and psychological well-being of over 10 million people continues to be affected by repercussions stemming from the Chernobyl nuclear disaster.6 This study systematically reviewed published research along with input from focus group findings to determine the extent of physical and psychological effects from this single incident. Future studies hope to elucidate the number of individuals similarly affected by other nuclear incidents such as that which occurred at the Fukushima Daiichi Power Plant on March 11th, 2011.  A similar literature review conducted by Green Cross Switzerland through the University of Southern California estimates that up to 385,000 individuals suffered psychological consequences from this incident.7 These incidents must be taken into account to fully understand the burden of disease resulting from the threat of radionuclide exposure. 

Furthermore, there is an additional population at risk of exposure to radionuclides via low-dose background radiation, and those personnel in the nuclear industry. Beginning with the development of the nuclear industry since the 1950’s, it is estimated that millions have been exposed to elevated levels of man-made radiation.8 Studies have shown such background radiation to cause an increase in infant morality, cancer rates and low-birth weights.9,10 Low radiation doses may also result in an increase frequency of mutations in chromosomes and genes in human somatic, bone marrow and muscle cells.11,12,13 Globally, it is estimated that over 10 million nuclear personnel are exposed to additional anthropogenic ionizing radiation on a daily basis.14

Calculating the physical health risks and burden of disease associated with exposure to radionuclides is a complex undertaking that is both nuanced and difficult to model. For example, elemental mercury disability weights have not been established for radiation exposure. Additionally, exposure to radiation is dependent on both time and wavelength. Alpha particles cannot penetrate the skin but are very dangerous if ingested. Gamma particles are always dangerous, but levels can vary greatly based on relatively small spatial differences. Attempting to capture the myriad ways people are exposed to radiation at contaminated sites, and to further estimate the disease burden would be a significant undertaking. 

 “Radionuclides” is therefore very much a catchall category, capturing a heterogeneous set of materials. Thus, unlike elemental mercury and lead, we do not feel confident in generating a DALY value for radionuclides. Accordingly, we list radionuclides as a top threat, though do no provide a DALY value.


Pathways & Routes of Exposure

In general, exposure to these radioactive materials occurs from ingestion and inhalation or external radiation exposure. Wastes from uranium mining and processing can contaminate water bodies and nearby soils, particularly through leaks and industrial failures. Both uranium and radon exposures have been associated with inhalation, while radium exposure has been seen to occur as a result of food contamination.15 Exposure can also occur from excessive use of radiation during medical treatments. 


Health Effects

In general, there is no safe level of radiation exposure. Acute health effects from a single large dose include nausea, vomiting and headaches. Increased exposure to radiation can result in radiation poisoning. The health effects from radiation poisoning include fatigue, weakness, fever, hair loss, dizziness, disorientation, diarrhea, blood in stool, low blood pressure and death. However, some health effects have been noted to be associated with particular radionuclides. It should be noted that some radioactive materials have also a chemical toxicity, (e.g. uranium) and are heavy metals. For example, uranium exposure has been associated with kidney damage (related to heavy metals) and DNA damage (related to radionuclides).

Ionizing radiation exposure causes damage primarily to the cells. If enough cells are hit by radiation, cancer development may result. In fact, radon is classified as a human lung carcinogen with studies have indicating that inhalation of radon can lead to an elevated risk for leukemia and has been noted as the second leading cause of lung cancer death in uranium miners.16,17 Chronic exposure to radon has also been associated with a decrease in white blood cells, which are important for the maintenance of a functional immune system. 

Children are particularly susceptible to radiation exposure. As they grow, their cell counts increase, thereby providing more opportunities for the radiation to interfere with critical development processes. Radiation exposure in children can result in a series of adverse health effects, particularly on fetal development.  Exposure to radiation while in the womb has been shown to result in smaller head or brain size, poorly formed eyes, abnormal growth patterns or mental retardation.18

The psychological impacts resulting from exposure to radionuclides have been thoroughly studied at the site of the Chernobyl nuclear disaster that took place on April 26th, 1986.  Psychological effects of such nuclear disasters include that deriving from displacement and stigmatization. These psychological effects may manifest themselves as on-going psychological stress, post-traumatic stress disorder (PTSD), diminished well being and may contribute to depression, anxiety and suicidal ideations. 

Anxiety and PTSD may stem from health concerns, loss of a family member, destruction of the community and discrimination in both marriage and employment.19 Rescue and emergency workers are particularly susceptible to such stresses relating to blame for post-disaster mismanagement, a large additional burden for those likely having been exposed to radionuclides during the recovery work. Stigmatization largely affects young women, who worry they are viewed negatively based on assumptions about the effects of radiation on pregnancy.20

Additional studies have shown exposure or the perceived threat of exposure to radionuclides has significant psychological consequences in children, which may present themselves as hyperactivity disorders, emotional problems, as well as conduct and peer problems.21 These psychological impacts will continue to weigh on both current and future generations. 

1 United States Nuclear Regulatory Commission. “Background on Radioactive Waste.” Available at, April 12, 2007

2 U.S. Environmental Protection Agency. “Commonly Encountered Radionuclides.” Available at, October 1, 2010.

3 Agency for Toxic Substances and Disease Registry “Case Studies in Environmental Medicine. Radon Toxicity.” Public Health Service, U.S. Department of Health and Human Services, 1992.

4 U.S. Environmental Protection Agency. “Commonly Encountered Radionuclides.” Available at, October 1, 2010.

5 U.S. Environmental Protection Agency. “Radionuclides (Including Radon, Radium and Uranium).” Available at, November 6, 2007.

6 Samet J, Patel S. Selected health consequences of the Chernobyl disaster: A further systematic literature review. Focus Group Findings, and Future Directions. 2013

7 JM, Director U, Chanson D. Fukushima Daiichi power plant disaster.

8 Yablokov A. A review and critical analysis of the .Effective dose of radiation. concept. Journal of Health and Pollution. 2013;3(5):13-28

9 Gould JM. The enemy within: The high cost of living near nuclear reactors: Breast cancer, AIDS, low birthweights, and other radiation-induced immune deficiency effects. Four Walls Eight Windows; 1996

10 Petrushkina N, Koshurnikova N, Kabirova N, Kuropatenko E, Zyrianov A, Brokhman S. Child mortality in Snezhinsk and Ozersk cities from the 1974-1995: Children registry and death rates in young population of the cities of Ozyorsk and Snezhinsk. . 1998:21-24

11 Livingston Kea. Radiobiological evaluation of immigrants from the vicinity of Chernobyl. Int J Radiat Biol. 1997;72(6):703-713

12 Cristaldi M, Ieradi L, Mascanzoni D, Mattei T. Environmental impact of the Chernobyl accident: Mutagenesis in bank voles from Sweden. Int J Radiat Biol. 1991;59(1):31-40

13 Goncharova R. Remote consequences of the Chernobyl disaster: Assessment after 13 years. Low doses of radiation: are they dangerous. 2000:289-314

14 Yablokov A. A review and critical analysis of the .Effective dose of radiation. concept, part II-an approach to an objective assessment of human radiation risk. Journal of Health Pollution. 2014;4(7):62-74

15 U.S. Environmental Protection Agency. .Radionuclides (Including Radon, Radium and Uranium).. Available at, November 6, 2007.

16 M. Al-Zoughool and D. Krewski. .Health Effects of Radon: A Review of the Literature.. International Journal of Radiation Biology. 85.1 (2009): 57-69.

17 B. Vacquier, et al. .Mortality Risk in the French Cohort of Uranium Miners: Extended Follow-up, 1946-1999.. Occupational and Environmental Medicine. 65.9 (2008): 597-604.

18 U.S. Environmental Protection Agency. .Radiation Protection: Health Effects.. Available at, August 28, 2008.

19 Kamiya K, Ozasa K, Akiba S, et al. Long-term effects of radiation exposure on health. The Lancet. 2015;386(9992):469-478

20 Glionna J. A year after tsunami, a cloud of distrust hangs over japan: The Fukushima nuclear disaster has left residents doubting their government, their source of energy, even the food they eat. Los Angeles Times. 2012;11

21 Hasegawa A, Tanigawa K, Ohtsuru A, et al. Health effects of radiation and other health problems in the aftermath of nuclear accidents, with an emphasis on fukushima. The Lancet. 2015;386(9992):479-488

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