Radiation Exposure



Radiation is energy that is sent out from a source. Radiation exposure is when a person is exposed to this energy.

There are different forms of radiation. Some come from nature and some are manmade. There are the ultraviolet (UV) rays from the sun. There is also the radiation used in microwaves to heat food. Radiation is divided into:

  • Ionizing radiation—a high-frequency radiation that is able to damage cells, has also been linked to cancer and other health problems
  • Nonionizing radiation—low in frequency and is not known to cause cancer (except for UV rays)
Ionizing RadiationNonionizing Radiation
Gamma raysVisible light
X-raysInfrared rays
UV rays (high-energy)Microwaves
Sub-atomic particlesRadio waves
UV rays (low-energy)

This fact sheet will focus on ionizing radiation.


A person can be exposed to ionizing radiation from:

  • X-rays
  • Radiation therapy used to treat certain types of cancer
  • Radioactive elements in the soil or public works systems, such as the water supply
  • Occupational exposures in workplaces, such as uranium mines
  • Radiation from nuclear disasters
External Radiation Therapy for Cancer
Radiation of Tumor
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Risk Factors

You are at risk for radiation exposure if you are near sources that generate it.

Ionizing radiation has been linked to health problems, but not all people who are exposed develop problems. For example, having a chest x-ray does expose you to some radiation, but the dose is low and your risk for health problems is low. Other tests, like CT scans, expose you to higher doses. Health effect risks from CT scans , while still small, are higher than the risk from a regular x-ray .

The greater the exposure, the more likely there will be health effects. For example, doctors treat some cancers with high doses of radiation. This not only kills cancer cells, but also healthy cells. Also, people exposed to large nuclear accidents can be injured by the high amounts of radiation.


There is also the risk of cancer. Cancer may take years to develop after you have been exposed to radiation. Some cancers linked with ionizing radiation exposure are:

  • Leukemia
  • Lung cancer
  • Skin cancer
  • Thyroid cancer
  • Multiple myeloma
  • Breast cancer in women and men
  • Stomach cancer



Over exposure that occurs accidentally, such as from nuclear accidents, can cause radiation sickness. Symptoms may include:

  • Nausea
  • Weakness
  • Hair loss
  • Diarrhea
  • Bleeding
  • Burns
  • Loss of organ functions


You will be asked about your symptoms and medical history. A physical exam will be done.

Your bodily fluids may be tested. This can be done with:

  • Blood tests
  • Stool tests
  • Urine tests

The amount of radiation absorbed by your body may be measured. This can be done using a radiation survey meter.



If you have been contaminated, the material will be removed to stop further cell damage. You may be bathed in lukewarm water and soap. Your radiation levels will also be monitored.

If you have radiation sickness, you will be monitored and treated closely while your body heals. Treatment depends on what parts of your body are damaged.

Radioactive iodine can be absorbed by your thyroid gland. This can injure the gland and lead to thyroid cancer. To block your body from absorbing this type of radiation, you may be treated with potassium iodine.


There are policies to prevent the public from dangerous levels of radiation. Safety measures are taken when it is used for medical treatment or is part of a work environment. Talk to your doctor about the necessity for medical or dental radiation procedures.

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

Edits to original content made by Denver Health.

a (Ionizing Radiation Exposure)


Centers for Disease Control and Prevention http://www.cdc.gov 

Radiation Emergency Medical Managemen https://www.remm.nlm.gov 


BC Centre for Disease Control http://www.bccdc.ca 

Health Canada http://www.hc-sc.gc.ca 


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Colang JE, Killion JB, Vano E. Patient dose from CT: a literature review. Radiol Technol. 2007;79(1):17-26.

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Radiation and potassium iodide (KI). Centers for Disease Control and Prevention website. Available at: http://emergency.cdc.gov/radiation/japan/ki.asp. Updated October 17, 2014. Accessed September 6, 2016.

Radiation emergency medical management: choose appropriate algorithm—evaluate for contamination and/or exposure. Health and Human Services website. Available at: https://www.remm.nlm.gov/newptinteract.htm#skip. Updated August 16, 2016. Accessed September 6, 2016.

Radiation exposure and cancer. American Cancer Society website. Available at: http://www.cancer.org/cancer/cancercauses/radiationexposureandcancer/index. Accessed September 6, 2016.