Skip to main content

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 Radiation Nonionizing Radiation
Gamma rays Visible light
X-rays Infrared rays
UV rays (high-energy) Microwaves
Sub-atomic particles Radio 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
  • Workplace environment, such as uranium mines
  • Radiation from nuclear disasters
External Radiation of a Cancerous Growth
Radiation of Tumor
Copyright © Nucleus Medical Media, Inc.

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:


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 from you so it will stop damaging your cells. 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. But the best prevention is to stay away from radiation sources.

Revision Information

  • Centers for Disease Control and Prevention

  • Radiation Emergency Medical Management—US Department of Health and Human Services

  • BC Centre for Disease Control

  • Health Canada

  • Brenner DJ. Should we be concerned about the rapid increase in CT usage? Rev Environ Health. 2010;25(1):63-68. Review.

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

  • Frequently asked questions on potassium iodide (KI). United States Food and Drug Administration website. Available at: Updated October 27, 2014. Accessed May 27, 2015.

  • Gross whole-body contamination. United States Department of Health and Human Services website. Available at: Updated November 21, 2014. Accessed May 27, 2015.

  • How to perform a survey for radiation contamination. United States Department of Health and Human Services website. Available at: Updated November 21, 2014. Accessed May 27, 2015.

  • Potassium iodide (KI). Centers for Disease Control and Prevention website. Available at: . Updated October 10, 2014. Accessed May 27, 2015.

  • Radiation emergency medical management: choose appropriate algorithm—evaluate for contamination and/or exposure. United States Department of Health and Human Services website. Available at: Updated November 21, 2014. Accessed May 27, 2015.

  • Radiation exposure and cancer. American Cancer Society website. Available at: . Accessed May 27, 2015.