Radiation is a naturally occurring form of energy. Everyone is exposed to small amounts of radiation, but exposure to very high doses may cause serious illness and death.
Radiation is a form of invisible energy given off by atoms, which are the tiny particles that make up chemical elements. Radiation is energy that moves in the form of waves or high-speed particles. Radiation occurs naturally in the environment in sunlight. The power of radiation has been harnessed by man to be used for the benefit of society as in energy produced by nuclear power plants and in medicine where x-rays are used to diagnose disease and injury and radiation therapy is used to treat people diagnosed with cancer. Radiation is used in everyday household products such as cellular phones and microwave ovens. Radiation can also be used as a means of social and geopolitical control such as nuclear weapons and bioterrorism.
There are two types of radiation, non-iodizing radiation and iodizing radiation.
Non-ionizing radiation does not change the structure of an atom. Instead, it excites molecules and shakes them up. Natural sunlight, sun lamps, microwave ovens, radios, and televisions are sources of non-ionizing radiation. Non-ionizing radiation usually does not cause tissue damage.
Ionizing radiation is the more energetic form of radiation that can change the structure of an atom. Exposure to ionizing radiation can increase the risk for cancer and cause illness because it can damage molecules within the cells of the body, prevent the cells from functioning properly, and destroy those cells. Naturally occurring ionizing radiation comes from distant parts of the universe and from the sun. Radon, which is a colorless, odorless, radioactive gas, provides most of the background radiation on earth. Medical x-rays are a source of human-made ionizing radiation. Other sources of radiation are radioactive elements, which are used in medical research, nuclear power plants, and nuclear bombs.
Radiation sickness occurs when living beings (humans or animals) are exposed to very large doses of ionizing radiation.
Radiation is around people naturally in the form of sunlight. People are exposed to small amounts of radiation when they use everyday household products such as microwave ovens, cellular phones, electric blankets, remote controllers, autofocus cameras, video monitors, televisions, laser printers, tanning lamps and beds, laser toys and devices, WiFi routers, computers, printers and other devices with wireless connections, and digital display equipment.
When being diagnosed and treated for disease or injury, people are exposed to varying amounts of radiation when they have x-rays, mammograms, laser therapy, and various forms of radiation therapy.
Radiation exposure can occur acutely as a single large exposure or chronically as a series of small exposures spread over time. Exposure can be accidental such as occurred at Three Mile Island and Chernobyl or intentional as when a person receives radiation therapy for cancer.
People who work in occupations that place them close to radioactive materials are at increased risk for radiation exposure. Some occupations that increase the possible risk to radiation exposure are those who work in nuclear power plants, where x-rays are done, where radiation therapy is administered, and in areas that use radioactive materials in production or research.
Both small and large doses of certain types of radiation are used in health care. For example, medical professionals use x-rays and CT scans (computed tomography) to diagnose illnesses, and radiotherapy (high doses of radiation targeted at tumors) to kill cancer cells.
Exposure to very high doses of radiation or long-term exposure to smaller amounts, however, increases the risk of injury or illness.
Damaging effects of radiation depend on:
Radiation sickness is more likely to occur when a person is exposed to very high doses of radiation over a short period of time. Overexposure to radiation may cause:
Signs of radiation sickness are nausea, vomiting, fatigue, diarrhea, hair loss, skin burns, internal bleeding, hemorrhage, central nervous system damage causing altered consciousness, and impaired organ function (such as the liver, kidneys, and brain).
The following are strategies to limit exposure to radiation in people who may be at risk:
See also Bioterrorism Agents: Overview • Cancer: Overview • Cataracts • Immune System and Other Body Defenses: Overview • Leukemia • Lung Cancer • Malignant Melanoma • Thyroid Disease
Doyle, Kathryn. “Long-Term Low-Dose Radiation Exposure May Increase Leukemia Risk.” Scientific American. July 10, 2015. http://www.scientificamerican.com/article/study-of-300-000-workersw-many-years-of-exposure-to-low-doses-of-radiation-were-found-tohave-an-risk-of-dying-from-leukemia/ (accessed April 5, 2016).
Ochiai, Eiichiro. Hiroshima to Fukushima: Biohazards of Radiation. New York: Springer, 2013.
Povinec, Pavel P., Katsumi Hirose, and Michio Aoyama. Fukushima Accident: Radioactivity Impact on the Environment. Philadelphia: Elsevier, 2013.
Centers for Disease Control and Prevention. “Radiation and Your Health.” http://www.cdc.gov/nceh/radiation/default.htm (accessed April 5, 2016).
Frontline. “Nuclear Reaction: Why Do Americans Fear Nuclear Power?” PBS. http://www.pbs.org/wgbh/pages/frontline/shows/reaction/ (accessed November 15, 2015).
MedlinePlus. “Radiation Exposure.” U.S. National Library of Medicine, National Institutes of Health. https://www.nlm.nih.gov/medlineplus/ radiationexposure.html (accessed April 5, 2016).
U.S. Environmental Protection Agency. “Radiation Protection.” http://www2.epa.gov/radiation/ (accessed April 5, 2016).
American Cancer Society. 250 Williams St. NW, Atlanta, GA 30303. Toll-free: 800-227-2345. Website: http://www.cancer.org (accessed April 5, 2016).
Centers for Disease Control and Prevention. 1600 Clifton Rd., Atlanta, GA 30329. Toll-free: 800-232-4636. Website: http://www.cdc.gov (accessed April 5, 2016).
National Institutes of Health. 9000 Rockville Pk., Bethesda, MD 20892. Telephone: 301-496-4000. Website: http://www.nih.gov (accessed April 5, 2016)
U.S. Environmental Protection Agency. Radiation Protection Division. 1200 Pennsylvania Ave. NW (MC 6608T), Washington, DC 20460. Telephone: 202-343-9290. Website: http://www.epa.gov (accessed April 5, 2016).
World Health Organization. Avenue Appia 20, CH 1211 Geneva 27, Switzerland. Telephone: 41-22-791-2111. Website: http://www.who.int/ionizing_radiation/en . (accessed April 5, 2016).
* melanoma is the most serious and potentially deadly form of skin cancer. The most important risk factor related to the development of melanoma is the amount of exposure to ultraviolet radiation. People with blonde or red hair, light-colored eyes, fair complexions which burn or blister easy with sun exposure, and who have had excessive sun exposure during their childhood and teen years are at highest risk for the development of melanoma. Other risk factors include having a family history of melanoma and having more than 100 moles on the body (50 moles if under age 20 years).
* cataract is a condition in which the lens of the eye (or both eyes) become progressively less transparent, or becomes cloudy, leading to blurring of the vision. Usually associated with the aging process, in most people, exposure to ultraviolet radiation as a result of indoor tanning can result in the development of cataracts in much younger people.