X-rays, Gamma Rays, and Cancer Risk

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Other sources of man-made radiation

People may also be exposed to ionizing radiation from other man-made sources.

Nuclear weapons

The atomic bombs dropped on Nagasaki and Hiroshima, Japan exposed many people to radiation from x-rays, gamma rays, and neutrons. Some people died fairly quickly as a result of burns and radiation sickness, but many survived. The survivors were exposed to different amounts of radiation, depending largely on how far they were from the explosions. Only about 2% of the survivors were exposed to high amounts of radiation (1000 mSv or more), while almost one-third were exposed to doses that are relatively low (less than 5 mSv). Much of the information that we have about radiation and cancer risks comes from studies of more than 105,000 of the survivors.

The United States government conducted above-ground nuclear tests in the South Pacific and in the state of Nevada between 1945 and 1962. Other countries also conducted above-ground tests. Many people in the military at the time were part of training exercises in the area and were exposed to ionizing radiation from these tests. Others were exposed to radiation while working at facilities making the bombs or at other nuclear sites.

Non-military people living near or downwind of nuclear test sites may have also been exposed to radioactive byproducts. Levels of radiation are likely to be higher near these sites, but some radioactive particles from the tests entered the atmosphere and traveled great distances, landing thousands of miles away from the original site. While exposure levels were likely to be higher at the time of testing, some radiation in the soil today is the result of these tests.

Programs have been set up to give financial support to people who were exposed to nuclear weapons testing and developed cancer. More information on this topic is available in our document Cancer Compensation Programs for People Exposed to Radiation as a Part of Nuclear Weapons Testing.

Nuclear power plants

Emissions of radiation from nuclear power plants are carefully monitored and controlled. According to the Environmental Protection Agency (EPA), nuclear power plant operations account for less than one-hundredth (1/100) of a percent of the average American’s total radiation exposure.

Nuclear power plant accidents: Accidents at nuclear power plants are rare, but they have the potential to expose people to high levels of radiation.

In 1986, an accident at the nuclear power plant at Chernobyl (in Ukraine) exposed millions of people living in the area to radiation, either directly or from radioactive elements released into the air that ended up deposited on the ground. The emergency clean-up workers were exposed to the highest levels of radiation. Although the average dose to clean-up workers was about 100 mSv, some were exposed to very high doses – more than 1000 mSv. The average doses to people living in the area (some of whom were evacuated) ranged from 10 to 50 mSv.

In 2011, an earthquake and tsunami struck the coast of Japan that resulted in damage to the Fukushima Dai-ichi Nuclear Power Plant in Fukushima Prefecture, Japan. Radiation was released into the air, contaminating soil, food, and water (both fresh and seawater). Within the plant, radiation levels reached as high as 10,000 mSv per hour early on. An area of more than 300 square miles around the plant was also found to be contaminated with radiation, although at lower levels than within the plant. Because of high radiation levels, many areas were evacuated. The health effects of this disaster are still being studied.

Workplace exposures

Some people can be exposed to radiation at work. For example:

  • People who work in nuclear power plants may be exposed to higher levels of radiation than the general public, although their exposure levels are monitored carefully.
  • People who work in uranium mines are monitored because of their exposure to radiation in the form of radon.
  • People who work in health or dental care, particularly those who work with x-ray (or other imaging test) equipment or who work with radioactive isotopes, may also be exposed to radiation at work. Radiation exposure may also occur at some research labs.

In the United States, people who are likely to be exposed to radiation in the workplace are monitored carefully. Exposure is limited to an effective dose of 100 mSv over 5 years, with a maximum of 50 mSv in any single year.

Consumer products

Some consumer products contain small amounts of ionizing radiation.

For example, tobacco products contain low levels of radiation, which may come from the soil it’s grown in or the fertilizer used to help it grow. Tobacco may account for a significant portion of the yearly radiation that smokers are exposed to.

Some building materials used in the home or other structures may contain low levels of naturally occurring radiation. The amount of radiation can vary depending on what they’re made of, but the levels are unlikely to contribute much to a person’s overall exposure to radiation, according to the EPA.

Many smoke detectors contain a small amount of a very low-level radioactive material that helps detect the smoke. This material is sealed in a container and does not pose a significant risk of radiation exposure.

Food irradiation

Ionizing radiation can be used to kill bacteria and other germs on certain foods, which may make them safer to eat and help them last longer. Some people may be concerned that irradiated food may itself contain radiation.

It’s important to understand that the radiation does not stay in the food. According to the United States Department of Agriculture (USDA), irradiating food does not cause it to become radioactive and does not change nutritional value of the food any more than cooking or freezing it might.

Airport security scanners

In recent years, some airports have begun to use whole body scanners as a way to detect objects hidden by clothing. These scanners are different from the metal detectors most people are familiar with.

One type of body scanner, based on backscatter technology, uses very weak x-rays aimed at the surface of the body to capture a whole body image. The Transportation Security Administration (TSA) says the radiation from such a scan is about the same amount a person gets from cosmic rays during 2 minutes in an airplane in flight. A person would need to get more than 1,000 backscatter scans in a year to reach the same dose they’d get from a standard chest x-ray, according to the American College of Radiology (ACR).

The other type of body scanner is based on millimeter wave technology. Neither millimeter wave scanners nor metal detectors expose people to x-rays or gamma rays.


Last Medical Review: 05/02/2013
Last Revised: 04/18/2014