Antoine Henri Becquerel, a French scientist, first discovered radiation emanating from an element in 1896. He was examining X-rays by photographing uranium crystals. Becquerel believed that the uranium was absorbing energy from the sun and then emitting X-rays. However, the phenomenon could be observed even when the uranium was not exposed to sunlight. The photographs were not the result of X-rays, but rather the emission of gamma rays from the radioactivity of uranium.(1)

Gamma rays and X-rays are identical in nature. The different names simply have to do with the origin of X-rays from electron tubes and of gamma rays from disintegrating nuclei of radioactive elements. Later, it was observed that uranium emitted not only gamma radiation, but also particles. It was found that uranium was mixed in with other elements called decay products; some emitted heavy particles (called alpha particles, later identified as helium nuclei) and others lighter particles (called beta particles, later identified as electrons).

After these discoveries at the end of the nineteenth century, scientists began to explore these phenomena and their applications, often in a cavalier manner, common at that time. At first, the dangerous effects of certain forms of radiation were unknown; highly radioactive substances were used in a variety of applications. But attempts to use X-rays in medical applications produced early evidence of cancers among medical practitioners caused by repeated exposure to X-rays. In another well-known example, World War I clock and instrument dials were painted with radium-226 to make them luminescent. The "dial painters" unfortunately ingested substantial quantities of radium by licking their brushes in order to make the most precise markings possible on the clock. The link between the alpha-radiation from the radium that the dial painters were exposed to and the illnesses they contracted was established in the 1920s. The amount of radium-226 in the bones of the victims was a small fraction of a milligram (a milligram is a thousandth of a gram).

X-rays and radiation also have had some beneficial effects over the last century. As science has come to better understand its effects, modern medicine has made many uses of radiation in research and treatment. Radio-iodine has been used until recently as a diagnostic tool, especially in treating thyroid problems. X-rays continue to be used extensively in diagnostics. However, practices using X-rays, radium, and radon (a radioactive decay product of uranium-238) for supposed medical treatment which amounted to quackery and which flew in the face of the well-established evidence of the dangers of radiation, persisted well into the twentieth century. Radio-iodine was also discharged as a result of military plutonium production and of atmospheric nuclear testing, increasing cancer and other risks to exposed people.

Since the 1940s, the history of radiation has been linked to both nuclear power and nuclear weapons. Nuclear power, while generating electricity, also creates radioactive waste. There is also a finite probability of catastrophic accidents, as demonstrated by the Chernobyl accident. Nuclear reactors operate by splitting heavy elements like uranium into lighter elements and releasing energy in the process (fission). Many of the products of fission are highly radioactive. Nuclear weapons testing has released a large amount of radioactive material into the air, water, and land. The nuclear weapons industry has also created radioactive wastes. There is as yet no generally accepted method of disposing of long-lived highly radioactive wastes.

March 1, 1896: Becquerel discovers radioactivity

January 3, 1901: First report of death due to X-rays

September 12, 1922: First radium-related dial painter death

Late 1938: First detection of nuclear fission. Experimentally confirmed by Frisch on January 13, 1939.

February 25, 1941: Discovery of plutonium

December 2, 1942: First controlled nuclear chain reaction

July 16, 1945: The first nuclear explosion (the Trinity Test) at the Alamogordo Bombing Range in New Mexico

August 6, 1945: Bombing of Hiroshima

August 9, 1945: Bombing of Nagasaki

July 1946: First post-World War II nuclear weapons tests at Bikini.

August 29, 1949: Soviet Union detonates its first nuclear weapon

December 8, 1953: Eisenhower announces the Atoms for Peace Program

August 8, 1955: First UN Conference on peaceful uses of Atomic Energy

1956: Calder Hall reactor, the world's first commercial electricity generating station begins operation, at Windscale site in northern England. It is also used for making plutonium for weapons.

October 10-11, 1957: Fire at a nuclear reactor at Windscale

December 2, 1957: Shippingport (first US power reactor) begins operating

1967: U.S. nuclear arsenal reaches its peak at 32,500

March 28, 1979: Three Mile Island, Pennsylvania Accident

1986: Russian nuclear arsenal reaches its peak at 45,000.

April 26, 1986: Chernobyl Accident spreads radioactive fallout over a large region.

1994: Active US and Russian nuclear stockpiles at approximately one-third of their peak levels.

Notes:

1. Effective whole body dose from a single chest X ray: approximately 10 mrem (0.15 mSv).
2. Estimate of medical X-ray procedures in 1990: between 260 and 330 million
3. Number of medical tests and studies using radioactive materials in 1987: 7 690 000
4. These figures do not reflect the large doses obtained by certain groups of people such as radiation workers in nuclear weapons plants. Of particular note also should be the high exposures received from various sources during the 1940s and 1950s by needless X-rays from machines of poor quality. Prominent among these were chest X-rays given to children from mobile machines. Most of the carcinogenic consequences of such exposures would have begun manifesting themselves only from the 1970s onward.

Alpha Radiation: Energetic helium nuclei (two protons and two neutrons) emitted from the nucleus of a heavier element in the process of radioactive decay of the element.

Beta Radiation: Energetic electrons or positrons (particles identical to electrons, but with a positive electrical charge) from the nuclei of an element in the process of radioactive decay of the element.

Gamma Radiation: Electromagnetic waves, released during radioactive decay, that can ionize atoms and split chemical bonds. Gamma rays are similar to X-rays, the latter term being applied usually to electromagnetic waves emitted by electron accelerators, as for instance in medical equipment.

Return to SDA Vol. 4 No. 3 Main Page
Return to SDA Main Page
Return to IEER Home Page

Institute for Energy and Environmental Research

Comments to Outreach Coordinator, ieer@ieer.org
Takoma Park, Maryland, USA

Last updated: August, 1996

1. "Centennial Calendar: X Rays 1895-1995 Radioactivity 1896-1996." Health Physics Society.

2. Main Source for radiation-related information: "Centennail Clendar: X Rays 1895-1995 Radioactivity 1896-1996." Health Physics Society. For additional sources, contact IEER for a copy of the back issue of this newsletter.