May 1, 2011

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Radiation Sources Range from Cigarettes to CT Scans

How many millisieverts are you getting? A special online-only addition to May 2011's Graphic Science

By Mark Fischetti

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Japan's Fukushima Daiichi nuclear reactor accident has focused new attention on how much ionizing radiation people are exposed to from different sources (see list below). By far the largest source is medical imaging technology (see "Graphic Science: Exposed" in the May 2011 issue). Americans, on average, are exposed to 3.1 millisieverts of radiation a year from natural background factors such as radon gas from the Earth and cosmic rays from the universe. Safety experts recommend the public receive less than one millisievert a year beyond that level, although they do not include medical procedures in that limit because the procedures may bring health benefits. Here's a list of common sources.

Average Radiation Dose to Entire Body (millisieverts)

Natural background (U.S.) per year: 3.1

Airport scanner (backscatter method): 0.0001

Natural gas cooking per year: 0.0004

Arm x-ray: 0.001

Bone density x-ray: 0.001

Highway travel per year: 0.004

Dental x-ray: 0.005

Domestic airline flight (five hours): 0.017

Smoking one pack of cigarettes per day for a year: 0.36

Mammogram: 0.4

Fukushima emergency workers per hour: 1.0

Brain CT scan: 2.0

Thyroid scan (nuclear medicine): 4.8

Brain scan(nuclear medicine): 6.9

Pelvis CT scan: 10

Coronary CT angiography: 16

Astronaut on space station for one year: 72 Sources: National Council on Radiation Protection and Measurements; RadiologyInfo.org

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Mark Fischetti was a senior editor at Scientific American for nearly 20 years and covered sustainability issues, including climate, environment, energy, and more. He assigned and edited feature articles and news by journalists and scientists and also wrote in those formats. He was founding managing editor of two spin-off magazines: Scientific American Mind and Scientific American Earth 3.0. His 2001 article “Drowning New Orleans” predicted the widespread disaster that a storm like Hurricane Katrina would impose on the city. Fischetti has written as a freelancer for the New York Times, Sports Illustrated, Smithsonian and many other outlets. He co-authored the book Weaving the Web with Tim Berners-Lee, inventor of the World Wide Web, which tells the real story of how the Web was created. He also co-authored The New Killer Diseases with microbiologist Elinor Levy. Fischetti has a physics degree and has twice served as Attaway Fellow in Civic Culture at Centenary College of Louisiana, which awarded him an honorary doctorate. In 2021 he received the American Geophysical Union’s Robert C. Cowen Award for Sustained Achievement in Science Journalism. He has appeared on NBC’s Meet the Press, CNN, the History Channel, NPR News and many radio stations.

More by Mark Fischetti

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