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Somewhere between about 13,695 and 16,390 Americans have died or are yet to die as a result of fallout from nuclear weapons testing by this country and other nations, based on a report by three experts from the National Cancer Institute.

The report does not present a total tally, but the general numbers given add up to that range.

Around 49,000 cases of thyroid cancer — possibly 5 percent to 10 percent of which may prove fatal — can be attributed to ingesting radioactive iodine particles released by atomic bomb tests of the 1950s and '60s at the Nevada Test Site. A main route for this internal exposure would be iodine picked up by grazing cattle, which went into milk.

The report, "Fallout from Nuclear Weapons Tests and Cancer Risks," printed in American Scientist magazine, says almost all these thyroid cases would be in people who were under age 20 for at least part of the period 1951-57. That is because age at exposure plays a role in cancer.

About 4,900 additional U.S. cases of thyroid cancer may be due to global nuclear testing, bombs set off by the former Soviet Union, France, England and China, says the report in the magazine's January-February issue. (If the 5 to 10 percent fatality rate holds true for these, deaths would be 245 to 490.)

By comparison, without fallout, about 400,000 thyroid cancers could have been expected among Americans alive at that time, it adds.

For external radiation exposure, which does not count cancer caused by radioactive iodine in milk, 22,000 cancers are expected, about half of them fatal. These were attributed both to NTS fallout and global fallout.

An estimated 1,800 leukemia deaths caused by external exposure, from both domestic and foreign fallout, are part of the tally.

For perspective, the numbers of fallout cancers and deaths are small compared with the huge toll that cancer takes anyway. About 1.5 million leukemia deaths might be expected among Americans who were alive in 1952, compared with the 1,800 deaths caused by fallout.

Cancer is so common that 42 percent of Americans will have the affliction sometime in their lives, which would amount to about 60 million people among America's population in 1952 (when bombs were going off above ground at the NTS), it adds. Around 25 percent of the cancers are expected to be fatal, according to the report.

The report also cites research by University of Utah scientists into the relationship between fallout and cancer.

Authors of the article are Steven L. Simon, Andre Bouville and Charles E. Land, all of the National Cancer Institute, which is based at Bethesda, Md. The NCI is part of the National Institutes of Health, U.S. Department of Health and Human Services.

The report draws upon decades of research on the physics of fallout, so it is not completely new, Simon said. But he added that it does offer relatively new material, including distribution of fallout across the United States and cancer risks. That information was not widely known and resulted from the institute's research.

Among facts cited by the report are that while fallout exposures happened 50 to 60 years ago, so far only about half the number of expected cancers have shown up. That's because some cancers have lengthy dormancy periods before they are detected.

The number of fallout-caused cancer deaths in a low-population region, such as Washington County, may seem relatively few because not many people lived there then, according to Simon.

But the report shows how fallout spread throughout the country. The report says fallout decreased with distance from the NTS, and the prevailing wind was from west to east.

One map shows four different wind patterns for the 43-kiloton SIMON nuclear bomb test of April 25, 1953.

The lowest winds tracked, at 10,000 feet, swept through Nevada, over the Great Salt Lake and then east, crossing the Delmarva Peninsula and heading over the Atlantic Ocean on April 28. The highest-level wind, at 40,000 feet, went through northern Texas and veered northeast, traveling through many Eastern states before drifting into Canada.

Another factor involved rainstorms as global fallout was more likely to descend from clouds if rain fell. For one period studied, early 1951, deposition of Cesium-137 from global fallout was higher in northwestern Utah than in most of the southern part of the state.

It also shows the deposition of global fallout in several Western and Midwestern states and the entire country east of the Mississippi.

However, maps of distribution of fallout from the Nevada Test Site display different patterns.

One showing total doses to the red bone marrow of people born on Jan. 1, 1951, from all NTS tests, has highest levels in west-central Nevada, southeastern Utah, part of northern Utah, a section of Colorado and two spots in central Idaho.

Another map, showing total external and internal doses to the thyroid glands of adults in 1951 caused by fallout from all Nevada tests, shows the hottest spot in Nevada, with the next hottest splashed across the country and covering most of Nevada, all of Utah, most of Colorado, and parts of Wyoming, Idaho, Montana and states in the Midwest. Other relatively hot spots show up on the Gulf Coast, New England and the area where Kentucky, Ohio and West Virginia meet.

Internal doses from global fallout were "considerably smaller" for the thyroid but greater for red bone marrow than those from NTS fallout, the report says. Exposure to the thyroid could cause thyroid cancer, while red bone marrow exposure could cause leukemia.

In addition, the report mentions the "extremely high-dose fallout exposures experienced by 82 residents of the Marshall Islands" following one American test dubbed BRAVO, which happened in 1954.

Understanding the risks and patterns of fallout in the past could help Americans in the future, should they be called upon to face nuclear terrorism, the authors say.

The report "really synthesized many years of work and many people's findings and efforts," Simon told the Deseret Morning News in a telephone interview. (He also discussed the matter by e-mail.)

"This is not an alarmist paper in any way," he added. In addition, he emphasized that the numbers are "very approximate . . . ."

"It can be said that this represents our best understanding to date."

Simon added, "The bottom line was not the number of cancers that will occur. The bottom line was communicating . . . an understanding about fallout."