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Strontium-90 Found in Cow’s Milk in North Dakota


In 1957, Dr. Albert Schweitzer warned the world about the dangers of nuclear fallout from atomic-bomb testing. The humanitarian told of “radioactive particles” that “remained in the air” after nuclear-weapon explosions. Schweitzer said radioactive fallout drifted down to earth, “brought down by rain, snow, mist and dew little by little,” and got into the human body through contaminated food and water.

The Nobel Peace Prize winner identified Strontium-90 as one of the chief radioactive dangers found in nuclear fallout. Strontium is an earth-metal that turns radioactive in atomic-bomb explosions. Strontium-90 does not exist naturally; it only exists in nuclear fallout. Its half-life of 28 years makes it dangerous for 40 years, with the potential for causing bone cancer and death.

On this date in 1966, a United Press International news story, entitled “Radioactive Milk Creates U.S. Puzzle,” told of the lingering effects of Strontium-90 in cow’s-milk in North Dakota. It seems that radioactive dust containing Strontium-90 had drifted to the Northern Plains from above-ground nuclear testing in Nevada.

The Nevada Test Site, located northwest of Las Vegas, began nuclear-bomb tests in 1951, and scientists exploded nearly 100 nuclear bombs there through 1958. The government always made sure that the wind was blowing to the north or east, so that the fallout would not drift over Los Angeles or Las Vegas. This put North Dakota directly in the path of the radioactive dust.

In 1959, radioactivity was found in wheat and milk in the northern U-S. The fallout landed on grass in pastures, and cows ate the grass, concentrating Strontium-90 in cow’s milk.

In 1961, the city of Mandan gained national notoriety for having a concentration of Strontium-90 in cow’s-milk eight times higher than milk from Wisconsin or New York. An Atomic Energy Commission scientist thought that “more radioactive dust [had] fallen for some reason around Mandan, where the milk samples” came from.

Other news intensified Strontium-90 fears. Russia conducted numerous nuclear-bomb tests in 1961, causing the U.S. Public Health Service to advise parents to warn all children not to eat newly-fallen snow, which could hold radioactivity. Children thus became wary of eating either white snow or yellow snow.

Out of these swirls of controversy came the Nuclear Test-Ban Treaty of 1963, prohibiting bomb testing in the atmosphere, underwater, or in outer space, reducing long-term fears of Strontium-90.

Dakota Datebook written by Dr. Steve Hoffbeck, History Department, MSU Moorhead.

Sources: “Radioactive Milk Creates U.S. Puzzle,” Oakland [CA] Tribune, August 16, 1966, p. 17.

“Excerpts From Message By Schweitzer,” New York Times, April 24, 1957, p. 4.

“A.E.C. Aide Says Dr. Schweitzer Errs,” New York Times, April 26, 1957, p. 1, 6.

“In the 1950’s, the Government Said Its Atomic Tests in Nevada Were Safe,” New York Times, February 9, 1986, p. SM33-35.

“Parents Advised To Warn Children Not To Eat Snow,” Cedar Rapids [IA] Gazette, December 6, 1961, p. 10B.

Robert Farrington, “High Strontium 90 Level in N. Dakota Puzzles Scientists,” Austin [MN] Herald, June 7, 1958, p. 4.

“Science: Man and Strontium 90,” Time Magazine, February 18, 1957.

“H-Bomb Fallout Is Hot Campaign Issue,” Austin [MN] Herald, October 25, 1956, p. 1.

“NE Iowa Snow Not Radioactive,” Waterloo [IA] Sunday Courier, December 10, 1961, p. 1.

“Nuclear Test Ban Treaty,” JFK Presidential Library and Museum website,, accessed on July 23, 2013.

“NRC: Backgrounder on Radiation Protection and the “Tooth Fairy Issue,” U.S. Nuclear Regulatory Commission website,, accessed on July 23, 2013.