strontium 90

American  

noun

Chemistry.

1. a harmful radioactive isotope of strontium, produced in certain nuclear reactions and present in their fallout.

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strontium 90 Scientific  

1. A radioactive isotope of strontium having a mass number of 90 and a half-life of 28 years. Strontium 90 is the most dangerous component of the fallout from nuclear explosions because it is easily absorbed by the body. It is also used in medicine to treat cancer.

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Etymology

Origin of strontium 90

First recorded in 1950–55

Example Sentences

He found his political voice when he encountered the indifference of government authorities to the high levels of strontium 90 in the atmosphere from atomic tests.

From New York Times • Oct. 1, 2012

During a second testing phase, it found a 50 percent decline in strontium 90 in children born in 1968, compared with those born five years earlier, immediately after the treaty went into effect.

From New York Times • Jan. 10, 2011

The study ultimately found that children born in St. Louis in 1963 had 50 times as much strontium 90 in their teeth as children born in 1950 — before most of the atomic tests.

From New York Times • Jan. 10, 2011

The chief villains in fallout are three radioactive isotopes known as strontium 90, cesium 137 and iodine 131.

From Time Magazine Archive

But they shouldn't have strontium 90 or cesium 137.

From Time Magazine Archive