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Strontium is a soft, silver-gray metal with 4 stable isotopes. Strontium-90 is the only radioactive isotope with a half-life long enough to be an environmental concern. [Argonne]


Six atoms of Sr-90 are produced for every 100 fissions (6% yield). It is a waste product in spent nuclear fuel. Used as a generator of electricity for weather stations, buoys, and satellites; [Argonne] Used as a tracer in medicine and agriculture; Used in the treatment of bone cancer and eye diseases; It was widely dispersed as fallout from nuclear weapon testing in the 1950s and 1960s, but current levels in the environment are very low. [EPA Radionuclides] "It decays to Yttrium-90, which is a short-lived high energy particle emitter, which greatly increases the radiological effect of 90Sr exposures." [Reference #2]


Source: Nuclear fission Half-Life: 29 years Effective Half-Life: 15 years Specific Activity: 140 Ci/g Decay Mode: Beta GI Absorption: 30-40% Lung Clearance Half-Time: Years for all insoluble compounds and SrTi03; Days for all soluble compounds except SrTi03; Critical Organ: Bone Internal Toxicity: Very High Annual Limit on Intake: 0.004 mCi Radiation Energy (MeV): Beta 0.546 (100%) + Y-90 daughters; [See Glossary for references.] See "Radiation, ionizing."


EPA standards limit Sr-90 in drinking water not to exceed 8 pCi/L. [HSDB]

Reference Link

Strontium | Radiation Protection | US EPA

Exposure Assessment
Half Life

"The majority of 90Sr (> 50%) is rapidly cleared from the body within a week following exposure, only a small amount remains after a year, largely in the skeleton." [Reference #2]

Reference Link

IARC pdf: x- and gamma-Radiation

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