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CAS Number: 7440-24-6
Synonyms: Sr-89, Sr-90, strontium carbonate, strontium chloride
Contaminant Type: Radiological

Some drinking water sources have low levels of radionuclides.  While stable strontium isotopes exist in nature, strontium has two primary radionuclides that are detected in drinking water. Strontium-89 and strontium-90 are both anthropogenic nuclides present in water from the use of cooling water for nuclear reactors and from industrial sources.  Both radionuclides are beta particle emitters and are regulated in drinking water.  Radioactive strontium is regulated in drinking water due to its radiotoxicity [584].  The half-lives of strontium-89 and strontium-90 are 51 days and 29 years, respectively [1760].  Because of its prevalence and activity, strontium-90 is a larger concern for water utilities.

Emitted particles ionize or destabilize atoms as they pass through the body's cells damaging chromosomes, which can lead to cancer. Radioactive strontium can be taken up by bone, damaging bone marrow and reducing blood cell counts. It is not known whether radioactive strontium has harmful effects on human reproduction [1760].

Radioactive strontium and other beta particle emitters are regulated in drinking water with a combined maximum contaminant level of 4 mrem per year [584], or 8 picoCuries/L. 

USEPA has identified ion exchange and reverse osmosis as Best Available Technologies (BATs) for the control of radioactive strontium in drinking water [566].

Because radioactive strontium is able to travel with percolating waters to underlying layers of soil and into groundwater, it is found in both surface and ground waters [1764].  In the National Inorganics and Radionuclides Survey (NIRS) of ground waters, gross beta-particle activity detects exceeded the study screening level of 50 pCi/L in 9 of 990 public water supplies [586].

Naturally-occurring strontium is present in the earth's crust at an average concentration of 0.04%. In seawater, it is the tenth most abundant element [1764].  Strontium is used industrially as a lead scavenger and in steel production.  Strontium carbonate is used in pyrotechnics.  Strontium chloride is used in toothpaste.  Natural strontium is not regulated in drinking water, but is of concern because of its bone and skeletal effects.  This concern has led to its inclusion in the third round of the Unregulated Contaminants Monitoring Rule, and in the Contaminants Candidate List 3. 

Date of Literature Search: August 2010, July 2014

566 USEPA; 2002; Implementation Guidance for Radionuclides; Implementation Guidance for Radionuclides; EPA-816-F-00-002. Office of Ground Water and Drinking Water, USEPA, Washington, DC.
584 USEPA; 2007; Basic information about radionuclides in drinking water; http://www.epa.gov/safewater/radionuclides/basicinformation.html; As posted on August 27, 2007. Office of Ground and Drinking Water, USEPA, Washington, DC.
586 USEPA; 2000; Radionuclides Notice of Data Availability: Technical Support Document; Radionuclides Notice of Data Availability: Technical Support Document; Targeting and Analysis Branch Standards and Risk Management Division, Office of Ground Water and Drinking Water, US EPA, Washington, DC.
1760 Agency for Toxic Substances and Disease Registry U.S. Public Health Services and U.S. Environmental Protection Agency; 2004; Toxicological Profile for Strontium; Toxicological Profile for Strontium; 189:196; U.S. Public Health Service and U.S. Environmental Protection Agency
1764 Chegrouche, S., Mellah, A., and Barkat, M.; 2009; Removal of strontium from aqueous solutions by adsorption onto activated carbon: kinetic and thermodynamic studies; Desalination; 235 (2009): 306-318