Caesium-137

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| image1 = Cs-137-decay.svg

| caption1 = ¹³⁷Cs decay scheme showing half-lives, daughter nuclides, and types and proportion of radiation emitted.

| image2 = Caesium-137 Gamma Ray Spectrum-en.svg

| caption2 = ¹³⁷Cs gamma spectrum. The characteristic 662 keV peak does not originate directly from ¹³⁷Cs, but from the decay of ^137mBa to its stable state.

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Caesium-137 has a half-life of about 30.04 years.Bé, M. M., Chisté, V., Dulieu, C., Browne, E., Baglin, C., Chechev, V., ... & Lee, K. B. (2006). [https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.473.8724&rep=rep1&type=pdf Table of Radionuclides (vol. 3–A= 3 to 244)]. Monographie BIPM, 5.

About 94.6% decays by beta emission to a metastable nuclear isomer of barium: barium-137m (^137mBa, Ba-137m). The remainder directly populates the ground state of ¹³⁷Ba, which is stable. Barium-137m has a half-life of about 153 seconds, and is responsible for all of the gamma ray emissions in samples of ¹³⁷Cs. Barium-137m decays to the ground state by emission of photons having energy 0.6617 MeV.{{cite book |title=Radionuclide and Radiation Protection Handbook |year=2002 |last1=Delacroix |first1=D. |last2=Guerre |first2=J. P. |last3=Leblanc |first3=P. |last4=Hickman |first4=C. |isbn=978-1870965873 |publisher=Nuclear Technology Publishing}} A total of 85.1% of ¹³⁷Cs decay generates gamma ray emission in this manner. One gram of ¹³⁷Cs has an activity of 3.215 terabecquerel (TBq).{{cite journal|last1=Bunting|first1=R. L.|title=Nuclear Data Sheets for A=137|journal=Nuclear Data Sheets 15|date=1975|volume=335}}

Caesium-137 has a number of practical uses. In small amounts, it is used to calibrate radiation-detection equipment.{{cite web|url=https://www.emergency.cdc.gov/radiation/isotopes/cesium.asp|title=CDC Radiation Emergencies {{pipe}} Radioisotope Brief: Cesium-137 (Cs-137)|publisher=CDC|access-date=5 November 2013}} In medicine, it is used in radiation therapy. In industry, it is used in flow meters, thickness gauges, moisture-density gauges (for density readings, with americium-241/beryllium providing the moisture reading),{{cite web |url=https://www.epa.gov/radiation/radionuclide-basics-cesium-137 |title=Cesium {{pipe}} Radiation Protection {{pipe}} US EPA |publisher=EPA |date=14 February 2023 |access-date=30 March 2023}} and in borehole logging devices.{{cite web |url=https://www.qsa-global.com/cesium-137-owl-sources |title=Cesium-137 (Cs-137) for Oil Well Logging |access-date=29 June 2024}}

Caesium-137 is not widely used for industrial radiography because it is hard to obtain a very high specific activity material with a well defined (and small) shape as caesium from used nuclear fuel contains stable caesium-133 and also long-lived caesium-135. Isotope separation is too costly compared to cheaper alternatives. Also the higher specific activity caesium sources tend to be made from very soluble caesium chloride (CsCl), as a result if a radiography source was damaged it would increase the spread of the contamination. It is possible to make water insoluble caesium sources (with various ferrocyanide compounds such as {{chem|Ni|2|Fe|(CN)|6}}, and ammonium ferric hexacyano ferrate (AFCF), Giese salt, ferric ammonium ferrocyanide but their specific activity will be much lower. Other chemically inert caesium compounds include caesium-aluminosilicate-glasses akin to the natural mineral pollucite. The latter has been used in demonstration of chemically stable water-insoluble forms of nuclear waste for disposal in deep geological repositories. A large emitting volume will harm the image quality in radiography. The isotopes {{Chem|192|Ir|link=Iridium-192}} and {{chem|60|Co|link=cobalt-60}} are preferred for radiography, since iridium and cobalt are chemically non-reactive metals and can be obtained with much higher specific activities by the activation of stable {{chem|191|Ir}} and {{chem|59|Co}} in high flux reactors. However, while {{chem|137|Cs}} is a waste product produced in great quantities in nuclear fission reactors, {{chem|192|Ir}} and {{chem|60|Co}} are specifically produced in commercial and research reactors and their life cycle entails the destruction of the involved high-value elements. Cobalt-60 decays to stable nickel, whereas iridium-192 can decay to either stable osmium or platinum. Due to the residual radioactivity and legal hurdles, the resulting material is not commonly recovered even from "spent" radioactive sources, meaning in essence that the entire mass is "lost" for non-radioactive uses.

As an almost purely synthetic isotope, caesium-137 has been used to date wine and detect counterfeits{{cite web |url=https://www.npr.org/blogs/thesalt/2014/06/03/318241738/how-atomic-particles-became-the-smoking-gun-in-wine-fraud-mystery |title=How Atomic Particles Helped Solve A Wine Fraud Mystery |publisher=NPR |date=3 June 2014 |access-date=4 March 2015}} and as a relative-dating material for assessing the age of sedimentation occurring after 1945.{{cite journal |last1=Williams |first1=H. F. L. |title=Assessing the impact of weir construction on recent sedimentation using cesium-137 |journal=Environmental Geology |volume=26 |issue=3 |year=1995 |pages=166–171 |issn=0943-0105 |doi=10.1007/BF00768738|bibcode=1995EnGeo..26..166W |s2cid=129177016 }}

Caesium-137 is also used as a radioactive tracer in geologic research to measure soil erosion and deposition; its affinity for fine sediments is useful in this application.{{cite journal |last1=Loughran |first1=Robert |title=The measurement of soil erosion |journal=Progress in Physical Geography |date=1 June 1989 |volume=221 |issue=2 |pages=216–233 |doi=10.1177/030913338901300203 |bibcode=1989PrPG...13..216L |s2cid=140599684 }}

Caesium-137 reacts with water, producing a water-soluble compound (caesium hydroxide). The biological behaviour of caesium is similar to that of potassium{{Cite journal |last=Avery |first=Simon V. |year=1995 |title=Caesium accumulation by microorganisms: uptake mechanisms, cation competition, compartmentalization and toxicity |journal=Journal of Industrial Microbiology |volume=14 |issue=2 |pages=76–84 |doi=10.1007/BF01569888 |issn=0169-4146 |pmid=7766213 |s2cid=21144768 |doi-access=free}} and rubidium. After entering the body, caesium gets more or less uniformly distributed throughout the body, with the highest concentrations in soft tissue.{{Cite book |last1=Delacroix |first1=D. |title=Radionuclide and Radiation Protection Data Handbook 2002 |last2=Guerre |first2=J. P. |last3=Leblanc |first3=P. |last4=Hickman |first4=C. |publisher=Nuclear Technology Publishing |year=2002 |isbn=978-1-870965-87-3 |edition=2nd}} {{rp|114}} However, unlike group 2 radionuclides like radium and strontium-90, caesium does not bioaccumulate and is excreted relatively quickly. The biological half-life of caesium is about 70 days.{{Cite web |last=R. Nave |title=Biological Half-life |url=http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/biohalf.html |website=Hyperphysics}}

A 1961 experiment showed that mice dosed with 21.5 μCi/g had a 50% fatality within 30 days (implying an LD₅₀ of 245 μg/kg).{{Cite book |last=Moskalev |first=Yu. I. |url=https://books.google.com/books?id=K4wPAQAAMAAJ |title=Distribution, Biological Effects, and Migration of Radioactive Isotopes |date=1961 |publisher=United States Atomic Energy Commission |editor-last=Lebedinskiĭ |editor-first=A. V. |series=Translation Series |publication-date=April 1974 |page=220 |chapter=Biological Effects of Cesium-137 |id=AEC-tr-7512 |editor-last2=Moskalev |editor-first2=Yu. I. |chapter-url=https://books.google.com/books?id=K4wPAQAAMAAJ&pg=PA220}} A similar experiment in 1972 showed that when dogs are subjected to a whole body burden of 3800 μCi/kg (140 MBq/kg, or approximately 44 μg/kg) of caesium-137 (and 950 to 1400 rads), they die within 33 days, while animals with half of that burden all survived for a year.{{Cite journal |last=Redman |first=H.C. |display-authors=etal |year=1972 |title=Toxicity of 137-CsCl in the Beagle. Early Biological Effects |journal=Radiation Research |volume=50 |issue=3 |pages=629–648 |bibcode=1972RadR...50..629R |doi=10.2307/3573559 |jstor=3573559 |pmid=5030090}}

Important researches have shown a remarkable concentration of ¹³⁷Cs in the exocrine cells of the pancreas, which are those most affected by cancer.{{Cite journal |last1=Nelson |first1=Arne |last2=Ullberg |first2=Sven |last3=Kristoffersson |first3=Harry |last4=Ronnback |first4=Curt |date=May 1961 |title=Distribution of Radiocesium in Mice |journal=Acta Radiologica |language=en |volume=55 |issue=5 |pages=374–384 |doi=10.3109/00016926109175132 |issn=0001-6926 |pmid=13728254 |doi-access=free}}{{Cite journal |last=Sodee |first=DB |date=January 1964 |title=HG-197, As a scanning Nucleotide |department=Letter to the Editor |journal=J Nucl Med |volume=5 |issue=5 |pages=74–75 |pmid=14113151}}{{Cite journal |last=Venturi |first=Sebastiano |year=2020 |title=Correlation between radioactive cesium and the increase of pancreatic cancer: A Hypothesis. |url=https://cyberleninka.ru/article/n/correlation-between-radioactive-cesium-and-the-increase-of-pancreatic-cancer-a-hypothesis/pdf |journal=Biosfera |volume=12 |issue=4 |pages=21–30 |doi=10.24855/biosfera.v12i4.556 |s2cid=229377336 |doi-access=free}} In 2003, in autopsies performed on 6 children who died in the polluted area near Chernobyl (of reasons not directly linked to the Chernobyl disaster; mostly sepsis), where they also reported a higher incidence of pancreatic tumors, Bandazhevsky found a concentration of ¹³⁷Cs 3.9 times higher than in their livers (1359 vs 347 Bq/kg, equivalent to 36 and 9.3 nCi/kg in these organs, 600 Bq/kg = 16 nCi/kg in the body according to measurements), thus demonstrating that pancreatic tissue is a strong accumulator and secretor in the intestine of radioactive cesium.{{Cite journal |last=Bandazhevsky Y.I. |year=2003 |title=Chronic Cs-137 incorporation in children's organs. |journal=Swiss Med. Wkly. |volume=133 |issue=35–36 |pages=488–90 |doi=10.4414/smw.2003.10226 |pmid=14652805 |s2cid=28184979 |doi-access=free}}

Accidental ingestion of caesium-137 can be treated with Prussian blue (Fe{{su|p=III|b=4}}[Fe{{su|p=II}}(CN){{su|b=6}}]{{su|b=3}}), which binds to it chemically and reduces the biological half-life to 30 days.{{Cite web |title=CDC Radiation Emergencies {{pipe}} Facts About Prussian Blue |url=https://www.cdc.gov/nceh/radiation/emergencies/prussianblue.htm |url-status=dead |archive-url=https://web.archive.org/web/20131020123050/http://www.bt.cdc.gov/radiation/prussianblue.asp |archive-date=20 October 2013 |access-date=5 November 2013 |publisher=CDC}}

File:Cs-137 from nuclear tests vector.svg. Test explosions "Simon" and "Harry" were both from Operation Upshot–Knothole in 1953, while the test explosions "George" and "How" were from Operation Tumbler–Snapper in 1952.]]

{{Medium-lived fission products}}

Caesium-137, along with other radioactive isotopes caesium-134, iodine-131, xenon-133, and strontium-90, were released into the environment during nearly all nuclear weapon tests and some nuclear accidents, most notably the Chernobyl disaster and the Fukushima Daiichi disaster.

Caesium-137 in the environment is substantially anthropogenic (human-made). Caesium-137 is produced from the nuclear fission of plutonium and uranium, and decays into barium-137.{{cite web |author=Takeshi Okumura |date=21 October 2003 |title=The material flow of radioactive cesium-137 in the U.S. 2000 |url=http://www.epa.gov/rpdweb00/docs/source-management/csfinallongtakeshi.pdf |publisher=US Environmental Protection Agency |work=epa.gov/}} By observing the characteristic gamma rays emitted by this isotope, one can determine whether the contents of a given sealed container were made before or after the first atomic bomb explosion (Trinity test, 16 July 1945), which spread some of it into the atmosphere, quickly distributing trace amounts of it around the globe. This procedure has been used by researchers to check the authenticity of certain rare wines, most notably the purported "Jefferson bottles".{{cite web |author1=Peter Hellman|author2=Mitch Frank |date=1 April 2010 |url=http://www.winespectator.com/webfeature/show/id/42436 |title=News Analysis: Christie's Is Counterfeit Crusader's Biggest Target |work=Wine Spectator |access-date=5 November 2013}} Surface soils and sediments are also dated by measuring the activity of ¹³⁷Cs.

Bombs in the arctic area of Novaja Zemlja and bombs detonated in or near the stratosphere released cesium-137 that landed in upper Lapland, Finland. Measurements of cesium-137 in 1960's was reportedly 45,000 becquerels. Figures from 2011 have a mid range of about 1,100 becquerels, but strangely, cancer cases are no more common there than elsewhere.[https://www.rcinet.ca/eye-on-the-arctic/2017/04/05/lapland-reindeer-herders-still-carrying-radiation-from-cold-war-nuclear-tests/ Lapland reindeer herders still carrying radiation from Cold War nuclear tests Yle news. 5 April 2017][https://stuk.fi/en/nuclear-tests-in-the-atmosphere Nuclear tests in the atmosphere STUK radiation and nuclear safety]{{Cite journal |last1=Salminen-Paatero |first1=Susanna |last2=Thölix |first2=Laura |last3=Kivi |first3=Rigel |last4=Paatero |first4=Jussi |date=July 2019 |title=Nuclear contamination sources in surface air of Finnish Lapland in 1965–2011 studied by means of 137Cs, 90Sr, and total beta activity |journal=Environmental Science and Pollution Research |language=en |volume=26 |issue=21 |pages=21511–21523 |doi=10.1007/s11356-019-05451-0 |pmid=31127522 |issn=0944-1344|pmc=6647534 |bibcode=2019ESPR...2621511S }}

{{main|Chernobyl disaster}}

As of today and for the next few hundred years or so, caesium-137 and strontium-90 continue to be the principal source of radiation in the zone of alienation around the Chernobyl nuclear power plant, and pose the greatest risk to health, owing to their approximately 30 year half-life and biological uptake. The mean contamination of caesium-137 in Germany following the Chernobyl disaster was 2000 to 4000 Bq/m².{{Citation needed|reason=The whole of Germany was not equally affected for the mean to be useful or accurate. Either the values should be properly cited or replaced with a useful metric|date=June 2019}} This corresponds to a contamination of 1 mg/km² of caesium-137, totaling about 500 grams deposited over all of Germany. In Scandinavia, some reindeer and sheep exceeded the Norwegian legal limit (3000 Bq/kg) 26 years after Chernobyl.{{cite web|work=The Foreigner|date=21 May 2012|title=Higher radiation in Jotunheimen than first believed|author1=Sandelson, Michael|author2=Smith, Lyndsey|url=https://theforeigner.no/pages/news/higher-radiation-in-jotunheimen-than-first-believed/|access-date=21 May 2012 |url-status=dead |archive-url=https://web.archive.org/web/20181002065054/https://theforeigner.no/pages/news/higher-radiation-in-jotunheimen-than-first-believed/ |archive-date=2 October 2018}} As of 2016, the Chernobyl caesium-137 has decayed by half, but could have been locally concentrated by much larger factors.

{{main|Fukushima Daiichi nuclear disaster}}

File:Fukushima- Panache-25-mars.svg

In April 2011, elevated levels of caesium-137 were also being found in the environment after the Fukushima Daiichi nuclear disasters in Japan. In July 2011, meat from 11 cows shipped to Tokyo from Fukushima Prefecture was found to have 1,530 to 3,200 becquerels per kilogram of ¹³⁷Cs, considerably exceeding the Japanese legal limit of 500 becquerels per kilogram at that time.{{cite web |date=9 July 2011 |title=High levels of caesium in Fukushima beef |url=http://www.iol.co.za/news/world/high-levels-of-caesium-in-fukushima-beef-1.1096205 |publisher=Independent Online}} In March 2013, a fish caught near the plant had a record 740,000 becquerels per kilogram of radioactive caesium, above the 100 becquerels per kilogram government limit.{{cite web |date=17 March 2013 |title=Fish near Fukushima reportedly contains high Cesium level |url=http://www.huffingtonpost.com/2013/03/17/fish-fukushima-cesium_n_2894350.html |work=Huffington Post}} A 2013 paper in Scientific Reports found that for a forest site 50 km from the stricken plant, ¹³⁷Cs concentrations were high in leaf litter, fungi and detritivores, but low in herbivores.{{cite journal |last1=Murakami |first1=Masashi |last2=Ohte |first2=Nobuhito |last3=Suzuki |first3=Takahiro |last4=Ishii |first4=Nobuyoshi |last5=Igarashi |first5=Yoshiaki |last6=Tanoi |first6=Keitaro |title=Biological proliferation of cesium-137 through the detrital food chain in a forest ecosystem in Japan |journal=Scientific Reports |volume=4 |page=3599 |year=2014 |issn=2045-2322 |doi=10.1038/srep03599 |pmid=24398571 |pmc=3884222 |bibcode=2014NatSR...4E3599M}} By the end of 2014, "Fukushima-derived radiocaesium had spread into the whole western North Pacific Ocean", transported by the North Pacific current from Japan to the Gulf of Alaska. It has been measured in the surface layer down to 200 meters and south of the current area down to 400 meters.{{cite journal |language=ja, en |last1=Kumamoto |first1=Yuichiro |display-authors=etal |date=2017 |department=Special Articles |title=Radiation and analytical chemistry – Five years since the Fukushima Daiichi nuclear power plant accident |journal=Bunseki Kagaku |volume=66 |issue=3 |pages=137–148 |doi=10.2116/bunsekikagaku.66.137|doi-access=free }}

Cesium-137 is reported to be the major health concern in Fukushima. A number of techniques are being considered that will be able to strip out 80% to 95% of the caesium from contaminated soil and other materials efficiently and without destroying the organic material in the soil. These include hydrothermal blasting. The caesium precipitated with ferric ferrocyanide (Prussian blue) would be the only waste requiring special burial sites.{{cite journal |author=Normile, Dennis |title=Cooling a hot zone |journal=Science |volume=339 |issue=6123 |date=1 March 2013 |pages=1028–1029|doi=10.1126/science.339.6123.1028 |pmid=23449572 |bibcode=2013Sci...339.1028N }} The aim is to get annual exposure from the contaminated environment down to 1 mSv above background. The most contaminated area where radiation doses are greater than 50 mSv/year must remain off limits, but some areas that are currently less than 5 mSv/year may be decontaminated, allowing 22,000 residents to return.{{Citation needed|reason=There is no source provided stating why 50mSv/year is a contamination level that must make a place remain off limits, nor to suggest that it is not possible to decontaminate from such a level.|date=October 2020}}

{{clear}}

Caesium-137 gamma sources have been involved in several radiological accidents and incidents.

In the Goiânia accident of 1987, an improperly disposed of radiation therapy system from an abandoned clinic in Goiânia, Brazil, was removed, then cracked to be sold in junkyards. The glowing caesium salt was then to be sold to curious, unadvised buyers.{{cite web |title=How one handful of powder contaminated a whole city |url=https://www.youtube.com/watch?v=-k3NJXGSIIA |archive-url=https://ghostarchive.org/varchive/youtube/20211221/-k3NJXGSIIA |archive-date=21 December 2021 |url-status=live|first=Kyle |last=Hill |publisher=YouTube |date=4 September 2021 |access-date=26 September 2021}}{{cbignore}} This led to four confirmed deaths and several serious injuries from radiation contamination.{{cite book|title=The Radiological Accident in Goiânia|publisher=IAEA|year=1988|isbn=92-0-129088-8|url=https://www-pub.iaea.org/MTCD/publications/PDF/Pub815_web.pdf}}

{{cite web

| date=26 April 2011

| title=Vítima do césio-137 lembra depressão e preconceito após acidente

| url=http://www.bbc.com/portuguese/noticias/2011/04/110421_cesio_entrevista_jc.shtml

| publisher=BBC Brasil

}}

The Kramatorsk radiological accident happened in 1989 when a small capsule 8x4 mm in size of caesium-137 was found inside the concrete wall of an apartment building in Kramatorsk, Ukrainian SSR. It is believed that the capsule, originally a part of a measurement device, was lost in the late 1970s and ended up mixed with gravel used to construct the building in 1980. Over 9 years, two families had lived in the apartment. By the time the capsule was discovered, 6 residents of the building had died, 4 from leukemia and 17 more receiving varying doses of radiation.{{Cite web|url=https://www.orangesmile.com/extreme/en/radioactive-zones/infected-apartment-in-kramatorsk.htm|title=Infected Apartment in Kramatorsk | Series 'The most radioactive zones on the planet' | OrangeSmile.com|website=www.orangesmile.com}}

The 1994 Tammiku incident involved the theft of radioactive material from a nuclear waste storage facility in Männiku, Saku Parish, Harju County, Estonia. Three brothers, unaware of the facility's nature, broke into a shed while scavenging for scrap metal. One of the brothers received a 4,000 rad whole-body dose from a caesium-137 source that had been released from a damaged container, succumbing to radiation poisoning 12 days later.{{cn|date=October 2024}}

In 1997, several Georgian soldiers suffered radiation poisoning and burns. They were eventually traced back to training sources left abandoned, forgotten, and unlabeled after the dissolution of the Soviet Union. One was a caesium-137 pellet in a pocket of a shared jacket that released about 130,000 times the level of background radiation at 1 meter distance.{{cite journal | last=Lluma | first=Diego | title = Former Soviet Union: What the Russians left behind | journal = Bulletin of the Atomic Scientists |date=May–June 2000 | volume = 56 | issue = 3| pages = 14–17 | doi=10.2968/056003005 | s2cid=145248534 }}

In the Acerinox accident of 1998, the Spanish recycling company Acerinox accidentally melted down a mass of radioactive caesium-137 that came from a gamma-ray generator.{{cite journal

| author = J.M. LaForge

| year = 1999

| url = http://www.earthislandprojects.org/EIJOURNAL/winter99/wr_winter99cesium.html

| title = Radioactive Caesium Spill Cooks Europe

| journal = Earth Island Journal

| volume = 14

| issue = 1

| access-date = 28 March 2009

| archive-url = https://web.archive.org/web/20080905135613/http://www.earthislandprojects.org/eijournal/winter99/wr_winter99cesium.html

| archive-date = 5 September 2008

| url-status = usurped

| df = dmy-all

}}

In 2009, a Chinese cement company (in Tongchuan, Shaanxi Province) was demolishing an old, unused cement plant and did not follow standards for handling radioactive materials. This caused some caesium-137 from a measuring instrument to be included with eight truckloads of scrap metal on its way to a steel mill, where the radioactive caesium was melted down into the steel.

{{cite web

| date=27 March 2009

| title=Chinese 'find' radioactive ball

| url=http://news.bbc.co.uk/2/hi/asia-pacific/7967285.stm

| work=BBC News

}}

In March 2015, the Norwegian University of Tromsø lost 8 radioactive samples, including samples of caesium-137, americium-241, and strontium-90. The samples were moved out of a secure location to be used for education. When the samples were supposed to be returned, the university was unable to find them. {{As of|2015|11|04}}, the samples are still missing.

{{cite web

| date=4 November 2015

| title=UiT har mistet radioaktivt stoff – kan ha blitt kastet

| url=http://www.itromso.no/nyheter/2015/11/04/UiT-har-mistet-radioaktivt-stoff-%E2%80%93-kan-ha-blitt-kastet-11767390.ece

| publisher= iTromsø

}}

{{cite web

| date=4 November 2015

| title=Stort metallskap sporløst forsvunnet. Inneholder radioaktive stoffer

|url=https://www.dagbladet.no/nyheter/stort-metallskap-sporlost-forsvunnet-inneholder-radioaktive-stoffer/60586284

|publisher= Dagbladet

}}

On 3 and 4 March 2016, unusually high levels of caesium-137 were detected in the air in Helsinki, Finland. According to STUK, the country's nuclear regulator, measurements showed 4,000 μBq/m³ – about 1,000 times the usual level. An investigation by the agency traced the source to a building from which STUK and a radioactive waste treatment company operate.{{Cite web|url=http://www.stuk.fi/web/en/-/cesium-137-now-traced-back-to-the-property-s-garage-and-parts-of-its-basement-premises|title=Cesium 137 now traced back to the property's garage and parts of its basement premises - Tiedote-en - STUK|website=www.stuk.fi|access-date=10 March 2016}}{{Cite web|url=https://nucleus.iaea.org/sites/iec/cam/Shared%20Documents/CAM%202016/Presentations/Session%205/Session%205a/CAM-PRE-2016%20Session%205%20-%20Aaltonen%20H%20-%20Finland%20.pdf|title=Cesium-137 contamination at STUK's premises in March 2016|author=Hannele Aaltonen|publisher=IAEA|access-date=13 October 2018}}

{{clear}}

Thirteen people were exposed to caesium-137 in May 2019 at the Research and Training building in the Harborview Medical Center complex. A contract crew was transferring the caesium from the lab to a truck when the powder was spilled. Five people were decontaminated and released, but 8 who were more directly exposed were taken to the hospital while the research building was evacuated.{{Cite web|url=https://www.kuow.org/stories/13-exposed-to-radioactivity-at-seattle-hospital |title=13 exposed to radioactivity|date=3 May 2019|author=Casey Martin|website=KUOW}}

{{further|Western Australian radioactive capsule incident}}

Public health authorities in Western Australia issued an emergency alert for a stretch of road measuring about 1,400 km after a capsule containing caesium-137 was lost in transport on 25 January 2023. The 8 mm capsule contained a small quantity of the radioactive material when it disappeared from a truck. The State Government immediately launched a search, with the WA Department of Health's chief health officer Andrew Robertson warning an exposed person could expect to receive the equivalent of "about 10 X-rays an hour". Experts warned, if the capsule were found, the public should stay at least 5 metres away.

{{cite web |date=27 January 2023 |title=Emergency warning after tiny radioactive capsule lost during transport from Newman mine to Perth |url=https://thewest.com.au/news/wa/emergency-warning-after-tiny-radioactive-capsule-lost-during-transport-from-newman-mine-to-perth-c-9577183 |publisher=The West Australian}} The capsule was found on 1 February 2023.

{{cite web |date=1 February 2023 |title=Missing radioactive capsule found in WA outback after frantic search |url=https://www.abc.net.au/news/2023-02-01/australian-radioactive-capsule-found-in-wa-outback-rio-tinto/101917828 |publisher=ABC News}}

A caesium-137 capsule went missing from a steam power plant in Prachin Buri province, Thailand on 23 February 2023, triggering a search by officials from Thailand's Office of Atoms for Peace (OAP) and the Prachin Buri provincial administration. However, the Thai public was not notified until 14 March.{{Cite web |title=Frantic search for radioactive material missing from power plant in Prachin Buri |url=https://www.thaipbsworld.com/frantic-search-for-radioactive-material-missing-from-power-plant-in-prachin-buri/ |access-date=2023-03-15 |website=www.thaipbsworld.com |language=en-US}}

On 20 March, the Secretary-General of the OAP and the governor of Prachin Buri held a press conference stating that they had found caesium-137 contaminated furnace dust at a steel melting plant in Kabin Buri district.{{Cite news |title=Caesium-137 found at local metal work in Prachin buri |url=https://www.bangkokpost.com/thailand/general/2532099/caesium-contaminated-factory-dust-now-safely-contained/ |access-date=2023-03-20 |newspaper=Bangkok Post |language=en-US}}

On Friday, 5 April an emergency regime was introduced in the Russian city of Khabarovsk after a local resident accidentally discovered that radiation levels had jumped sharply in one of the industrial areas of the city. According to volunteers of the dosimetric control group, the dosimeter at the NP site showed up to 800 microsieverts, which is 1600 times the safe value.

Employees of the Ministry of Emergency Situations fenced off the area of {{convert|30|by|30|meters}}, where they found a capsule with caesium from a defectoscope. The find was placed in a protective container and taken away for disposal. This was first reported by the Novaya Gazeta.{{cite news |lang=uk |url=https://tsn.ua/svit/nadzvichayna-situaciya-u-habarovsku-radiaciyniy-fon-u-1600-raziv-perevischiv-normu-2551414.html |script-title=uk: Надзвичайна ситуація у Хабаровську: радіаційний фон у 1600 разів перевищив норму |website=tsn.ua |first=Bogdan |last=Skavron |date=2024-04-05}}

• Commonly used gamma-emitting isotopes

{{Reflist|30em}}

• {{cite book|doi=10.1016/S0166-1116(08)71715-1|chapter=4.2. The Transfer of Radiocaesium from Soil to Plants and Fungi in Seminatural Ecosystems|title=Nordic Radioecology - the Transfer of Radionuclides through Nordic Ecosystems to Man|volume=62|pages=265–286|series=Studies in Environmental Science|year=1994|last1=Olsen|first1=Rolf A.|isbn=9780444816177}}

• [http://toxnet.nlm.nih.gov/cgi-bin/sis/search/r?dbs+hsdb:@term+@na+@rel+cesium,+radioactive NLM Hazardous Substances Databank – Cesium, Radioactive]
• [https://web.archive.org/web/20110721184504/http://www.armscontrol.info/reports/authors/liolios/cesium-137%20dirty%20bomb%20occasional%20paper.pdf Cesium-137 dirty bombs by Theodore Liolios]

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Category:Isotopes of caesium

Category:Fission products

Category:Radioisotope fuels

Category:Radioactive contamination