View source for Cadmium

{{Other uses}}
{{Use dmy dates|date=September 2020}}
{{infobox cadmium}}

'''Cadmium''' is a [[chemical element]]; it has [[chemical symbol|symbol]] '''Cd''' and [[atomic number]] 48. This soft, silvery-white [[metal]] is chemically similar to the two other stable metals in [[group 12 element|group 12]], [[zinc]] and [[mercury (element)|mercury]]. Like zinc, it demonstrates [[oxidation state]] +2 in most of its compounds, and like mercury, it has a lower melting point than the [[transition metal]]s in [[group 3 element|groups 3]] through [[group 11 element|11]]. Cadmium and its [[Congener (chemistry)|congeners]] in group 12 are often not considered transition metals, in that they do not have partly filled ''d'' or ''f'' electron shells in the elemental or common oxidation states. The average concentration of cadmium in Earth's crust is between 0.1 and 0.5 parts per million (ppm). It was discovered in 1817 simultaneously by [[Friedrich Stromeyer|Stromeyer]] and [[Karl Samuel Leberecht Hermann|Hermann]], both in Germany, as an impurity in [[zinc carbonate]].

Cadmium occurs as a minor component in most zinc ores and is a byproduct of zinc production. It was used for a long time in the 1900s as a corrosion-resistant plating on [[steel]], and cadmium compounds are used as red, orange, and yellow [[cadmium pigments|pigment]]s, to color [[Glass coloring and color marking|glass]], and to stabilize [[plastic]]. Cadmium's use is generally decreasing because it is [[toxicity|toxic]] (it is specifically listed in the European [[Restriction of Hazardous Substances Directive]]<ref name="ReferenceA">{{cite book
 |last1=Morrow |first1=H.
 |date=2010
 |chapter=Cadmium and Cadmium Alloys
 |title=Kirk-Othmer Encyclopedia of Chemical Technology
 |publisher=[[John Wiley & Sons]]
 |pages=1–36
 |doi=10.1002/0471238961.0301041303011818.a01.pub3
 |isbn=978-0-471-23896-6
|title-link=Kirk-Othmer Encyclopedia of Chemical Technology
 }}</ref>) and [[nickel–cadmium battery|nickel–cadmium batteries]] have been replaced with [[nickel–metal hydride battery|nickel–metal hydride]] and [[lithium-ion battery|lithium-ion]] batteries. Due to it being a [[neutron poison]], cadmium is also used as a component of [[control rod]]s in nuclear fission reactors. One of its few new uses is in [[Cadmium telluride photovoltaics|cadmium telluride]] [[solar panel]]s.

Although cadmium has no known biological function in higher organisms, a cadmium-dependent [[carbonic anhydrase]] has been found in marine [[diatom]]s.

==Characteristics==
===Physical properties===
Cadmium is a soft, [[malleable]], [[Ductility|ductile]], silvery-white [[divalent]] metal. It is similar in many respects to zinc but forms [[Complex (chemistry)|complex]] compounds.<ref name="Holl">
{{cite book
 |last1=Holleman |first1=A. F.
 |last2=Wiberg |first2=E.
 |last3=Wiberg |first3=Nils
 |date=1985
 |chapter=Cadmium
 |title=Lehrbuch der Anorganischen Chemie, 91–100
 |publisher=[[Walter de Gruyter]]
 |pages=1056–1057
 |isbn=978-3-11-007511-3
|language=de}}</ref> Unlike most other metals, cadmium is resistant to [[corrosion]] and is used as a protective [[Plating|plate]] on other metals. As a bulk metal, cadmium is [[insoluble]] in water<ref name=PubChem>{{cite web |title=Cadmium 3.2.6 Solubility |url=https://pubchem.ncbi.nlm.nih.gov/compound/cadmium#section=Solubility |publisher=PubChem |access-date=25 November 2021}}</ref> and is not [[Flammability|flammable]]; however, in its powdered form it may burn and release [[Cadmium oxide|toxic fumes]].<ref name = "ATSDR">
{{cite web
 |title=Case Studies in Environmental Medicine (CSEM) Cadmium
 |url=http://www.atsdr.cdc.gov/csem/cadmium/cdcontents.html
 |publisher=Agency for Toxic Substances and Disease Registry
 |access-date=30 May 2011
 |archive-url=https://web.archive.org/web/20110606014211/http://www.atsdr.cdc.gov/csem/cadmium/cdcontents.html
 |archive-date=6 June 2011
}}</ref>

===Chemical properties===
{{Category see also|Cadmium compounds}}

Although cadmium usually has an [[oxidation state]] of +2, it also exists in the +1 state. Cadmium and its [[Congener (chemistry)|congeners]] are not always considered transition metals, in that they do not have partly filled d or f electron shells in the elemental or common oxidation states.<ref>
{{cite book
 |last=Cotton |first=F. A.
 |date=1999
 |chapter=Survey of Transition-Metal Chemistry
 |title=Advanced Inorganic Chemistry
 |pages=633 |edition=6th
 |publisher=[[John Wiley and Sons]]
 |isbn=978-0-471-19957-1
}}</ref> Cadmium burns in air to form brown amorphous [[cadmium oxide]] (CdO); the [[crystal]]line form of this compound is a dark red which changes color when heated, similar to [[zinc oxide]]. [[Hydrochloric acid]], [[sulfuric acid]], and [[nitric acid]] dissolve cadmium by forming [[cadmium chloride]] (CdCl<sub>2</sub>), [[cadmium sulfate]] (CdSO<sub>4</sub>), or [[cadmium nitrate]] (Cd(NO<sub>3</sub>)<sub>2</sub>). The oxidation state +1 can be produced by dissolving cadmium in a mixture of cadmium chloride and [[aluminium chloride]], forming the Cd<sub>2</sub><sup>2+</sup> cation, which is similar to the Hg<sub>2</sub><sup>2+</sup> cation in [[mercury(I) chloride]].<ref name="Holl" />
:Cd + CdCl<sub>2</sub> + 2 AlCl<sub>3</sub> → Cd<sub>2</sub>(AlCl<sub>4</sub>)<sub>2</sub>
The structures of many cadmium complexes with [[nucleobase]]s, [[amino acid]]s, and [[vitamin]]s have been determined.<ref>{{cite book
|last1=Carballo
|first1=Rosa
|last2=Castiñeras
|first2=Alfonso
|last3=Domínguez-Martin
|first3=Alicia
|last4=García-Santos
|first4=Isabel
|last5=Niclós-Guttiérrez
|first5=Juan
|title=Cadmium: From Toxicity to Essentiality
|chapter=Solid State Structures of Cadmium Complexes with Relevance for Biological Systems
|editor=Astrid Sigel
|editor2=Helmut Sigel
|editor3=Roland K. O. Sigel
|series=Metal Ions in Life Sciences
|volume=11
|date=2013
|publisher=Springer
|pages=145–189
|doi=10.1007/978-94-007-5179-8_7|pmid=23430774
|isbn=978-94-007-5178-1
|hdl=11093/232
}}
</ref>

===Isotopes===
[[File:Cadmium cutoff.png|thumb|left|The cadmium-113 total cross section clearly showing the cadmium cut-off]]
{{Main|Isotopes of cadmium}}
Naturally occurring cadmium is composed of eight [[isotope]]s. Two of them are [[radionuclide|radioactive]], and three are expected to [[radioactive decay|decay]] but have not measurably done so under laboratory conditions. The two natural radioactive isotopes are <sup>113</sup>Cd ([[beta decay]], half-life is {{val|7.7|e=15|u=y}}) and <sup>116</sup>Cd (two-neutrino [[double beta decay]], half-life is {{val|2.9|e=19|u=y}}). The other three are <sup>106</sup>Cd, <sup>108</sup>Cd (both [[double electron capture]]), and <sup>114</sup>Cd (double beta decay); only lower limits on these half-lives have been determined. At least three isotopes&nbsp;– <sup>110</sup>Cd, <sup>111</sup>Cd, and <sup>112</sup>Cd&nbsp;– are stable. Among the isotopes that do not occur naturally, the most long-lived are <sup>109</sup>Cd with a half-life of 462.6&nbsp;days, and <sup>115</sup>Cd with a half-life of 53.46&nbsp;hours. All of the remaining radioactive isotopes have half-lives of less than 2.5&nbsp;hours, and the majority have half-lives of less than 5&nbsp;minutes. Cadmium has 8 known [[meta state]]s, with the most stable being <sup>113m</sup>Cd (''t''<sub>1⁄2</sub>&nbsp;= 14.1&nbsp;years), <sup>115m</sup>Cd (''t''<sub>1⁄2</sub>&nbsp;= 44.6&nbsp;days), and <sup>117m</sup>Cd (''t''<sub>1⁄2</sub>&nbsp;= 3.36&nbsp;hours).<ref name="NUBASE">{{NUBASE 2003}}</ref>

The known isotopes of cadmium range in [[atomic mass]] from 94.950&nbsp;[[atomic mass unit|u]] (<sup>95</sup>Cd) to 131.946&nbsp;u (<sup>132</sup>Cd). For isotopes lighter than 112&nbsp;u, the primary [[decay mode]] is [[electron capture]] and the dominant [[decay product]] is element&nbsp;47 ([[silver]]). Heavier isotopes decay mostly through [[beta emission]] producing element&nbsp;49 ([[indium]]).<ref name="NUBASE" />

One isotope of cadmium, <sup>113</sup>Cd, [[neutron capture|absorbs neutrons]] with high selectivity: With very high probability, neutrons with energy below the ''cadmium cut-off'' will be absorbed; those higher than the ''cut-off will be transmitted''. The cadmium cut-off is about 0.5&nbsp;eV, and neutrons below that level are deemed [[slow neutron]]s, distinct from intermediate and [[fast neutron]]s.<ref>
{{cite book
 |last=Knoll |first=G. F.
 |date=2000
 |title=Radiation Detection and Measurement
 |page=505
 |publisher=[[John Wiley & Sons|Wiley]]
 |isbn=978-0-471-07338-3
}}</ref>

Cadmium is created via the [[s-process]] in low- to medium-mass stars with masses of 0.6&nbsp;to 10&nbsp;[[Sun|solar masses]], over thousands of years. In that process, a [[silver]] atom captures a [[neutron]] and then undergoes [[beta decay]].<ref>
{{cite book
 |last1=Padmanabhan |first1=T.
 |date=2001
 |chapter=Stellar Nucleosynthesis
 |chapter-url=https://books.google.com/books?id=TOjwtYYb63cC&pg=PA230
 |title=Theoretical Astrophysics, Volume II: Stars and Stellar Systems
 |pages=230–236
 |publisher=[[Cambridge University Press]]
 |isbn=978-0-521-56631-5
}}</ref>

==History==
[[File:Friedrich Stromeyer.jpg|thumb|upright|left|[[Friedrich Stromeyer]]]]
Cadmium ([[Latin]] ''cadmia'', [[Greek language|Greek]] ''καδμεία'' meaning "[[Calamine (mineral)|calamine]]", a cadmium-bearing mixture of minerals that was named after the Greek mythological character Κάδμος, [[Cadmus]], the founder of [[Ancient Thebes (Boeotia)|Thebes]]) was [[discovery of the chemical elements|discovered]] in contaminated zinc compounds sold in pharmacies in Germany<ref name="Roloff">{{cite journal | journal =Journal des practischen Arzneykunde und Wundarzneykunst (Hufelands Journal) | url = https://babel.hathitrust.org/cgi/pt?id=mdp.39015011938910&view=1up&seq=224 | issue= 2 Februar Stück| pages = 110| title = Wichtige Nachricht für Aerzte und Apoteker – Entdeckung eines Arsenikgehalts in der Zinkblume und des Zinkvitriols in Tartarus vitriolis| last = Rolof|year = 1795}}</ref> in 1817 by [[Friedrich Stromeyer]].<ref>

{{cite journal
 |last=Hermann |first=C. S.
 |date=1818
 |title=Noch ein schreiben über das neue Metall
 |url=http://gallica.bnf.fr/ark:/12148/bpt6k150680/f125.chemindefer
 |journal=[[Annalen der Physik]]
 |volume=59 |issue=5 |pages=113–116
 |bibcode=1818AnP....59..113H
 |doi=10.1002/andp.18180590511
}}</ref> [[Karl Samuel Leberecht Hermann]] simultaneously investigated the discoloration in zinc oxide and found an impurity, first suspected to be [[arsenic]], because of the yellow precipitate with [[hydrogen sulfide]]. Additionally Stromeyer discovered that one supplier sold zinc carbonate instead of zinc oxide.<ref name="ReferenceA" /> Stromeyer found the new element as an impurity in [[zinc carbonate]] (calamine), and, for 100 years, Germany remained the only important producer of the metal. The metal was named after the Latin word for calamine, because it was found in this zinc ore. Stromeyer noted that some impure samples of calamine changed color when heated but pure calamine did not. He was persistent in studying these results and eventually isolated cadmium metal by [[Roasting (metallurgy)|roasting]] and reducing the [[cadmium sulfide|sulfide]]. The potential for cadmium yellow as pigment was recognized in the 1840s, but the lack of cadmium limited this application.<ref>
{{cite book
 |last1=Waterston |first1=W.
 |last2=Burton |first2=J. H.
 |date=1844
 |title=Cyclopædia of commerce, mercantile law, finance, commercial geography and navigation
 |url=https://books.google.com/books?id=84VAAAAAYAAJ&pg=PA122
 |page=122
 |publisher=[[H. G. Bohn]]
 }}</ref><ref>
{{cite book
 |last1=Rowbotham |first1=T.
 |last2=Rowbotham |first2=T. L.
 |date=1850
 |title=The Art of Landscape Painting in Water Colours
 |url=https://books.google.com/books?id=Q-cHAAAAQAAJ&pg=PA10
 |page=10
 |publisher=Windsor and Newton
 }}</ref><ref name="Cadold">
{{cite book
 |last1=Ayres |first1=R. U.
 |last2=Ayres |first2=L.
 |last3=Råde |first3=I.
 |date=2003
 |title=The Life Cycle of Copper, Its Co-Products and Byproducts
 |url=https://books.google.com/books?id=gGHOz1G3AqwC&pg=PA135
 |pages=135–141
 |publisher=[[Springer (publisher)|Springer]]
 |isbn=978-1-4020-1552-6
}}</ref>

Even though cadmium and its compounds are toxic in certain forms and concentrations, the [[British Pharmaceutical Codex]] from 1907 states that [[cadmium iodide]] was used as a [[medication]] to treat "enlarged joints, scrofulous glands, and chilblains".<ref>
{{cite book
 |last=Dunglison |first=R.
 |date=1866
 |title=Medical Lexicon: A Dictionary of Medical Science
 |url=https://archive.org/details/medicallexicona02dunggoog
 |pages=[https://archive.org/details/medicallexicona02dunggoog/page/n162 159]
 |publisher=[[Henry C. Lea]]
 }}</ref>

In 1907, the [[International Astronomical Union]] defined the international [[ångström]] in terms of a red cadmium spectral line (1 wavelength = 6438.46963&nbsp;Å).<ref>{{Cite web |url=http://thesciencedictionary.org/international-angstrom/ |title=International Angstrom |website=Science Dictionary |date=2013-09-14 |access-date=2014-09-24 |archive-url=https://web.archive.org/web/20181118101806/http://thesciencedictionary.org/international-angstrom/ |archive-date=18 November 2018 |url-status=dead }}</ref><ref>{{Cite web |url=http://www.sizes.com/units/angstrom.htm |title=angstrom or ångström |website=Sizes.com |date=2010-10-28 |access-date=2014-09-24 |archive-date=9 July 2023 |archive-url=https://web.archive.org/web/20230709193325/https://www.sizes.com/units/angstrom.htm |url-status=dead }}</ref> This was adopted by the 7th [[General Conference on Weights and Measures]] in 1927. In 1960, the definitions of both the [[metre]] and ångström were changed to use [[krypton]].<ref>
{{cite journal
 |last=Burdun |first=G. D.
 |date=1958
 |title=On the new determination of the meter
 |journal=Measurement Techniques
 |volume=1 |issue=3 |pages=259–264
 |doi=10.1007/BF00974680
|bibcode=1958MeasT...1..259B
 |s2cid=121450003
 }}</ref>

After the industrial scale production of cadmium started in the 1930s and 1940s, the major application of cadmium was the coating of iron and steel to prevent corrosion; in 1944, 62% and in 1956, 59% of the cadmium in the United States was used for [[plating]].<ref name="ReferenceA" /><ref name="YB1956">
{{cite book
|last=Lansche |first=A. M.
|date=1956
|chapter=Cadmium
|title=Minerals Yearbook, Volume I: Metals and Minerals (Except Fuels)
|chapter-url=http://digicoll.library.wisc.edu/cgi-bin/EcoNatRes/EcoNatRes-idx?type=turn&entity=EcoNatRes.MinYB1956v1.p0289&id=EcoNatRes.MinYB1956v1&isize=XL&q1=cadmium
|publisher=[[United States Geological Survey]]
|access-date=21 April 2008
}}</ref> In 1956, 24% of the cadmium in the United States was used for a second application in red, orange and yellow pigments from sulfides and selenides of cadmium.<ref name="YB1956" />

The stabilizing effect of cadmium chemicals like the carboxylates cadmium laurate and cadmium stearate on [[polyvinyl chloride|PVC]] led to an increased use of those compounds in the 1970s and 1980s. The demand for cadmium in pigments, coatings, stabilizers, and alloys declined as a result of environmental and health regulations in the 1980s and 1990s; in 2006, only 7% of total cadmium consumption was used for plating, and only 10% was used for pigments.<ref name="ReferenceA" />
At the same time, these decreases in consumption were compensated by a growing demand for cadmium for nickel–cadmium batteries, which accounted for 81% of the cadmium consumption in the United States in 2006.<!--The overall consumption of cadmium has decreased by more than 90% from the 1970s till 2008.--><ref name="usgs">{{cite web
 |url=http://minerals.usgs.gov/minerals/pubs/commodity/cadmium/
 |title=USGS Mineral Information: Cadmium
 |publisher=[[United States Geological Survey]]
 |access-date=8 August 2009
}}</ref>

==Occurrence==
[[File:CadmiumMetalUSGOV.jpg|thumb|left|Cadmium metal]]
{{see also|Category:Cadmium minerals}}
Cadmium makes up about 0.1&nbsp;[[Parts per million|ppm]] of [[Earth's crust]] and is the 65th most abundant element.<ref>{{Cite book |last=Emsley |first=John |url=https://books.google.com/books?id=j-Xu07p3cKwC&dq=%E2%80%9C65th+most+abundant+element%E2%80%9D&pg=PA78 |title=Nature's Building Blocks: An A-Z Guide to the Elements |date=2003 |publisher=Oxford University Press |isbn=978-0-19-850340-8 |language=en}}</ref> It is much rarer than zinc, which makes up about 65&nbsp;ppm.<ref>
{{cite journal
 |last1=Wedepohl |first1=K. H.
 |date=1995
 |title=The composition of the continental crust
 |journal=[[Geochimica et Cosmochimica Acta]]
 |volume=59 |issue=7 |pages=1217–1232
 |bibcode=1995GeCoA..59.1217W
 |doi=10.1016/0016-7037(95)00038-2
}}</ref> No significant deposits of cadmium-containing ores are known. The only cadmium [[mineral]] of importance, [[greenockite]] (Cd[[sulfur|S]]), is nearly always associated with [[sphalerite]] (ZnS). This association is caused by geochemical similarity between zinc and cadmium, with no geological process likely to separate them. Thus, cadmium is produced mainly as a byproduct of mining, smelting, and refining sulfidic ores of zinc, and, to a lesser degree, [[lead]] and [[copper]]. Small amounts of cadmium, about 10% of consumption, are produced from secondary sources, mainly from dust generated by recycling iron and steel scrap. Production in the United States began in 1907,<ref name="Cadold" /> but wide use began after World War I.<ref name="price">
{{cite web
 |last=Plachy |first=J.
 |date=1998
 |url=http://minerals.usgs.gov/minerals/pubs/commodity/cadmium/140798.pdf |archive-url=https://web.archive.org/web/20000816225332/http://minerals.usgs.gov/minerals/pubs/commodity/cadmium/140798.pdf |archive-date=2000-08-16 |url-status=live
 |title=Annual Average Cadmium Price
 |pages=17–19
 |publisher=[[U.S. Geological Survey]]
 |access-date=16 June 2010
}}</ref><ref name="lifecycle">
{{cite journal
 |last1=Fthenakis |first1=V. M.
 |date=2004
 |title=Life cycle impact analysis of cadmium in CdTe PV production
 |journal=[[Renewable and Sustainable Energy Reviews]]
 |volume=8 |issue=4 |pages=303–334
 |doi=10.1016/j.rser.2003.12.001
 |bibcode=2004RSERv...8..303F
 |url=https://zenodo.org/record/1259335
 }}</ref>

Metallic cadmium can be found in the [[Vilyuy River]] basin in [[Siberia]].<ref>{{cite journal
 |last1=Fleischer |first1=M.
 |last2=Cabri |first2=L. J.
 |last3=Chao |first3=G. Y.
 |last4=Pabst |first4=A.
 |date=1980
 |title=New Mineral Names
 |url=http://www.minsocam.org/ammin/AM65/AM65_1065.pdf |archive-url=https://ghostarchive.org/archive/20221010/http://www.minsocam.org/ammin/AM65/AM65_1065.pdf |archive-date=2022-10-10 |url-status=live
 |journal=[[American Mineralogist]]
 |volume=65 |pages=1065–1070
}}</ref>

Rocks mined for phosphate fertilizers contain varying amounts of cadmium, resulting in a cadmium concentration of as much as 300&nbsp;mg/kg in the fertilizers and a high cadmium content in agricultural soils.<ref>{{cite journal
 |last1=Grant |first1=C. A.
 |last2=Sheppard |first2=S. C.
 |date=2008
 |title=Fertilizer impacts on cadmium availability in agricultural soils and crops
 |journal=[[Human and Ecological Risk Assessment]]
 |volume=14 |issue=2 |pages=210–228
 |doi=10.1080/10807030801934895
|bibcode=2008HERA...14..210G
 |s2cid=84548398
 }}</ref><ref>{{cite journal
 |last1=Jiao |first1=Y.
 |last2=Grant |first2=C. A.
 |last3=Bailey |first3=L. D.
 |date=2004
 |title=Effects of phosphorus and zinc fertilizer on cadmium uptake and distribution in flax and durum wheat
 |journal=[[Journal of the Science of Food and Agriculture]]
 |volume=84 |issue=8 |pages=777–785
 |doi=10.1002/jsfa.1648
|bibcode=2004JSFA...84..777J
 }}</ref> Coal can contain significant amounts of cadmium, which ends up mostly in [[coal fly ash]].<ref>{{cite journal
 |last1=Bettinelli |first1=M.
 |last2=Baroni |first2=U.
 |last3=Pastorelli |first3=N.
 |date=1988
 |title=Determination of arsenic, cadmium, lead, antimony, selenium and thallium in coal fly ash using the stabilised temperature platform furnace and Zeeman-effect background correction
 |journal=[[Journal of Analytical Atomic Spectrometry]]
 |volume=3 |issue=7 |pages=1005–1011
 |doi=10.1039/JA9880301005
}}</ref>

Cadmium in soil can be absorbed by crops such as rice and cocoa. In 2002, the [[Ministry of Agriculture of the People's Republic of China|Chinese ministry of agriculture]] measured that 28% of [[rice]] it sampled had excess lead and 10% had excess cadmium above limits defined by law. ''[[Consumer Reports]]'' tested 28 brands of [[dark chocolate]] sold in the United States in 2022, and found cadmium in all of them, with 13 exceeding the California Maximum Allowable Dose level.<ref>[https://www.wbur.org/hereandnow/2023/02/01/dark-chocolate-lead-cadmium Dark chocolate is high in cadmium and lead. How much is safe to eat?]</ref>

Some plants such as [[Willow|willow trees]] and [[Populus|poplars]] have been found to clean both lead and cadmium from soil.<ref>{{Cite news|url=https://www.economist.com/news/briefing/21723128-and-fixing-it-will-be-hard-and-costly-most-neglected-threat-public-health-china|title=The most neglected threat to public health in China is toxic soil|newspaper=The Economist|access-date=2017-06-13|date=2017-06-08}}</ref>

Typical background concentrations of cadmium do not exceed 5&nbsp;ng/m<sup>3</sup> in the atmosphere; 2&nbsp;mg/kg in soil; 1&nbsp;μg/L in freshwater and 50&nbsp;ng/L in seawater.<ref>
{{cite book
 |last1=Rieuwerts|first1=J.
 |date=2015
 |title=The Elements of Environmental Pollution
 |page=166
 |publisher=Routledge
 |isbn=978-0-415-85920-2
}}</ref> Concentrations of cadmium above 10 μg/L may be stable in water having low total solute concentrations and ''p'' H and can be difficult to remove by conventional water treatment processes.<ref>{{Cite journal|last=Hem|first=John D.|date=1972|title=Chemistry and occurrence of cadmium and zinc in surface water and groundwater|journal=Water Resources Research|language=en|volume=8|issue=3|pages=661–679|doi=10.1029/WR008i003p00661|bibcode=1972WRR.....8..661H|issn=1944-7973}}</ref>

==Production==
Cadmium is a common impurity in [[zinc]] ores, and it is most often isolated during the [[Zinc smelting|production of zinc]]. Some zinc ores concentrates from [[zinc sulfate]] ores contain up to 1.4% of cadmium.<ref name="Cd-Trend">
{{cite book
 |last=Golberg |first=D. C.
 |date=1969
 |title=Trends in Usage of Cadmium: Report
 |url=https://books.google.com/books?id=okArAAAAYAAJ
 |pages=1–3
 |publisher=[[United States National Research Council|US NRC]]/[[National Academy of Sciences|NAS]]/[[National Academy of Engineering|NAE]]
|display-authors=etal}}</ref> In the 1970s, the output of cadmium was {{convert|6.5|lb|order=flip}} per ton of zinc.<ref name="Cd-Trend" /> Zinc [[sulfide]] ores are roasted in the presence of [[oxygen]], converting the zinc sulfide to the [[oxide]]. Zinc metal is produced either by [[smelting]] the oxide with [[carbon]] or by [[electrolysis]] in [[sulfuric acid]]. Cadmium is isolated from the zinc metal by [[vacuum distillation]] if the zinc is smelted, or cadmium sulfate is [[precipitate]]d from the electrolysis solution.<ref name="lifecycle" /><ref>
{{cite book
 |last1=Scoullos |first1=M. J.
 |date=2001
 |title=Mercury, Cadmium, Lead: Handbook for Sustainable Heavy Metals Policy and Regulation
 |url=https://books.google.com/books?id=9yzN-QGag_8C&pg=PA104
 |pages=104–116
 |publisher=[[Springer (publisher)|Springer]]
 |isbn=978-1-4020-0224-3
}}</ref>

The [[British Geological Survey]] reports that in 2001, China was the top producer of cadmium with almost one-sixth of the world's production, closely followed by South Korea and Japan.<ref>{{cite book|last1=Hetherington|first1=L. E.|title=World Mineral Production 2002–06|date=2008|publisher=[[British Geological Survey]]|page=15|chapter=Production of Cadmium|display-authors=etal|access-date=15 April 2012|chapter-url=http://nora.nerc.ac.uk/3260/2/FINAL_WMP_2002_2006_COMPLETE_WEB.pdf|archive-url=https://web.archive.org/web/20121108102639/http://nora.nerc.ac.uk/3260/2/FINAL_WMP_2002_2006_COMPLETE_WEB.pdf|archive-date=2012-11-08|url-status=dead}}</ref>

<gallery widths="200" heights="160">
File:Cadmium - world production trend.svg|History of the world production of cadmium
File:2022cadmium.png|Cadmium production in 2010
</gallery>

==Applications==
Cadmium is a common component of electric batteries, [[cadmium pigments|pigments]],<ref name="colors" /> coatings,<ref name="fff" /> and electroplating.<ref name="HgCdPb" />

===Batteries===
[[File:NiCd various.jpg|thumb|Ni–Cd batteries]]
In 2009, 86% of cadmium was used in [[Battery (electricity)|batteries]], predominantly in [[rechargeable battery|rechargeable]] [[nickel–cadmium battery|nickel–cadmium batteries]]. Nickel–cadmium cells have a nominal cell potential of 1.2&nbsp;[[Volt|V]]. The cell consists of a positive [[nickel hydroxide]] [[electrode]] and a negative cadmium electrode plate separated by an [[alkaline]] [[electrolyte]] ([[potassium hydroxide]]).<ref>{{cite book |last= Krishnamurthy |first= N. |date= 2 July 2013 |title= Engineering Chemistry, 2nd edition |location= New York |publisher= PHI Learning Private Limited |pages= 82–83 |isbn= 978-81-203-3666-7 }}</ref> The European Union put a limit on cadmium in electronics in 2004 of 0.01%,<ref>{{CELEX|32011L0065|text=Directive 2011/65/EU of the European Parliament and of the Council of 8 June 2011 on the restriction of the use of certain hazardous substances in electrical and electronic equipment}}</ref> with some exceptions, and in 2006 reduced the limit on cadmium content to 0.002%.<ref name="EC_Directive">{{CELEX|32006L0066|text=Directive 2006/66/EC of the European Parliament and of the Council of 6 September 2006 on batteries and accumulators and waste batteries and accumulators and repealing Directive 91/157/EEC}}</ref> Another type of battery based on cadmium is the [[silver–cadmium battery]].

===Electroplating===
[[File:CdSeqdots.jpg|thumb|A photograph and representative spectrum of [[photoluminescence]] from colloidal CdSe [[quantum dot]]s]]
Cadmium [[electroplating]], consuming 6% of the global production, is used in the aircraft industry to reduce [[corrosion]] of steel components.<ref name="HgCdPb">{{cite book|url = https://books.google.com/books?id=9yzN-QGag_8C|title = Mercury, Cadmium, Lead: Handbook for Sustainable Heavy Metals Policy and Regulation|first1 = Michael J.|last1 = Scoullos|last2= Vonkeman|first2=Gerrit H.|last3 = Thornton|first3=Iain|last4 = Makuch |first4=Zen| publisher = Springer|date = 2001|isbn = 978-1-4020-0224-3}}</ref> This coating is passivated by [[Chromate and dichromate|chromate]] salts.<ref name="fff">{{cite web |url=http://ftp.rta.nato.int/public//PubFulltext/RTO/MP/RTO-MP-025///MP-025-15.pdf |title=Advances to Protective Coatings and their Application to Ageing Aircraft |last1=Smith|first1=C.J.E.|last2=Higgs|first2=M.S.|last3=Baldwin|first3=K.R. |date=20 April 1999 |publisher=RTO MP-25 |access-date=29 May 2011 |url-status=dead |archive-url=https://web.archive.org/web/20110517202722/http://ftp.rta.nato.int/public/ |archive-date=17 May 2011}}</ref> A limitation of cadmium plating is [[hydrogen embrittlement]] of high-strength steels from the electroplating process. Therefore, steel parts heat-treated to tensile strength above 1300 MPa (200 ksi) should be coated by an alternative method (such as special low-embrittlement cadmium electroplating processes or physical vapor deposition).

Titanium embrittlement from cadmium-plated tool residues resulted in banishment of those tools (and the implementation of routine tool testing to detect cadmium contamination) in the A-12/SR-71, U-2, and subsequent aircraft programs that use titanium.<ref>{{cite web|url = https://www.cia.gov/library/center-for-the-study-of-intelligence/csi-publications/books-and-monographs/a-12/breaking-through-technological-barriers.html|archive-url = https://web.archive.org/web/20071009211528/https://www.cia.gov/library/center-for-the-study-of-intelligence/csi-publications/books-and-monographs/a-12/breaking-through-technological-barriers.html|url-status = dead|archive-date = 9 October 2007|title = CIA – Breaking Through Technological Barriers – Finding The Right Metal (A-12 program)|date=1 October 2007}}</ref>

===Nuclear technology===
Cadmium is used in the [[control rod]]s of nuclear reactors, acting as a very effective [[neutron poison]] to control [[neutron flux]] in [[nuclear fission]].<ref name="HgCdPb" /> When cadmium rods are inserted in the core of a nuclear reactor, cadmium absorbs neutrons,<ref>{{Cite web |title=Cadmium (Cd) {{!}} AMERICAN ELEMENTS ® |url=https://www.americanelements.com/cd.html |access-date=2024-08-16 |website=American Elements: The Materials Science Company |language=en}}</ref> preventing them from creating additional fission events, thus controlling the amount of reactivity. The [[pressurized water reactor]] designed by [[Westinghouse Electric Company]] uses an alloy consisting of 80% silver, 15% indium, and 5% cadmium.<ref name="HgCdPb" />

Cadmium foil is a convenient mask material that can be wrapped around samples in neutron scattering experiments.  The toxicity of cadmium, and the fact that a relatively high-energy gamma photon is emitted during neutron absorption that may have a strong effect on the instrument background, mean that cadmium has somewhat lost favour against alternatives.  Boron-based materials are much less toxic and produce gamma photons of significantly lower energy, for example.

===Televisions===
[[Quantum dot display|QLED TVs]] have been starting to include cadmium in construction. Some companies have been looking to reduce the environmental impact of human exposure and pollution of the material in televisions during production.<ref>{{Cite news|url=https://theconversation.com/are-quantum-dot-tvs-and-their-toxic-ingredients-actually-better-for-the-environment-35953|title=Are quantum dot TVs – and their toxic ingredients – actually better for the environment?|last=Maynard|first=Andrew|work=The Conversation|access-date=2017-07-23|language=en}}</ref>

===Anticancer drugs===
Complexes based on cadmium and other heavy metals have potential for the treatment of cancer, but their use is often limited due to toxic side effects.<ref>{{Cite journal|last1=Abyar|first1=Selda|last2=Khandar|first2=Ali Akbar|last3=Salehi|first3=Roya|last4=Abolfazl Hosseini-Yazdi|first4=Seyed|last5=Alizadeh|first5=Effat|last6=Mahkam|first6=Mehrdad|last7=Jamalpoor|first7=Amer|last8=White|first8=Jonathan M.|last9=Shojaei|first9=Motahhareh|last10=Aizpurua-Olaizola|first10=O.|last11=Masereeuw|first11=Rosalinde|display-authors=3|date=December 2019|title=In vitro nephrotoxicity and anticancer potency of newly synthesized cadmium complexes|journal=Scientific Reports|language=en|volume=9|issue=1|pages=14686|doi=10.1038/s41598-019-51109-9|issn=2045-2322|pmc=6789105|pmid=31604983|bibcode=2019NatSR...914686A}}</ref>

===Compounds===
[[File:Tyne and Wear Metro train 4001 at Pelaw 01.jpg|thumb|Train painted with [[Cadmium pigments|cadmium orange]]]]
[[Cadmium oxide]] was used in black and white television phosphors and in the blue and green phosphors of color television cathode ray tubes.<ref>{{cite journal|journal = [[Environmental Science & Technology]] |volume = 36|issue = 1|pages = 69–75|date = 2002|doi = 10.1021/es010517q|title = Recycling of Scrap Cathode Ray Tubes|first1 = Ching-Hwa|last1 = Lee|pmid = 11811492|last2 = Hsi|first2 = C. S.|bibcode = 2002EnST...36...69L }}</ref> [[Cadmium sulfide]] (CdS) is used as a photoconductive surface coating for photocopier drums.<ref>{{cite book|chapter-url = https://books.google.com/books?id=8Yt6GzSEZRkC&pg=PR18|title =Electronic materials: from silicon to organics|first1= L. S.|last1 = Miller|first2=J. B. |last2= Mullin|publisher = Springer|date = 1991|isbn = 978-0-306-43655-0|page = 273|chapter = Crystalline Cadmium Sulfide}}</ref>

[[File:Cadmium sulfide.jpg|thumb|left|upright=0.5|Cadmium sulfide]]
Various cadmium salts are used in paint pigments, with CdS as a [[Cadmium pigments|yellow pigment]] being the most common. [[Cadmium selenide]] is a red pigment, commonly called ''cadmium red''. To painters who work with the pigment, cadmium provides the most brilliant and durable yellows, oranges, and reds&nbsp;– so much so that during production, these colors are significantly toned down before they are ground with oils and binders or blended into [[watercolor]]s, [[gouache]]s, [[Acrylic paint|acrylics]], and other paint and pigment formulations. Because these pigments are potentially toxic, users should use a [[barrier cream]] on the hands to prevent absorption through the skin<ref name="colors">{{cite book|chapter = Cadmium Pigments|chapter-url = https://books.google.com/books?id=_OrB0ew_HgAC&pg=PA121|pages = 121–123|isbn = 978-3-527-30363-2|publisher = Wiley-VCH|date = 2005|title = Industrial inorganic pigments|first1 = Gunter|last1 = Buxbaum|first2 = Gerhard|last2 = Pfaff}}{{Dead link|date=March 2023 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> even though the amount of cadmium absorbed into the body through the skin is reported to be less than 1%.<ref name = "ATSDR" />

In [[polyvinyl chloride|PVC]], cadmium was used as heat, light, and weathering stabilizers.<ref name="HgCdPb" /><ref>{{cite book|chapter-url = https://books.google.com/books?id=YUkJNI9QYsUC&pg=PA149|page = 149|first = Thomas C.|last = Jennings|isbn = 978-1-56990-379-7| publisher = Hanser Verlag|date = 2005|title = PVC handbook|chapter = Cadmium Environmental Concerns}}</ref> Currently, cadmium stabilizers have been completely replaced with barium-zinc, calcium-zinc and organo-tin stabilizers. Cadmium is used in many kinds of [[solder]] and bearing alloys, because it has a low [[coefficient of friction]] and fatigue resistance.<ref name="HgCdPb" /> It is also found in some of the lowest-melting [[alloy]]s, such as [[Wood's metal]].<ref>{{cite book|first1= George Stuart|last1= Brady|first2= George S.|last2= Brady|first3= Henry R.|last3= Clauser|first4 = John A.|last4 = Vaccari|isbn = 978-0-07-136076-0|url = https://books.google.com/books?id=vIhvSQLhhMEC&pg=PA425|title = Materials handbook: an encyclopedia for managers, technical professionals, purchasing and production managers, technicians, and supervisors|publisher = McGraw-Hill Professional|date = 2002| page = 425}}</ref>

===Semiconductors===
Cadmium is an element in some [[semiconductor]] materials. Cadmium sulfide, cadmium selenide, and [[cadmium telluride]] are used in some [[photodetectors]] and [[solar cell]]s. [[HgCdTe]] detectors are sensitive to mid-[[infrared]] light<ref name="HgCdPb" /> and used in some motion detectors.

===Laboratory uses===
[[File:HeCd laser.jpg|thumb|Violet light from a [[helium]] cadmium metal vapor [[laser]]. The highly [[monochromatic]] color arises from the 441.563 nm transition [[spectral line|line]] of cadmium.]]
Helium–cadmium lasers are a common source of blue or ultraviolet laser light. Lasers at wavelengths of 325, 354 and 442&nbsp;nm are made using this [[gain medium]]; some models can switch between these wavelengths. They are notably used in [[fluorescence microscopy]] as well as various laboratory uses requiring laser light at these wavelengths.<ref>{{cite web| url = http://www.olympusfluoview.com/java/hecdlasers/index.html| title = Helium–Cadmium Lasers| publisher = Olympus| access-date = 14 May 2011| url-status = dead| archive-url = https://web.archive.org/web/20110715000100/http://www.olympusfluoview.com/java/hecdlasers/index.html| archive-date = 15 July 2011}}</ref><ref>{{cite book|chapter-url = https://books.google.com/books?id=JxASQpi0LXoC&pg=PA488| chapter = Helium–cadmium Laser|title = Lasers: Principles, Types and Applications|isbn = 978-81-224-1492-9|author1 = Nambiar, K.R|date = 2006| publisher = New Age International}}</ref>

Cadmium selenide [[quantum dot]]s emit bright [[luminescence]] under UV excitation (He–Cd laser, for example). The color of this luminescence can be green, yellow or red depending on the particle size. Colloidal solutions of those particles are used for imaging of biological tissues and solutions with a [[fluorescence microscope]].<ref>{{cite news|url=http://mix.msfc.nasa.gov/abstracts.php?p=3906|publisher=NASA|title=Cadmium Selenium Testing for Microbial Contaminants|date=10 June 2003|access-date=20 November 2009|archive-url=https://web.archive.org/web/20110725023512/http://mix.msfc.nasa.gov/abstracts.php?p=3906|archive-date=25 July 2011|url-status=dead}}</ref>

In molecular biology, cadmium is used to block [[Voltage-gated calcium channel|voltage-dependent calcium channels]] from fluxing calcium ions, as well as in [[Hypoxia (medical)|hypoxia]] research to stimulate [[proteasome]]-dependent degradation of [[Hypoxia-inducible factors|Hif-1α]].<ref>{{cite journal|journal = European Journal of Biochemistry|volume = 267|issue = 13|pages = 4198–4204|date = 2000|doi = 10.1046/j.1432-1327.2000.01453.x|title = Cadmium blocks hypoxia-inducible factor (HIF)-1-mediated response to hypoxia by stimulating the proteasome-dependent degradation of HIF-1alpha|first1 = Chun Y. S.|last1 = Park J. W.|pmid = 10866824|last2 = Choi|first2 = E.|last3 = Kim|first3 = G. T.|last4 = Choi|first4 = H.|last5 = Kim|first5 = C. H.|last6 = Lee|first6 = M. J.|last7 = Kim|first7 = M. S.|last8 = Park|first8 = J. W.|doi-access = free}}</ref>

Cadmium-selective sensors based on the [[fluorophore]] [[BODIPY]] have been developed for imaging and sensing of cadmium in cells.<ref>{{cite book
|last1=Taki
|first1=Masayasu
|title=Cadmium: From Toxicity to Essentiality
|chapter=Imaging and Sensing of Cadmium in Cells
|editor=Astrid Sigel
|editor2=Helmut Sigel
|editor3=Roland K. O. Sigel
|series=Metal Ions in Life Sciences
|volume=11
|date=2013
|publisher=Springer
|pages=99–115
|doi=10.1007/978-94-007-5179-8_5|pmid=23430772
|isbn=978-94-007-5178-1
}}
</ref> One powerful method for monitoring cadmium in aqueous environments involves [[electrochemistry]]. By employing a [[self-assembled monolayer]] one can obtain a cadmium selective electrode with a [[Parts-per notation|ppt]]-level sensitivity.<ref>{{Cite journal|last1=Noyhouzer|first1=Tomer|last2=Mandler|first2=Daniel|date=2011-01-17|title=Determination of low levels of cadmium ions by the under potential deposition on a self-assembled monolayer on gold electrode|journal=Analytica Chimica Acta|volume=684|issue=1–2|pages=1–7|doi=10.1016/j.aca.2010.10.021|pmid=21167979|bibcode=2011AcAC..684....1N }}</ref>

==Biological role==
Cadmium has no known function in higher organisms and is considered toxic.<ref>Hogan, C. Michael (2010). [http://editors.eol.org/eoearth/wiki/Heavy_metal ''Heavy metal''. Encyclopedia of Earth. National Council for Science and the Environment.] E. Monosson and C. Cleveland (eds.). Washington DC.</ref> Cadmium is considered an environmental pollutant hazardous to living organisms.<ref name="xu">{{cite journal|display-authors=3 |vauthors=Xu L, Zhang F, Tang M, Wang Y, Dong J, Ying J, Chen Y, Hu B, Li C, Liu L |title=Melatonin confers cadmium tolerance by modulating critical heavy metal chelators and transporters in radish plants |journal=Journal of Pineal Research |volume=69 |issue=1 |pages=e12659 |date=August 2020 |pmid=32323337 |doi=10.1111/jpi.12659|url=https://api.research-repository.uwa.edu.au/ws/files/169558801/AAM_XuL_Melatonin_confers_cadmium_tolerance_by_modulating.pdf }}</ref> A cadmium-dependent [[carbonic anhydrase]] has been found in some marine [[diatom]]s,<ref name="Diatom">{{cite journal
|title = A cadmium enzyme from a marine diatom
|display-authors=3
|first1 = Todd W.
|last1 = Lane
|journal = Nature
|volume = 435
|issue = 42
|pages = 42
|date = 2005
|pmid = 15875011
|url = http://www.whoi.edu/cms/files/msaito/2005/5/LaneSaitoMorel_CdCA_Nature2005_2944.pdf
|doi = 10.1038/435042a
|last2 = Saito
|first2 = Mak A.
|last3 = George
|first3 = Graham N.
|last4 = Pickering
|first4 = Ingrid J.
|last5 = Prince
|first5 = Roger C.
|last6 = Morel
|first6 = François M. M.|bibcode = 2005Natur.435...42L |s2cid = 52819760
|doi-access = free
}}</ref> which live in environments with low zinc concentrations.<ref>{{cite journal
|title = A biological function for cadmium in marine diatoms
|first1 = Todd W.
|last1 = Lane
|journal = Proc. Natl. Acad. Sci.
|volume = 97
|issue = 9
|pages = 4627–4631
|date = 2000
|doi = 10.1073/pnas.090091397
|pmid = 10781068
|last2 = Morel
|first2 = F. M.
|pmc = 18283|bibcode = 2000PNAS...97.4627L |doi-access = free
}}</ref>

Cadmium is preferentially absorbed in the kidneys of humans. Up to about 30&nbsp;mg of cadmium is commonly inhaled throughout human childhood and adolescence.<ref>{{cite journal|last1= Perry|first1 = HM Jr.| last2= Thind|first2 =G. S.| last3= Perry|first3 =E. F.|date = 1976| pmid = 775217 |title =The biology of cadmium|volume = 60|issue = 4|pages = 759–69|journal = The Medical Clinics of North America|doi = 10.1016/S0025-7125(16)31859-4}}</ref>

Cadmium is under research for its potential [[toxicity]] to increase the risk of [[cancer]], [[cardiovascular disease]], and [[osteoporosis]].<ref>{{cite journal|year=2014|last1=Luevano|first1=J|title=A Review of Molecular Events of Cadmium-Induced Carcinogenesis|journal=Journal of Environmental Pathology, Toxicology and Oncology|volume=33|issue=3|pages=183–194|last2=Damodaran|first2=C|pmid=25272057|doi=10.1615/jenvironpatholtoxicoloncol.2014011075|pmc=4183964}}</ref><ref>{{cite journal|pmid=23991990|year=2013|last1=Rahim|first1=F|title=Breast cancer frequency and exposure to cadmium: A meta-analysis and systematic review|journal=Asian Pacific Journal of Cancer Prevention|volume=14|issue=7|pages=4283–7|last2=Jalali|first2=A|last3=Tangestani|first3=R|url=http://journal.waocp.org/article_27945_d5fc7ccf25acb7c8169ba197aa4355ba.pdf |archive-url=https://ghostarchive.org/archive/20221010/http://journal.waocp.org/article_27945_d5fc7ccf25acb7c8169ba197aa4355ba.pdf |archive-date=2022-10-10 |url-status=live|doi=10.7314/apjcp.2013.14.7.4283|doi-access=free}}</ref><ref>{{cite journal|pmc=3858820|year=2013|last1=Tellez-Plaza|first1=M|title=Cadmium Exposure and Clinical Cardiovascular Disease: A Systematic Review|journal=Current Atherosclerosis Reports|volume=15|issue=10|pages=10.1007/s11883–013–0356–2|last2=Jones|first2=M. R.|last3=Dominguez-Lucas|first3=A|last4=Guallar|first4=E|last5=Navas-Acien|first5=A|doi=10.1007/s11883-013-0356-2|pmid=23955722}}</ref><ref>{{cite journal|pmid=23877535|year=2013|last1=James|first1=K. A.|title=Environmental cadmium exposure and osteoporosis: A review|journal=International Journal of Public Health|volume=58|issue=5|pages=737–45|last2=Meliker|first2=J. R.|doi=10.1007/s00038-013-0488-8|s2cid=11265947}}</ref>

=== Environmental impact ===
The [[biogeochemistry]] of cadmium and its release to the environment is under research.<ref>
{{cite book
|last1=Cullen
|first1=Jay T.
|last2=Maldonado
|first2=Maria T.
|title=Cadmium: From Toxicity to Essentiality
|chapter=Biogeochemistry of Cadmium and Its Release to the Environment
|editor=Astrid Sigel
|editor2=Helmut Sigel
|editor3=Roland K. O. Sigel
|series=Metal Ions in Life Sciences
|volume=11
|date=2013
|publisher=Springer
|pages=31–62
|doi=10.1007/978-94-007-5179-8_2|pmid=23430769
|isbn=978-94-007-5178-1
}}
</ref><ref>{{cite book
|last1=Crea
|first1=Francesco
|last2=Foti
|first2=Claudia
|last3=Milea
|first3=Demetrio
|last4=Sammartano
|first4=Silvio
|title=Cadmium: From Toxicity to Essentiality
|chapter=Speciation of Cadmium in the Environment
|editor=Astrid Sigel
|editor2=Helmut Sigel
|editor3=Roland K. O. Sigel
|series=Metal Ions in Life Sciences
|volume=11
|date=2013
|publisher=Springer
|pages=63–83
|doi=10.1007/978-94-007-5179-8_3|pmid=23430770
|isbn=978-94-007-5178-1
}}
</ref>

==Safety==
{{Main|Cadmium poisoning}}
{{Chembox
|container_only = yes
|Section7={{Chembox Hazards
| ExternalSDS =
| GHSPictograms = {{GHS06}} {{GHS08}} {{GHS09}}
| GHSSignalWord = Danger
| HPhrases = {{H-phrases|H301|H330|H341|H350|H361fd|H372|H410}}
| PPhrases = {{P-phrases|P201|P202|P260|P264|P273|P304 + P340 + P310}}
| GHS_ref  =<ref>GHS: {{cite web |url=https://www.sigmaaldrich.com/MSDS/MSDS/DisplayMSDSPage.do?country=US&language=en&productNumber=265454&brand=ALDRICH&PageToGoToURL=https%3A%2F%2Fwww.sigmaaldrich.com%2Fcatalog%2Fproduct%2Faldrich%2F265454%3Flang%3Den |title=Safety Data Sheet |publisher=Sigma-Aldrich|date=2021-09-12 |access-date=2021-12-22}}</ref>
| NFPA-H = 4
| NFPA-F = 0
| NFPA-R = 0
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Individuals and organizations have been reviewing cadmium's bioinorganic aspects for its toxicity.<ref>{{cite book
|last1=Maret
|first1=Wolfgang
|last2=Moulis
|first2=Jean-Marc
|title=Cadmium: From Toxicity to Essentiality
|chapter=The Bioinorganic Chemistry of Cadmium in the Context of Its Toxicity
|editor=Astrid Sigel
|editor2=Helmut Sigel
|editor3=Roland K. O. Sigel
|series=Metal Ions in Life Sciences
|volume=11
|date=2013
|publisher=Springer
|pages=1–30
|doi=10.1007/978-94-007-5179-8_1|pmid=23430768
|isbn=978-94-007-5178-1
}}
</ref> The most dangerous form of occupational exposure to cadmium is inhalation of fine dust and fumes, or ingestion of highly soluble cadmium compounds.<ref name="ReferenceA" /> Inhalation of cadmium fumes can result initially in [[metal fume fever]], but may progress to chemical [[pneumonitis]], [[pulmonary edema]], and death.<ref>{{cite book|url = https://books.google.com/books?id=vgHXTId8rnYC|title = Principles and Methods of Toxicology|first = Andrew Wallace|last = Hayes|publisher = CRC Press|place = Philadelphia|date = 2007|pages = 858–861|isbn=978-0-8493-3778-9}}</ref>

Cadmium is also an environmental hazard. Human exposure is primarily from fossil fuel combustion, phosphate fertilizers, natural sources, iron and steel production, cement production and related activities, nonferrous metals production, and municipal solid waste incineration.<ref name="ReferenceA" /> Other sources of cadmium include bread, root crops, and vegetables.<ref name="news.yahoo.com">Mann, Denise (23 April 2012) [https://web.archive.org/web/20120426102047/http://news.yahoo.com/heavy-metal-foods-cosmetics-spur-breast-cancer-spread-200608223.html Can Heavy Metal in Foods, Cosmetics Spur Breast Cancer Spread?] HealthDayBy via Yahoo</ref>

[[File:Jinzu River.jpg|right|thumb|[[Jinzū River]] area, which was contaminated with cadmium]]
There have been a few instances of general population poisoning as the result of long-term exposure to cadmium in contaminated food and water. Research into an estrogen mimicry that may induce breast cancer is ongoing, {{as of|2012|lc=yes}}.<ref name="news.yahoo.com" /> In the decades leading up to [[World War II]], mining operations contaminated the [[Jinzū River]] in Japan with cadmium and traces of other toxic metals. As a consequence, cadmium accumulated in the rice crops along the riverbanks downstream of the mines. Some members of the local agricultural communities consumed the contaminated rice and developed [[itai-itai]] disease and renal abnormalities, including [[proteinuria]] and [[glucosuria]].<ref>{{cite journal|title = Environmental cadmium exposure, adverse effects, and preventative measures in Japan|first1 = Koji|last1 = Nogawa|journal = Biometals|date = 2004|volume = 17|issue = 5|pages =581–587|doi = 10.1023/B:BIOM.0000045742.81440.9c|pmid = 15688869|last2 = Kobayashi|first2 = E.|last3 = Okubo|first3 = Y.|last4 = Suwazono|first4 = Y.|s2cid = 8053594}}</ref> The victims of this poisoning were almost exclusively post-menopausal women with low iron and low body stores of other minerals. Similar general population cadmium exposures in other parts of the world have not resulted in the same health problems because the populations maintained sufficient iron and other mineral levels. Thus, although cadmium is a major factor in the itai-itai disease in Japan, most researchers have concluded that it was one of several factors.<ref name="ReferenceA" />

Cadmium is one of ten substances banned by the European Union's [[Restriction of Hazardous Substances]] (RoHS) directive, which regulates hazardous substances in electrical and electronic equipment, but allows for certain exemptions and exclusions from the scope of the law.<ref>{{CELEX|32006D0690|text=2006/690/EC: Commission Decision of 12 October 2006 amending, for the purposes of adapting to technical progress, the Annex to Directive 2002/95/EC of the European Parliament and of the Council as regards exemptions for applications of lead in crystal glass (notified under document number C(2006) 4789)}}</ref>

The International Agency for Research on Cancer has classified cadmium and cadmium compounds as carcinogenic to humans.<ref>{{Cite book |author=IARC Working Group on the Evaluation of Carcinogenic Risks to Humans|url=https://www.worldcat.org/oclc/29943893 |title=Beryllium, cadmium, mercury, and exposures in the glass manufacturing industry |year=1993 |isbn=92-832-1258-4 |location=Geneva|publisher= International Agency for Research on Cancer, Secretariat of the World Health Organization|oclc=29943893}}</ref> Although occupational exposure to cadmium is linked to lung and prostate cancer, there is still uncertainty about the carcinogenicity of cadmium in low environmental exposure. Recent data from epidemiological studies suggest that intake of cadmium through diet is associated with a higher risk of endometrial, breast, and prostate cancer as well as with osteoporosis in humans.<ref>{{Cite journal
 | pmid = 22850555
| pmc = 3425979
| year = 2012
| last1 = Julin
| first1 = B.
| title = Dietary cadmium exposure and prostate cancer incidence: A population-based prospective cohort study
| journal = British Journal of Cancer
| volume = 107
| issue = 5
| pages = 895–900
| last2 = Wolk
| first2 = A.
| last3 = Johansson
| first3 = J. E.
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| first4 = S. O.
| last5 = Andrén
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| last6 = Akesson
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| doi = 10.1038/bjc.2012.311
}}</ref><ref>{{Cite journal
 | pmid = 22465267
| year = 2012
| last1 = Engström
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| title = Associations between dietary cadmium exposure and bone mineral density and risk of osteoporosis and fractures among women
| journal = Bone
| volume = 50
| issue = 6
| pages = 1372–8
| last2 = Michaëlsson
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Cadmium exposure is associated with a large number of illnesses including kidney disease,<ref name="zn-cd.diseases" /> early atherosclerosis, hypertension, and cardiovascular diseases.<ref>[http://www.medinewsdirect.com/?p=704 Cadmium Exposure can Induce Early Atherosclerotic Changes] {{webarchive|url=https://web.archive.org/web/20120315135304/http://www.medinewsdirect.com/?p=704 |date=15 March 2012 }}, Medinews Direct, 7 September 2009</ref> Although studies show a significant correlation between cadmium exposure and occurrence of disease in human populations, a molecular mechanism has not yet been identified. One hypothesis holds that cadmium is an [[endocrine disruptor]] and some experimental studies have shown that it can interact with different [[Hormone|hormonal]] signaling pathways. For example, cadmium can bind to the [[estrogen receptor]] alpha,<ref>{{Cite journal
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The [[tobacco plant]] absorbs and accumulates [[heavy metals]] such as cadmium from the surrounding soil into its leaves. Following tobacco smoke inhalation, these are readily absorbed into the body of users.<ref>{{Cite journal |doi=10.1016/j.talanta.2011.12.027|pmid=22284492|title=Preconcentration and determination of copper in tobacco leaves samples by using a minicolumn of sisal fiber (Agave sisalana) loaded with Alizarin fluorine blue by FAAS|journal=Talanta|volume=89|issue=1|pages=276–279|year=2012|last1=Dias|first1=Fábio de S.|last2=Bonsucesso|first2=Josemário S.|last3=Oliveira|first3=Lucas C.|last4=Dos Santos|first4=Walter N.L.|doi-access=free}}</ref> Tobacco smoking is the most important single source of cadmium exposure in the general population. An estimated 10% of the cadmium content of a cigarette is inhaled through smoking. Absorption of cadmium through the lungs is more effective than through the gut. As much as 50% of the cadmium inhaled in cigarette smoke may be absorbed.<ref>{{cite journal|doi = 10.1146/annurev.pu.04.050183.002055|doi-access=free|journal = Annual Review of Public Health|volume = 4|pmid = 6860444|pages = 367–73|date = 1983|title = Cadmium|first = L.|last = Friberg}}</ref>
On average, cadmium concentrations in the blood of smokers is 4&nbsp;to 5 times greater than non-smokers and in the kidney, 2–3 times greater than in non-smokers. Despite the high cadmium content in cigarette smoke, there seems to be little exposure to cadmium from [[passive smoking]].<ref>{{cite journal|journal = Scandinavian Journal of Work, Environment & Health|volume = 24|pages = 11–51|date = 1998|title = Health effects of cadmium exposure – a review of the literature and a risk estimate|first = L.|last = Jarup|pmid = 9569444}}</ref>

In a non-smoking population, food is the greatest source of exposure. High quantities of cadmium can be found in [[crustacean]]s, [[Mollusca|mollusks]], [[offal]], [[frog legs]], [[cocoa solids]], bitter and semi-bitter [[chocolate]], [[seaweed]], [[fungi]] and [[algae]] products. However, grains, vegetables, and starchy roots and tubers are consumed in much greater quantity in the U.S., and are the source of the greatest dietary exposure there.<ref name="efsa.europa.eu">{{cite web|url=http://www.efsa.europa.eu/en/efsajournal/pub/2551|title=Cadmium dietary exposure in the European population – European Food Safety Authority|website=www.efsa.europa.eu|date=2012-01-18}}</ref> Most plants bio-accumulate metal toxins such as cadmium and when composted to form organic fertilizers, yield a product that often can contain high amounts (e.g., over 0.5&nbsp;mg) of metal toxins for every kilogram of fertilizer. Fertilizers made from animal dung (e.g., cow dung) or urban waste can contain similar amounts of cadmium. The cadmium added to the soil from fertilizers (rock phosphates or organic fertilizers) become bio-available and toxic only if the [[soil pH]] is low (i.e., acidic soils). In the European Union, an analysis of almost 22,000 topsoil samples with LUCAS survey concluded that 5.5% of samples have concentrations higher than 1&nbsp;mg kg<sup>−1</sup>.<ref>{{Cite journal |last1=Ballabio |first1=Cristiano |last2=Jones |first2=Arwyn |last3=Panagos |first3=Panos |date=2024-02-01 |title=Cadmium in topsoils of the European Union – An analysis based on LUCAS topsoil database |journal=Science of the Total Environment |language=en |volume=912 |pages=168710 |doi=10.1016/j.scitotenv.2023.168710|doi-access=free |pmid=38008327 |bibcode= 2024ScTEn.91268710B}}</ref>

Zinc, copper, calcium, and iron ions, and selenium with vitamin C are used to treat cadmium intoxication, although it is not easily reversed.<ref name="zn-cd.diseases">{{cite web|url=http://www.arltma.com/Articles/CadmiumToxDoc.htm|title=ARL : Cadmium Toxicity|website=www.arltma.com|access-date=7 July 2016|archive-date=9 September 2019|archive-url=https://web.archive.org/web/20190909101141/http://www.arltma.com/Articles/CadmiumToxDoc.htm|url-status=dead}}</ref>

===Regulations===
Because of the adverse effects of cadmium on the environment and human health, the supply and use of cadmium is restricted in Europe under the [[Registration, Evaluation, Authorisation and Restriction of Chemicals|REACH Regulation]].

The EFSA Panel on Contaminants in the Food Chain specifies that 2.5 μg/kg body weight is a tolerable weekly intake for humans.<ref name="efsa.europa.eu" /> The Joint FAO/WHO Expert Committee on Food Additives has declared 7 μg/kg body weight to be the provisional tolerable weekly intake level.<ref>{{cite web|url=http://www.inchem.org/documents/jecfa/jeceval/jec_297.htm|title=JECFA Evaluations-CADMIUM-|website=www.inchem.org}}</ref> The state of [[California]] requires a food label to carry a warning about potential exposure to cadmium on products such as cocoa powder.<ref>such as seen on the organic cocoa powder marketed by Better Body Foods, for example</ref> The European Commission has put in place the EU regulation (2019/1009) on fertilizing products (EU, 2019), adopted in June 2019 and fully applicable as of July 2022. It sets a Cd limit value in phosphate fertilizers to 60&nbsp;mg kg<sup>−1</sup> of P<sub>2</sub>O<sub>5</sub>.

The U.S. [[Occupational Safety and Health Administration]] (OSHA) has set the [[permissible exposure limit]] (PEL) for cadmium at a time-weighted average (TWA) of 0.005 ppm. The [[National Institute for Occupational Safety and Health]] (NIOSH) has not set a [[recommended exposure limit]] (REL) and has designated cadmium as a known human carcinogen. The [[IDLH]] (immediately dangerous to life and health) level for cadmium is 9&nbsp;mg/m<sup>3</sup>.<ref>{{PGCH|0087}}</ref>
{| class="wikitable"
!Lethal dose<ref>{{IDLH|7440439|Cadmium compounds (as Cd)}}</ref>
!Organism
!Route
!Time
|-
|LD<sub>50</sub>: 225&nbsp;mg/kg
|rat
|oral
|n/a
|-
|LD<sub>50</sub>: 890&nbsp;mg/kg
|mouse
|oral
|n/a
|-
|LC<sub>50</sub>: 25&nbsp;mg/m<sup>3</sup>
|rat
|airborne
|30 min
|}

In addition to mercury, the presence of cadmium in some [[Nickel–cadmium battery#Environmental impact|batteries]] has led to the requirement of proper disposal (or recycling) of batteries.

===Product recalls===
In May 2006, a sale of the seats from [[Arsenal F.C.]]'s old stadium, [[Arsenal Stadium|Highbury]] in London, England was cancelled when the seats were discovered to contain trace amounts of cadmium.<ref>{{Cite news| title = Toxic fears hit Highbury auction| work = BBC Sport| access-date =29 November 2010| date = 10 May 2006| url = http://news.bbc.co.uk/sport1/hi/football/teams/a/arsenal/4757797.stm}}</ref> Reports of high levels of cadmium use in children's jewelry in 2010 led to a US [[Consumer Product Safety Commission]] investigation.<ref>{{Cite news| title = U.S. to Develop Safety Standards for Toxic Metals| work = Business Week| access-date =12 January 2010| date = 12 January 2010| url = http://www.businessweek.com/news/2010-01-12/u-s-to-develop-safety-standards-for-toxic-metals-update1-.html| archive-url = https://web.archive.org/web/20100123234520/http://www.businessweek.com/news/2010-01-12/u-s-to-develop-safety-standards-for-toxic-metals-update1-.html| url-status = dead| archive-date = 23 January 2010}}</ref> The U.S. CPSC issued specific recall notices for cadmium content in jewelry sold by [[Claire's]]<ref>{{Cite news| title = Claire's Recalls Children's Metal Charm Bracelets Due to High Levels of Cadmium| work = U.S. Consumer Product Safety Commission| access-date = 5 June 2010| date = 10 May 2010| url = http://www.cpsc.gov/CPSCPUB/PREREL/prhtml10/10227.html| url-status = dead| archive-url = https://web.archive.org/web/20100531181434/http://www.cpsc.gov/cpscpub/prerel/prhtml10/10227.html| archive-date = 31 May 2010}}</ref> and [[Wal-Mart]]<ref>{{Cite news| title = FAF Inc. Recalls Children's Necklaces Sold Exclusively at Walmart Stores Due to High Levels of Cadmium| work = U.S. Consumer Product Safety Commission| access-date = 5 June 2010| date = 29 January 2010| url = http://www.cpsc.gov/CPSCPUB/PREREL/prhtml10/10127.html| url-status = dead| archive-url = https://web.archive.org/web/20100527202913/http://www.cpsc.gov/cpscpub/prerel/prhtml10/10127.html| archive-date = 27 May 2010}}</ref> stores.

In June 2010, [[McDonald's]] voluntarily recalled more than 12&nbsp;million promotional ''[[Shrek Forever After|Shrek Forever After 3D]]'' Collectible Drinking Glasses because of the cadmium levels in paint pigments on the glassware.<ref>{{Cite news| title = McDonald's Recalls 12&nbsp;Million 'Shrek' Glasses| work = The New York Times| access-date =5 June 2010| date = 4 June 2010| url = https://www.nytimes.com/2010/06/05/business/05recall.html| first=William| last=Neuman}}</ref> The glasses were manufactured by [[Arc International (tableware)|Arc International]], of [[Millville, New Jersey]], USA.<ref>{{Cite news| title = McDonald's Recalls Movie Themed Drinking Glasses Due to Potential Cadmium Risk| work = U.S. Consumer Product Safety Commission| access-date = 5 June 2010| date = 4 June 2010| url = http://www.cpsc.gov/CPSCPUB/PREREL/prhtml10/10257.html| url-status = dead| archive-url = https://web.archive.org/web/20100607024105/http://www.cpsc.gov/cpscpub/prerel/prhtml10/10257.html| archive-date = 7 June 2010}}</ref>

==See also==
* [[Red List building materials]]
* [[Toxic heavy metal]]

==Notes==
{{Notelist}}

==References==
{{Reflist}}

==Further reading==
* {{cite book
|last1=Hartwig
|first1=Andrea
|title=Cadmium: From Toxicity to Essentiality
|chapter=Cadmium and Cancer
|editor=Astrid Sigel
|editor2=Helmut Sigel
|editor3=Roland K. O. Sigel
|series=Metal Ions in Life Sciences
|volume=11
|date=2013
|publisher=Springer
|pages=491–507
|doi=10.1007/978-94-007-5179-8_15|pmid=23430782
|isbn=978-94-007-5178-1
}}
* Agency for Toxic Substances and Disease Registry (ATSDR) (2012). Toxicological Profile for Cadmium. U.S. Department of Health and Human Services, Public Health Service. https://www.atsdr.cdc.gov/toxprofiles/tp5.pdf
* {{Cite book |last=Nordberg |first=Gunnar F. |title=Handbook on the toxicology of metals |publisher=Academic Press |year=2007 |isbn=978-0-12-369413-3 |edition=3rd |pages=445–486 |language=English}}

==External links==
{{Wiktionary|cadmium}}
{{Commons}}
{{EB1911 poster|Cadmium}}
* [http://www.periodicvideos.com/videos/048.htm Cadmium] at ''[[The Periodic Table of Videos]]'' (University of Nottingham)
* [https://www.atsdr.cdc.gov/csem/csem.asp?csem=6&po=0 ATSDR Case Studies in Environmental Medicine: Cadmium Toxicity] U.S. [[Department of Health and Human Services]]
<!--* [http://ecb.jrc.ec.europa.eu/documents/Existing-Chemicals/RISK_ASSESSMENT/REPORT/cdoxidereport302.pdf European Union Risk Assessment Reports on Cadmium Metal and Cadmium Oxide]-->
* [https://www.cdc.gov/niosh/topics/Cadmium National Institute for Occupational Safety and Health&nbsp;– Cadmium Page]
* [https://toxnet.nlm.nih.gov/cgi-bin/sis/search2/r?dbs+hsdb:@term+@na+@rel+cadmium,+elemental NLM Hazardous Substances Databank&nbsp;– Cadmium, Elemental]
{{Clear}}

{{Periodic table (navbox)}}
{{Cadmium compounds}}

{{Authority control}}

{{Good article}}

[[Category:Cadmium| ]]
[[Category:Chemical elements]]
[[Category:Transition metals]]
[[Category:Endocrine disruptors]]
[[Category:IARC Group 1 carcinogens]]
[[Category:Chemical hazards]]
[[Category:Soil contamination]]
[[Category:Testicular toxicants]]
[[Category:Native element minerals]]
[[Category:Chemical elements with hexagonal close-packed structure]]