Revision as of 19:29, 18 February 2014 editSmokefoot (talk | contribs)Autopatrolled, Extended confirmed users, Pending changes reviewers, Rollbackers74,247 edits revert well intentioned edits, RSC is really just a mirror site, not a good source, and this article is about F-← Previous edit | Latest revision as of 02:30, 5 December 2024 edit undoEMDASHERY (talk | contribs)1 editm →Safety: Oversimplified, misleading, if not an outright lie; the "cited" report *does not examine a single study on IQ in children performed in the US* (pgs. 19-30); "fluoridation is misspelled as "flouridation"; poor quality source (USA Today); the report is by NTP, a composite agency (not the NIH alone); the length of the report is not relevant. | ||
(797 intermediate revisions by more than 100 users not shown) | |||
Line 1: | Line 1: | ||
{{ |
{{Short description|Ion of fluorine}} | ||
{{About|the fluoride ion|a review of fluorine compounds|Compounds of fluorine|the fluoride additive used in toothpaste|Fluoride therapy}} | |||
{{ionbox | |||
{{Distinguish|Floride (disambiguation){{!}}Floride|Fluorite}} | |||
| IUPACName = Fluoride<ref>{{cite web|url=http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=28179|title=Fluorides – PubChem Public Chemical Database|work=The PubChem Project|location=USA|publisher=National Center for Biotechnology Information|at=Identification}}</ref> | |||
{{Use dmy dates|date=July 2022}} | |||
{{Chembox | |||
| IUPACName = Fluoride<ref>{{cite web|url=https://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=28179|title=Fluorides – PubChem Public Chemical Database|work=The PubChem Project|location=USA|publisher=National Center for Biotechnology Information|at=Identification}}</ref> | |||
| ImageFileL1 = F- crop.svg | | ImageFileL1 = F- crop.svg | ||
| ImageSizeL1 = |
| ImageSizeL1 = 100px | ||
| ImageFileR1 = |
| ImageFileR1 = Fluoride_ion.svg | ||
| ImageSizeR1 = |
| ImageSizeR1 = 100px | ||
| |
|Section1={{Chembox Identifiers | ||
| |
| CASNo = 16984-48-8 | ||
| |
| CASNo_Ref = {{cascite|correct|CAS}} | ||
| UNII_Ref = {{fdacite|correct|FDA}} | |||
| PubChem = 28179 | |||
| UNII = Q80VPU408O | |||
| PubChem_Ref = {{pubchemcite|correct|pubchem}} | |||
| |
| PubChem = 28179 | ||
| ChemSpiderID = 26214 | |||
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | |||
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | |||
| KEGG = C00742 | |||
| KEGG_Ref = {{keggcite|correct|kegg}} | | KEGG = C00742 | ||
| KEGG_Ref = {{keggcite|correct|kegg}} | |||
| |
| MeSHName = Fluoride | ||
| |
| ChEBI = 17051 | ||
| |
| ChEMBL = 1362 | ||
| |
| ChEMBL_Ref = {{ebicite|correct|EBI}} | ||
| |
| Gmelin = 14905 | ||
| |
| SMILES = | ||
| |
| StdInChI = 1S/FH/h1H/p-1 | ||
| |
| StdInChI_Ref = {{stdinchicite|correct|chemspider}} | ||
| |
| StdInChIKey = KRHYYFGTRYWZRS-UHFFFAOYSA-M | ||
| |
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} | ||
}} | }} | ||
| |
|Section2={{Chembox Properties | ||
| |
| Formula = {{Chem|F|-}} | ||
| F=1 | |||
| MolarMass = 18.9984032 g mol<sup>−1</sup> | |||
| ConjugateAcid = ] | |||
}} | }} | ||
| |
|Section3={{Chembox Thermochemistry | ||
| |
| DeltaHf = −333 kJ mol<sup>−1</sup> | ||
| |
| Entropy = 145.58 J/mol K (gaseous)<ref>{{cite web |url=http://webbook.nist.gov/cgi/cbook.cgi?ID=C16984488&Mask=1#Thermo-Gas |title=Fluorine anion |pages=1–1951 |publisher=NIST |access-date=July 4, 2012|year=1998 |last1=Chase |first1=M. W. }}</ref> | ||
}} | }} | ||
| |
|Section4={{Chembox Related | ||
| |
| OtherAnions = {{unbulleted list|]|]|]}} | ||
}} | }} | ||
}} | }} | ||
'''Fluoride''' {{IPAc-en|f|l|ɔr|aɪ|d}} is an ] ] of ] with the ] {{Chem|F|−}} |
'''Fluoride''' ({{IPAc-en|ˈ|f|l|ʊər|aɪ|d|,_|ˈ|f|l|ɔr|-}})<ref name="wells313">{{cite book|last1=Wells|first1=J.C.|title=Longman pronunciation dictionary|date=2008|publisher=Pearson Education Limited/Longman|location=Harlow, England|isbn=9781405881180|page=313|edition=3rd}}. According to this source, {{IPAc-en|ˈ|f|l|uː|ə|r|aɪ|d}} is a possible pronunciation in British English.</ref> is an ], ] ] of ], with the ] {{Chem|F|−}} (also written {{Chem||−}}), whose salts are typically white or colorless. Fluoride salts typically have distinctive bitter tastes, and are odorless. Its salts and minerals are important ] and industrial chemicals, mainly used in the production of ] for ]s. Fluoride is classified as a weak base since it only partially associates in solution, but concentrated fluoride is corrosive and can attack the skin. | ||
Fluoride is the simplest |
Fluoride is the simplest fluorine ]. In terms of charge and size, the fluoride ] resembles the ] ion. Fluoride ions occur on ] in several minerals, particularly ], but are present only in trace quantities in bodies of water in nature. | ||
== Nomenclature == | == Nomenclature == | ||
Fluorides include compounds that contain ionic fluoride and those in which fluoride does not dissociate. The nomenclature does not distinguish these situations. For example, ] and ] are not sources of fluoride ions under ordinary conditions. | |||
The systematic name ''fluoride'', the valid ] name, is determined according to the additive nomenclature. However, the name ''fluoride'' is also used in compositional IUPAC nomenclature which does not take the nature of bonding involved into account. | |||
''Fluoride'' is also used non-systematically, to describe compounds which releases hydrogen fluoride upon acidification, or a compound that otherwise incorporates fluorine in some form, such as ] and ]. Hydrogen fluoride is itself an example of a non-systematic name of this nature. However, it is also a ], and the ] for ''fluorane''. | |||
''Fluoride'' is also used non-systematically, to describe compounds which release fluoride upon dissolving. Hydrogen fluoride is itself an example of a non-systematic name of this nature. However, it is also a ], and the ] for ''fluorane''.{{citation needed|date = September 2017}} | |||
==Occurrence== | |||
] | |||
] is estimated to be the 13th-most ] in Earth's crust and is widely dispersed in nature, entirely in the form of fluorides. The vast majority is held in ], the most commercially important of which is ] (CaF<sub>2</sub>).<ref name=Aigueperse/> Natural weathering of some kinds of rocks,<ref>{{cite journal |last1=Derakhshani |first1=R |last2=Raoof |first2=A |last3=Mahvi |first3=AH |last4=Chatrouz |first4=H |title=Similarities in the Fingerprints of Coal Mining Activities, High Ground Water Fluoride, and Dental Fluorosis in Zarand District, Kerman Province, Iran |journal=Fluoride |date=2020 |volume=53 |issue=2 |pages=257–267}}</ref><ref>{{cite journal |last1=Derakhshani |first1=R |last2=Tavallaie |first2=M |last3=Malek Mohammad |first3=T |last4=Abbasnejad |first4=A |last5=Haghdoost |first5=A |title=Occurrence of fluoride in groundwater of Zarand region, Kerman province, Iran |journal=Fluoride |date=2014 |volume=47 |issue=2 |pages=133–138}}</ref> as well as human activities, releases fluorides into the ] through what is sometimes called the ]. | |||
===In water=== | |||
Fluoride is naturally present in groundwater, ] and ] sources, as well as in rainwater, particularly in urban areas.<ref>{{cite web |url= https://www.atsdr.cdc.gov/phs/phs.asp?id=210&tid=38 |title= Public Health Statement for Fluorides, Hydrogen Fluoride, and Fluorine |publisher= ] |date= September 2003 }}</ref> Seawater fluoride levels are usually in the range of 0.86 to 1.4 mg/L, and average 1.1 mg/L<ref>{{cite web|url=http://www.env.gov.bc.ca/wat/wq/BCguidelines/fluoride/fluoridetoo-01.html|title=Ambient Water Quality Criteria for Fluoride|publisher=Government of British Columbia|access-date=8 October 2014|archive-date=24 September 2015|archive-url=https://web.archive.org/web/20150924035152/http://www.env.gov.bc.ca/wat/wq/BCguidelines/fluoride/fluoridetoo-01.html|url-status=dead}}</ref> (milligrams per ]). For comparison, ] concentration in seawater is about 19 g/L. The low concentration of fluoride reflects the insolubility of the ] fluorides, e.g., CaF<sub>2</sub>. | |||
Concentrations in fresh water vary more significantly. ] such as rivers or lakes generally contains between 0.01 and 0.3 mg/L.<ref>{{cite book|last1=Liteplo|first1=Dr R.|last2=Gomes|first2=R.|last3=Howe|first3=P.|last4=Malcolm|first4=Heath|title=FLUORIDES - Environmental Health Criteria 227 : 1st draft|date=2002|publisher=World Health Organization|location=Geneva|isbn=978-9241572279|url=http://www.inchem.org/documents/ehc/ehc/ehc227.htm#1.4}}</ref> ] (well water) concentrations vary even more, depending on the presence of local fluoride-containing minerals. For example, natural levels of under 0.05 mg/L have been detected in parts of Canada but up to 8 mg/L in parts of China; in general levels rarely exceed 10 mg/litre<ref name=Fawell>{{cite web|author1=Fawell, J.K.|title=Fluoride in Drinking-water Background document for development of WHO Guidelines for Drinking-water Quality|url=https://www.who.int/water_sanitation_health/dwq/chemicals/fluoride.pdf|publisher=World Health Organization|access-date=6 May 2016|ref=WHO/SDE/WSH/03.04/96|language=en|display-authors=etal}}</ref> | |||
* In parts of Asia the groundwater can contain dangerously high levels of fluoride, leading to serious ].<ref>{{cite journal |last1=Yadav |first1=Krishna Kumar |last2=Kumar |first2=Sandeep |last3=Pham |first3=Quoc Bao |last4=Gupta |first4=Neha |last5=Rezania |first5=Shahabaldin |last6=Kamyab |first6=Hesam |last7=Yadav |first7=Shalini |last8=Vymazal |first8=Jan |last9=Kumar |first9=Vinit |last10=Tri |first10=Doan Quang |last11=Talaiekhozani |first11=Amirreza |last12=Prasad |first12=Shiv |last13=Reece |first13=Lisa M. |last14=Singh |first14=Neeraja |last15=Maurya |first15=Pradip Kumar |last16=Cho |first16=Jinwoo |title=Fluoride contamination, health problems and remediation methods in Asian groundwater: A comprehensive review |journal=Ecotoxicology and Environmental Safety |date=October 2019 |volume=182 |pages=109362 |doi=10.1016/j.ecoenv.2019.06.045|pmid=31254856 |bibcode=2019EcoES.18209362Y |s2cid=195764865 }}</ref> | |||
* Worldwide, 50 million people receive water from water supplies that naturally have close to the "optimal level".<ref>{{cite web|last1=Tiemann|first1=Mary|title=Fluoride in Drinking Water: A Review of Fluoridation and Regulation Issues|url=https://www.fas.org/sgp/crs/misc/RL33280.pdf|publisher=Congressional Research Service|access-date=6 May 2016|ref=7-5700 www.crs.gov RL33280|page=3|date=April 5, 2013}}</ref> | |||
* In other locations the level of fluoride is very low, sometimes leading to ] of public water supplies to bring the level to around 0.7–1.2 ppm. | |||
*] can increase local fluoride levels<ref>{{cite journal |last1=Chandio |first1=Tasawar Ali |last2=Khan |first2=Muhammad Nasiruddin |last3=Muhammad |first3=Maria Taj |last4=Yalcinkaya |first4=Ozcan |last5=Wasim |first5=Agha Arslan |last6=Kayis |first6=Ahmet Furkan |title=Fluoride and arsenic contamination in drinking water due to mining activities and its impact on local area population |journal=Environmental Science and Pollution Research |date=January 2021 |volume=28 |issue=2 |pages=2355–2368 |doi=10.1007/s11356-020-10575-9|pmid=32880840 |bibcode=2021ESPR...28.2355C |s2cid=221463681 }}</ref> | |||
Fluoride can be present in rain, with its concentration increasing significantly upon exposure to volcanic activity<ref>{{cite journal |last1=Bellomo |first1=Sergio |last2=Aiuppa |first2=Alessandro |last3=D’Alessandro |first3=Walter |last4=Parello |first4=Francesco |title=Environmental impact of magmatic fluorine emission in the Mt. Etna area |journal=Journal of Volcanology and Geothermal Research |date=August 2007 |volume=165 |issue=1–2 |pages=87–101 |doi=10.1016/j.jvolgeores.2007.04.013|bibcode=2007JVGR..165...87B }}</ref> or atmospheric pollution derived from burning fossil fuels or other sorts of industry,<ref>{{cite journal|last1=Smith|first1=Frank A.|last2=Hodge|first2=Harold C.|last3=Dinman|first3=B. D.|title=Airborne fluorides and man: Part I|journal=CRC Critical Reviews in Environmental Control|date=9 January 2009|volume=8|issue=1–4|pages=293–371|doi=10.1080/10643387709381665}}</ref><ref>{{cite journal|last1=Smith|first1=Frank A.|last2=Hodge|first2=Harold C.|last3=Dinman|first3=B. D.|title=Airborne fluorides and man: Part II|journal=CRC Critical Reviews in Environmental Control|date=9 January 2009|volume=9|issue=1|pages=1–25|doi=10.1080/10643387909381666}}</ref> particularly ]s.<ref>{{cite journal |last1=Arnesen |first1=A.K.M. |last2=Abrahamsen |first2=G. |last3=Sandvik |first3=G. |last4=Krogstad |first4=T. |title=Aluminium-smelters and fluoride pollution of soil and soil solution in Norway |journal=Science of the Total Environment |date=February 1995 |volume=163 |issue=1–3 |pages=39–53 |doi=10.1016/0048-9697(95)04479-K|bibcode=1995ScTEn.163...39A }}</ref> | |||
===In plants=== | |||
All vegetation contains some fluoride, which is absorbed from soil and water.<ref name=Fawell /> Some plants concentrate fluoride from their environment more than others. All tea leaves contain fluoride; however, mature leaves contain as much as 10 to 20 times the fluoride levels of young leaves from the same plant.<ref>{{cite journal |vauthors=Wong MH, Fung KF, Carr HP |title=Aluminium and fluoride contents of tea, with emphasis on brick tea and their health implications |journal=Toxicology Letters |volume=137 |issue=1–2 |pages=111–20 |year=2003 |pmid=12505437 |doi=10.1016/S0378-4274(02)00385-5 }}</ref><ref name="pmid18078704">{{cite journal |vauthors=Malinowska E, Inkielewicz I, Czarnowski W, Szefer P |title=Assessment of fluoride concentration and daily intake by human from tea and herbal infusions |journal=Food Chem. Toxicol. |volume=46 |issue=3 |pages=1055–61 |year=2008 |pmid=18078704 |doi=10.1016/j.fct.2007.10.039}}</ref><ref>{{cite journal |vauthors=Gardner EJ, Ruxton CH, Leeds AR |title=Black tea—helpful or harmful? A review of the evidence |journal=European Journal of Clinical Nutrition |volume=61 |issue=1 |pages=3–18 |year=2007 |pmid=16855537 |doi=10.1038/sj.ejcn.1602489 |doi-access= }}</ref> | |||
== Chemical properties == | == Chemical properties == | ||
=== Basicity === | === Basicity === | ||
Fluoride can act as a ]. It can combine with a ] ({{ |
Fluoride can act as a ]. It can combine with a ] ({{H+}}): | ||
:F<sup>–</sup> + H<sup>+</sup> → HF | |||
This neutralization reaction forms ] (HF), the conjugate acid of fluoride. | |||
:{{chem2 | F- + H+ -> HF }} | |||
In aqueous solution, fluoride has a ] value of 10.8. It is therefore a ], and tends to remain as the fluoride ion rather than generating a substantial amount of hydrogen fluoride. That is, the following equilibrium favours the left-hand side in water: | |||
:F<sup>–</sup> + H<sub>2</sub>O {{EqmL}} HF + HO<sup>–</sup> | |||
However, upon prolonged contact with moisture, fluoride salts will decompose to their respective hydroxides or oxides, as the hydrogen fluoride escapes. Fluoride is distinct in this regard among the halides. The identity of the solvent can have a dramatic effect on the equilibrium shifting it to the right-hand side, greatly increasing the rate of decomposition. | |||
This neutralization reaction forms ] (HF), the ] of fluoride. | |||
=== Structure === | |||
In aqueous solution, fluoride has a ] value of 10.8. It is therefore a ], and tends to remain as the fluoride ion rather than generating a substantial amount of hydrogen fluoride. That is, the following equilibrium favours the left-hand side in water: | |||
Counter-intuitively, unlike the lower halides, the variety of possible salts containing true fluoride ions is rather restricted. Most metal fluorides are highly polar, covalently bonded molecular networks instead of ionic lattices. All of the alkali metal fluorides, and most of the alkali earth metal fluorides are true salts. In such true salts, fluoride typically assumes the primitive or face-centred cubic motifs. Fluoride is also found with weakly coordinating counter cations, such as in ], in which it assumes the close-packed hexagonal motif. Under aqueous conditions, fluoride exists as a trigonal pyramidal-shaped hydrated complex, namely <sup>-</sup>. Fluoride has the smallest monatomic, crystal and effective, ionic radii: 199 and 133 pm, respectively. | |||
:{{chem2 | F- + H2O <-> HF + HO- }} | |||
=== Chemical reactions === | |||
However, upon prolonged contact with moisture, soluble fluoride salts will decompose to their respective hydroxides or oxides, as the hydrogen fluoride escapes. Fluoride is distinct in this regard among the halides. The identity of the solvent can have a dramatic effect on the equilibrium shifting it to the right-hand side, greatly increasing the rate of decomposition. | |||
Upon treatment with a standard acid, fluoride salts convert to ] and metal ]s. With strong acids, it can be doubly protonated to give {{Chem|H|2|F|+}}. Oxidation of fluoride gives fluorine. Solutions of inorganic fluorides in water contain F<sup>−</sup> and ] {{chem|HF|2|-}}.<ref>Holleman, A. F.; Wiberg, E. (2001) ''Inorganic Chemistry'', Academic Press: San Diego, ISBN 0-12-352651-5.</ref> Few inorganic fluorides are soluble in water without undergoing significant hydrolysis. In terms of its reactivity, fluoride differs significantly from ] and other halides, and is more strongly solvated in ]s due to its smaller radius/charge ratio. Its closest chemical relative is ]. When relatively ], for example in nonprotic solvents, fluoride anions are called "naked". Naked fluoride is a very strong ],<ref>{{cite journal|author=Schwesinger, Reinhard; Link, Reinhard; Wenzl, Peter; Kossek, Sebastian |title=Anhydrous phosphazenium fluorides as sources for extremely reactive fluoride ions in solution|doi=10.1002/chem.200500838|year=2006|journal=Chemistry – A European Journal|volume=12|issue=2|pages=438}}</ref> it is easily reacted with Lewis acids, forming strong adducts. Fluoride is susceptible to ] radiation, ejecting an electron to become highly reactive atomic fluorine. It has a ] of 2.87 Volts. | |||
=== |
=== Structure of fluoride salts=== | ||
Salts containing fluoride are numerous and adopt myriad structures. Typically the fluoride anion is surrounded by four or six cations, as is typical for other halides. ] and ] adopt the same structure. For compounds containing more than one fluoride per cation, the structures often deviate from those of the chlorides, as illustrated by the main fluoride mineral ] (CaF<sub>2</sub>) where the Ca<sup>2+</sup> ions are surrounded by eight F<sup>−</sup> centers. In CaCl<sub>2</sub>, each Ca<sup>2+</sup> ion is surrounded by six Cl<sup>−</sup> centers. The difluorides of the transition metals often adopt the ] structure whereas the dichlorides have ] structures. | |||
===Inorganic chemistry=== | |||
At physiological pHs, ] is usually fully ionised to fluoride. In ], fluoride and hydrogen fluoride are equivalent. Fluorine, in the form of fluoride, is considered to be a ] for human health, necessary to prevent dental cavities, and to promote healthy bone growth.<ref name="who.int">. World Health Organization, 2004, p. 2.</ref> The tea plant (''Camellia sinensis'' L.) is a known accumulator of fluorine compounds, released upon forming infusions such as the common beverage. The fluorine compounds decompose into products including fluoride ions. Fluoride is the most bioavailable form of fluorine, and as such, tea is potentially a vehicle for fluoride dosing.<ref name=Chan2013>{{Cite journal|last=Chan|first=Laura|coauthors=Mehra, Aradhana; Saikat, Sohel; Lynch, Paul|title=Human exposure assessment of fluoride from tea (''Camellia sinensis'' L.): A UK based issue?|journal=Food Research International|date=May 2013|volume=51|issue=2|pages=564–570|url=http://www.sciencedirect.com/science/article/pii/S0963996913000446|accessdate=9 August 2013|doi=10.1016/j.foodres.2013.01.025}}</ref> Approximately, fifty percent of absorbed fluoride is excreted renally with a twenty four hour period. The remainder can be retained in the oral cavity, and lower digestive tract. Fasting dramatically increases the rate of fluoride absorption to near hundred percent, from a sixty to eighty percent when taken with food.<ref name=Chan2013 /> Per a 2013 study, it was found that consumption of one litre of tea a day, can potentially supply the daily recommended intake of 4 mg per day. Some lower quality brands can supply up to a 120 percent of this amount. Fasting can increase this to 150 percent. The study indicates that tea drinking communities are at an increased risk of fluorosis, in the case where water fluoridation is in effect.<ref name=Chan2013 /> Fluoride ion in low doses in the mouth reduces tooth decay. For this reason, it is used in toothpaste and water fluoridation. At much higher doses, fluoride causes health complications and can be toxic. | |||
Upon treatment with a standard acid, fluoride salts convert to ] and metal ]s. With strong acids, it can be doubly protonated to give ]. Oxidation of fluoride gives fluorine. Solutions of inorganic fluorides in water contain F<sup>−</sup> and ] {{chem|HF|2|-}}.<ref>{{cite book|last1=Wiberg|last2=Holleman|first2=A.F.|title=Inorganic chemistry|date=2001|publisher=Academic Press, W. de Gruyter.|location=San Diego, Calif. : Berlin|isbn=978-0-12-352651-9|edition=1st English ed., by Nils Wiberg.}}</ref> Few inorganic fluorides are soluble in water without undergoing significant hydrolysis. In terms of its reactivity, fluoride differs significantly from ] and other halides, and is more strongly solvated in ]s due to its smaller radius/charge ratio. Its closest chemical relative is ], since both have similar geometries. | |||
===Naked fluoride=== | |||
==Occurrence== | |||
Most fluoride salts dissolve to give the bifluoride ({{chem|HF|2|-}}) anion. Sources of true F<sup>−</sup> anions are rare because the highly basic fluoride anion abstracts protons from many, even adventitious, sources. Relative ] fluoride, which does exist in aprotic solvents, is called "naked". '''Naked fluoride''' is a strong ],<ref>{{cite journal |last1=Schwesinger |first1=Reinhard |last2=Link |first2=Reinhard |last3=Wenzl |first3=Peter |last4=Kossek |first4=Sebastian |title=Anhydrous Phosphazenium Fluorides as Sources for Extremely Reactive Fluoride Ions in Solution |journal=Chemistry: A European Journal |volume=12 |issue=2 |pages=438–45 |year=2005 |pmid=16196062 |doi=10.1002/chem.200500838 }}</ref> and a powerful nucleophile. Some quaternary ammonium salts of naked fluoride include ] and ].<ref name=dimagno>{{cite journal |author1=Haoran Sun |author2=Stephen G. DiMagno |name-list-style=amp | title= Anhydrous Tetrabutylammonium Fluoride | journal= ] | year= 2005 | volume= 127 | pages= 2050–1| doi=10.1021/ja0440497 | pmid= 15713075 | issue= 7}}</ref> ] fluoride is another example.<ref>{{cite journal |doi=10.1021/ja00103a045|title=Cobaltocenium Fluoride: A Novel Source of "Naked" Fluoride Formed by Carbon-Fluorine Bond Activation in a Saturated Perfluorocarbon|year=1994|last1=Bennett|first1=Brian K.|last2=Harrison|first2=Roger G.|last3=Richmond|first3=Thomas G.|journal=Journal of the American Chemical Society|volume=116|issue=24|pages=11165–11166}}</ref> However, they all lack structural characterization in aprotic solvents. Because of their high basicity, many so-called naked fluoride sources are in fact bifluoride salts. In late 2016 ] fluoride was synthesized that is the closest approximation of a thermodynamically stable and structurally characterized example of a "naked" fluoride source in an aprotic solvent (acetonitrile).<ref>{{cite journal | last1 = Alič | first1 = B. | last2 = Tavčar | first2 = G. | year = 2016 | title = Reaction of N-heterocyclic carbene (NHC) with different HF sources and ratios – A free fluoride reagent based on imidazolium fluoride | journal = J. Fluorine Chem. | volume = 192 | pages = 141–146 | doi = 10.1016/j.jfluchem.2016.11.004 }}</ref> The sterically demanding imidazolium cation stabilizes the discrete anions and protects them from polymerization.<ref>{{cite journal | last1 = Alič | first1 = B. | last2 = Tramšek | first2 = M. | last3 = Kokalj | first3 = A. | last4 = Tavčar | first4 = G. | year = 2017| title = Discrete GeF5– Anion Structurally Characterized with a Readily Synthesized Imidazolium Based Naked Fluoride Reagent | journal = Inorg. Chem. | volume = 56 | issue = 16| pages = 10070–10077 | doi = 10.1021/acs.inorgchem.7b01606 | pmid = 28792216 }}</ref><ref>{{cite journal | last1 = Zupanek | first1 = Ž. | last2 = Tramšek | first2 = M. | last3 = Kokalj | first3 = A. | last4 = Tavčar | first4 = G. | year = 2018| title = Reactivity of VOF3 with N-Heterocyclic Carbene and Imidazolium Fluoride: Analysis of Ligand–VOF3 Bonding with Evidence of a Minute π Back-Donation of Fluoride | journal = Inorg. Chem. | volume = 57 | issue = 21| pages = 13866–13879 | doi = 10.1021/acs.inorgchem.8b02377 | pmid = 30353729 | s2cid = 53031199 }}</ref> | |||
] | |||
Many fluoride minerals are known, but of paramount commercial importance is ].<ref name=Aigueperse/> It is composed of calcium fluoride, with small impurities. The soft, colorful mineral is found worldwide and is common. | |||
=== Biochemistry === | |||
In seawater, fluoride concentration averages 1.3 ] (ppm). For comparison, ] concentration in seawater is about 19,000 ppm. The low concentration of fluoride reflects the insolubility of the ] fluorides, e.g., CaF<sub>2</sub>. | |||
At physiological pHs, ] is usually fully ionised to fluoride. In ], fluoride and hydrogen fluoride are equivalent. Fluorine, in the form of fluoride, is considered to be a ] for human health, necessary to prevent dental cavities, and to promote healthy bone growth.<ref name="who.int">{{cite web|last1=Fawell|first1=J. |title=Fluoride in Drinking-water|url=https://www.who.int/water_sanitation_health/dwq/chemicals/fluoride.pdf|publisher=World Health Organization|access-date=10 March 2016}}</ref> The tea plant ('']'' L.) is a known accumulator of fluorine compounds, released upon forming infusions such as the common beverage. The fluorine compounds decompose into products including fluoride ions. Fluoride is the most bioavailable form of fluorine, and as such, tea is potentially a vehicle for fluoride dosing.<ref name=Chan2013>{{Cite journal|last=Chan|first=Laura|author2=Mehra, Aradhana |author3=Saikat, Sohel |author4= Lynch, Paul |title=Human exposure assessment of fluoride from tea (''Camellia sinensis'' L.): A UK based issue?|journal=Food Research International|date=May 2013|volume=51|issue=2|pages=564–570|doi=10.1016/j.foodres.2013.01.025}}</ref> Approximately, 50% of absorbed fluoride is excreted renally with a twenty-four-hour period. The remainder can be retained in the oral cavity, and lower digestive tract. Fasting dramatically increases the rate of fluoride absorption to near 100%, from a 60% to 80% when taken with food.<ref name=Chan2013 /> Per a 2013 study, it was found that consumption of one litre of tea a day, can potentially supply the daily recommended intake of 4 mg per day. Some lower quality brands can supply up to a 120% of this amount. Fasting can increase this to 150%. The study indicates that tea drinking communities are at an increased risk of ] and ], in the case where water fluoridation is in effect.<ref name=Chan2013 /> Fluoride ion in low doses in the mouth reduces tooth decay.<ref>{{Cite web | url=http://oradyne.net/fluoride-free-toothpaste/ | title=Fluoride Free Toothpaste – Fluoride (Finally!) Explained| date=2016-06-27}}</ref> For this reason, it is used in toothpaste and water fluoridation. At much higher doses and frequent exposure, fluoride causes health complications and can be toxic. | |||
Fluoride is found naturally in low concentration in drinking water and foods. Fresh water supplies generally contain between 0.01–0.3 ppm.<ref name="who.int"/><ref>. World Health Organization, 2002, p. 38.</ref> In some locations, the fresh water contains dangerously high levels of fluoride, leading to serious ]. | |||
==Applications== | ==Applications== | ||
{{See also|Fluorochemical industry|Biological aspects of fluorine|Fluorine}} | {{See also|Fluorochemical industry|Biological aspects of fluorine|Fluorine}} | ||
Fluoride salts and hydrofluoric acid are the main fluorides of industrial value. | |||
Fluoride salts and hydrofluoric acid are the main fluorides of industrial value. Compounds with C-F bonds fall into the realm of ]. The main uses of fluoride, in terms of volume, are in the production of cryolite, Na<sub>3</sub>AlF<sub>6</sub>. It is used in ]. Formerly, it was mined, but now it is derived from hydrogen fluoride. Fluorite is used on a large scale to separate slag in steelmaking. | |||
===Organofluorine chemistry=== | |||
Hydrofluoric acid and its anhydrous form, ], is also used in the production of ] Hydrofluoric acid has a variety of specialized applications, including its ability to dissolve glass.<ref name=Aigueperse>{{Ullmann | book | first = Jean | last = Aigueperse | coauthors = Mollard, Paul; Devilliers, Didier; Chemla, Marius; Faron, Robert; Romano, Renée; Cuer, Jean Pierre | title = Fluorine Compounds, Inorganic| year = 2005 | doi = 10.1002/14356007.a11_307 | page = 307}}</ref> | |||
{{main|Organofluorine chemistry}} | |||
Organofluorine compounds are pervasive. Many drugs, many polymers, refrigerants, and many inorganic compounds are made from fluoride-containing reagents. Often fluorides are converted to hydrogen fluoride, which is a major reagent and precursor to reagents. Hydrofluoric acid and its anhydrous form, ], are particularly important.<ref name="Aigueperse">{{cite encyclopedia|last1=Aigueperse|first1=Jean|encyclopedia=Ullmann's Encyclopedia of Industrial Chemistry|last2=Mollard|first2=Paul|last3=Devilliers|first3=Didier|last4=Chemla|first4=Marius|last5=Faron|first5=Robert|last6=Romano|first6=René|last7=Cuer|first7=Jean Pierre|year=2000|doi=10.1002/14356007.a11_307|isbn=978-3527306732|chapter=Fluorine Compounds, Inorganic}}</ref> | |||
===Production of metals and their compounds=== | |||
Mined ] (CaF<sub>2</sub>) is a commodity chemical used in steel-making. | |||
The main uses of fluoride, in terms of volume, are in the production of cryolite, Na<sub>3</sub>AlF<sub>6</sub>. It is used in ]. Formerly, it was mined, but now it is derived from hydrogen fluoride. Fluorite is used on a large scale to separate slag in steel-making. Mined ] (CaF<sub>2</sub>) is a commodity chemical used in steel-making. ] is employed in the purification of uranium isotopes. | |||
===Cavity prevention=== | ===Cavity prevention=== | ||
{{main|Fluoride therapy|Water fluoridation}} | {{main|Fluoride therapy|Water fluoridation}} | ||
] | ] | ||
Fluoride-containing compounds are used in topical and systemic ] for preventing ]. They are used for ] and in many products associated with ].<ref name="mcdonagh2000">{{cite journal| |
Fluoride-containing compounds, such as ] or ] are used in topical and systemic ] for preventing ]. They are used for ] and in many products associated with ].<ref name="mcdonagh2000">{{cite journal|author1=McDonagh M. S. |author2=Whiting P. F. |author3=Wilson P. M. |author4=Sutton A. J. |author5=Chestnutt I. |author6=Cooper J. |author7=Misso K. |author8=Bradley M. |author9=Treasure E. |author10=Kleijnen J. |year=2000 |title=Systematic review of water fluoridation |journal=] |volume=321 |issue=7265| pages=855–859|doi=10.1136/bmj.321.7265.855 |pmid=11021861|pmc=27492}}</ref> Originally, sodium fluoride was used to fluoridate water; ] (H<sub>2</sub>SiF<sub>6</sub>) and its salt ] (Na<sub>2</sub>SiF<sub>6</sub>) are more commonly used additives, especially in the United States. The fluoridation of water is known to prevent tooth decay<ref>{{cite journal |vauthors=Griffin SO, Regnier E, Griffin PM, Huntley V |title=Effectiveness of fluoride in preventing caries in adults |journal=J. Dent. Res. |volume=86 |issue=5 |pages=410–5 |year=2007 |pmid=17452559 |doi=10.1177/154405910708600504|hdl=10945/60693 |s2cid=58958881 |hdl-access=free }}</ref><ref>{{cite journal |author1=Winston A. E. |author2=Bhaskar S. N. |title=Caries prevention in the 21st century |journal=J. Am. Dent. Assoc. |volume=129 |issue=11 |pages=1579–87 |date=1 November 1998 |pmid=9818575 |url=http://jada.ada.org/cgi/pmidlookup?view=long&pmid=9818575 |archive-url=https://archive.today/20120715143950/http://jada.ada.org/cgi/pmidlookup?view=long&pmid=9818575 |url-status=dead |archive-date=15 July 2012 |doi=10.14219/jada.archive.1998.0104 }}</ref> and is considered by the U.S. ] to be "one of 10 great public health achievements of the 20th century".<ref>{{cite web|title=Community Water Fluoridation|url=https://www.cdc.gov/fluoridation/|publisher=Centers for Disease Control and Prevention|access-date=10 March 2016}}</ref><ref>{{cite web|title=Ten Great Public Health Achievements in the 20th Century|url=https://www.cdc.gov/about/history/tengpha.htm|publisher=Centers for Disease Control and Prevention|access-date=10 March 2016|archive-url=https://web.archive.org/web/20160313072852/http://www.cdc.gov/about/history/tengpha.htm|archive-date=2016-03-13|url-status=dead}}</ref> In some countries where large, centralized water systems are uncommon, fluoride is delivered to the populace by fluoridating table salt. For the method of action for cavity prevention, see ]. Fluoridation of water has its critics {{crossreference|(see ])}}.<ref>{{cite journal |author=Newbrun E |title=The fluoridation war: a scientific dispute or a religious argument? |journal=Journal of Public Health Dentistry |volume=56 |issue=5 Spec No |pages=246–52 |year=1996 |pmid=9034969 |doi=10.1111/j.1752-7325.1996.tb02447.x}}</ref> Fluoridated ] is in common use. ] show the efficacy of 500 ppm fluoride in toothpastes.<ref>{{Cite journal|last1=Walsh|first1=Tanya|last2=Worthington|first2=Helen V.|last3=Glenny|first3=Anne-Marie|last4=Marinho|first4=Valeria Cc|last5=Jeroncic|first5=Ana|date=March 4, 2019|title=Fluoride toothpastes of different concentrations for preventing dental caries|journal=Cochrane Database of Systematic Reviews|volume=3|issue=3|pages=CD007868|doi=10.1002/14651858.CD007868.pub3|issn=1469-493X|pmc=6398117|pmid=30829399}}</ref><ref>{{Cite web|title=Remineralization of initial carious lesions in deciduous enamel after application of dentifrices of different fluoride concentrations|url=https://www.springermedizin.de/remineralization-of-initial-carious-lesions-in-deciduous-enamel-/8679072|access-date=2021-02-24|website=springermedizin.de|language=de}}</ref> However, no beneficial effect can be detected when more than one fluoride source is used for daily oral care.<ref>{{Cite journal|last1=Hausen|first1=H.|last2=Kärkkäinen|first2=S.|last3=Seppä|first3=L.|date=February 2000|title=Application of the high-risk strategy to control dental caries|url=https://pubmed.ncbi.nlm.nih.gov/10634681/|journal=Community Dentistry and Oral Epidemiology|volume=28|issue=1|pages=26–34|doi=10.1034/j.1600-0528.2000.280104.x|issn=0301-5661|pmid=10634681}}</ref>{{request quotation|date=August 2021}} | ||
=== |
===Laboratory reagent=== | ||
Fluoride salts are commonly used in biological assay processing to ] the activity of ], such as ]/] phosphatases.<ref>{{cite journal |vauthors=Nakai C, Thomas JA |title=Properties of a phosphoprotein phosphatase from bovine heart with activity on glycogen synthase, phosphorylase, and histone |journal=J. Biol. Chem. |volume=249 |issue=20 |pages=6459–67 |year=1974 |doi=10.1016/S0021-9258(19)42179-0 |pmid=4370977 |url=http://www.jbc.org/cgi/pmidlookup?view=long&pmid=4370977|doi-access=free }}</ref> Fluoride mimics the ] ] ion in these enzymes' active sites.<ref>{{cite journal |vauthors=Schenk G, Elliott TW, Leung E |title=Crystal structures of a purple acid phosphatase, representing different steps of this enzyme's catalytic cycle |journal=BMC Struct. Biol. |volume=8 |page=6 |year=2008 |pmid=18234116 |doi=10.1186/1472-6807-8-6 |pmc=2267794|display-authors=etal |doi-access=free }}</ref> ] and ] are also used as phosphatase inhibitors, since these compounds are structural mimics of the ] group and can act as analogues of the ] of the reaction.<ref>{{cite journal |vauthors=Wang W, Cho HS, Kim R |title=Structural characterization of the reaction pathway in phosphoserine phosphatase: crystallographic "snapshots" of intermediate states |journal=J. Mol. Biol. |volume=319 |issue=2 |pages=421–31 |year=2002 |pmid=12051918 |doi=10.1016/S0022-2836(02)00324-8 |display-authors=etal}}</ref><ref>{{cite journal |vauthors=Cho H, Wang W, Kim R |title=BeF(3)(-) acts as a phosphate analog in proteins phosphorylated on aspartate: structure of a BeF(3)(-) complex with phosphoserine phosphatase |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=98 |issue=15 |pages=8525–30 |year=2001 |pmid=11438683 |doi=10.1073/pnas.131213698 |pmc=37469|bibcode = 2001PNAS...98.8525C |display-authors=etal|doi-access=free }}</ref> | |||
==Dietary recommendations== | |||
Fluoride salts are commonly used in biological assay processing to ] the activity of ], such as ]/] phosphatases.<ref>{{cite journal |author=Nakai C, Thomas JA |title=Properties of a phosphoprotein phosphatase from bovine heart with activity on glycogen synthase, phosphorylase, and histone |journal=J. Biol. Chem. |volume=249 |issue=20 |pages=6459–67 |year=1974 |pmid=4370977 |doi= |url=http://www.jbc.org/cgi/pmidlookup?view=long&pmid=4370977}}</ref> Fluoride mimics the ] ] ion in these enzymes' active sites.<ref>{{cite journal |author=Schenk G, Elliott TW, Leung E, ''et al.'' |title=Crystal structures of a purple acid phosphatase, representing different steps of this enzyme's catalytic cycle |journal=BMC Struct. Biol. |volume=8 |page=6 |year=2008 |pmid=18234116 |doi=10.1186/1472-6807-8-6 |pmc=2267794}}</ref> ] and ] are also used as phosphatase inhibitors, since these compounds are structural mimics of the ] group and can act as analogues of the ] of the reaction.<ref>{{cite journal |author=Wang W, Cho HS, Kim R, ''et al.'' |title=Structural characterization of the reaction pathway in phosphoserine phosphatase: crystallographic "snapshots" of intermediate states |journal=J. Mol. Biol. |volume=319 |issue=2 |pages=421–31 |year=2002 |pmid=12051918 |doi=10.1016/S0022-2836(02)00324-8 }}</ref><ref>{{cite journal |author=Cho H, Wang W, Kim R, ''et al.'' |title=BeF(3)(-) acts as a phosphate analog in proteins phosphorylated on aspartate: structure of a BeF(3)(-) complex with phosphoserine phosphatase |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=98 |issue=15 |pages=8525–30 |year=2001 |pmid=11438683 |doi=10.1073/pnas.131213698 |pmc=37469|bibcode = 2001PNAS...98.8525C }}</ref> | |||
The U.S. Institute of Medicine (IOM) updated Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for some minerals in 1997. Where there was not sufficient information to establish EARs and RDAs, an estimate designated Adequate Intake (AI) was used instead. AIs are typically matched to actual average consumption, with the assumption that there appears to be a need, and that need is met by what people consume. The current AI for women 19 years and older is 3.0 mg/day (includes pregnancy and lactation). The AI for men is 4.0 mg/day. The AI for children ages 1–18 increases from 0.7 to 3.0 mg/day. The major known risk of ] appears to be an increased risk of bacteria-caused tooth cavities. As for safety, the IOM sets tolerable upper intake levels (ULs) for vitamins and minerals when evidence is sufficient. In the case of fluoride the UL is 10 mg/day. Collectively the EARs, RDAs, AIs and ULs are referred to as ]s (DRIs).<ref name="DRItext">{{cite book | last1 = Institute of Medicine | title = Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D and Fluoride | chapter = Fluoride | publisher = The National Academies Press | year = 1997 | location = Washington, DC | pages = 288–313 | doi = 10.17226/5776 | pmid = 23115811 | isbn = 978-0-309-06403-3 | chapter-url = https://www.nap.edu/read/5776/chapter/10| author1-link = Institute of Medicine }}</ref> | |||
The ] (EFSA) refers to the collective set of information as Dietary Reference Values, with Population Reference Intake (PRI) instead of RDA, and Average Requirement instead of EAR. AI and UL are defined the same as in the United States. For women ages 18 and older the AI is set at 2.9 mg/day (including pregnancy and lactation). For men, the value is 3.4 mg/day. For children ages 1–17 years, the AIs increase with age from 0.6 to 3.2 mg/day. These AIs are comparable to the U.S. AIs.<ref>{{cite web | title = Overview on Dietary Reference Values for the EU population as derived by the EFSA Panel on Dietetic Products, Nutrition and Allergies| year = 2017| url = https://www.efsa.europa.eu/sites/default/files/assets/DRV_Summary_tables_jan_17.pdf}}</ref> The EFSA reviewed safety evidence and set an adult UL at 7.0 mg/day (lower for children).<ref name="EFSAtext">{{citation| title = Tolerable Upper Intake Levels For Vitamins And Minerals| publisher = European Food Safety Authority| year = 2006| url = http://www.efsa.europa.eu/sites/default/files/efsa_rep/blobserver_assets/ndatolerableuil.pdf}}</ref> | |||
==Toxicology== | |||
For U.S. food and dietary supplement labeling purposes, the amount of a vitamin or mineral in a serving is expressed as a percent of Daily Value (%DV). Although there is information to set Adequate Intake, fluoride does not have a Daily Value and is not required to be shown on food labels.<ref name="FedReg">{{cite web|url=https://www.gpo.gov/fdsys/pkg/FR-2016-05-27/pdf/2016-11867.pdf |title=Federal Register May 27, 2016 Food Labeling: Revision of the Nutrition and Supplement Facts Labels. FR page 33982.}}</ref> | |||
==Estimated daily intake== | |||
Daily intakes of fluoride can vary significantly according to the various sources of exposure. Values ranging from 0.46 to 3.6–5.4 mg/day have been reported in several studies (IPCS, 1984).<ref name="who.int" /> In areas where water is ] this can be expected to be a significant source of fluoride, however fluoride is also naturally present in virtually all foods and beverages at a wide range of concentrations.<ref>{{cite web |url=http://ndb.nal.usda.gov/ndb/nutrients/report?nutrient1=313&nutrient2=&nutrient3=&fg=&max=25&subset=0&offset=0&sort=c&totCount=563&measureby=g |archive-url=https://web.archive.org/web/20140526022117/http://ndb.nal.usda.gov/ndb/nutrients/report?nutrient1=313&nutrient2=&nutrient3=&fg=&max=25&subset=0&offset=0&sort=c&totCount=563&measureby=g |url-status=dead |archive-date=26 May 2014 |title=Nutrient Lists|publisher=Agricultural Research Service United States Department of Agriculture|access-date=25 May 2014}}</ref> The maximum safe daily consumption of fluoride is 10 mg/day for an adult (U.S.) or 7 mg/day (European Union).<ref name="DRItext" /><ref name="EFSAtext" /> | |||
The upper limit of fluoride intake from all sources (fluoridated water, food, beverages, fluoride dental products and dietary fluoride supplements) is set at 0.10 mg/kg/day for infants, toddlers, and children through to 8 years old. For older children and adults, who are no longer at risk for dental fluorosis, the upper limit of fluoride is set at 10 mg/day regardless of weight.<ref>{{cite journal | doi = 10.1111/j.1752-7325.1999.tb03272.x | volume=59 | title=Total Fluoride Intake and Implications for Dietary Fluoride Supplementation | year=1999 | journal=Journal of Public Health Dentistry | pages=211–223 | last1 = Levy | first1 = Steven M. | last2 = Guha-Chowdhury | first2 = Nupur| issue=4 | pmid=10682326 }}</ref> | |||
{| class="wikitable" | |||
|+ Examples of fluoride content | |||
|- | |||
! Food/Drink !! Fluoride<br />(mg per 1000g/ppm) !! Portion !! Fluoride<br />(mg per portion) | |||
|- | |||
| Black tea (brewed) || style="text-align: right;"|3.73 || 1 cup, 240 g (8 fl oz) || style="text-align: right;"|0.884 | |||
|- | |||
| Raisins, seedless || style="text-align: right;"|2.34 || small box, {{convert|43|g|oz|abbr=on}} || style="text-align: right;"|0.101 | |||
|- | |||
| Table wine || style="text-align: right;"|1.53 || Bottle, {{convert|750|mL|impoz|abbr=on}} || style="text-align: right;"|1.150 | |||
|- | |||
| Municipal tap-water,<br />(Fluoridated) || style="text-align: right;"|0.81 || Recommended daily intake,<br /> {{convert|3|L|USgal}} || style="text-align: right;"|2.433 | |||
|- | |||
| Baked potatoes, Russet || style="text-align: right;"|0.45 || Medium potato, {{convert|140|g|lb|abbr=on}} || style="text-align: right;"|0.078 | |||
|- | |||
| Lamb || style="text-align: right;"|0.32 || Chop, {{convert|170|g|oz|abbr=on}} || style="text-align: right;"|0.054 | |||
|- | |||
| Carrots || style="text-align: right;"|0.03 || 1 large carrot, {{convert|72|g|oz|abbr=on}} || style="text-align: right;"|0.002 | |||
|- | |||
| colspan="4" style="text-align: center;" | Source: Data taken from United States Department of Agriculture, {{Webarchive|url=https://web.archive.org/web/20140301101828/http://ndb.nal.usda.gov/ndb/nutrients/index |date=2014-03-01 }}<ref>{{Cite web |title=Food Composition Databases: Food Search: Fluoride |url=https://ndb.nal.usda.gov/ndb/nutrients/report/nutrientsfrm?max=25&offset=0&totCount=0&nutrient1=313&nutrient2=&subset=0&sort=c&measureby=g |archive-url=https://web.archive.org/web/20181205193315/https://ndb.nal.usda.gov/ndb/nutrients/report/nutrientsfrm?max=25&offset=0&totCount=0&nutrient1=313&nutrient2=&subset=0&sort=c&measureby=g |url-status=dead |archive-date=5 December 2018 |publisher=], ] |access-date=5 December 2018}}</ref> | |||
|} | |||
== Safety == | |||
{{main|Fluoride toxicity}} | {{main|Fluoride toxicity}} | ||
=== Ingestion === | |||
Soluble fluoride salts, of which ] is the most common, are only mildly toxic, although they have resulted in both accidental and suicidal deaths from ].<ref name=Aigueperse/> The lethal dose for most adult humans is estimated at 5 to 10 g (which is equivalent to 32 to 64 mg/kg elemental fluoride/kg body weight).<ref>{{cite book | last = Gosselin | first = RE | coauthors = Smith RP, Hodge HC | authorlink = | title = Clinical toxicology of commercial products | publisher = Williams & Wilkins| location = Baltimore (MD) | year = 1984 | pages =III–185–93| isbn =0-683-03632-7 }}</ref><ref>{{cite book | last = Baselt | first = RC | coauthors = | authorlink = | title = Disposition of toxic drugs and chemicals in man | publisher = Biomedical Publications| location = Foster City (CA) | year = 2008 | pages =636–40| isbn =978-0-9626523-7-0}}</ref><ref>{{cite book | last = IPCS | first = | coauthors = | authorlink = | title = Environmental health criteria 227 (Fluoride) | publisher = International Programme on Chemical Safety, World Health Organization| location = Geneva | year = 2002 | page =100| isbn =92-4-157227-2}}</ref> However, a case of a fatal poisoning of an adult with 4 grams of sodium fluoride is documented,<ref name=acute/> while a dose of 120 g sodium fluoride has been survived.<ref>{{cite journal | author=Abukurah AR, Moser AM Jr, Baird CL, Randall RE Jr, Setter JG, Blanke RV | title=Acute sodium fluoride poisoning | journal=JAMA | year=1972 | pages=816–7 | volume=222 | issue=7 | pmid=4677934 | doi=10.1001/jama.1972.03210070046014}}</ref> For ] (Na<sub>2</sub>SiF<sub>6</sub>), the ] (LD<sub>50</sub>) orally in rats is 0.125 g/kg, corresponding to 12.5 g for a 100 kg adult.<ref name="merck">The Merck Index, 12th edition, Merck & Co., Inc., 1996</ref> | |||
According to the U.S. Department of Agriculture, the Dietary Reference Intakes, which is the "highest level of daily nutrient intake that is likely to pose no risk of adverse health effects" specify 10 mg/day for most people, corresponding to 10 L of fluoridated water with no risk. For young children the values are smaller, ranging from 0.7 mg/d to 2.2 mg/d for infants.<ref>{{cite web|title=Dietary Reference Intakes: EAR, RDA, AI, Acceptable Macronutrient Distribution Ranges, and UL |url=http://fnic.nal.usda.gov/dietary-guidance/dietary-reference-intakes/dri-tables-and-application-reports|publisher=United States Department of Agriculture|access-date=9 September 2017}}</ref> Water and food sources of fluoride include community water fluoridation, seafood, tea, and gelatin.<ref>{{cite web|title=Fluoride in diet|url=https://www.nlm.nih.gov/medlineplus/ency/article/002420.htm|publisher=U.S. National Library of Medicine|access-date=10 March 2016}}</ref> | |||
Soluble fluoride salts, of which ] is the most common, are toxic, and have resulted in both accidental and self-inflicted deaths from ].<ref name=Aigueperse/> The lethal dose for most adult humans is estimated at 5 to 10 g (which is equivalent to 32 to 64 mg elemental fluoride per kg body weight).<ref>{{cite book | last = Gosselin | first = RE |author2=Smith RP |author3=Hodge HC | title = Clinical toxicology of commercial products | publisher = Williams & Wilkins| location = Baltimore (MD) | year = 1984 | pages =III–185–93| isbn =978-0-683-03632-9 }}</ref><ref>{{cite book |last=Baselt |first=RC |url=https://archive.org/details/dispositionoftox0000base_v7n5/page/636/mode/2up |title=Disposition of toxic drugs and chemicals in man |publisher=Biomedical Publications |year=2008 |isbn=978-0-9626523-7-0 |location=Foster City (CA) |pages=636–40 |url-access=registration}}</ref><ref>{{cite book | last = IPCS | title = Environmental health criteria 227 (Fluoride) | publisher = International Programme on Chemical Safety, World Health Organization| location = Geneva | year = 2002 | page =100| isbn =978-92-4-157227-9}}</ref> A case of a fatal poisoning of an adult with 4 grams of sodium fluoride is documented,<ref name=acute/> and a dose of 120 g sodium fluoride has been survived.<ref>{{cite journal |vauthors=Abukurah AR, ((Moser AM Jr)), Baird CL, ((Randall RE Jr)), Setter JG, Blanke RV | title=Acute sodium fluoride poisoning | journal=JAMA | year=1972 | pages=816–7 | volume=222 | issue=7 | pmid=4677934 | doi=10.1001/jama.1972.03210070046014}}</ref> For ] (Na<sub>2</sub>SiF<sub>6</sub>), the ] (LD<sub>50</sub>) orally in rats is 125 mg/kg, corresponding to 12.5 g for a 100 kg adult.<ref name="merck">The Merck Index, 12th edition, Merck & Co., Inc., 1996</ref> | |||
The fatal period ranges from 5 min to 12 hours.<ref name=acute/> The mechanism of toxicity involves the combination of the fluoride anion with the calcium ions in the blood to form insoluble ], resulting in ]; calcium is indispensable for the function of the nervous system, and the condition can be fatal. | |||
Treatment may involve oral administration of dilute ] or ] to prevent further absorption, and injection of ] to increase the calcium levels in the blood.<ref name=acute>{{cite journal|pmid=20323400|pmc=1581810|year=1945|last1=Rabinowitch|first1=IM|title=Acute Fluoride Poisoning|volume=52|issue=4|pages=345–9|journal=Canadian Medical Association |
Treatment may involve oral administration of dilute ] or ] to prevent further absorption, and injection of ] to increase the calcium levels in the blood.<ref name=acute>{{cite journal|pmid=20323400|pmc=1581810|year=1945|last1=Rabinowitch|first1=IM|title=Acute Fluoride Poisoning|volume=52|issue=4|pages=345–9|journal=Canadian Medical Association Journal}}</ref> ] is more dangerous than salts such as NaF because it is corrosive and volatile, and can result in fatal exposure through inhalation or upon contact with the skin; calcium gluconate gel is the usual antidote.<ref>{{cite journal |vauthors=Muriale L, Lee E, Genovese J, Trend S | year = 1996 | title = Fatality due to acute fluoride poisoning following dermal contact with hydrofluoric acid in a palynology laboratory | journal = Ann. Occup. Hyg. | volume = 40 | issue = 6| pages = 705–710 | pmid = 8958774 | doi = 10.1016/S0003-4878(96)00010-5 }}</ref> | ||
In the higher doses used to treat ], sodium fluoride can cause pain in the legs and incomplete stress fractures when the doses are too high; it also irritates the stomach, sometimes so severely as to cause ulcers. Slow-release and ]-coated versions of sodium fluoride do not have gastric side effects in any significant way, and have milder and less frequent complications in the bones.<ref>{{ |
In the higher doses used to treat ], sodium fluoride can cause pain in the legs and incomplete stress fractures when the doses are too high; it also irritates the stomach, sometimes so severely as to cause ulcers. Slow-release and ]-coated versions of sodium fluoride do not have gastric side effects in any significant way, and have milder and less frequent complications in the bones.<ref>{{cite journal |vauthors=Murray TM, Ste-Marie LG |title=Prevention and management of osteoporosis: consensus statements from the Scientific Advisory Board of the Osteoporosis Society of Canada. 7. Fluoride therapy for osteoporosis |journal=CMAJ |volume=155 |issue=7 |pages=949–54 |year=1996 |pmid=8837545 |pmc=1335460}}</ref> In the lower doses used for ], the only clear adverse effect is ], which can alter the appearance of children's teeth during ]; this is mostly mild and is unlikely to represent any real effect on aesthetic appearance or on public health.<ref>{{cite book |url=http://nhmrc.gov.au/_files_nhmrc/file/publications/synopses/Eh41_Flouridation_PART_A.pdf |year=2007 |title=A systematic review of the efficacy and safety of fluoridation |author=National Health and Medical Research Council (Australia) |isbn=978-1-86496-415-8 |access-date=2010-02-21 |archive-url=https://web.archive.org/web/20091014191758/http://www.nhmrc.gov.au/_files_nhmrc/file/publications/synopses/Eh41_Flouridation_PART_A.pdf |archive-date=2009-10-14 |url-status=dead }} Summary: {{cite journal |author= Yeung CA |title= A systematic review of the efficacy and safety of fluoridation |journal= Evid.-Based Dent. |volume=9 |issue=2 |pages=39–43 |year=2008 |pmid=18584000 |doi=10.1038/sj.ebd.6400578 |doi-access=free }}</ref> Fluoride was known to enhance bone mineral density at the lumbar spine, but it was not effective for vertebral fractures and provoked more nonvertebral fractures.<ref>{{cite journal|last=Haguenauer|first=D|author2=Welch, V |author3=Shea, B |author4=Tugwell, P |author5=Adachi, JD |author6= Wells, G |title=Fluoride for the treatment of postmenopausal osteoporotic fractures: a meta-analysis.|journal=Osteoporosis International |date=2000|volume=11|issue=9|pages=727–38|pmid=11148800 |doi=10.1007/s001980070051|s2cid=538666}}</ref> In areas that have naturally occurring high levels of fluoride in ] which is used for ], both ] and ] can be prevalent and severe.<ref>{{cite web |author=World Health Organization |year=2004 |title=Fluoride in drinking-water |url=https://www.who.int/water_sanitation_health/dwq/chemicals/en/fluoride.pdf |url-status=dead |archive-url=https://web.archive.org/web/20160304082148/http://www.who.int/water_sanitation_health/dwq/chemicals/en/fluoride.pdf |archive-date=2016-03-04 |access-date=2014-02-13}}</ref> | ||
==== Hazard maps for fluoride in groundwater ==== | |||
In areas that have naturally occurring high levels of fluoride in groundwater both ] and ] can be prevalent and severe.<ref>http://www.who.int/water_sanitation_health/dwq/chemicals/en/fluoride.pdf</ref> | |||
Around one-third of the human population drinks water from groundwater resources. Of this, about 10%, approximately 300 million people, obtain water from groundwater resources that are heavily contaminated with arsenic or fluoride.<ref>Eawag (2015) Geogenic Contamination Handbook – Addressing Arsenic and Fluoride in Drinking Water. C.A. Johnson, A. Bretzler (Eds.), Swiss Federal Institute of Aquatic Science and Technology (Eawag), Duebendorf, Switzerland. (download: www.eawag.ch/en/research/humanwelfare/drinkingwater/wrq/geogenic-contamination-handbook/)</ref> These trace elements derive mainly from minerals.<ref>{{cite journal | last1 = Rodríguez-Lado | first1 = L. | last2 = Sun | first2 = G. | last3 = Berg | first3 = M. | last4 = Zhang | first4 = Q. | last5 = Xue | first5 = H. | last6 = Zheng | first6 = Q. | last7 = Johnson | first7 = C.A. | year = 2013 | title = Groundwater arsenic contamination throughout China | url = https://www.dora.lib4ri.ch/eawag/islandora/object/eawag%3A7346| journal = Science | volume = 341 | issue = 6148| pages = 866–868 | doi = 10.1126/science.1237484 | pmid = 23970694 | bibcode = 2013Sci...341..866R | s2cid = 206548777 }}</ref> Maps locating potential problematic wells are available.<ref></ref> | |||
== Other derivatives == | |||
=== Topical === | |||
Concentrated fluoride solutions are corrosive.<ref>{{cite journal |vauthors=Nakagawa M, Matsuya S, Shiraishi T, Ohta M |title=Effect of fluoride concentration and pH on corrosion behavior of titanium for dental use |journal=Journal of Dental Research |volume=78 |issue=9 |pages=1568–72 |year=1999 |pmid=10512392 |doi=10.1177/00220345990780091201|s2cid=32650790 }}</ref> Gloves made of ] are worn when handling fluoride compounds. The hazards of solutions of fluoride salts depend on the concentration. In the presence of ]s, fluoride salts release ], which is corrosive, especially toward glass.<ref name=Aigueperse/> | |||
== Other derivatives == | |||
Organic and inorganic anions are produced from fluoride, including: | Organic and inorganic anions are produced from fluoride, including: | ||
*] used as an etchant for glass. | *], used as an etchant for glass<ref>{{Cite web|url=http://www.eng.chimko.com/item29/|title=Ammonium bifluoride in the glass industry - Chimex Ltd}}</ref> | ||
*] | *] | ||
*] | *] | ||
*] used in organometallic synthesis |
*] used in organometallic synthesis | ||
*] used as an electrolyte in commercial secondary batteries. | *] used as an electrolyte in commercial secondary batteries. | ||
*] | *] | ||
== Safety == | |||
Concentrated fluoride solutions are toxic through dermal contact and must, therefore, be handled with appropriate care, since it causes skin irritation, eye damage, and irritation to mucous membranes. ] gloves offer no protection, so specially resistant gloves, such as those made of ] rubber, are worn when handling fluoride compounds. The hazards of solutions of fluoride salts depend on the concentration, and counterion. | |||
Concentrated fluoride solutions are handled in a fume hood because of the toxic vapours. Very dilute fluoride solutions are harmless. However, ingestion of stronger solutions are more dangerous to human and animal life. | |||
Due to incompatibilities, it is recommended to keep fluoride salts away from acids. | |||
== See also == | == See also == | ||
{{Portal|Medicine}} | |||
* ] | |||
*{{Portal-inline|size=tiny|Dentistry}} | |||
* ] | |||
*] | |||
*] | * ] | ||
* ] | |||
*] | |||
* ] | |||
*] | |||
* ] | |||
== References == | == References == | ||
{{Reflist|35em}} | {{Reflist|35em}} | ||
== External links == | == External links == | ||
{{Commons category|Fluorides}} | |||
* ] | |||
* , ] | |||
* | |||
* | |||
{{Fluorides}} | |||
{{Monatomic anion compounds}} | |||
{{Authority control}} | |||
] | |||
] | |||
] | ] | ||
] | |||
] | |||
] |
Latest revision as of 02:30, 5 December 2024
Ion of fluorine This article is about the fluoride ion. For a review of fluorine compounds, see Compounds of fluorine. For the fluoride additive used in toothpaste, see Fluoride therapy. Not to be confused with Floride or Fluorite.
| |||
Names | |||
---|---|---|---|
IUPAC name Fluoride | |||
Identifiers | |||
CAS Number | |||
3D model (JSmol) | |||
ChEBI | |||
ChEMBL | |||
ChemSpider | |||
Gmelin Reference | 14905 | ||
KEGG | |||
MeSH | Fluoride | ||
PubChem CID | |||
UNII | |||
InChI
| |||
SMILES
| |||
Properties | |||
Chemical formula | F | ||
Molar mass | 18.998403163 g·mol | ||
Conjugate acid | Hydrogen fluoride | ||
Thermochemistry | |||
Std molar entropy (S298) |
145.58 J/mol K (gaseous) | ||
Std enthalpy of formation (ΔfH298) |
−333 kJ mol | ||
Related compounds | |||
Other anions | |||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). Infobox references |
Fluoride (/ˈflʊəraɪd, ˈflɔːr-/) is an inorganic, monatomic anion of fluorine, with the chemical formula F
(also written
), whose salts are typically white or colorless. Fluoride salts typically have distinctive bitter tastes, and are odorless. Its salts and minerals are important chemical reagents and industrial chemicals, mainly used in the production of hydrogen fluoride for fluorocarbons. Fluoride is classified as a weak base since it only partially associates in solution, but concentrated fluoride is corrosive and can attack the skin.
Fluoride is the simplest fluorine anion. In terms of charge and size, the fluoride ion resembles the hydroxide ion. Fluoride ions occur on Earth in several minerals, particularly fluorite, but are present only in trace quantities in bodies of water in nature.
Nomenclature
Fluorides include compounds that contain ionic fluoride and those in which fluoride does not dissociate. The nomenclature does not distinguish these situations. For example, sulfur hexafluoride and carbon tetrafluoride are not sources of fluoride ions under ordinary conditions.
The systematic name fluoride, the valid IUPAC name, is determined according to the additive nomenclature. However, the name fluoride is also used in compositional IUPAC nomenclature which does not take the nature of bonding involved into account. Fluoride is also used non-systematically, to describe compounds which release fluoride upon dissolving. Hydrogen fluoride is itself an example of a non-systematic name of this nature. However, it is also a trivial name, and the preferred IUPAC name for fluorane.
Occurrence
Fluorine is estimated to be the 13th-most abundant element in Earth's crust and is widely dispersed in nature, entirely in the form of fluorides. The vast majority is held in mineral deposits, the most commercially important of which is fluorite (CaF2). Natural weathering of some kinds of rocks, as well as human activities, releases fluorides into the biosphere through what is sometimes called the fluorine cycle.
In water
Fluoride is naturally present in groundwater, fresh and saltwater sources, as well as in rainwater, particularly in urban areas. Seawater fluoride levels are usually in the range of 0.86 to 1.4 mg/L, and average 1.1 mg/L (milligrams per litre). For comparison, chloride concentration in seawater is about 19 g/L. The low concentration of fluoride reflects the insolubility of the alkaline earth fluorides, e.g., CaF2.
Concentrations in fresh water vary more significantly. Surface water such as rivers or lakes generally contains between 0.01 and 0.3 mg/L. Groundwater (well water) concentrations vary even more, depending on the presence of local fluoride-containing minerals. For example, natural levels of under 0.05 mg/L have been detected in parts of Canada but up to 8 mg/L in parts of China; in general levels rarely exceed 10 mg/litre
- In parts of Asia the groundwater can contain dangerously high levels of fluoride, leading to serious health problems.
- Worldwide, 50 million people receive water from water supplies that naturally have close to the "optimal level".
- In other locations the level of fluoride is very low, sometimes leading to fluoridation of public water supplies to bring the level to around 0.7–1.2 ppm.
- Mining can increase local fluoride levels
Fluoride can be present in rain, with its concentration increasing significantly upon exposure to volcanic activity or atmospheric pollution derived from burning fossil fuels or other sorts of industry, particularly aluminium smelters.
In plants
All vegetation contains some fluoride, which is absorbed from soil and water. Some plants concentrate fluoride from their environment more than others. All tea leaves contain fluoride; however, mature leaves contain as much as 10 to 20 times the fluoride levels of young leaves from the same plant.
Chemical properties
Basicity
Fluoride can act as a base. It can combine with a proton ( H):
- F + H → HF
This neutralization reaction forms hydrogen fluoride (HF), the conjugate acid of fluoride.
In aqueous solution, fluoride has a pKb value of 10.8. It is therefore a weak base, and tends to remain as the fluoride ion rather than generating a substantial amount of hydrogen fluoride. That is, the following equilibrium favours the left-hand side in water:
- F + H2O ⇌ HF + HO
However, upon prolonged contact with moisture, soluble fluoride salts will decompose to their respective hydroxides or oxides, as the hydrogen fluoride escapes. Fluoride is distinct in this regard among the halides. The identity of the solvent can have a dramatic effect on the equilibrium shifting it to the right-hand side, greatly increasing the rate of decomposition.
Structure of fluoride salts
Salts containing fluoride are numerous and adopt myriad structures. Typically the fluoride anion is surrounded by four or six cations, as is typical for other halides. Sodium fluoride and sodium chloride adopt the same structure. For compounds containing more than one fluoride per cation, the structures often deviate from those of the chlorides, as illustrated by the main fluoride mineral fluorite (CaF2) where the Ca ions are surrounded by eight F centers. In CaCl2, each Ca ion is surrounded by six Cl centers. The difluorides of the transition metals often adopt the rutile structure whereas the dichlorides have cadmium chloride structures.
Inorganic chemistry
Upon treatment with a standard acid, fluoride salts convert to hydrogen fluoride and metal salts. With strong acids, it can be doubly protonated to give H
2F
. Oxidation of fluoride gives fluorine. Solutions of inorganic fluorides in water contain F and bifluoride HF
2. Few inorganic fluorides are soluble in water without undergoing significant hydrolysis. In terms of its reactivity, fluoride differs significantly from chloride and other halides, and is more strongly solvated in protic solvents due to its smaller radius/charge ratio. Its closest chemical relative is hydroxide, since both have similar geometries.
Naked fluoride
Most fluoride salts dissolve to give the bifluoride (HF
2) anion. Sources of true F anions are rare because the highly basic fluoride anion abstracts protons from many, even adventitious, sources. Relative unsolvated fluoride, which does exist in aprotic solvents, is called "naked". Naked fluoride is a strong Lewis base, and a powerful nucleophile. Some quaternary ammonium salts of naked fluoride include tetramethylammonium fluoride and tetrabutylammonium fluoride. Cobaltocenium fluoride is another example. However, they all lack structural characterization in aprotic solvents. Because of their high basicity, many so-called naked fluoride sources are in fact bifluoride salts. In late 2016 imidazolium fluoride was synthesized that is the closest approximation of a thermodynamically stable and structurally characterized example of a "naked" fluoride source in an aprotic solvent (acetonitrile). The sterically demanding imidazolium cation stabilizes the discrete anions and protects them from polymerization.
Biochemistry
At physiological pHs, hydrogen fluoride is usually fully ionised to fluoride. In biochemistry, fluoride and hydrogen fluoride are equivalent. Fluorine, in the form of fluoride, is considered to be a micronutrient for human health, necessary to prevent dental cavities, and to promote healthy bone growth. The tea plant (Camellia sinensis L.) is a known accumulator of fluorine compounds, released upon forming infusions such as the common beverage. The fluorine compounds decompose into products including fluoride ions. Fluoride is the most bioavailable form of fluorine, and as such, tea is potentially a vehicle for fluoride dosing. Approximately, 50% of absorbed fluoride is excreted renally with a twenty-four-hour period. The remainder can be retained in the oral cavity, and lower digestive tract. Fasting dramatically increases the rate of fluoride absorption to near 100%, from a 60% to 80% when taken with food. Per a 2013 study, it was found that consumption of one litre of tea a day, can potentially supply the daily recommended intake of 4 mg per day. Some lower quality brands can supply up to a 120% of this amount. Fasting can increase this to 150%. The study indicates that tea drinking communities are at an increased risk of dental and skeletal fluorosis, in the case where water fluoridation is in effect. Fluoride ion in low doses in the mouth reduces tooth decay. For this reason, it is used in toothpaste and water fluoridation. At much higher doses and frequent exposure, fluoride causes health complications and can be toxic.
Applications
See also: Fluorochemical industry, Biological aspects of fluorine, and FluorineFluoride salts and hydrofluoric acid are the main fluorides of industrial value.
Organofluorine chemistry
Main article: Organofluorine chemistryOrganofluorine compounds are pervasive. Many drugs, many polymers, refrigerants, and many inorganic compounds are made from fluoride-containing reagents. Often fluorides are converted to hydrogen fluoride, which is a major reagent and precursor to reagents. Hydrofluoric acid and its anhydrous form, hydrogen fluoride, are particularly important.
Production of metals and their compounds
The main uses of fluoride, in terms of volume, are in the production of cryolite, Na3AlF6. It is used in aluminium smelting. Formerly, it was mined, but now it is derived from hydrogen fluoride. Fluorite is used on a large scale to separate slag in steel-making. Mined fluorite (CaF2) is a commodity chemical used in steel-making. Uranium hexafluoride is employed in the purification of uranium isotopes.
Cavity prevention
Main articles: Fluoride therapy and Water fluoridationFluoride-containing compounds, such as sodium fluoride or sodium monofluorophosphate are used in topical and systemic fluoride therapy for preventing tooth decay. They are used for water fluoridation and in many products associated with oral hygiene. Originally, sodium fluoride was used to fluoridate water; hexafluorosilicic acid (H2SiF6) and its salt sodium hexafluorosilicate (Na2SiF6) are more commonly used additives, especially in the United States. The fluoridation of water is known to prevent tooth decay and is considered by the U.S. Centers for Disease Control and Prevention to be "one of 10 great public health achievements of the 20th century". In some countries where large, centralized water systems are uncommon, fluoride is delivered to the populace by fluoridating table salt. For the method of action for cavity prevention, see Fluoride therapy. Fluoridation of water has its critics (see Water fluoridation controversy). Fluoridated toothpaste is in common use. Meta-analysis show the efficacy of 500 ppm fluoride in toothpastes. However, no beneficial effect can be detected when more than one fluoride source is used for daily oral care.
Laboratory reagent
Fluoride salts are commonly used in biological assay processing to inhibit the activity of phosphatases, such as serine/threonine phosphatases. Fluoride mimics the nucleophilic hydroxide ion in these enzymes' active sites. Beryllium fluoride and aluminium fluoride are also used as phosphatase inhibitors, since these compounds are structural mimics of the phosphate group and can act as analogues of the transition state of the reaction.
Dietary recommendations
The U.S. Institute of Medicine (IOM) updated Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for some minerals in 1997. Where there was not sufficient information to establish EARs and RDAs, an estimate designated Adequate Intake (AI) was used instead. AIs are typically matched to actual average consumption, with the assumption that there appears to be a need, and that need is met by what people consume. The current AI for women 19 years and older is 3.0 mg/day (includes pregnancy and lactation). The AI for men is 4.0 mg/day. The AI for children ages 1–18 increases from 0.7 to 3.0 mg/day. The major known risk of fluoride deficiency appears to be an increased risk of bacteria-caused tooth cavities. As for safety, the IOM sets tolerable upper intake levels (ULs) for vitamins and minerals when evidence is sufficient. In the case of fluoride the UL is 10 mg/day. Collectively the EARs, RDAs, AIs and ULs are referred to as Dietary Reference Intakes (DRIs).
The European Food Safety Authority (EFSA) refers to the collective set of information as Dietary Reference Values, with Population Reference Intake (PRI) instead of RDA, and Average Requirement instead of EAR. AI and UL are defined the same as in the United States. For women ages 18 and older the AI is set at 2.9 mg/day (including pregnancy and lactation). For men, the value is 3.4 mg/day. For children ages 1–17 years, the AIs increase with age from 0.6 to 3.2 mg/day. These AIs are comparable to the U.S. AIs. The EFSA reviewed safety evidence and set an adult UL at 7.0 mg/day (lower for children).
For U.S. food and dietary supplement labeling purposes, the amount of a vitamin or mineral in a serving is expressed as a percent of Daily Value (%DV). Although there is information to set Adequate Intake, fluoride does not have a Daily Value and is not required to be shown on food labels.
Estimated daily intake
Daily intakes of fluoride can vary significantly according to the various sources of exposure. Values ranging from 0.46 to 3.6–5.4 mg/day have been reported in several studies (IPCS, 1984). In areas where water is fluoridated this can be expected to be a significant source of fluoride, however fluoride is also naturally present in virtually all foods and beverages at a wide range of concentrations. The maximum safe daily consumption of fluoride is 10 mg/day for an adult (U.S.) or 7 mg/day (European Union).
The upper limit of fluoride intake from all sources (fluoridated water, food, beverages, fluoride dental products and dietary fluoride supplements) is set at 0.10 mg/kg/day for infants, toddlers, and children through to 8 years old. For older children and adults, who are no longer at risk for dental fluorosis, the upper limit of fluoride is set at 10 mg/day regardless of weight.
Food/Drink | Fluoride (mg per 1000g/ppm) |
Portion | Fluoride (mg per portion) |
---|---|---|---|
Black tea (brewed) | 3.73 | 1 cup, 240 g (8 fl oz) | 0.884 |
Raisins, seedless | 2.34 | small box, 43 g (1.5 oz) | 0.101 |
Table wine | 1.53 | Bottle, 750 mL (26 imp fl oz) | 1.150 |
Municipal tap-water, (Fluoridated) |
0.81 | Recommended daily intake, 3 litres (0.79 US gal) |
2.433 |
Baked potatoes, Russet | 0.45 | Medium potato, 140 g (0.31 lb) | 0.078 |
Lamb | 0.32 | Chop, 170 g (6.0 oz) | 0.054 |
Carrots | 0.03 | 1 large carrot, 72 g (2.5 oz) | 0.002 |
Source: Data taken from United States Department of Agriculture, National Nutrient Database Archived 2014-03-01 at the Wayback Machine |
Safety
Main article: Fluoride toxicityIngestion
According to the U.S. Department of Agriculture, the Dietary Reference Intakes, which is the "highest level of daily nutrient intake that is likely to pose no risk of adverse health effects" specify 10 mg/day for most people, corresponding to 10 L of fluoridated water with no risk. For young children the values are smaller, ranging from 0.7 mg/d to 2.2 mg/d for infants. Water and food sources of fluoride include community water fluoridation, seafood, tea, and gelatin.
Soluble fluoride salts, of which sodium fluoride is the most common, are toxic, and have resulted in both accidental and self-inflicted deaths from acute poisoning. The lethal dose for most adult humans is estimated at 5 to 10 g (which is equivalent to 32 to 64 mg elemental fluoride per kg body weight). A case of a fatal poisoning of an adult with 4 grams of sodium fluoride is documented, and a dose of 120 g sodium fluoride has been survived. For sodium fluorosilicate (Na2SiF6), the median lethal dose (LD50) orally in rats is 125 mg/kg, corresponding to 12.5 g for a 100 kg adult.
Treatment may involve oral administration of dilute calcium hydroxide or calcium chloride to prevent further absorption, and injection of calcium gluconate to increase the calcium levels in the blood. Hydrogen fluoride is more dangerous than salts such as NaF because it is corrosive and volatile, and can result in fatal exposure through inhalation or upon contact with the skin; calcium gluconate gel is the usual antidote.
In the higher doses used to treat osteoporosis, sodium fluoride can cause pain in the legs and incomplete stress fractures when the doses are too high; it also irritates the stomach, sometimes so severely as to cause ulcers. Slow-release and enteric-coated versions of sodium fluoride do not have gastric side effects in any significant way, and have milder and less frequent complications in the bones. In the lower doses used for water fluoridation, the only clear adverse effect is dental fluorosis, which can alter the appearance of children's teeth during tooth development; this is mostly mild and is unlikely to represent any real effect on aesthetic appearance or on public health. Fluoride was known to enhance bone mineral density at the lumbar spine, but it was not effective for vertebral fractures and provoked more nonvertebral fractures. In areas that have naturally occurring high levels of fluoride in groundwater which is used for drinking water, both dental and skeletal fluorosis can be prevalent and severe.
Hazard maps for fluoride in groundwater
Around one-third of the human population drinks water from groundwater resources. Of this, about 10%, approximately 300 million people, obtain water from groundwater resources that are heavily contaminated with arsenic or fluoride. These trace elements derive mainly from minerals. Maps locating potential problematic wells are available.
Topical
Concentrated fluoride solutions are corrosive. Gloves made of nitrile rubber are worn when handling fluoride compounds. The hazards of solutions of fluoride salts depend on the concentration. In the presence of strong acids, fluoride salts release hydrogen fluoride, which is corrosive, especially toward glass.
Other derivatives
Organic and inorganic anions are produced from fluoride, including:
- Bifluoride, used as an etchant for glass
- Tetrafluoroberyllate
- Hexafluoroplatinate
- Tetrafluoroborate used in organometallic synthesis
- Hexafluorophosphate used as an electrolyte in commercial secondary batteries.
- Trifluoromethanesulfonate
See also
- Per- and polyfluoroalkyl substances
- Fluorine-19 nuclear magnetic resonance spectroscopy
- Fluoride deficiency
- Fluoride selective electrode
- Fluoride therapy
- Sodium monofluorophosphate
References
- "Fluorides – PubChem Public Chemical Database". The PubChem Project. USA: National Center for Biotechnology Information. Identification.
- Chase, M. W. (1998). "Fluorine anion". NIST. pp. 1–1951. Retrieved 4 July 2012.
- Wells, J.C. (2008). Longman pronunciation dictionary (3rd ed.). Harlow, England: Pearson Education Limited/Longman. p. 313. ISBN 9781405881180.. According to this source, /ˈfluːəraɪd/ is a possible pronunciation in British English.
- ^ Aigueperse, Jean; Mollard, Paul; Devilliers, Didier; Chemla, Marius; Faron, Robert; Romano, René; Cuer, Jean Pierre (2000). "Fluorine Compounds, Inorganic". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a11_307. ISBN 978-3527306732.
- Derakhshani, R; Raoof, A; Mahvi, AH; Chatrouz, H (2020). "Similarities in the Fingerprints of Coal Mining Activities, High Ground Water Fluoride, and Dental Fluorosis in Zarand District, Kerman Province, Iran". Fluoride. 53 (2): 257–267.
- Derakhshani, R; Tavallaie, M; Malek Mohammad, T; Abbasnejad, A; Haghdoost, A (2014). "Occurrence of fluoride in groundwater of Zarand region, Kerman province, Iran". Fluoride. 47 (2): 133–138.
- "Public Health Statement for Fluorides, Hydrogen Fluoride, and Fluorine". ATSDR. September 2003.
- "Ambient Water Quality Criteria for Fluoride". Government of British Columbia. Archived from the original on 24 September 2015. Retrieved 8 October 2014.
- Liteplo, Dr R.; Gomes, R.; Howe, P.; Malcolm, Heath (2002). FLUORIDES - Environmental Health Criteria 227 : 1st draft. Geneva: World Health Organization. ISBN 978-9241572279.
- ^ Fawell, J.K.; et al. "Fluoride in Drinking-water Background document for development of WHO Guidelines for Drinking-water Quality" (PDF). World Health Organization. Retrieved 6 May 2016.
- Yadav, Krishna Kumar; Kumar, Sandeep; Pham, Quoc Bao; Gupta, Neha; Rezania, Shahabaldin; Kamyab, Hesam; Yadav, Shalini; Vymazal, Jan; Kumar, Vinit; Tri, Doan Quang; Talaiekhozani, Amirreza; Prasad, Shiv; Reece, Lisa M.; Singh, Neeraja; Maurya, Pradip Kumar; Cho, Jinwoo (October 2019). "Fluoride contamination, health problems and remediation methods in Asian groundwater: A comprehensive review". Ecotoxicology and Environmental Safety. 182: 109362. Bibcode:2019EcoES.18209362Y. doi:10.1016/j.ecoenv.2019.06.045. PMID 31254856. S2CID 195764865.
- Tiemann, Mary (5 April 2013). "Fluoride in Drinking Water: A Review of Fluoridation and Regulation Issues" (PDF). Congressional Research Service. p. 3. Retrieved 6 May 2016.
- Chandio, Tasawar Ali; Khan, Muhammad Nasiruddin; Muhammad, Maria Taj; Yalcinkaya, Ozcan; Wasim, Agha Arslan; Kayis, Ahmet Furkan (January 2021). "Fluoride and arsenic contamination in drinking water due to mining activities and its impact on local area population". Environmental Science and Pollution Research. 28 (2): 2355–2368. Bibcode:2021ESPR...28.2355C. doi:10.1007/s11356-020-10575-9. PMID 32880840. S2CID 221463681.
- Bellomo, Sergio; Aiuppa, Alessandro; D’Alessandro, Walter; Parello, Francesco (August 2007). "Environmental impact of magmatic fluorine emission in the Mt. Etna area". Journal of Volcanology and Geothermal Research. 165 (1–2): 87–101. Bibcode:2007JVGR..165...87B. doi:10.1016/j.jvolgeores.2007.04.013.
- Smith, Frank A.; Hodge, Harold C.; Dinman, B. D. (9 January 2009). "Airborne fluorides and man: Part I". CRC Critical Reviews in Environmental Control. 8 (1–4): 293–371. doi:10.1080/10643387709381665.
- Smith, Frank A.; Hodge, Harold C.; Dinman, B. D. (9 January 2009). "Airborne fluorides and man: Part II". CRC Critical Reviews in Environmental Control. 9 (1): 1–25. doi:10.1080/10643387909381666.
- Arnesen, A.K.M.; Abrahamsen, G.; Sandvik, G.; Krogstad, T. (February 1995). "Aluminium-smelters and fluoride pollution of soil and soil solution in Norway". Science of the Total Environment. 163 (1–3): 39–53. Bibcode:1995ScTEn.163...39A. doi:10.1016/0048-9697(95)04479-K.
- Wong MH, Fung KF, Carr HP (2003). "Aluminium and fluoride contents of tea, with emphasis on brick tea and their health implications". Toxicology Letters. 137 (1–2): 111–20. doi:10.1016/S0378-4274(02)00385-5. PMID 12505437.
- Malinowska E, Inkielewicz I, Czarnowski W, Szefer P (2008). "Assessment of fluoride concentration and daily intake by human from tea and herbal infusions". Food Chem. Toxicol. 46 (3): 1055–61. doi:10.1016/j.fct.2007.10.039. PMID 18078704.
- Gardner EJ, Ruxton CH, Leeds AR (2007). "Black tea—helpful or harmful? A review of the evidence". European Journal of Clinical Nutrition. 61 (1): 3–18. doi:10.1038/sj.ejcn.1602489. PMID 16855537.
- Wiberg; Holleman, A.F. (2001). Inorganic chemistry (1st English ed., by Nils Wiberg. ed.). San Diego, Calif. : Berlin: Academic Press, W. de Gruyter. ISBN 978-0-12-352651-9.
- Schwesinger, Reinhard; Link, Reinhard; Wenzl, Peter; Kossek, Sebastian (2005). "Anhydrous Phosphazenium Fluorides as Sources for Extremely Reactive Fluoride Ions in Solution". Chemistry: A European Journal. 12 (2): 438–45. doi:10.1002/chem.200500838. PMID 16196062.
- Haoran Sun & Stephen G. DiMagno (2005). "Anhydrous Tetrabutylammonium Fluoride". Journal of the American Chemical Society. 127 (7): 2050–1. doi:10.1021/ja0440497. PMID 15713075.
- Bennett, Brian K.; Harrison, Roger G.; Richmond, Thomas G. (1994). "Cobaltocenium Fluoride: A Novel Source of "Naked" Fluoride Formed by Carbon-Fluorine Bond Activation in a Saturated Perfluorocarbon". Journal of the American Chemical Society. 116 (24): 11165–11166. doi:10.1021/ja00103a045.
- Alič, B.; Tavčar, G. (2016). "Reaction of N-heterocyclic carbene (NHC) with different HF sources and ratios – A free fluoride reagent based on imidazolium fluoride". J. Fluorine Chem. 192: 141–146. doi:10.1016/j.jfluchem.2016.11.004.
- Alič, B.; Tramšek, M.; Kokalj, A.; Tavčar, G. (2017). "Discrete GeF5– Anion Structurally Characterized with a Readily Synthesized Imidazolium Based Naked Fluoride Reagent". Inorg. Chem. 56 (16): 10070–10077. doi:10.1021/acs.inorgchem.7b01606. PMID 28792216.
- Zupanek, Ž.; Tramšek, M.; Kokalj, A.; Tavčar, G. (2018). "Reactivity of VOF3 with N-Heterocyclic Carbene and Imidazolium Fluoride: Analysis of Ligand–VOF3 Bonding with Evidence of a Minute π Back-Donation of Fluoride". Inorg. Chem. 57 (21): 13866–13879. doi:10.1021/acs.inorgchem.8b02377. PMID 30353729. S2CID 53031199.
- ^ Fawell, J. "Fluoride in Drinking-water" (PDF). World Health Organization. Retrieved 10 March 2016.
- ^ Chan, Laura; Mehra, Aradhana; Saikat, Sohel; Lynch, Paul (May 2013). "Human exposure assessment of fluoride from tea (Camellia sinensis L.): A UK based issue?". Food Research International. 51 (2): 564–570. doi:10.1016/j.foodres.2013.01.025.
- "Fluoride Free Toothpaste – Fluoride (Finally!) Explained". 27 June 2016.
- McDonagh M. S.; Whiting P. F.; Wilson P. M.; Sutton A. J.; Chestnutt I.; Cooper J.; Misso K.; Bradley M.; Treasure E.; Kleijnen J. (2000). "Systematic review of water fluoridation". British Medical Journal. 321 (7265): 855–859. doi:10.1136/bmj.321.7265.855. PMC 27492. PMID 11021861.
- Griffin SO, Regnier E, Griffin PM, Huntley V (2007). "Effectiveness of fluoride in preventing caries in adults". J. Dent. Res. 86 (5): 410–5. doi:10.1177/154405910708600504. hdl:10945/60693. PMID 17452559. S2CID 58958881.
- Winston A. E.; Bhaskar S. N. (1 November 1998). "Caries prevention in the 21st century". J. Am. Dent. Assoc. 129 (11): 1579–87. doi:10.14219/jada.archive.1998.0104. PMID 9818575. Archived from the original on 15 July 2012.
- "Community Water Fluoridation". Centers for Disease Control and Prevention. Retrieved 10 March 2016.
- "Ten Great Public Health Achievements in the 20th Century". Centers for Disease Control and Prevention. Archived from the original on 13 March 2016. Retrieved 10 March 2016.
- Newbrun E (1996). "The fluoridation war: a scientific dispute or a religious argument?". Journal of Public Health Dentistry. 56 (5 Spec No): 246–52. doi:10.1111/j.1752-7325.1996.tb02447.x. PMID 9034969.
- Walsh, Tanya; Worthington, Helen V.; Glenny, Anne-Marie; Marinho, Valeria Cc; Jeroncic, Ana (4 March 2019). "Fluoride toothpastes of different concentrations for preventing dental caries". Cochrane Database of Systematic Reviews. 3 (3): CD007868. doi:10.1002/14651858.CD007868.pub3. ISSN 1469-493X. PMC 6398117. PMID 30829399.
- "Remineralization of initial carious lesions in deciduous enamel after application of dentifrices of different fluoride concentrations". springermedizin.de (in German). Retrieved 24 February 2021.
- Hausen, H.; Kärkkäinen, S.; Seppä, L. (February 2000). "Application of the high-risk strategy to control dental caries". Community Dentistry and Oral Epidemiology. 28 (1): 26–34. doi:10.1034/j.1600-0528.2000.280104.x. ISSN 0301-5661. PMID 10634681.
- Nakai C, Thomas JA (1974). "Properties of a phosphoprotein phosphatase from bovine heart with activity on glycogen synthase, phosphorylase, and histone". J. Biol. Chem. 249 (20): 6459–67. doi:10.1016/S0021-9258(19)42179-0. PMID 4370977.
- Schenk G, Elliott TW, Leung E, et al. (2008). "Crystal structures of a purple acid phosphatase, representing different steps of this enzyme's catalytic cycle". BMC Struct. Biol. 8: 6. doi:10.1186/1472-6807-8-6. PMC 2267794. PMID 18234116.
- Wang W, Cho HS, Kim R, et al. (2002). "Structural characterization of the reaction pathway in phosphoserine phosphatase: crystallographic "snapshots" of intermediate states". J. Mol. Biol. 319 (2): 421–31. doi:10.1016/S0022-2836(02)00324-8. PMID 12051918.
- Cho H, Wang W, Kim R, et al. (2001). "BeF(3)(-) acts as a phosphate analog in proteins phosphorylated on aspartate: structure of a BeF(3)(-) complex with phosphoserine phosphatase". Proc. Natl. Acad. Sci. U.S.A. 98 (15): 8525–30. Bibcode:2001PNAS...98.8525C. doi:10.1073/pnas.131213698. PMC 37469. PMID 11438683.
- ^ Institute of Medicine (1997). "Fluoride". Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D and Fluoride. Washington, DC: The National Academies Press. pp. 288–313. doi:10.17226/5776. ISBN 978-0-309-06403-3. PMID 23115811.
- "Overview on Dietary Reference Values for the EU population as derived by the EFSA Panel on Dietetic Products, Nutrition and Allergies" (PDF). 2017.
- ^ Tolerable Upper Intake Levels For Vitamins And Minerals (PDF), European Food Safety Authority, 2006
- "Federal Register May 27, 2016 Food Labeling: Revision of the Nutrition and Supplement Facts Labels. FR page 33982" (PDF).
- "Nutrient Lists". Agricultural Research Service United States Department of Agriculture. Archived from the original on 26 May 2014. Retrieved 25 May 2014.
- Levy, Steven M.; Guha-Chowdhury, Nupur (1999). "Total Fluoride Intake and Implications for Dietary Fluoride Supplementation". Journal of Public Health Dentistry. 59 (4): 211–223. doi:10.1111/j.1752-7325.1999.tb03272.x. PMID 10682326.
- "Food Composition Databases: Food Search: Fluoride". Agricultural Research Service, United States Department of Agriculture. Archived from the original on 5 December 2018. Retrieved 5 December 2018.
- "Dietary Reference Intakes: EAR, RDA, AI, Acceptable Macronutrient Distribution Ranges, and UL". United States Department of Agriculture. Retrieved 9 September 2017.
- "Fluoride in diet". U.S. National Library of Medicine. Retrieved 10 March 2016.
- Gosselin, RE; Smith RP; Hodge HC (1984). Clinical toxicology of commercial products. Baltimore (MD): Williams & Wilkins. pp. III–185–93. ISBN 978-0-683-03632-9.
- Baselt, RC (2008). Disposition of toxic drugs and chemicals in man. Foster City (CA): Biomedical Publications. pp. 636–40. ISBN 978-0-9626523-7-0.
- IPCS (2002). Environmental health criteria 227 (Fluoride). Geneva: International Programme on Chemical Safety, World Health Organization. p. 100. ISBN 978-92-4-157227-9.
- ^ Rabinowitch, IM (1945). "Acute Fluoride Poisoning". Canadian Medical Association Journal. 52 (4): 345–9. PMC 1581810. PMID 20323400.
- Abukurah AR, Moser AM Jr, Baird CL, Randall RE Jr, Setter JG, Blanke RV (1972). "Acute sodium fluoride poisoning". JAMA. 222 (7): 816–7. doi:10.1001/jama.1972.03210070046014. PMID 4677934.
- The Merck Index, 12th edition, Merck & Co., Inc., 1996
- Muriale L, Lee E, Genovese J, Trend S (1996). "Fatality due to acute fluoride poisoning following dermal contact with hydrofluoric acid in a palynology laboratory". Ann. Occup. Hyg. 40 (6): 705–710. doi:10.1016/S0003-4878(96)00010-5. PMID 8958774.
- Murray TM, Ste-Marie LG (1996). "Prevention and management of osteoporosis: consensus statements from the Scientific Advisory Board of the Osteoporosis Society of Canada. 7. Fluoride therapy for osteoporosis". CMAJ. 155 (7): 949–54. PMC 1335460. PMID 8837545.
- National Health and Medical Research Council (Australia) (2007). A systematic review of the efficacy and safety of fluoridation (PDF). ISBN 978-1-86496-415-8. Archived from the original (PDF) on 14 October 2009. Retrieved 21 February 2010. Summary: Yeung CA (2008). "A systematic review of the efficacy and safety of fluoridation". Evid.-Based Dent. 9 (2): 39–43. doi:10.1038/sj.ebd.6400578. PMID 18584000.
- Haguenauer, D; Welch, V; Shea, B; Tugwell, P; Adachi, JD; Wells, G (2000). "Fluoride for the treatment of postmenopausal osteoporotic fractures: a meta-analysis". Osteoporosis International. 11 (9): 727–38. doi:10.1007/s001980070051. PMID 11148800. S2CID 538666.
- World Health Organization (2004). "Fluoride in drinking-water" (PDF). Archived from the original (PDF) on 4 March 2016. Retrieved 13 February 2014.
- Eawag (2015) Geogenic Contamination Handbook – Addressing Arsenic and Fluoride in Drinking Water. C.A. Johnson, A. Bretzler (Eds.), Swiss Federal Institute of Aquatic Science and Technology (Eawag), Duebendorf, Switzerland. (download: www.eawag.ch/en/research/humanwelfare/drinkingwater/wrq/geogenic-contamination-handbook/)
- Rodríguez-Lado, L.; Sun, G.; Berg, M.; Zhang, Q.; Xue, H.; Zheng, Q.; Johnson, C.A. (2013). "Groundwater arsenic contamination throughout China". Science. 341 (6148): 866–868. Bibcode:2013Sci...341..866R. doi:10.1126/science.1237484. PMID 23970694. S2CID 206548777.
- Groundwater Assessment Platform
- Nakagawa M, Matsuya S, Shiraishi T, Ohta M (1999). "Effect of fluoride concentration and pH on corrosion behavior of titanium for dental use". Journal of Dental Research. 78 (9): 1568–72. doi:10.1177/00220345990780091201. PMID 10512392. S2CID 32650790.
- "Ammonium bifluoride in the glass industry - Chimex Ltd".
External links
- "Fluoride in Drinking Water: A Review of Fluoridation and Regulation Issues", Congressional Research Service
- U.S. government site for checking status of local water fluoridation
Monatomic anion compounds | |
---|---|
Group 1 | |
Group 13 | |
Group 14 | |
Group 15 (Pnictides) | |
Group 16 (Chalcogenides) | |
Group 17 (Halides) |