Sodium fluoride#Medical imaging

File:Sodium fluoride tablets.jpg

{{See also|Fluoride therapy|Water fluoridation}}

Fluoride salts are often added to municipal drinking water (as well as to certain food products in some countries) for the purpose of maintaining dental health. The fluoride enhances the strength of teeth by the formation of fluorapatite, a naturally occurring component of tooth enamel.{{cite book|last1=Bourne|first1= Geoffrey H.|title=Dietary research and guidance in health and disease|date=1986|publisher=Karger|location=Basel|isbn=978-3-8055-4341-5|page=153}}{{cite book|last1=Klein|first1=Cornelis|editor-first=Cornelius S.|editor-last=Hurlbut|title=Manual of Mineralogy (after James D. Dana)|date=1999|publisher=J. Wiley|location=New York|isbn=978-0-471-31266-6|edition=21st ed., rev.}}{{cite journal|last1=Selwitz|first1=Robert H|last2=Ismail|first2=Amid I|last3=Pitts|first3=Nigel B|title=Dental caries|journal=The Lancet|date=January 2007|volume=369|issue=9555|pages=51–59|doi=10.1016/S0140-6736(07)60031-2|pmid=17208642|s2cid=204616785}} Although sodium fluoride is used to fluoridate water and is the standard by which other water-fluoridation compounds are gauged, hexafluorosilicic acid (H₂SiF₆) and its salt sodium hexafluorosilicate (Na₂SiF₆) are more commonly used additives in the United States.{{Citation |url=http://cdc.gov/fluoridation/pdf/statistics/1992.pdf |title= Fluoridation census 1992 |author= Division of Oral Health, National Center for Prevention Services, CDC |year=1993 |access-date=29 December 2008 |postscript=.}}

Fluoride supplementation has been extensively studied for the treatment of postmenopausal osteoporosis. This supplementation does not appear to be effective; even though sodium fluoride increases bone density, it does not decrease the risk of fractures.{{cite journal|last1=Haguenauer|first1=D|last2=Welch|first2=V|last3=Shea|first3=B|last4=Tugwell|first4=P|last5=Wells|first5=G|title=Fluoride for treating postmenopausal osteoporosis.|journal=The Cochrane Database of Systematic Reviews|date=2000|volume=2010|issue=4|pages=CD002825|pmid=11034769|doi=10.1002/14651858.CD002825|pmc=8453489}}{{cite journal|last1=Vestergaard|first1=P|last2=Jorgensen|first2=NR|last3=Schwarz|first3=P|last4=Mosekilde|first4=L|title=Effects of treatment with fluoride on bone mineral density and fracture risk—a meta-analysis.|journal=Osteoporosis International|date=March 2008|volume=19|issue=3|pages=257–68|pmid=17701094|doi=10.1007/s00198-007-0437-6|s2cid=25890845}}

In medical imaging, fluorine-18-labelled sodium fluoride (USP, sodium fluoride Na¹⁸F) is one of the oldest tracers used in positron emission tomography (PET), having been in use since the 1960s.{{cite journal|last1=Blau|first1=Monte|last2=Ganatra|first2=Ramanik|last3=Bender|first3=Merrill A.|title=18F-fluoride for bone imaging|journal=Seminars in Nuclear Medicine|date=January 1972|volume=2|issue=1|pages=31–37|doi=10.1016/S0001-2998(72)80005-9|pmid=5059349}} Relative to conventional bone scintigraphy carried out with gamma cameras or SPECT systems, PET offers more sensitivity and spatial resolution. Fluorine-18 has a half-life of 110 min, which requires it to be used promptly once produced; this logistical limitation hampered its adoption in the face of the more convenient technetium-99m-labelled radiopharmaceuticals. However, fluorine-18 is generally considered to be a superior radiopharmaceutical for skeletal imaging. In particular it has a high and rapid bone uptake accompanied by very rapid blood clearance, which results in a high bone-to-background ratio in a short time.{{cite journal|last1=Ordonez|first1=A. A.|last2=DeMarco|first2=V. P.|last3=Klunk|first3=M. H.|last4=Pokkali|first4=S.|last5=Jain|first5=S.K.|title=Imaging Chronic Tuberculous Lesions Using Sodium [18F]Fluoride Positron Emission Tomography in Mice.|journal=Molecular Imaging and Biology|date=October 2015|volume=17|issue=5|pages=609–614|doi=10.1007/s11307-015-0836-6|pmid=25750032|pmc=4561601}} Additionally the annihilation photons produced by decay of ¹⁸F have a high energy of 511 keV compared to the 140 keV photons of ^99mTc.{{cite journal|last1=Grant|first1=F. D.|last2=Fahey|first2=F. H.|last3=Packard|first3=A. B.|last4=Davis|first4=R. T.|last5=Alavi|first5=A.|last6=Treves|first6=S. T.|title=Skeletal PET with 18F-Fluoride: Applying New Technology to an Old Tracer|journal=Journal of Nuclear Medicine|date=12 December 2007|volume=49|issue=1|pages=68–78|doi=10.2967/jnumed.106.037200|pmid=18077529|doi-access=free}}

Sodium fluoride has a variety of specialty chemical applications in synthesis and extractive metallurgy. It reacts with electrophilic chlorides including acyl chlorides, sulfur chlorides, and phosphorus chloride.{{citation | last = Halpern | first = D.F. | contribution = Sodium Fluoride | title = Encyclopedia of Reagents for Organic Synthesis | year = 2001 | publisher = John Wiley & Sons | doi = 10.1002/047084289X.rs071| isbn = 978-0-471-93623-7 }} Like other fluorides, sodium fluoride finds use in desilylation in organic synthesis. Sodium fluoride can be used to produce fluorocarbons via the Finkelstein reaction; this process has the advantage of being simple to perform on a small scale but is rarely used on an industrial scale due to the existence of more effective techniques (e.g. Electrofluorination, Fowler process).

Sodium fluoride is sometimes added at relatively high concentrations (~20 mM) to protein lysis buffers in order to inhibit endogenous phosphatases and thereby protect phosphorylated protein sites.{{cite journal | last1=Somerville | first1=Laura L. | last2=Wang | first2=Kuan | title=Sarcomere matrix of striated muscle: In vivo phosphorylation of titin and nebulin in mouse diaphragm muscle | journal=Archives of Biochemistry and Biophysics | publisher=Elsevier BV | volume=262 | issue=1 | year=1988 | issn=0003-9861 | doi=10.1016/0003-9861(88)90174-9 | pages=118–129| pmid=3355162 }} Sodium pyrophosphate and Sodium orthovanadate are also used for this purpose.{{cite web | title=Overview of Protease and Phosphatase Inhibition for Protein Preparation - US | website=Thermo Fisher Scientific | date=10 May 2017 | url=https://www.thermofisher.com/us/en/home/life-science/protein-biology/protein-biology-learning-center/protein-biology-resource-library/pierce-protein-methods/protease-phosphatase-inhibitors.html | access-date=3 February 2023}}

Inorganic fluorides such as fluorosilicates and sodium fluoride complex magnesium ions as magnesium fluorophosphate. They inhibit enzymes such as enolase that require Mg²⁺ as a prosthetic group. Thus, fluoride poisoning prevents phosphate transfer in oxidative metabolism.{{citation | author=Metcalf, Robert L. | contribution=Insect Control | title=Ullmann's Encyclopedia of Industrial Chemistry | edition=7th | publisher=Wiley | year=2007 | page=9| title-link=Ullmann's Encyclopedia of Industrial Chemistry }} Sodium fluoride, patented as an insecticide in 1896, was commonly used through the 1970s on ants and other domestic pests,{{cite book|last1=Weinstein|first1=L.H.|url=https://books.google.com/books?id=hll2t6FVmgkC|title=Fluorides in the Environment: Effects on Plants and Animals|last2=Davison|first2=A.|date=2004|publisher=CABI Publishing|isbn=9780851998725|page=76|language=en}} and as a stomach poison for plant-feeding insects.{{cite book|last1=House|first1=James E.|url=https://books.google.com/books?id=pu3HBQAAQBAJ&q=Descriptive+Inorganic+Chemistry|title=Descriptive Inorganic Chemistry|last2=House|first2=Kathleen A.|date=10 September 2015|publisher=Academic Press|isbn=978-0-12-802979-4|page=397|language=en}}

Its use, along with that of sodium fluorosilicate, declined over the 20th century as the products were banned or restricted due to the possibility of poisoning, intentional or accidental. In 1942, for instance, 47 inmates at the Oregon State Hospital died after consuming scrambled eggs which had been inadvertently prepared with sodium fluoride; while assisting the cooks, another inmate had confused a container of insecticide—used by the hospital to control cockroaches—with powdered milk, which was stored nearby.{{cite news|url=https://www.nytimes.com/1983/10/04/obituaries/unsuspecting-poisoner-of-47-at-a-hospital-in-1942-is-dead.html|title=Unsuspecting Poisoner of 47 At a Hospital in 1942 Is Dead|work=The New York Times|date=4 October 1983|access-date=4 August 2016|archive-date=20 August 2016|archive-url=https://web.archive.org/web/20160820204404/http://www.nytimes.com/1983/10/04/obituaries/unsuspecting-poisoner-of-47-at-a-hospital-in-1942-is-dead.html|url-status=live}}

Sodium fluoride is used as a cleaning agent (e.g., as a "laundry sour").

Sodium fluoride can be used in a nuclear molten-salt reactor, which sodium fluoride is used as the reactor's coolant.{{Cite web |title=Molten Salt Reactors - World Nuclear Association |url=https://world-nuclear.org/information-library/current-and-future-generation/molten-salt-reactors |access-date=2025-03-26 |website=world-nuclear.org}}

{{See also|Fluoride poisoning}}

The lethal dose for a 70 kg (154 lb) human is estimated at 5–10 g.

Fluorides, particularly aqueous solutions of sodium fluoride, are rapidly and quite extensively absorbed by the human body.{{citation | author=Kapp, Robert | contribution=Fluorine | title=Encyclopedia of Toxicology | edition=2nd | volume=2 | publisher=Elsevier | year=2005 | pages=343–346}}

Fluorides interfere with electron transport and calcium metabolism. Calcium is essential for maintaining cardiac membrane potentials and in regulating coagulation. High ingestion of fluoride salts or hydrofluoric acid may result in fatal arrhythmias due to profound hypocalcemia. Chronic over-absorption can cause hardening of bones, calcification of ligaments, and buildup on teeth. Fluoride can cause irritation or corrosion to eyes, skin, and nasal membranes.{{citation | author=Greene Shepherd | contribution=Fluoride | title=Encyclopedia of Toxicology | edition=2nd | volume=2 | publisher=Elsevier | year=2005 | pages=342–343}}

Sodium fluoride is classed as toxic by both inhalation (of dusts or aerosols) and ingestion.[http://hazard.com/msds/mf/baker/baker/files/s3722.htm NaF MSDS]. hazard.com In high enough doses, it has been shown to affect the heart and circulatory system. For occupational exposures, the Occupational Safety and Health Administration and the National Institute for Occupational Safety and Health have established occupational exposure limits at 2.5 mg/m³ over an eight-hour time-weighted average.[https://www.cdc.gov/niosh/npg/npgd0563.html CDC – NIOSH Pocket Guide to Chemical Hazards]

In the higher doses used to treat osteoporosis, plain 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 peptic ulcer disease. Slow-release and enteric-coated versions of sodium fluoride do not have significant gastric side effects, and have milder and less frequent complications in the bones.{{cite journal |author=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 }} 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. A chronic fluoride ingestion of 1 ppm of fluoride in drinking water can cause mottling of the teeth (fluorosis) and an exposure of 1.7 ppm will produce mottling in 30%–50% of patients. Studies have shown that dental fluorosis negatively impacts the self-esteem and self-image of adolescents.{{cite journal |last1=Molina-Frechero |first1=N |last2=Nevarez-Rascón |first2=M |last3=Nevarez-Rascón |first3=A |last4=González-González |first4=R |last5=Irigoyen-Camacho |first5=ME |last6=Sánchez-Pérez |first6=L |last7=López-Verdin |first7=S |last8=Bologna-Molina |first8=R |title=Impact of Dental Fluorosis, Socioeconomic Status and Self-Perception in Adolescents Exposed to a High Level of Fluoride in Water. |journal=International Journal of Environmental Research and Public Health |date=12 January 2017 |volume=14 |issue=1 |page=73 |doi=10.3390/ijerph14010073 |doi-access=free |pmid=28085102 |pmc=5295324 }}{{cite journal |last1=Nilchian |first1=F |last2=Asgary |first2=I |last3=Mastan |first3=F |title=The Effect of Dental Fluorosis on the Quality of Life of Female High School and Precollege Students of High Fluoride-Concentrated Area. |journal=Journal of International Society of Preventive & Community Dentistry |date=July 2018 |volume=8 |issue=4 |pages=314–319 |doi=10.4103/jispcd.JISPCD_94_18 |doi-access=free |pmid=30123763 |pmc=6071349 }}

Sodium fluoride is an inorganic ionic compound, dissolving in water to give separated Na⁺ and F⁻ ions. Like sodium chloride, it crystallizes in a cubic motif where both Na⁺ and F⁻ occupy octahedral coordination sites;{{Citation | last = Wells | first = A.F. | year = 1984 | title = Structural Inorganic Chemistry | place = Oxford | publisher = Clarendon Press | isbn = 978-0-19-855370-0}}{{citation | url = http://www.atsdr.cdc.gov/toxprofiles/tp11.pdf | contribution = Chemical and physical information | title = Toxicological profile for fluorides, hydrogen fluoride, and fluorine | pages = 187 | publisher = Agency for Toxic Substances and Disease Registry (ATDSR) | date = September 2003 | access-date = 1 November 2008}} its lattice spacing, approximately 462 pm, is smaller than that of sodium chloride (564 pm).

The mineral form of NaF, villiaumite, is moderately rare. It is known from plutonic nepheline syenite rocks.{{Citation | url = http://rruff.geo.arizona.edu/doclib/hom/villiaumite.pdf | title = Mineral Handbook

| year = 2005 | publisher = Mineral Data Publishing | issue = version 1 | postscript = .}}

NaF is prepared by neutralizing hydrofluoric acid or hexafluorosilicic acid (H₂SiF₆), both byproducts of the reaction of fluorapatite (Ca₅(PO₄)₃F) from phosphate rock during the production of superphosphate fertilizer. Neutralizing agents include sodium hydroxide and sodium carbonate. Alcohols are sometimes used to precipitate the NaF:

:HF + NaOH → NaF + H₂O

From solutions containing HF, sodium fluoride precipitates as the bifluoride salt sodium bifluoride (NaHF₂). Heating the latter releases HF and gives NaF.

:HF + NaF ⇌ NaHF₂

In a 1986 report, the annual worldwide consumption of NaF was estimated to be several million tonnes.{{Ullmann|doi=10.1002/14356007.a11_307|title=Fluorine Compounds, Inorganic|year=2000|last1=Aigueperse|first1=Jean|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|isbn=3-527-30673-0}}

{{Commons category}}

{{reflist}}

{{Sodium compounds}}

{{Stomatological preparations}}

{{Fluorides}}

{{Portal bar | Medicine}}

{{Authority control}}

Category:Fluorides

Category:Metal halides

Category:Alkali metal fluorides

Category:Sodium compounds

Category:Dental drugs

Category:Rock salt crystal structure