Medical uses of silver: Difference between revisions

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{{inuse}}

{{nanomat}}
{{nanomat}}
True '''colloidal silver''' is a [[liquid]] [[suspension (chemistry)|suspension]] of [[microscopic]] particles of [[silver]]. A [[colloid]] is technically defined as particles which remain suspended without forming an [[Ionic liquid|ionic]], or dissolved solution.
True '''colloidal silver''' is a [[liquid]] [[suspension (chemistry)|suspension]] of [[microscopic]] particles of [[silver]]. A [[colloid]] is technically defined as particles which remain suspended without forming an [[Ionic liquid|ionic]], or dissolved solution.
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The antibacterial action of silver is dependent on the silver ion.<ref name="current-prob">{{cite journal |author=Lansdown AB |title=Silver in health care: antimicrobial effects and safety in use |journal=Curr. Probl. Dermatol. |volume=33 |issue= |pages=17–34 |year=2006 |pmid=16766878 |doi=10.1159/000093928 |url=}}</ref> Colloidal silver preparations primarily deliver inactive metallic silver, rather than the active microbicidal silver ion.<ref name="blue">{{cite journal |author=Okan D, Woo K, Sibbald RG |title=So what if you are blue? Oral colloidal silver and argyria are out: safe dressings are in |journal=Adv Skin Wound Care |volume=20 |issue=6 |pages=326–30 |year=2007 |month=June |pmid=17538258 |doi=10.1097/01.ASW.0000276415.91750.0f |url=| quote = Colloidal silver suspensions are solutions of submicroscopic metallic silver particles suspended in a colloid base. These products deliver predominantly inactive metallic silver, not the antimicrobial ionized form.}}</ref> There is no scientific evidence to support the effectiveness of colloidal silver ''[[in vivo]]''.<ref name="nccam"/> Some ''[[in vitro]]'' studies demonstrate an anti-bacterial effect of colloidal silver,<ref>{{cite journal |author=Tien DC, Tseng KH, Liao CY, Tsung TT |title=Colloidal silver fabrication using the spark discharge system and its antimicrobial effect on Staphylococcus aureus |journal=Med Eng Phys |volume=30 |issue=8 |pages=948–52 |year=2008 |month=October |pmid=18069039 |doi=10.1016/j.medengphy.2007.10.007 |url=}}</ref> although a study of a colloidal silver solution marketed on the [[Internet]] showed no such antimicrobial activity.<ref name="hasselt">{{cite journal |author=van Hasselt P, Gashe BA, Ahmad J |title=Colloidal silver as an antimicrobial agent: fact or fiction? |journal=J Wound Care |volume=13 |issue=4 |pages=154–5 |year=2004 |month=April |pmid=15114827 |doi= |url=}}</ref>
The antibacterial action of silver is dependent on the silver ion.<ref name="current-prob">{{cite journal |author=Lansdown AB |title=Silver in health care: antimicrobial effects and safety in use |journal=Curr. Probl. Dermatol. |volume=33 |issue= |pages=17–34 |year=2006 |pmid=16766878 |doi=10.1159/000093928 |url=}}</ref> Colloidal silver preparations primarily deliver inactive metallic silver, rather than the active microbicidal silver ion.<ref name="blue">{{cite journal |author=Okan D, Woo K, Sibbald RG |title=So what if you are blue? Oral colloidal silver and argyria are out: safe dressings are in |journal=Adv Skin Wound Care |volume=20 |issue=6 |pages=326–30 |year=2007 |month=June |pmid=17538258 |doi=10.1097/01.ASW.0000276415.91750.0f |url=| quote = Colloidal silver suspensions are solutions of submicroscopic metallic silver particles suspended in a colloid base. These products deliver predominantly inactive metallic silver, not the antimicrobial ionized form.}}</ref> There is no scientific evidence to support the effectiveness of colloidal silver ''[[in vivo]]''.<ref name="nccam"/> Some ''[[in vitro]]'' studies demonstrate an anti-bacterial effect of colloidal silver,<ref>{{cite journal |author=Tien DC, Tseng KH, Liao CY, Tsung TT |title=Colloidal silver fabrication using the spark discharge system and its antimicrobial effect on Staphylococcus aureus |journal=Med Eng Phys |volume=30 |issue=8 |pages=948–52 |year=2008 |month=October |pmid=18069039 |doi=10.1016/j.medengphy.2007.10.007 |url=}}</ref> although a study of a colloidal silver solution marketed on the [[Internet]] showed no such antimicrobial activity.<ref name="hasselt">{{cite journal |author=van Hasselt P, Gashe BA, Ahmad J |title=Colloidal silver as an antimicrobial agent: fact or fiction? |journal=J Wound Care |volume=13 |issue=4 |pages=154–5 |year=2004 |month=April |pmid=15114827 |doi= |url=}}</ref>


In animals and humans, silver accumulates in the body.<ref name="Fung/Bowen-121">Fung / Bowen 1996: 121.</ref> Chronic intake of silver products, especially colloidal silver, can result in silver or silver sulfide particles in the skin, a condition known as [[argyria]], one symptom of which is blue or gray discoloration of the skin; similarly, it can lead to silver in the eye (argyrosis) and in other organs.<ref name="Lansdown2006">{{cite journal |journal=Curr Probl Dermatol |year=2006 |volume=33 |pages=17–34 |title=Silver in health care: antimicrobial effects and safety in use |author=Lansdown AB |pmid=16766878 }}</ref> The discoloration occurs when silver is deposited in the skin and then darkened by sunlight, just as silver particles in [[photographic film]] darken when exposed to sunlight. Localized argyria can occur as a result of topical use of silver-containing remedies, while generalized argyria results from the ingestion of colloidal silver.<ref name="pmid-16021155">{{cite journal |author=Brandt D, Park B, Hoang M, Jacobe HT |title=Argyria secondary to ingestion of homemade silver solution |journal=J. Am. Acad. Dermatol. |volume=53 |issue=2 Suppl 1 |pages=S105–7 |year=2005 |month=August |pmid=16021155 |doi=10.1016/j.jaad.2004.09.026 |url=}}</ref> Argyria is usually permanent, and there is no known effective treatment;<ref name="pmid-16021155"/> the only practical method of minimizing its cosmetic disfigurement is avoiding the sun.<ref name="blue"/> While argyria is usually benign and limited to skin discoloration, there are isolated reports of more serious neurologic, renal, or hepatic complications.<ref name="pmid-16021155"/><ref>{{cite journal |author=Stepien KM, Morris R, Brown S, Taylor A, Morgan L |title=Unintentional silver intoxication following self-medication: an unusual case of corticobasal degeneration |journal=Ann. Clin. Biochem. |volume= |issue= |pages= |year=2009 |month=September |pmid=19729504 |doi=10.1258/acb.2009.009082 |url=}}</ref> A death has been reported in the medical literature as a result of colloidal silver use; in that case, a 71-year-old man developed [[status epilepticus]] which the authors felt was due to silver toxicity.<ref>{{cite journal |author=Mirsattari SM, Hammond RR, Sharpe MD, Leung FY, Young GB |title=Myoclonic status epilepticus following repeated oral ingestion of colloidal silver |journal=Neurology |volume=62 |issue=8 |pages=1408–10 |year=2004 |month=April |pmid=15111684 |doi= |url=http://www.neurology.org/cgi/pmidlookup?view=long&pmid=15111684}}</ref>
In animals and humans, silver accumulates in the body.<ref name="Fung/Bowen-121">Fung / Bowen 1996: 121.</ref> Chronic intake of silver products, especially colloidal silver, can result in silver or silver sulfide particles in the skin, a condition known as [[argyria]], one symptom of which is blue or gray discoloration of the skin; similarly, it can lead to silver in the eye (argyrosis) and in other organs.<ref>{{cite journal |journal=Curr Probl Dermatol |year=2006 |volume=33 |pages=17–34 |title=Silver in health care: antimicrobial effects and safety in use |author=Lansdown AB |pmid=16766878 }}</ref> The discoloration occurs when silver is deposited in the skin and then darkened by sunlight, just as silver particles in [[photographic film]] darken when exposed to sunlight. Localized argyria can occur as a result of topical use of silver-containing remedies, while generalized argyria results from the ingestion of colloidal silver.<ref name="pmid-16021155">{{cite journal |author=Brandt D, Park B, Hoang M, Jacobe HT |title=Argyria secondary to ingestion of homemade silver solution |journal=J. Am. Acad. Dermatol. |volume=53 |issue=2 Suppl 1 |pages=S105–7 |year=2005 |month=August |pmid=16021155 |doi=10.1016/j.jaad.2004.09.026 |url=}}</ref> Argyria is usually permanent, and there is no known effective treatment;<ref name="pmid-16021155"/> the only practical method of minimizing its cosmetic disfigurement is avoiding the sun.<ref name="blue"/> While argyria is usually benign and limited to skin discoloration, there are isolated reports of more serious neurologic, renal, or hepatic complications.<ref name="pmid-16021155"/><ref>{{cite journal |author=Stepien KM, Morris R, Brown S, Taylor A, Morgan L |title=Unintentional silver intoxication following self-medication: an unusual case of corticobasal degeneration |journal=Ann. Clin. Biochem. |volume= |issue= |pages= |year=2009 |month=September |pmid=19729504 |doi=10.1258/acb.2009.009082 |url=}}</ref> A death has been reported in the medical literature as a result of colloidal silver use; in that case, a 71-year-old man developed [[status epilepticus]] which the authors felt was due to silver toxicity.<ref>{{cite journal |author=Mirsattari SM, Hammond RR, Sharpe MD, Leung FY, Young GB |title=Myoclonic status epilepticus following repeated oral ingestion of colloidal silver |journal=Neurology |volume=62 |issue=8 |pages=1408–10 |year=2004 |month=April |pmid=15111684 |doi= |url=http://www.neurology.org/cgi/pmidlookup?view=long&pmid=15111684}}</ref>

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== Use as germicide and disinfectant ==

In the early 1900s, silver gained regulatory approval as an antimicrobial agent. Prior to the introduction of antibiotics, colloidal silver was used as a germicide and disinfectant.<ref name="Searle-germicide">{{cite book|last=Searle|first=A.B.|title=The Use of Colloids in Health and Disease|publisher=London Constable & Co.|location=Gerstein - University of Toronto : Toronto Collection|date=1920|chapter=Chapter VIII: Germicides and Disinfectants|url=http://www.archive.org/stream/useofcolloidsinh00searuoft#page/70/mode/2up }}</ref> In the 1940s, however, the use of silver as an antimicrobial agent diminished, with the introduction of antibiotics. <ref name="Chopra2007">{{cite journal|last=Chopra|first=Ian |date=February 16, 2007|title=The increasing use of silver-based products as antimicrobial agents: a useful development or a cause for concern?|journal=Journal of Antimicrobial Chemotherapy|issn=doi=10.1093/jac/dkm006 |url=http://jac.oxfordjournals.org/cgi/content/full/dkm006v2|doi=10.1093/jac/dkm006|volume=59|pages=587}}</ref>

===Silver compounds as antiseptics===

Silver compounds continue to be used in external preparations as antiseptics.<ref name="mskcc"/> Among the silver products still available are silver nitrate, which can be used to prevent [[conjunctivitis]] in newborn babies and to treat certain skin conditions, such as corns and warts, as well as silver sulfadiazine for the treatment of burns.<ref name="nccam">{{cite web| publisher = [[National Center for Complementary and Alternative Medicine]] | title = Colloidal Silver Products | url = http://nccam.nih.gov/health/silver/ |date = December 2006 | accessdate = 2008-10-06}}</ref> In the context of marketing claims about colloidal silver (see below), an article from the [[National Center for Complementary and Alternative Medicine]] points out that these drugs can have negative side effects, and, more importantly, that they are applied to the body and not taken internally.<ref name="nccam"/> [[Silver sulfadiazine]] replaced colloidal silver as the most common delivery system for using silver on the surface of burn wounds to control infection in the 1970s.<ref name="Burns2007"/> More recently, dressings incorporating nanocrystalline silver or silver-impregnated substances have become available.<ref name="Burns2007"/> These dressings deliver higher concentrations of the active silver ion, whereas colloidal silver solutions are largely or wholely composed of inactive metallic silver.<ref name="current-prob"/>

Silver compounds can be used in the treatment of "burns, open wounds, and chronic ulcers".<ref name="Burns2007">{{cite journal |author=Atiyeh BS, Costagliola M, Hayek SN, Dibo SA |title=Effect of silver on burn wound infection control and healing: review of the literature |journal=Burns |volume=33 |issue=2 |pages=139–48 |year=2007 |pmid=17137719 |doi=10.1016/j.burns.2006.06.010 }}</ref>

According to Lansdown (2006), the risk expected due to clinical exposure to silver is "minimal".<ref name="Lansdown2006"/> Only chronic ingestion or inhalation of silver preparations leads to an accumulation of silver in the human body and can cause argyria, argyrosis (accumulation of silver in the eye) and other conditions.<ref name="Lansdown2006"/>

=== Use as water disinfectant ===

⚫
Electrolytically dissolved silver has been used as a water disinfecting agent. Silver was added as a disinfectant to the drinking water supplies of Russian [[Mir|Mir orbital station]] and the [[International Space Station]].<ref>{{cite book | publisher = [[U.S. National Academy of Sciences]] | title = Spacecraft Water Exposure Guidelines for Selected Contaminants: Volume 1 | year = 2004 | url = http://books.nap.edu/openbook.php?record_id=10942&page=324 | page = 324}}</ref> The [[World Health Organization]] includes silver in a colloidal state produced by electrolysis of silver electrodes in water, and colloidal silver in water filters as two of a number of water disinfection methods specified to provide safe drinking water in [[developing country|developing countries]].<ref>{{cite web | publisher = [[World Health Organization]] | url = http://whqlibdoc.who.int/paho/2003/a85637.pdf | format = PDF | title = Water Disinfection | first = Felipe | last = Solsona | coauthors = Juan Pablo Mendez | date = 2003}}</ref> Along these lines, a ceramic filtration system coated with silver particles has been created by [[Ron Rivera (public health)|Ron Rivera]] of [[Potters for Peace]] and used in developing countries for water disinfection.<ref name='GuardianObit'>{{cite news | first=Caroline | last=Richmond | coauthors= |authorlink= | title=Ron Rivera: Potter who developed a water filter that saved lives in the third world | date=2008-10-16 | publisher= | url =http://www.guardian.co.uk/science/2008/oct/16/1 | work =The Guardian | pages = | accessdate = 2009-05-16 | language = }}</ref><ref>{{cite news | work = [[New York Times]] | title = Solution in a Pot | url = http://www.nytimes.com/2008/12/28/magazine/28rivera-t.html | first = Sara | last = Corbett | date = December 24, 2008 | accessdate = May 15, 2009}}</ref><ref name=Filtron>{{cite book |author= Committee on Creation of Science-based Industries in Developing Countries, Development, Security, and Cooperation, Policy and Global Affairs, National Research Council of the National Academies, Nigerian Academy of Science.|title=Mobilizing Science-Based Enterprises for Energy, Water, and Medicines in Nigeria |publisher=National Academies Press |location=Washington, D.C |year=2007 |pages=39 |isbn=0-309-11118-8 |oclc= |doi= |accessdate=}}</ref>


==Medical use==
==Medical use==
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=== Historical applications ===
=== Historical applications ===


Silver has had some medicinal uses going back for centuries. Physicians used it as an eyedrop for ophthalmic problems,<ref name="Roe-eye">{{cite journal|last=Roe|first=A. Legge|title=COLLOSOL ARGENTUM AND ITS OPHTHALMIC USES.|journal=British Medical Journal (Br Med J)|volume=Br Med J 1915;1;104|issue=bmj.1.2820.104|pages=104|url=http://www.bmj.com/cgi/reprint/1/2820/104}}</ref> for various infections,<ref>{{cite journal|last=Macleod|first=C.E.Alex |date=February 03, 1912|title=ELECTRIC METALLIC COLLOIDS AND THEIR THERAPEUTICAL APPLICATIONS.|journal=Lancet|volume=179 |issue=4614|pages=322–323|url=http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T1B-49M1Y8H-1P8&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=ee43f1da0ce9b15281b922faa16aa2d6|doi=10.1016/S0140-6736(01)66545-0}}</ref><ref name="Searle-uses">{{cite book|last=Searle|first=A.B.|title=The Use of Colloids in Health and Disease|publisher=London Constable & Co.|location=Gerstein - University of Toronto : Toronto Collection|date=1920|chapter=Chapter IX: Colloidal Remedies and Their Uses|url=http://www.archive.org/stream/useofcolloidsinh00searuoft#page/83/mode/1up }}</ref> and sometimes internally for diseases such as [[tropical sprue]], [[epilepsy]], [[gonorrhea]], and the common cold.<ref name="nccam">{{cite web| publisher = [[National Center for Complementary and Alternative Medicine]] | title = Colloidal Silver Products | url = http://nccam.nih.gov/health/silver/ |date = December 2006 | accessdate = 2008-10-06}}</ref><ref name="mskcc"/><ref name="Cantlie-Sprue">{{cite journal|last=Cantlie|first=James|date=November 15, 1913|title=SOME RECENT OBSERVATIONS ON SPRUE.|journal=British Medical Journal (BMJ)|issue=Br Med J 1913;2;1282-1302|pages=1296–1297|url=http://www.bmj.com/cgi/reprint/2/2759/1282?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=sprue&searchid=1&FIRSTINDEX=0&volume=2&issue=2759&resourcetype=HWCIT}}</ref> In the 1940s, however, the medical use of silver diminished, due to both the development of safe and effective modern antibiotics and concern about argyria and other side effects of silver products.<ref name="Fung/Wadhera2005">Fung / Wadhera 2005</ref><ref name="Fung/Bowen-120">Fung / Bowen 1996: 120.</ref>
Silver has had some medicinal uses going back for centuries. In the early 1900s, silver gained regulatory approval as an antimicrobial agent. Prior to the introduction of antibiotics, colloidal silver was used as a germicide and disinfectant.<ref name="Searle-germicide">{{cite book|last=Searle|first=A.B.|title=The Use of Colloids in Health and Disease|publisher=London Constable & Co.|location=Gerstein - University of Toronto : Toronto Collection|date=1920|chapter=Chapter VIII: Germicides and Disinfectants|url=http://www.archive.org/stream/useofcolloidsinh00searuoft#page/70/mode/2up }}</ref> Physicians used it as an eyedrop for ophthalmic problems,<ref name="Roe-eye">{{cite journal|last=Roe|first=A. Legge|title=COLLOSOL ARGENTUM AND ITS OPHTHALMIC USES.|journal=British Medical Journal (Br Med J)|volume=Br Med J 1915;1;104|issue=bmj.1.2820.104|pages=104|url=http://www.bmj.com/cgi/reprint/1/2820/104}}</ref> for various infections,<ref>{{cite journal|last=Macleod|first=C.E.Alex |date=February 03, 1912|title=ELECTRIC METALLIC COLLOIDS AND THEIR THERAPEUTICAL APPLICATIONS.|journal=Lancet|volume=179 |issue=4614|pages=322–323|url=http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T1B-49M1Y8H-1P8&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=ee43f1da0ce9b15281b922faa16aa2d6|doi=10.1016/S0140-6736(01)66545-0}}</ref><ref name="Searle-uses">{{cite book|last=Searle|first=A.B.|title=The Use of Colloids in Health and Disease|publisher=London Constable & Co.|location=Gerstein - University of Toronto : Toronto Collection|date=1920|chapter=Chapter IX: Colloidal Remedies and Their Uses|url=http://www.archive.org/stream/useofcolloidsinh00searuoft#page/83/mode/1up }}</ref> and sometimes internally for diseases such as [[tropical sprue]], [[epilepsy]], [[gonorrhea]], and the common cold.<ref name="nccam">{{cite web| publisher = [[National Center for Complementary and Alternative Medicine]] | title = Colloidal Silver Products | url = http://nccam.nih.gov/health/silver/ |date = December 2006 | accessdate = 2008-10-06}}</ref><ref name="mskcc"/><ref name="Cantlie-Sprue">{{cite journal|last=Cantlie|first=James|date=November 15, 1913|title=SOME RECENT OBSERVATIONS ON SPRUE.|journal=British Medical Journal (BMJ)|issue=Br Med J 1913;2;1282-1302|pages=1296–1297|url=http://www.bmj.com/cgi/reprint/2/2759/1282?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=sprue&searchid=1&FIRSTINDEX=0&volume=2&issue=2759&resourcetype=HWCIT}}</ref> In the 1940s, however, the medical use of silver diminished, due to both the development of safe and effective modern antibiotics and concern about argyria and other side effects of silver products.<ref name="increase_silver_use">{{cite journal|last=Chopra|first=Ian |date=February 16, 2007|title=The increasing use of silver-based products as antimicrobial agents: a useful development or a cause for concern?|journal=Journal of Antimicrobial Chemotherapy|issn=doi=10.1093/jac/dkm006 |url=http://jac.oxfordjournals.org/cgi/content/full/dkm006v2|doi=10.1093/jac/dkm006|volume=59|pages=587}}</ref><ref name="Fung/Wadhera2005">Fung / Wadhera 2005</ref><ref name="Fung/Bowen-120">Fung / Bowen 1996: 120.</ref>


Considering "direct
The use of colloidal silver preparations (CSP) to treat or prevent "gonorrhea and gonorrheal conjunctivitis due to purported bacteriocidal properties" has largely been replaced "by less toxic antimicrobials with substantiated effectiveness."<ref name="Fung/Bowen-120"/> Considering "direct application to mucous membranes in the nose, throat, urethra, and colon", there is "no evidence that CSP [colloidal silver preparations] are effective at these other sites and toxicity has been reported."<ref name="Fung/Bowen-120"/> Although "silver products were infrequently promoted for oral use, benefits have been even more questionable."<ref name="Fung/Bowen-120"/>
application to mucous membranes in the nose, throat, urethra, and colon", there is "no evidence that CSP [colloidal silver preparations] are effective at these other sites and toxicity has been reported."<ref name="Fung/Bowen-120"/> Although "silver products were infrequently promoted for oral use, benefits have been even more questionable."<ref name="Fung/Bowen-120"/>

A few prescription drugs containing silver are still available.<ref name="nccam">{{cite web| publisher = [[National Center for Complementary and Alternative Medicine]] | title = Colloidal Silver Products | url = http://nccam.nih.gov/health/silver/ |date = December 2006 | accessdate = 2008-10-06}}</ref><ref name="mskcc"/> Before 1960, colloidal silver was the most common delivery system for using silver on the surface of burn wounds to control infection. It was eventually replaced by other technology, including [[silver sulfadiazine]] in the 1970s and, more recently, dressings incorporating nanocrystalline silver or silver-impregnated substances.<ref>{{cite journal |author=Atiyeh BS, Costagliola M, Hayek SN, Dibo SA |title=Effect of silver on burn wound infection control and healing: review of the literature |journal=Burns |volume=33 |issue=2 |pages=139–48 |year=2007 |pmid=17137719 |doi=10.1016/j.burns.2006.06.010 }}</ref> These dressings deliver higher concentrations of the active silver ion, whereas colloidal silver solutions are largely or wholely composed of inactive metallic silver.<ref name="current-prob"/>


=== Current alternative medicine use ===
=== Current alternative medicine use ===
Line 59: Line 44:


In 2002, the [[Australian]] [[Therapeutic Goods Administration]] (TGA) found that there were no legitimate medical uses for colloidal silver and no evidence to support its marketing claims. Given the associated safety risks, the TGA concluded that "efforts should be made to curb the illegal availability of colloidal silver products, which is a significant public health issue."<ref name="Australia">{{cite web|url=http://www.tga.gov.au/docs/html/csilver.htm|title= Regulation of colloidal silver and related products|publisher= Australian [[Therapeutic Goods Administration]]|accessdate=2008-09-22|date=2005-11-09}}</ref></blockquote>
In 2002, the [[Australian]] [[Therapeutic Goods Administration]] (TGA) found that there were no legitimate medical uses for colloidal silver and no evidence to support its marketing claims. Given the associated safety risks, the TGA concluded that "efforts should be made to curb the illegal availability of colloidal silver products, which is a significant public health issue."<ref name="Australia">{{cite web|url=http://www.tga.gov.au/docs/html/csilver.htm|title= Regulation of colloidal silver and related products|publisher= Australian [[Therapeutic Goods Administration]]|accessdate=2008-09-22|date=2005-11-09}}</ref></blockquote>

⚫
== Use as water disinfectant ==

⚫
Electrolytically dissolved silver has been used as a water disinfecting agent. Silver was added as a disinfectant to the drinking water supplies of Russian [[Mir|Mir orbital station]] and the [[International Space Station]].<ref>{{cite book | publisher = [[U.S. National Academy of Sciences]] | title = Spacecraft Water Exposure Guidelines for Selected Contaminants: Volume 1 | year = 2004 | url = http://books.nap.edu/openbook.php?record_id=10942&page=324 | page = 324}}</ref> The [[World Health Organization]] includes silver in a colloidal state produced by electrolysis of silver electrodes in water, and colloidal silver in water filters as two of a number of water disinfection methods specified to provide safe drinking water in [[developing country|developing countries]].<ref>{{cite web | publisher = [[World Health Organization]] | url = http://whqlibdoc.who.int/paho/2003/a85637.pdf | format = PDF | title = Water Disinfection | first = Felipe | last = Solsona | coauthors = Juan Pablo Mendez | date = 2003}}</ref> Along these lines, a ceramic filtration system coated with silver particles has been created by [[Ron Rivera (public health)|Ron Rivera]] of [[Potters for Peace]] and used in developing countries for water disinfection.<ref name='GuardianObit'>{{cite news | first=Caroline | last=Richmond | coauthors= |authorlink= | title=Ron Rivera: Potter who developed a water filter that saved lives in the third world | date=2008-10-16 | publisher= | url =http://www.guardian.co.uk/science/2008/oct/16/1 | work =The Guardian | pages = | accessdate = 2009-05-16 | language = }}</ref><ref>{{cite news | work = [[New York Times]] | title = Solution in a Pot | url = http://www.nytimes.com/2008/12/28/magazine/28rivera-t.html | first = Sara | last = Corbett | date = December 24, 2008 | accessdate = May 15, 2009}}</ref><ref name=Filtron>{{cite book |author= Committee on Creation of Science-based Industries in Developing Countries, Development, Security, and Cooperation, Policy and Global Affairs, National Research Council of the National Academies, Nigerian Academy of Science.|title=Mobilizing Science-Based Enterprises for Energy, Water, and Medicines in Nigeria |publisher=National Academies Press |location=Washington, D.C |year=2007 |pages=39 |isbn=0-309-11118-8 |oclc= |doi= |accessdate=}}</ref>


==Literature==
==Literature==

Revision as of 08:09, 1 November 2009

Part of a series of articles on
Nanomaterials
Carbon nanotubes
Fullerenes
Other nanoparticles
Nanostructured materials

True colloidal silver is a liquid suspension of microscopic particles of silver. A colloid is technically defined as particles which remain suspended without forming an ionic, or dissolved solution.

The commercial alternative medicine product, also referred to as "colloidal silver", includes solutions that contain various concentrations of ionic silver compounds, silver colloids or silver compounds bound to proteins in water. Such products with concentrations of 30 parts per million (ppm) or less are typically manufactured using an electrolysis process, whereas those with higher concentrations of 50 ppm or more are usually silver compounds that have been bound with a protein. These solutions are currently marketed for internal and external use as an alternative medical remedy though there is no scientific evidence to support its effectiveness in vivo.[1]

Excessive ingestion of colloidal silver can result in argyria, a condition in which the skin irreversibly turns blue or grey.

Biological effects of silver

Further information: Silver and Argyria

The antibacterial action of silver is dependent on the silver ion.[2] Colloidal silver preparations primarily deliver inactive metallic silver, rather than the active microbicidal silver ion.[3] There is no scientific evidence to support the effectiveness of colloidal silver in vivo.[1] Some in vitro studies demonstrate an anti-bacterial effect of colloidal silver,[4] although a study of a colloidal silver solution marketed on the Internet showed no such antimicrobial activity.[5]

In animals and humans, silver accumulates in the body.[6] Chronic intake of silver products, especially colloidal silver, can result in silver or silver sulfide particles in the skin, a condition known as argyria, one symptom of which is blue or gray discoloration of the skin; similarly, it can lead to silver in the eye (argyrosis) and in other organs.[7] The discoloration occurs when silver is deposited in the skin and then darkened by sunlight, just as silver particles in photographic film darken when exposed to sunlight. Localized argyria can occur as a result of topical use of silver-containing remedies, while generalized argyria results from the ingestion of colloidal silver.[8] Argyria is usually permanent, and there is no known effective treatment;[8] the only practical method of minimizing its cosmetic disfigurement is avoiding the sun.[3] While argyria is usually benign and limited to skin discoloration, there are isolated reports of more serious neurologic, renal, or hepatic complications.[8][9] A death has been reported in the medical literature as a result of colloidal silver use; in that case, a 71-year-old man developed status epilepticus which the authors felt was due to silver toxicity.[10]

Medical use

Historical applications

Silver has had some medicinal uses going back for centuries. In the early 1900s, silver gained regulatory approval as an antimicrobial agent. Prior to the introduction of antibiotics, colloidal silver was used as a germicide and disinfectant.[11] Physicians used it as an eyedrop for ophthalmic problems,[12] for various infections,[13][14] and sometimes internally for diseases such as tropical sprue, epilepsy, gonorrhea, and the common cold.[1][15][16] In the 1940s, however, the medical use of silver diminished, due to both the development of safe and effective modern antibiotics and concern about argyria and other side effects of silver products.[17][18][19]

Considering "direct application to mucous membranes in the nose, throat, urethra, and colon", there is "no evidence that CSP [colloidal silver preparations] are effective at these other sites and toxicity has been reported."[19] Although "silver products were infrequently promoted for oral use, benefits have been even more questionable."[19]

A few prescription drugs containing silver are still available.[1][15] Before 1960, colloidal silver was the most common delivery system for using silver on the surface of burn wounds to control infection. It was eventually replaced by other technology, including silver sulfadiazine in the 1970s and, more recently, dressings incorporating nanocrystalline silver or silver-impregnated substances.[20] These dressings deliver higher concentrations of the active silver ion, whereas colloidal silver solutions are largely or wholely composed of inactive metallic silver.[2]

Current alternative medicine use

From approximately 1990 there has been a resurgence of the promotion of colloidal silver as an alternative medicine treatment, marketed with claims of it being an essential mineral supplements or that it can prevent or treat numerous diseases like cancer, diabetes, HIV/AIDS, and herpes, [21] as well as tuberculosis.[1] Although colloidal silver products are legally available at health food stores in the United States and Australia and are marketed over the Internet as a dietary supplement, it is illegal in the U.S. and Australia for marketers to make such claims of medical effectiveness for colloidal silver. There is no medical evidence that colloidal silver is effective for any of these claimed indications.[22][23] Silver is not an essential mineral in humans; there is no dietary requirement for silver, and no such thing as a silver "deficiency".[1]

Currently, there are no evidence-based medical uses for ingested colloidal silver. There are no clinical studies in humans demonstrating effectiveness, and a few reports of toxicity.[15] The U.S. National Center for Complementary and Alternative Medicine has issued an advisory indicating that the marketing claims made about colloidal silver are scientifically unsupported, and that the silver content of marketed supplements varies widely and can pose risks to the consumer.[1]

A number of case reports describe argyria after ingestion of colloidal silver marketed as an alternative-medicine treatment.[18][8][3][24] Colloidal silver may theoretically reduce the absorption of some medications, including tetracycline and quinolone antibiotics and penicillamine, thereby reducing the effectiveness of those medications.[15]

Government regulation

In August 1999, the U.S. Food and Drug Administration (FDA) banned colloidal silver sellers from claiming any therapeutic or preventive value for the product, noting that colloidal silver was being marketed for numerous diseases without evidence of safety or effectiveness.[23] The product now has the status of a dietary supplement in the US; it can be promoted with general "structure-function" claims, but cannot be marketed as preventing or treating any illness.[23] Following this ruling, the FDA has issued numerous warnings to Internet sites which have continued to promote colloidal silver as an antibiotic or for other medical purposes.[25][26]

In 2002, the Australian Therapeutic Goods Administration (TGA) found that there were no legitimate medical uses for colloidal silver and no evidence to support its marketing claims. Given the associated safety risks, the TGA concluded that "efforts should be made to curb the illegal availability of colloidal silver products, which is a significant public health issue."[27]

Use as water disinfectant

Electrolytically dissolved silver has been used as a water disinfecting agent. Silver was added as a disinfectant to the drinking water supplies of Russian Mir orbital station and the International Space Station.[28] The World Health Organization includes silver in a colloidal state produced by electrolysis of silver electrodes in water, and colloidal silver in water filters as two of a number of water disinfection methods specified to provide safe drinking water in developing countries.[29] Along these lines, a ceramic filtration system coated with silver particles has been created by Ron Rivera of Potters for Peace and used in developing countries for water disinfection.[30][31][32]

Literature

  • Fung MC, Bowen DL (1996). "Silver products for medical indications: risk-benefit assessment". J. Toxicol. Clin. Toxicol. 34 (1): 119–26. doi:10.3109/15563659609020246. PMID 8632503.
  • Wadhera A, Fung M (2005). "Systemic argyria associated with ingestion of colloidal silver". Dermatol. Online J. 11 (1): 12. PMID 15748553.

References

  1. ^ a b c d e f g "Colloidal Silver Products". National Center for Complementary and Alternative Medicine. December 2006. Retrieved 2008-10-06.
  2. ^ a b Lansdown AB (2006). "Silver in health care: antimicrobial effects and safety in use". Curr. Probl. Dermatol. 33: 17–34. doi:10.1159/000093928. PMID 16766878.
  3. ^ a b c Okan D, Woo K, Sibbald RG (2007). "So what if you are blue? Oral colloidal silver and argyria are out: safe dressings are in". Adv Skin Wound Care. 20 (6): 326–30. doi:10.1097/01.ASW.0000276415.91750.0f. PMID 17538258. Colloidal silver suspensions are solutions of submicroscopic metallic silver particles suspended in a colloid base. These products deliver predominantly inactive metallic silver, not the antimicrobial ionized form. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  4. ^ Tien DC, Tseng KH, Liao CY, Tsung TT (2008). "Colloidal silver fabrication using the spark discharge system and its antimicrobial effect on Staphylococcus aureus". Med Eng Phys. 30 (8): 948–52. doi:10.1016/j.medengphy.2007.10.007. PMID 18069039. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  5. ^ van Hasselt P, Gashe BA, Ahmad J (2004). "Colloidal silver as an antimicrobial agent: fact or fiction?". J Wound Care. 13 (4): 154–5. PMID 15114827. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  6. ^ Fung / Bowen 1996: 121.
  7. ^ Lansdown AB (2006). "Silver in health care: antimicrobial effects and safety in use". Curr Probl Dermatol. 33: 17–34. PMID 16766878.
  8. ^ a b c d Brandt D, Park B, Hoang M, Jacobe HT (2005). "Argyria secondary to ingestion of homemade silver solution". J. Am. Acad. Dermatol. 53 (2 Suppl 1): S105–7. doi:10.1016/j.jaad.2004.09.026. PMID 16021155. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  9. ^ Stepien KM, Morris R, Brown S, Taylor A, Morgan L (2009). "Unintentional silver intoxication following self-medication: an unusual case of corticobasal degeneration". Ann. Clin. Biochem. doi:10.1258/acb.2009.009082. PMID 19729504. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  10. ^ Mirsattari SM, Hammond RR, Sharpe MD, Leung FY, Young GB (2004). "Myoclonic status epilepticus following repeated oral ingestion of colloidal silver". Neurology. 62 (8): 1408–10. PMID 15111684. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  11. ^ Searle, A.B. (1920). "Chapter VIII: Germicides and Disinfectants". The Use of Colloids in Health and Disease. Gerstein - University of Toronto : Toronto Collection: London Constable & Co.
  12. ^ Roe, A. Legge. "COLLOSOL ARGENTUM AND ITS OPHTHALMIC USES". British Medical Journal (Br Med J). Br Med J 1915, 1, 104 (bmj.1.2820.104): 104.
  13. ^ Macleod, C.E.Alex (February 03, 1912). "ELECTRIC METALLIC COLLOIDS AND THEIR THERAPEUTICAL APPLICATIONS". Lancet. 179 (4614): 322–323. doi:10.1016/S0140-6736(01)66545-0. {{cite journal}}: Check date values in: |date= (help)
  14. ^ Searle, A.B. (1920). "Chapter IX: Colloidal Remedies and Their Uses". The Use of Colloids in Health and Disease. Gerstein - University of Toronto : Toronto Collection: London Constable & Co.
  15. ^ a b c d "About Herbs: Colloidal Silver". Memorial Sloan-Kettering Cancer Center. 2008-07-25. Retrieved 2008-10-03.
  16. ^ Cantlie, James (November 15, 1913). "SOME RECENT OBSERVATIONS ON SPRUE". British Medical Journal (BMJ) (Br Med J 1913, 2, 1282–1302): 1296–1297.
  17. ^ Chopra, Ian (February 16, 2007). "The increasing use of silver-based products as antimicrobial agents: a useful development or a cause for concern?". Journal of Antimicrobial Chemotherapy. 59: 587. doi:10.1093/jac/dkm006. ISSN doi=10.1093/jac/dkm006. {{cite journal}}: Check |issn= value (help); Missing pipe in: |issn= (help)
  18. ^ a b Fung / Wadhera 2005
  19. ^ a b c Fung / Bowen 1996: 120.
  20. ^ Atiyeh BS, Costagliola M, Hayek SN, Dibo SA (2007). "Effect of silver on burn wound infection control and healing: review of the literature". Burns. 33 (2): 139–48. doi:10.1016/j.burns.2006.06.010. PMID 17137719.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  21. ^ Fung / Bowen 1996: 121; They cite "Health Fraud Bulletin #19" as well as promotional materials from manufacturers of products and refer to written communication from February 1995.
  22. ^ Newman M, Kolecki P (2001). "Argyria in the ED". Am J Emerg Med. 19 (6): 525–6. doi:10.1053/ajem.2001.25773. PMID 11593479. {{cite journal}}: Unknown parameter |month= ignored (help)
  23. ^ a b c "Over-the-counter drug products containing colloidal silver ingredients or silver salts. Department of Health and Human Services (HHS), Public Health Service (PHS), Food and Drug Administration (FDA). Final rule". Fed Regist. 64 (158): 44653–8. 1999. PMID 10558603. {{cite journal}}: Unknown parameter |month= ignored (help)
  24. ^ Case reports of argyria related to colloidal silver products include:
  25. ^ "Colloidal Silver Not Approved". U.S. Food and Drug Administration. 2007-02-12. Retrieved 2008-09-22.
  26. ^ "FDA Warning Letter" (PDF). U.S. Food and Drug Administration. 2001-03-13. Retrieved 2008-09-22.
  27. ^ "Regulation of colloidal silver and related products". Australian Therapeutic Goods Administration. 2005-11-09. Retrieved 2008-09-22.
  28. ^ Spacecraft Water Exposure Guidelines for Selected Contaminants: Volume 1. U.S. National Academy of Sciences. 2004. p. 324.
  29. ^ Solsona, Felipe (2003). "Water Disinfection" (PDF). World Health Organization. {{cite web}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  30. ^ Richmond, Caroline (2008-10-16). "Ron Rivera: Potter who developed a water filter that saved lives in the third world". The Guardian. Retrieved 2009-05-16. {{cite news}}: Cite has empty unknown parameter: |coauthors= (help)
  31. ^ Corbett, Sara (December 24, 2008). "Solution in a Pot". New York Times. Retrieved May 15, 2009.
  32. ^ Committee on Creation of Science-based Industries in Developing Countries, Development, Security, and Cooperation, Policy and Global Affairs, National Research Council of the National Academies, Nigerian Academy of Science. (2007). Mobilizing Science-Based Enterprises for Energy, Water, and Medicines in Nigeria. Washington, D.C: National Academies Press. p. 39. ISBN 0-309-11118-8. {{cite book}}: |author= has generic name (help)CS1 maint: multiple names: authors list (link)

See also

External links

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