Colloidal silver

From Wikipedia, the free encyclopedia

Jump to: navigation, search

Part of a series of articles on
Nanomaterials

Fullerenes
Carbon nanotubes
Fullerene chemistry
Applications
In popular culture
Timeline
Carbon allotropes

Nanoparticles
Quantum dots
Nanostructures
Colloidal gold
Colloidal silver
Iron nanoparticles
Platinum nanoparticles

See also
Nanotechnology
This box: view • talk • edit

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 broader commercial definition of "colloidal silver" includes products that contain various concentrations of ionic silver, silver colloids, ionic silver compounds or silver proteins in purified water. Colloidal silver with concentrations of 30 parts per million (ppm) or less are typically manufactured using an electrolysis process, whereas colloidal silver with higher concentrations of 50 ppm or more are usually silver compounds that have been bound with a protein.

Currently, colloidal silver is marketed for internal use as an alternative medical remedy, though there is no scientific evidence of its effectiveness for any medical condition.[1][2] Excessive use can result in argyria, a form of silver toxicity.

Contents

[edit] History and applications

Prior to 1938, colloidal silver was widely promoted as a "cure-all", and silver products were prescribed by physicians as topical antibiotics.[3] However, with the development of more effective, less expensive antibiotics such as penicillin and sulfanilamide, medical use of colloidal silver ceased.[2] From approximately 1990, there has been a resurgence of the promotion of colloidal silver as an alternative medicine treatment, marketed with claims that it can prevent or treat numerous diseases.[4] In vitro evidence of an antimicrobial effect of colloidal silver is mixed; some studies have found it to lack any antibacterial effect,[5] while others have reported an effect attributed to silver ions which coexist in the colloid.[6] There is no evidence that any preparation of colloidal silver is effective in vivo.[2]

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 claims of medical effectiveness for colloidal silver, but some websites still list its use for the prevention of colds and flu, and the treatment of more serious conditions such as diabetes, cancer, chronic fatigue syndrome, HIV/AIDS, and tuberculosis, among other diseases.[7][8] There is no medical evidence that colloidal silver is effective for any of these claimed indications.[3][9] Silver is not an essential mineral in humans; there is no dietary requirement for silver, and no such thing as a silver "deficiency".[2]

Electrolytically dissolved silver was added as a disinfectant to the drinking water supplies of Russian Mir space missions and the International Space Station. [10]

Currently, there are no evidence-based medical uses for colloidal silver.[1] There are no clinical studies in humans demonstrating effectiveness, and several reports of toxicity.[11] 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.[2]

[edit] Toxicities and interactions

Main article: Argyria

Excessive intake of silver products may result in a condition known as argyria, one symptom of which is blue or gray discoloration of the skin.[12] 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.[13] Argyria is usually permanent, and there is no known effective treatment.[13] While argyria is usually benign and limited to skin discoloration, there are isolated reports of more serious neurologic, renal, or hepatic complications. 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.[13][14]

A number of case reports describe argyria after ingestion of colloidal silver marketed as an alternative-medicine treatment.[15] Colloidal silver may theoretically interact with some medications, including tetracycline and quinolone antibiotics and penicillamine, reducing the effectiveness of those medications.[11]

[edit] Government regulation

In August 1999, the U.S. Food and Drug Administration (FDA) banned colloidal silver sellers from claiming any therapeutic value for the product, noting that such products were being marketed for numerous diseases without evidence of effectiveness.[9] The FDA also banned over-the-counter sale of drug products containing colloidal silver due to the lack of safety or efficacy data. 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.[9] 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.[16][17]

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."[18]

[edit] See also

[edit] References

  1. ^ a b "Complementary/Integrative Medicine Therapies: Colloidal Silver". M. D. Anderson Cancer Center. February 2008. http://www.mdanderson.org/departments/cimer/display.cfm?id=ca255d3c-2ca8-46ed-a19011aa9f45cd23&method=displayfull&pn=5ac57a83-0f8d-4a3f-b743a0cdf23f193c. Retrieved on 2008-10-03. 
  2. ^ a b c d e "Colloidal Silver Products". National Center for Complementary and Alternative Medicine. December 2006. http://nccam.nih.gov/health/silver/. Retrieved on 2008-10-06. 
  3. ^ a b Newman M, Kolecki P (October 2001). "Argyria in the ED". Am J Emerg Med 19 (6): 525–6. doi:10.1053/ajem.2001.25773. PMID 11593479. 
  4. ^ Fung MC, Bowen DL (1996). "Silver products for medical indications: risk-benefit assessment". J. Toxicol. Clin. Toxicol. 34 (1): 119–26. PMID 8632503. 
  5. ^ van Hasselt P, Gashe BA, Ahmad J (April 2004). "Colloidal silver as an antimicrobial agent: fact or fiction?". J Wound Care 13 (4): 154–5. PMID 15114827. 
  6. ^ Tien DC, Tseng KH, Liao CY, Tsung TT (October 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. 
  7. ^ Fung MC, Weintraub M, Bowen DL (October 1995). "Colloidal silver proteins marketed as health supplements". JAMA 274 (15): 1196–7. PMID 7563503. 
  8. ^ Wadhera A, Fung M (2005). "Systemic argyria associated with ingestion of colloidal silver". Dermatol. Online J. 11 (1): 12. PMID 15748553. http://dermatology.cdlib.org/111/case_reports/argyria/wadhera.html. 
  9. ^ 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. August 1999. PMID 10558603. 
  10. ^ Spacecraft Water Exposure Guidelines for Selected Contaminants: Volume 1 (2004) Appendix 9. http://books.nap.edu/openbook.php?record_id=10942&page=324
  11. ^ a b "About Herbs: Colloidal Silver". Memorial Sloan-Kettering Cancer Center. 2008-07-25. http://www.mskcc.org/mskcc/html/69189.cfm. Retrieved on 2008-10-03. 
  12. ^ Baker CD, Federico MJ, Accurso FJ (December 2007). "Case report: skin discoloration following administration of colloidal silver in cystic fibrosis". Curr. Opin. Pediatr. 19 (6): 733–5. doi:10.1097/MOP.0b013e3282f11fee. PMID 18025945. 
  13. ^ a b c Brandt D, Park B, Hoang M, Jacobe HT (August 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. 
  14. ^ Mirsattari SM, Hammond RR, Sharpe MD, Leung FY, Young GB (April 2004). "Myoclonic status epilepticus following repeated oral ingestion of colloidal silver". Neurology 62 (8): 1408–10. PMID 15111684. http://www.neurology.org/cgi/pmidlookup?view=long&pmid=15111684. 
  15. ^ Case reports of argyria related to colloidal silver products include:
  16. ^ "Colloidal Silver Not Approved". U.S. Food and Drug Administration. 2007-02-12. http://www.fda.gov/cvm/CVM_Updates/silver.html. Retrieved on 2008-09-22. 
  17. ^ "FDA Warning Letter". U.S. Food and Drug Administration. 2001-03-13. http://www.fda.gov/cder/warn/cyber/2001/Cyber097.pdf. Retrieved on 2008-09-22. 
  18. ^ "Regulation of colloidal silver and related products". Australian Therapeutic Goods Administration. 2005-11-09. http://www.tga.gov.au/docs/html/csilver.htm. Retrieved on 2008-09-22. 

[edit] External links

Retrieved from "http://en.wikipedia.org/wiki/Colloidal_silver"
Personal tools