Special epidemiological studies on silver nanoparticles are not available so far. However, analysis of various consumer products show a possible release of nano silver from the products, depending on the application and on the designed use of silver nanoparticles in the final product.

 

Regardless of the particle size permanent exposure to silver can cause diseases, where high doses of silver are taken in and deposited in the body. Symptoms of the so-called argyria include irreversible staining of the skin and mucous membranes, whereas in case of argyrosis the silver deposits are locally confined. In Germany the occupational limit values for the handling of powdered substances are also applicable for silver nanoparticles and should not exceed a value of 0.01 mg/m³ for inhalable silver compounds.[13,4]

Mandatory Nano labelling in cosmetics, biocides and food

 

Looking at many consumer products it is not always clear whether silver is actually added in the nano form for functional or for promotional purposes only. To create more transparency for the consumers the EU has put into place mandatory labelling for nano-containing products in the cosmetics and biocides sector since July 2013 and for food since December 2014. The normal calculated dietary intake of silver is approximately 70-90 mg per day.[1,14]

 

Can textiles release nanoparticles? © Von Goetz, N et al. (2013)Can textiles release nanoparticles? © Von Goetz, N et al. (2013)

In Germany nano silver is not approved for use as a food supplement and considered a pharmaceutical product (colloidal silver) subjected to the regulations of the German Medicinal Products Act. Dietary supplements containing nanoscale heavy metals such as silver, gold, platinum, palladium, and iridium, however are already sold internationally on the internet and are therefore also available to German buyers.[10]

Commercially available products with integrated silver nanoparticles, such as performance sportswear, food packaging and various children's products have been shown to release silver ions and silver nanoparticles. Studies in which the wearing of silver nanoparticles containing sportswear was simulated in the laboratory have shown that both silver ions and silver nanoparticles are being released into artificial sweat. This would correspond to a worst case scenario of a non-negligible maximum exposure of the skin with 8.2 - 17.1 micrograms of silver per kg of body weight.[8]

 

Food packaging with vegetable content. © PhotoSG / fotolia.de

The same is also true for food packaging materials, but in this case the amounts found were far below the natural silver-load of humans. Nevertheless, in March 2014 the US Environmental Protection Agency (EPA) has banned the sale of the plastic containers investigated in this study.[9,2]

Analysis of (nano) silver containing consumer products for children. © Quadros M.E. et al. (2013)Analysis of (nano) silver containing consumer products for children. © Quadros M.E. et al. (2013)

In another study, various children's products including toys, clothes and wipes were tested on a possible release of nano silver or silver ions. Here the silver nanoparticles were firmly embedded in the product, so that only very small amounts of silver ions could be detected in artificial sweat or urine.[7]

 

Investigations of spray products that, according to the product description, contain silver nanoparticles only detected the silver in the form of silver chloride and silver agglomerates, but not in the nano form. However, the calculated exposure levels with silver for a worst case scenario were still below the WHO (World Health Organization) defined daily limit of 5 micrograms of silver per kg body weight.[6]

First human studies with commercially available silver nanoparticle products, e.g. in textiles, sprays or nano silver suspensions for oral intake, showed no negative health effects of the studied subjects. Nevertheless examining the products for longer periods as well as a possible chronic exposure to silver nanoparticles are necessary steps for a comprehensive assessment of consumer products containing silver nanoparticles.[5,6,3,11]

 

Taken together, it is not possible to make a general statement on the potential dangers of silver nanoparticle containing consumer products. Important clues are provided from the processing and integration of silver nanoparticles into the respective product.

 

Literature arrow down

  1. Boehmert, L et al. (2014). Nanotoxicology, 8(6): 631-642.
  2. Cushen, M et al. (2013). Food Chem, 139(1-4): 389-397.
  3. Hoefer, D et al. (2011). ISRN Dermatol, 2011 369603.
  4. Lee, JH et al. (2012). J Nanopart Res, 14(9): 1-10.
  5. Munger M.A. et al. (2014). Nanomedicine, 10(1): 1-9.
  6. Quadros, ME et al. (2011). Environ Sci Technol, 45(24): 10713-10719.
  7. Quadros, ME et al. (2013). Environ Sci Technol, 47(15): 8894-8901.
  8. Von Goetz, N et al. (2013). Environ Sci Technol, 47(17): 9979-9987.
  9. Von Goetz, N et al. (2013). Food Addit Contam Part A Chem Anal Control Expo Risk Assess, 30(3): 612-620.
  10. Arzneimittelgesetz (AMG) (2005). Gesetz über den Verkehr mit Arzneimitteln, gesetze-im-internet.de (Last access date: Dec 2014)
  11. Hadrup, N et al. (2014). Regul Toxicol Pharmacol, 68(1): 1-7.
  12. Richtlinie 94/36/EG des Europäischen Parlaments und des Rates vom 30. Juni 1994 über Farbstoffe, die in Lebensmitteln verwendet werden dürfen. (PDF-Dokument)
  13. SCENIHR (2014). EC-Report: Opinion on Nanosilver: safety, health and environmental effects and role in antimicrobial resistance.(PDF-Dokument)
  14. Wijnhoven, SWP et al. (2009), Nanotoxicology, 3(2): 109-U178.
  15. Moeller, M et al (2009). Nanotechnologie im Bereich der Lebensmittel, TA Swiss, vdf Hoschschulverlag AG, Zürich. ISBN 978-3-7281-3234-5.

 

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