Silver Nanoparticle Safety
Silver (0.001–0.1% weight/weight, based on 0.01–1 mg/mL concentration) Silver materials are currently used as main ingredients in several FDA-cleared and marketed skin products due to their unique antimicrobial properties and widely accepted skin safety profiles.1 The safety of silver as established by these products is noteworthy. Specifically, since 1989, at least 27 silver-based wound dressings, bandages, mesh foams, gels, and creams have been deemed safe and biocompatible and approved for use in human skin.2 Silver is also found in a wide array of FDA-approved implantable devices that include stents, defibrillators, pacemakers, catheters, IV infusion components, and needles.2
The safe use of silver materials including silver nanoparticles in skin formulations is widely reported in the literature. No adverse skin reactions were uncovered after 2 weeks of using silver-containing dressings to reduce catheter infections, nor in the 5-year subject follow up.3 Similarly, no tolerance issues were found in a randomized control trial comparing the biocompatibility of silver- and non-silver-based wound dressings for treating chronic and acute wounds over 2 weeks.4 One clinical study evaluated the silver absorption from silver-containing wound dressings for potential systemic effects in subjects. Despite covering up to 53% of the total body area for up to 19 days and measuring detectable levels of silver in the serum, clinical researchers saw no adverse skin effects, no changes in biochemical activity (including liver and renal function), and no hematological toxicity (including hemoglobin levels, platelet counts, and eosinophil counts).5 Notably, silver nanoparticles show promise as antimicrobial preservatives in cosmetics, as they have been shown to be effective at inhibiting microorganism growth, and are also highly stable, non-cytotoxic to human skin cells, and incapable of penetrating human skin.6
The literature further reports the safety of silver-coated implantable devices. Specifically, long-term rabbit models have been used to show that silver-coated polyurethane catheters are minimally inflammatory and comparable to uncoated controls.7 Clinical trials confirm these findings: for example, the implantation of silver-coated heart valve prostheses revealed no difference in the rate of complication compared to subjects with uncoated prostheses.8
The concentration of silver as provided by nanoComposix is typically much lower than the concentrations and nanoparticle forms of silver in cleared devices on the market today (Table 1).
Table 1: Comparison of silver (Ag+) in currently marketed products
|nanoComposix 0.01–1 mg/mL||Silver Nitrate 0.5% solution||Silver Sulfadiazine 1% cream||Silver Delivery (ACTICOAT)|
|Silver concentration||0.001–0.1% wt/wt||0.3% wt/wt||0.3% wt/wt||13% wt/wt|
- Nowack, B.; Krug, H. F.; Height, M. "120 Years of Nanosilver History: Implications for Policy Makers" Environ. Sci. Technol. 2011 PMID:21218770.
- accessdata.fda.gov accessed 10/3/2011
- Hill, M. L.; Baldwin, L; Slaughter, J. C.; Walsh, W. F.; Weitkamp, J. H. "Silver-alginate-coated dressing to reduce peripherally inserted central catheter (PICC) infections in NICU patients: a pilot randomized controlled trial" J. Perinatol 2010, 30, 469-473 PMID:20010613.
- Trial, C.; Darbas, H.; Lavigne, J. P.; Sotto, A.; Simoneau, G.; Tillet, Y.; Teot, L.; "Assessment of the antimicrobial effectiveness of a new silver alginate wound dressing: a RCT" J. Wound Care 2010, 19, 20-26 PMID:20081570.
- Vlachou, E.; Chipp, E.; Shale, E.; Wilson, Y. T.; Papini, R.; Moiemen, N. S. "The safety of nanocrystalline silver dressings on burns: a study of systemic silver absorption" Burns 2007, 33, 979-985 PMID:17959313.
- Kokura, S.; Handa, O.; Takagi, T.; Ishikawa, T.; Naito, Y.; Yoshikawa, T. "Silver nanoparticles as a safe preservative for use in cosmetics" Nanomedicine 2010, 6, 570-574 PMID:20060498.
- Oloffs, A; Grosse-Siestrup, C.; Bisson, S.; Rinck, M.; Rudolph, R.; Gross, U. "Biocompatibility of silver-coated polyurethane catheters and silver-coated Dacron material" Biomaterials 1994, 15, 753-758 PMID:7986938.
- Auer, J.; Berent, R.; Ng, C. K.; Punzengruber, C.; Mayr, H.; Lassnig, E.; Schwarz, C.; Puschmann, R.; Hartl, P.; Eber, B. "Early investigation of silver-coated Silzone heart valves prosthesis in 126 patients" J. Heart Valve Dis. 2001, 10, 717-723 PMID:11767176.