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Characterization of engineered nanoparticles in commercially available spray disinfectant products advertised to contain colloidal silver
Citation:
Rogers, K., J. Navratilova, A. Stefaniak, L. Bowers, A. Knepp, S. Al-Abed, P. Potter, A. Gitipour, I. Radwan, C. Nelson, AND K. Bradham. Characterization of engineered nanoparticles in commercially available spray disinfectant products advertised to contain colloidal silver. SCIENCE OF THE TOTAL ENVIRONMENT. Elsevier BV, AMSTERDAM, Netherlands, 619620:1375-1384, (2018).
Impact/Purpose:
Due to their unique characteristics and capabilities, metal-containing nanoparticles are increasingly incorporated into a wide range of consumer products. Data bases that track nanomaterial-containing products such as the Project on Emerging Nanomaterials (PEN)-Nanotechnology Consumer Inventory Products (CPI) and Nanodatabase currently contain over 450 silver nanoparticle (AgNP)-enabled consumer products (Vance et al., 2015; Hansen et al., 2016). AgNP-enabled products include fabrics (socks, athletic and mountaineering clothing, and children’s clothing), plastics (food containers, child cups and articles that may come into contact with multiple users), personal care products (shampoos, lotions, and toothpaste) spray disinfectants, and dietary supplements (advertised as immune boosters, and anti-infection agents) (Wasukan et al., 2015; Quadros et al., 2013; Tulve et al., 2015). Primarily due to their anti-microbial properties, AgNPs are one of the most significant contributors to the nanoparticle-enabled products and in particular the personal care products. This is significant because the personal care products area is one of the fastest growing market segments for nanomaterial-enabled products (Reed et al., 2014).
Description:
Given the potential for human exposure to silver nanoparticles from spray disinfectants and dietary supplements, we characterized the silver-containing nanoparticles in 22 commercial products that advertised the use of silver or colloidal silver as the active ingredient. Characterization parameters included: total silver, fractionated silver (particulate and dissolved), primary particle size distribution, hydrodynamic diameter, particle number, and plasmon resonance absorbance. A high degree of variability between claimed and measured values for total silver was observed. Only 7 of the products showed total silver concentrations within 20% of their nominally reported values. In addition, significant variations in the relative percentages of particulate vs. soluble silver were also measured in many of these products reporting to be colloidal. Primary silver particle size distributions by transmission electron microscopy (TEM) showed two populations of particles - smaller particles (< 5 nm) and larger particles between 20 and 40 nm. Hydrodynamic diameter measurements using nanoparticle tracking analysis (NTA) correlated well with TEM analysis for the larger particles. Z-average (Z-Avg) values measured using dynamic light scattering (DLS); however, were typically larger than both NTA or TEM particle diameters. Plasmon resonance absorbance signatures (peak absorbance at around 400 nm indicative of metallic silver nanoparticles) were only noted in 4 of the 9 yellow-brown colored suspensions. Although the total silver concentrations were variable among products, ranging from 0.54 mg/L to 960 mg/L, silver containing nanoparticles were identified in all of the product suspensions by TEM.
