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Colloidal Silver Consumer Products: Characterization and Cytotoxicity
Citation:
Rogers, K., T. Henson, J. Navratilova, M. Hughes, K. Bradham, A. Stefaniak, A. Knepp, AND L. Bowers. Colloidal Silver Consumer Products: Characterization and Cytotoxicity. 2019 American Chemical Society Fall Meeting, San Diego, CA, August 25 - 29, 2019.
Impact/Purpose:
One of the purposes for this presentation is to summarize ORD's framework for evaluation of nanoparticles across realistic environmental or biological systems. Consideration of environmental and biological compartments with associated parameters such as transfer rates, affinity coefficients, dissolution rates and other relevant parameters where applicable, will benefit the long-term ability to construct and evaluate quantitative, predictive modeling of both nanomaterial exposures and effects across product life cycles. Another purpose is to showcase some of the Agency's nanomaterials research under CSS.
Description:
Due to their anti-microbial properties, silver nanoparticles (AgNPs) are one of the most significant contributors to nanoparticle-enabled consumer products. Since colloidal silver products such as dietary supplements and spray disinfectants are intended for ingestion or direct contact, they show a high potential for exposure during product use. Consequently, we characterized silver-containing nanoparticles in 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. 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 the product suspensions by transmission electron microscopy (TEM)/energy dispersive X-ray spectroscopy (EDS). Since many of these products are meant for ingestion we also assessed the cytotoxicity of these consumer products in a rat intestinal epithelial cell (IEC-6) model. Silver nitrate showed an EC50 value of about 1µg/mL and PVP-stabilized silver nanoparticles (75 nm) showed an EC50 value of 250 µg/mL. Cytotoxic cell responses among the tested consumer products were attributable to soluble Ag, particulate Ag or the non-Ag product matrix components.
