Given the potential for human exposure to silver nanoparticles from spray disinfectants and dietary supplements, we characterized 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 with concentrations ranging from 0.54 mg/L to 960 mg/L. Although only 7 of the products showed total silver concentrations within 20% of their nominally reported values, silver containing nanoparticles were identified in all the product suspensions by transmission electron microscopy (TEM). Since many of these products are meant for ingestion, we simulated gastrointestinal exposure in selected products to determine bioaccessibility parameters such as particle aggregation, dissolution and chemical transformation. Incubation of products 4, 6, and 10 in apple juice, vinegar and synthetic stomach fluid (SSF) resulted in an increase in hydrodynamic diameter of silver nanoparticles (AgNPs) as measured by dynamic light scattering (DLS) and nanoparticle tracking analysis (NTA). Exposure of these products to SSF also resulted in the formation of AgCl determined by X-ray absorption spectroscopy (XAS) and TEM-energy dispersive X-ray spectroscopy (EDS). For the products tested in the simulated GI system, AgNP aggregation and formation of low solubility AgCl would suggest a decrease in bioaccessibility from the original formulations.

Characterization of the bioaccessibility of nanoparticles in consumer products advertised to contain colloidal silver

2019 Fall National Meeting

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