Characterization of Airborne Particle Release from Nanotechnology-enabled Clothing Products

Application of silver-based biocides in face masks intended for general use requires regulatory control

Silver-based biocides are applied in face masks because of their antimicrobial properties. The added value of biocidal silver treatment of face masks to control SARS-CoV-2 infection needs to be balanced against possible toxicity due to inhalation exposure. Direct measurement of silver (particle) release to estimate exposure is problematic. Therefore, this study optimized methodologies to characterize silver-based biocides directly in the face masks, by measuring their total silver content using ICP-MS and ICP-OES based methods, and by visualizing the type(s) and localization of silver-based biocides using electron microscopy based methods. Thirteen of 20 selected masks intended for general use contained detectable amounts of silver ranging from 3 μg to 235 mg. Four of these masks contained silver nanoparticles, of which one mask was silver coated. Comparison of the silver content with limit values derived from existing inhalation exposure limits for both silver ions and silver nanoparticles allowed to differentiate safe face masks from face masks that require a more extensive safety assessment. These findings urge for in depth characterization of the applications of silver-based biocides and for the implementation of regulatory standards, quality control and product development based on the safe-by-design principle for nanotechnology applications in face masks in general.

Cloth Face Masks Containing Silver: Evaluating the Status

Amid the coronavirus disease 2019 pandemic, demand for cloth face masks containing nanosilver has increased. Common product claims such as "antiviral" and "antimicrobial" can be attractive to buyers seeking to protect themselves from this respiratory disease, but it is important to note that filtration capabilities are the main factor to prevent virus transmission and that antimicrobial ability is a secondary protection factor. Silver has long been known to be antibacterial, and growing research supports additional antiviral properties. In this study, 40 masks claiming to contain silver were evaluated for substantiated antiviral and antimicrobial claims using methods available to the public. Criteria for determining the validity of substantiated claims included the use of patented technology, international certification for antimicrobial and/or antiviral textile by ISO or ASTM, EPA pesticide registration, and peer-reviewed literature. Our analysis showed that, of the 40 masks, 21 had substantiated claims. Using scanning electron microscopy (SEM), two of the substantiated face masks (A and B) were examined for silver identification for further confirmation. Mask A uses silver and copper ions attached to zeolite particles; the zeolite particles discovered through SEM were approximately 90-200 nm in diameter. In mask B, particles of silver and titanium at the 250 nm size were found. In conclusion, these certifications or patents are not enough to determine credibility, and stricter regulations by federal agencies on product testing for manufacturers that make claims are necessary to ensure the efficacy of the product advertised, as well as a cloth face mask inhalation standard.

Characterization of an aerosol generation system to assess inhalation risks of aerosolized nano-enabled consumer products

Objective: The aerosolization of common nano-enabled consumer products such as cosmetics has significantly increased engineered nanoparticle inhalation risks. While several studies have investigated the impact of cosmetic dermal exposures, inhalation hazards of aerosolized cosmetics are much less known but could pose considerable harm to users due to potential co-exposure of nanoparticles and other product components.Materials and Methods: In this study, we developed a fully automated aerosol generation system to examine the aerosol properties of four aerosolized nano-enabled cosmetics using real-time monitoring and sampling instrumentation. Physicochemical characterization of aerosols was conducted using scanning electron microscopy coupled with energy dispersive x-ray spectroscopy (SEM-EDX). Characterization and calibration of animal exposure pods coupled to the system were also performed by measuring and comparing particle concentrations between pods.Results and Discussion: Results show peak emissions are shade dependent and varied between 12,000-22,000 particles/cm³ with modal diameters ranging from 36 nm-1.3 µm. SEM-EDX analysis determined that the original products and collected aerosols have similar morphological features consisting of micron-sized particles decorated with nanoparticles and crystalline structures. Mean total particle concentration in pods at 5 and 10 mg/m³ target levels were 2.22E + 05 #/cm³ and 4.33E + 05 #/cm³, respectively, with <10% variability between pods.Conclusions: The fully automated exposure platform described herein provides reproducible aerosol generation, conforms to recommended guidelines on chemical testing, and therefore is suitable for future in vivo toxicological assessments to examine potential respiratory hazards of aerosolized nano-enabled consumer products.