COVID-19's Role in Reshaping the Use of Antimicrobial Nanomaterial Technology
Grocery stores are filled with aisles and aisles of packaged foods, but we seldom think of how this packaging may be actively working towards keeping our food fresh and safe. We view this packaging as only a barrier between food and the environment, or passive packaging. However, some packaging, known as active packaging, actually contains added compounds that work in various ways to effectively extend the shelf-life of food.
European Commission Regulation (EC) No 450/2009 sets out requirements for active and intelligent food contact materials, and defines active packaging as materials that “deliberately incorporate components that would release or absorb substances into or from packaged food or the environment surrounding the food” (European Commission, 2009). Passive packaging acts as a barrier between food and the external environment, but is limited in its ability to extend the shelf-life of foods (Yildirim et al., 2017). Thus, active packaging’s intended purpose is to extend shelf-life, while maintaining food’s viability, which has become especially crucial, given the current increase in consumer demand for fresh, high-quality, and ready-to-eat food products (Soltani Firouz et al., 2021). Two main categories of active packaging exist: 1) active scavenging systems, or absorbers that remove undesired particles (e.g.,odor, ethylene, moisture, etc.) from food; and 2) active releasing systems, or emitters that add compounds (e.g, antimicrobials, antioxidants, flavors, etc.) to foods. These systems have various potential benefits and can be used for packaging many different food products (Yildirim et al., 2017).
Many compounds that can be added to packaging to have antimicrobial activity, but silver-based active ingredients, such as silver-oxides and silver nanoparticles, have been shown to be effective against various pathogenic microorganisms (Aziman et al., 2021; Carbone et al., 2016). This silver ion technology can be applied at all stages of the manufacturing process. The silver ions act through binding to, preventing growth of, and eventually causing the death of microbes. The antimicrobial mechanisms are shown in Figure 1. Silver nanoparticles have been used extensively as antimicrobial agents in food packaging. However, certain concerns do exist regarding the risks associated with potentially ingesting silver ions that migrate into food (Ahari & Khoshboui Lahijani, 2021). While these nanoparticles have been shown to exert toxic effects in both in vitro and in vivo studies, limited information exists as to the toxicity associated with their ingestion on human health, and results have been inconclusive (Jimenez et al., 2017). Studies have been conducted, though, on silver ion migration from nanoparticles in packaging to food, which have indicated that acidic food, microwave heating, and using nanofillers may increase migration, though the levels of migration are below the limits set by safety authorities (Carbone et al., 2016). The European Food Safety Authority (ESFA) recommends that silver migration from packaging should not exceed 0.05 mg/L in water or 0.05 mg/kg in food (EFSA, 2011).
This silver ion technology is also available for use in textiles, plastics, paper, and coatings, so the antimicrobial food packaging commercialization has rapidly grown and expanded into other industries (Aziman et al., 2021). Certain conventional paper products, such as handwipes, paper towels, and facial tissues, have previously contained antimicrobial compounds, and, recently, non-conventional paper products have also begun to exploit these properties (Patel, 2020). Further, silver nanoparticle antimicrobial paper and products have been used to help reduce the spread of COVID-19. One precaution, amongst many, that most airlines took during the onset of the pandemic was removing in-flight magazines, but many of these monthly publications can now be found again in seat-back pockets, thanks to silver ion microbicidal technology. Many of these magazines now state on the cover that they have been treated with an antimicrobial process in order to reduce COVID-19 contamination risk, even though full efficacy of these technologies has not yet been tested against SARS-CoV2 specifically, and there is not yet an efficacy test method available (Addmaster, 2021). There is, however known efficacy testing of these technologies on other enveloped viruses. With hygiene and safety now at the forefront of consumer thinking, and businesses and travel reopening, the demand for antibacterial and antimicrobial commercial products is likely to continue to increase in the future. Thus, further research efforts should be undertaken in order to confidently assess any human health risks associated with these nanomaterials.
Cardno ChemRisk scientists have extensive professional experience evaluating the possible hazards and risks posed by chemicals in consumer products. Please contact Dr. Ernest Fung for more information on our capabilities regarding consumer products. Cardno ChemRisk is also experienced at developing and assisting with COVID-19 risk management and response plans for a variety of industries (e.g., construction, food and beverage manufacturers, manufacturing, media, and television, and retailers). To learn more about the ways Cardno ChemRisk can support your business, please visit our website.
Figure 1. Antimicrobial Mechanisms of Silver Nanoparticles (Yin et al., 2020)