Resolving the "health vs environment" dilemma with sustainable disinfection during the COVID-19 pandemic

Recent advances and new insights on the construction of photocatalytic systems for environmental disinfection

Photocatalysis, as a sustainable and environmentally friendly green technology, has garnered widespread recognition and application across various fields. Especially its potential in environmental disinfection has been highly valued by researchers. This study commences with foundational research on photocatalytic disinfection technology and provides a comprehensive overview of its current developmental status. It elucidates the complexity of the interface reaction mechanism between photocatalysts and microorganisms, providing valuable insights from the perspectives of materials and microorganisms. This study reviews the latest design and modification strategies (Build heterojunction, defect engineering, and heteroatom doping) for photocatalysts in environmental disinfection. Moreover, this study investigates the research focuses and links in constructing photocatalytic disinfection systems, including photochemical reactors, light sources, and material immobilization technologies. It studies the complex challenges and influencing factors generated by different environmental media during the disinfection process. Simultaneously, a comprehensive review extensively covers the research status of photocatalytic disinfection concerning bacteria, fungi, and viruses. It reveals the observable efficiency differences caused by the microstructure of microorganisms during photocatalytic reactions. Based on these influencing factors, the economy and effectiveness of photocatalytic disinfection systems are analyzed and discussed. Finally, this study summarizes the current application status of photocatalytic disinfection products. The challenges faced by the synthesis and application of future photocatalysts are proposed, and the future development in this field is discussed. The potential for research and innovation has been further emphasized, with the core on improving efficiency, reducing costs, and strengthening the practical application of photocatalysis in environmental disinfection.

Efficacy of Violet-Blue (405 nm) LED Lamps for Disinfection of High-Environmental-Contact Surfaces in Healthcare Facilities: Leading to the Inactivation of Microorganisms and Reduction of MRSA Contamination

Effective disinfection procedures in healthcare facilities are essential to prevent transmission. Chemical disinfectants, hydrogen peroxide vapour (HPV) systems and ultraviolet (UV) light are commonly used methods. An emerging method, violet-blue light at 405 nm, has shown promise for surface disinfection. Its antimicrobial properties are based on producing reactive oxygen species (ROS) that lead to the inactivation of pathogens. Studies have shown significant efficacy in reducing bacterial levels on surfaces and in the air, reducing nosocomial infections. The aim of this study was to evaluate the antimicrobial effectiveness of violet-blue (405 nm) LED lamps on high-contact surfaces in a hospital infection-control laboratory. High-contact surfaces were sampled before and after 7 days of exposure to violet-blue light. In addition, the effect of violet-blue light on MRSA-contaminated surfaces was investigated. Exposure to violet-blue light significantly reduced the number of bacteria, yeasts and moulds on the sampled surfaces. The incubator handle showed a low microbial load and no growth after irradiation. The worktable and sink showed an inconsistent reduction due to shaded areas. In the second experiment, violet-blue light significantly reduced the microbial load of MRSA on surfaces, with a greater reduction on steel surfaces than on plastic surfaces. Violet-blue light at 405 nm has proven to be an effective tool for pathogen inactivation in healthcare settings Violet-blue light shows promise as an additional and integrated tool to reduce microbial contamination in hospital environments but must be used in combination with standard cleaning practices and infection control protocols. Further research is needed to optimise the violet-blue, 405 nm disinfection method.

Risks of benzalkonium chlorides as emerging contaminants in the environment and possible control strategies from the perspective of ecopharmacovigilance

An unprecedented increase in the use of disinfection products triggered by the coronavirus disease 2019 (COVID-19) pandemic is resulting in aggravating environmental loads of disinfectants as emerging contaminants, which has been considered a cause for worldwide secondary disasters. This review analyzed the literature published in the last decade about occurrence, bioaccumulation, and possible environmental risks of benzalkonium chlorides (BKCs) as emerging contaminants. Results indicated that BKCs globally occurred in municipal wastewater, surface water, groundwater, reclaimed water, sludge, sediment, soil, roof runoff, and residential dust samples across 13 countries. The maximum residual levels of 30 mg/L and 421 μg/g were reported in water and solid environmental samples, respectively. Emerging evidences suggested possible bioaccumulation of BKCs in plants, even perhaps humans. Environmentally relevant concentrations of BKCs exert potential adverse impacts on aquatic and terrestrial species, including genotoxicity, respiratory toxicity, behavioural effects and neurotoxicity, endocrine disruption and reproductive impairment, phytotoxicity, etc. Given the intrinsic biocidal and preservative properties of disinfectants, the inductive effects of residual BKCs in environment in terms of resistance and imbalance of microorganisms have been paid special attention. Considering the similarities of disinfectants to pharmaceuticals, from the perspective of ecopharmacovigilance (EPV), a well-established strategy for pharmaceutical emerging contaminants, we use the control of BKC pollution as a case, and provide some recommendations for employing the EPV measures to manage environmental risks posed by disinfectant emerging contaminants.

Assessment of Residual Chlorine Interaction with Different Microelements in Stormwater Sediments

One consequence of intensive outdoor disinfection using chlorinated compounds is environmental pollution. It has been found that disinfectants are the most effective tool to avoid the spread of infections and viruses. Studies have shown that the use of chlorine-based disinfectants (sodium hypochlorite) leaves residual chlorine and other disinfection byproducts in the environment. They also have harmful effects on, inter alia, water quality, ecosystems, as well as exacerbating the corrosion of surfaces. To meet regulatory standards, monitoring of the presence of residual chlorine in the environment is vitally important. The aim of this study is to analyse the occurrence of residual chlorine in stormwater after outdoor disinfection using sodium hypochlorite and to investigate its interaction with different microelements as well their possible impacts. Stormwater samples collected at permanently disinfected locations were analysed via X-ray absorption spectroscopy. The concentrations of Cl and the following elements Na, Si, K, Ca, Cr, Fe, Ni, Cu, Zn were detected and their relationship with chlorine was determined using the Python programming language. The research presents Cl concentration values (%) that vary from 0.02 to 0.04. The results of the modelling revealed strong correlations between Cl and Fe (value 0.65) and Ca (value -0.61) and the occurrence of CaCl₂ and FeCl₃. The strong relationship between Cl and Fe explains the significant increase in surface corrosion after disinfection with chlorine-based substances.

Knowledge, attitudes and practice regarding environmental friendly disinfectants for household use among residents of China in the post-pandemic period

Background

A sharp rise in household consumption of disinfectants triggered by COVID-19 pandemic has generated tremendous environmental burden and risks of disinfectant emissions in the post-pandemic period. To address this emerging challenge, replacing highly hazardous disinfectants with more environmental friendly alternatives has been accepted as an inherently effective solution to environment issues posed by disinfectant emerging contaminants. However, no study has yet been done to explore the potential customers' attitudes and the market prospect of environmental friendly disinfectants until now.

Methods

This cross-sectional questionnaire-based survey was conducted from January to March, 2022, among resident volunteers in China, to explore the practices, knowledge and attitudes of the public regarding environmental friendly disinfectants for household use.

Results

Among a total of 1,861 Chinese residents finally included in the analyses, 18% agreed or strongly agreed that they paid special attention to the environmental certification label on the product, and only bought the environmental certified disinfectant products; 16% and 10% were using environmental friendly disinfectants for hand sanitization and environmental disinfection, respectively. The mean self-assessed and actual knowledge scores were 2.42 ± 1.74 and 2.12 ± 1.97, respectively, out of a total of 5. Participants having good practices of consuming environmental friendly disinfectants achieved higher knowledge scores. Residents' overall attitudes toward the development, consumption and application of environmental friendly disinfectants were very positive. "Possible conflict between disinfection effectiveness and environmental factor of disinfectants in a context of severe COVID-19 pandemic" was considered as the most important barrier jeopardizing the participants' usage intention for environmental friendly disinfectants.

Conclusions

These data suggested most residents of China had a positive attitude, poor knowledge and practices toward environmental friendly disinfectants. More should be done to enhance the residents' environmental knowledge levels about disinfectants, and to further develop and promote disinfectant products with both excellent disinfection activity and environmentally friendly attributes.