Can chlorine dioxide prevent the spreading of coronavirus or other viral infections? Medical hypotheses

Process Technologies for Disinfection of Food-Contact Surfaces in the Dry Food Industry: A Review

The survival characteristics of bacterial pathogens, including Salmonella spp., Listeria monocytogenes, Staphylococcus aureus, and Escherichia coli, in foods with a low water activity (aw) have been extensively examined and reported. Microbial attachment on the food-contact surfaces can result in cross-contamination and compromise the safety of low-aw foods. The bactericidal potential of various conventional and novel disinfection technologies has been explored in the dry food industry. However, the attachment behavior of bacterial pathogens to food-contact surfaces in low-aw conditions and their subsequent response to the cleaning and disinfection practices requires further elucidation. The review summarizes the elements that influence disinfection, such as the presence of organic residues, persistent strains, and the possibility of microbial biotransfer. This review explores in detail the selected dry disinfection technologies, including superheated steam, fumigation, alcohol-based disinfectants, UV radiation, and cold plasma, that can be used in the dry food industry. The review also highlights the use of several wet disinfection technologies employing chemical antimicrobial agents against surface-dried microorganisms on food-contact surfaces. In addition, the disinfection efficacy of conventional and novel technologies against surface-dried microorganisms on food-contact surfaces, as well as their advantages and disadvantages and underlying mechanisms, are discussed. Dry food processing facilities should implement stringent disinfection procedures to ensure food safety. Environmental monitoring procedures and management techniques are essential to prevent adhesion and allow the subsequent inactivation of microorganisms.

Application of chlorine dioxide and its disinfection mechanism

Chlorine dioxide (ClO2) is a strong oxidizing agent and an efficient disinfectant. Due to its broad-spectrum bactericidal properties, good inactivation effect on the vast majority of bacteria and pathogenic microorganisms, low resistance to drugs, and low generation of halogenated by-products, chlorine dioxide is widely used in fields such as water purification, food safety, medical and public health, and living environment. This review introduced the properties and application status of chlorine dioxide, compared the action mode, advantages and disadvantages of various disinfectants. The mechanism of chlorine dioxide inactivating bacteria, fungi and viruses were reviewed. The lethal target of chlorine dioxide to bacteria and fungi is to destroy the structure of cell membrane, change the permeability of cell membrane, and make intracellular substances flow out, leading to their death. The lethal targets for viruses are the destruction of viral protein capsids and the degradation of RNA fragments. The purpose of this review is to provide more scientific guidance for the application of chlorine dioxide disinfectants.

Amoebicidal effect of chlorine dioxide gas against pathogenic Naegleria fowleri and Acanthamoeba polyphaga

The pathogenic free-living amoebae, Naegleria fowleri and Acanthamoeba polyphaga, are found in freshwater, soil, and unchlorinated or minimally chlorinated swimming pools. N. fowleri and A. polyphaga are becoming problematic as water leisure activities and drinking water are sources of infection. Chlorine dioxide (ClO2) gas is a potent disinfectant that is relatively harmless to humans at the concentration used for disinfection. In this study, we examined the amoebicidal effects of ClO2 gas on N. fowleri and A. polyphaga. These amoebae were exposed to ClO2 gas from a ready-to-use product (0.36 ppmv/h) for 12, 24, 36, and 48 h. Microscopic examination showed that the viability of N. fowleri and A. polyphaga was effectively inhibited by treatment with ClO2 gas in a time-dependent manner. The growth of N. fowleri and A. polyphaga exposed to ClO2 gas for 36 h was completely inhibited. In both cases, the mRNA levels of their respective actin genes were significantly reduced following treatment with ClO2 gas. ClO2 gas has an amoebicidal effect on N. fowleri and A. polyphaga. Therefore, ClO2 gas has been proposed as an effective agent for the prevention and control of pathogenic free-living amoeba contamination.

The Virucidal Effect of the Chlorination of Water at the Initial Phase of Disinfection May Be Underestimated If Contact Time Calculations Are Used

For the microbiological safety of drinking water, disinfection methods are used to remove or inactivate microorganisms. Chlorine and chlorine dioxide are often used as disinfectants in drinking water treatment plants (DWTPs). We investigated the effectiveness of these chemicals in inactivate echovirus 30 (E30), simian 11 rotavirus (RV SA11), and human adenovirus type 2 (HAdV2) in purified water from a DWTP. Within two minutes of contact, chlorine dioxide inactivated E30 by 4-log10, RV SA11 by 3-log10, and HAdV2 could not be detected, while chlorine reduced E30 by 3-log10, RV SA11 by 2-3log10, and HAdV2 by 3-4log10. However, viral genomes could be detected for up to 2 h using qPCR. The CT method, based on a combination of disinfectant concentration and contact time, during such a short initial phase, is problematic. The high concentrations of disinfectant needed to neutralize organic matter may have a strong immediate effect on virus viability. This may lead to the underestimation of disinfection and overdosing of disinfectants in water with organic contamination. These results are useful for the selection of disinfection systems for reuse of treated wastewater and in the risk assessment of water treatment processes using chlorine and chlorine dioxide.

Short- and long term antibacterial effects of a single rinse with different mouthwashes: A randomized clinical trial

Objectives

Reducing the microbial level in the aerosol created during dental procedures is essential to avoiding infections. The aim of this study was to examine the change in Streptococcus mutans (S. mutans) and the total bacterial load in human saliva in vivo after a single rinse with different mouthwashes.

Material and methods

One mL of unstimulated saliva was collected from volunteers with poor oral hygiene at baseline and 5 min after a 1-min rinsing with diluted Solumium Oral® (hyper-pure 0.0015% chlorine dioxide; ClO2), Listerine Total Care®, Corsodyl® (0.2% chlorhexidine-digluconate; CHX), or BioGate Si*CLEAN for bacterial investigation. In a second study, volunteers rinsed with 0.003% ClO2 or CHX for 1 min, and saliva was collected at baseline, after 5 min, and after 90 min. After plating, the total plate and S. mutans colony numbers were determined.

Results

In the first study, ClO2 and CHX similarly reduced both total germ and S. mutans numbers, while Listerine Total Care® decreased only the S. mutans counts. BioGate Si*Clean had no effect on either the total germ or S. mutans numbers. In the second study, an increasing tendency toward bacterial regrowth was observed with CHX after 90 min compared to the 5-min value, while no change was measured after ClO2 rinsing.

Conclusion

Hyper-pure ClO2 rinsing may be a new promising preventive and therapeutic adjuvant in dental practice, as it is similar in effectiveness to the gold standard CHX-containing mouthwashes, especially in patients concerned with taste or tooth discoloration during oral health therapy.

Phosphorylated Cotton Cellulose as a Matrix for Generating Chlorine Dioxide

Currently, developing disinfectant materials is of utmost importance. A significant advantage of our fabric is its reusability. The disinfectants based on a natural polymer of cellulose have been barely investigated. Our work presents a modified cellulose material, and the data obtained for the first time on the chlorine dioxide generation process when treating the material with a sodium chlorite alcohol solution. A method of applying NaClO₂ onto the fabric by impregnating it with a solution sprayed by an aerosol generator is proposed. This kind of fabric is capable of withstanding multiple usages after pre-washing and rinsing. The lowest alcohols-methanol, ethanol and isopropanol-are proposed as optimal solvents. It was shown that the phosphorylated cotton cellulose fabric impregnated with this solution generates chlorine dioxide during the first 25-35 min. Neither humidity nor expedites improve the process of releasing the chlorine dioxide, but high moisture content in the air causes the complete absorption of ClO₂ by microdrops and its removal from the gas environment. A promising technique for removing the excess ClO₂ by the means of UV treatment is proposed: after 15 min of treating ClO₂ in the gas phase, it disappears entirely. These materials could be used as disinfectants in different industries, such as food and industrial manufacturing.

A review on disinfection methods for inactivation of waterborne viruses

Water contamination is a global health problem, and the need for safe water is ever-growing due to the public health implications of unsafe water. Contaminated water could contain pathogenic bacteria, protozoa, and viruses that are implicated in several debilitating human diseases. The prevalence and survival of waterborne viruses differ from bacteria and other waterborne microorganisms. In addition, viruses are responsible for more severe waterborne diseases such as gastroenteritis, myocarditis, and encephalitis among others, hence the need for dedicated attention to viral inactivation. Disinfection is vital to water treatment because it removes pathogens, including viruses. The commonly used methods and techniques of disinfection for viral inactivation in water comprise physical disinfection such as membrane filtration, ultraviolet (UV) irradiation, and conventional chemical processes such as chlorine, monochloramine, chlorine dioxide, and ozone among others. However, the production of disinfection by-products (DBPs) that accompanies chemical methods of disinfection is an issue of great concern due to the increase in the risks of harm to humans, for example, the development of cancer of the bladder and adverse reproductive outcomes. Therefore, this review examines the conventional disinfection approaches alongside emerging disinfection technologies, such as photocatalytic disinfection, cavitation, and electrochemical disinfection. Moreover, the merits, limitations, and log reduction values (LRVs) of the different disinfection methods discussed were compared concerning virus removal efficiency. Future research needs to merge single disinfection techniques into one to achieve improved viral disinfection, and the development of medicinal plant-based materials as disinfectants due to their antimicrobial and safety benefits to avoid toxicity is also highlighted.

Coronaviruses and SARS-CoV-2 in sewerage and their removal: Step by step in wastewater treatment plants

The fate of Coronaviruses (CoVs) and in particular SARS-CoV-2 in wastewater treatment plants (WWTPs) has not been completely understood yet, but an adequate knowledge on the removal performances in WWTPs could help to prevent waterborne transmission of the virus that is still under debate. CoVs and SARS-CoV-2 are discharged from faeces into the sewer network and reach WWTPs within a few hours. This review presents the fate of SARS-CoV-2 and other CoVs in the primary, secondary and tertiary treatments of WWTPs as well as in sludge treatments. The viral loads decrease progressively along with the treatments from 20 to 3.0E+06 GU/L (Genomic Units/L) in the influent wastewater to concentrations below 2.50E+05 GU/L after secondary biological treatments and finally to negative concentrations (below detection limit) in disinfected effluents. Reduction of CoVs is due to (i) natural decay under unfavourable conditions (solids, microorganisms, temperature) for relatively long hydraulic retention times and (ii) processes of sedimentation, filtration, predation, adsorption, disinfection. In primary and secondary settling, due to the hydrophobic properties, a partial accumulation of CoVs may occur in the separated sludge. In secondary treatment (i.e. activated sludge) CoVs and SARS-CoV-2 loads can be reduced only by about one logarithm (∼90%). To enhance this removal, tertiary treatment with ultrafiltration (Membrane Bioreactors) and chemical disinfection or UV light is needed. CoVs and SARS-CoV-2 in the sludge (1.2E+04-4.6E+08 GU/L) can be inactivated significantly in the thermophilic digestion (55 °C), while mesophilic temperatures (33-37 °C) are not efficient. Additional studies are required to investigate the infectivity of SARS-CoV-2 in WWTPs, especially in view of increasing interest in wastewater reclamation and reuse.

Formulation of Chlorine-Dioxide-Releasing Nanofibers for Disinfection in Humid and CO2-Rich Environment

Background: Preventing infectious diseases has become particularly relevant in the past few years. Therefore, antiseptics that are harmless and insusceptible to microbial resistance mechanisms are desired in medicine and public health. In our recent work, a poly(ethylene oxide)-based nanofibrous mat loaded with sodium chlorite was formulated. Methods: We tested the chlorine dioxide production and bacterial inactivation of the fibers in a medium, modeling the parameters of human exhaled air (ca. 5% (v/v) CO2, T = 37 °C, RH > 95%). The morphology and microstructure of the fibers were investigated via scanning electron microscopy and infrared spectroscopy. Results: Smooth-surfaced, nanoscale fibers were produced. The ClO2-producing ability of the fibers decreased from 65.8 ppm/mg to 4.8 ppm/mg with the increase of the sample weight from 1 to 30 mg. The effect of CO2 concentration and exposure time was also evaluated. The antibacterial activity of the fibers was tested in a 24 h experiment. The sodium-chlorite-loaded fibers showed substantial antibacterial activity. Conclusions: Chlorine dioxide was liberated into the gas phase in the presence of CO2 and water vapor, eliminating the bacteria. Sodium-chlorite-loaded nanofibers can be sources of prolonged chlorine dioxide production and subsequent pathogen inactivation in a CO2-rich and humid environment. Based on the results, further evaluation of the possible application of the formulation in face-mask filters as medical devices is encouraged.

Drug safety of frequently used drugs and substances for self-medication in COVID-19

During the COVID-19 pandemic, the behavior of self-medication has increased. The dissemination of misleading information regarding the efficacy of certain drugs or substances for the prevention and treatment of COVID-19 has been the major contributing factor for this phenomenon. Alongside with the increase in self-medication behavior, the inherent risks to this act such as drug-drug interactions, adverse events, drug toxicity, and masking of symptoms have also increased. Self-medication in the context of COVID-19 has led to drug misuse leading in some cases to the development of fatal adverse drug reactions. It is important that during this ongoing pandemic drugs with potential clinical efficacy against COVID-19 are adequately analyzed regarding their efficacy, safety, and monitoring. The aim of this review is to describe the available evidence regarding the efficacy, safety, and monitoring of the drugs and substances that have been shown to be frequently used for self-medication in patients with COVID-19 (hydroxychloroquine, non-steroidal anti-inflammatory drugs, ivermectin, azithromycin, vitamins, aspirin, and chlorine dioxide) to adequately characterize their risks, safe use, monitoring strategies, and to reinforce the concept that these substances should not be used for self-medication and require a medical prescription.

Plain Language Summary

Drug safety of frequently used drugs and substances for self-medication in COVID-19 Dissemination of information about potential COVID-19 treatments has led individuals to self-medicate and expose themselves to risks such as drug-drug interactions, side effects, antibiotic resistance, and misdiagnosis. There is a need to review the medical literature to evaluate the safety and efficacy of the drugs and substances commonly used by the population for the treatment and prevention of SARS CoV-2 infection. In this review, we included drugs that are frequently used for self-medication and commonly advertised such as ivermectin, hydroxychloroquine, chlorine dioxide, azithromycin, and non-steroidal anti-inflammatory drugs, among others. A brief introduction of the drug and its mechanism of action, followed by a summary of the efficacy in COVID-19 and safety, will be described for each drug in order to promote their responsible use.

Ozone for SARS-CoV-2 inactivation on surfaces and in liquid cell culture media

This study evaluated the inactivation of SARS-CoV-2, the virus responsible for COVID-19, by ozone using virus grown in cell culture media either dried on surfaces (plastic, glass, stainless steel, copper, and coupons of ambulance seat and floor) or suspended in liquid. Treatment in liquid reduced SARS-CoV-2 at a rate of 0.92 ± 0.11 log10-reduction per ozone CT dose(mg min/L); where CT is ozone concentration times exposure time. On surface, the synergistic effect of CT and relative humidity (RH) was key to virus inactivation; the rate varied from 0.01 to 0.27 log10-reduction per ozone CT value(g min/m3) as RH varied from 17% to 70%. Depletion of ozone by competitive reactions with the medium constituents, mass transfer limiting the penetration of ozone to the bulk of the medium, and occlusion of the virus in dried matrix were postulated as potential mechanisms that reduce ozone efficacy. RH70% was found plausible since it provided the highest disinfection rate while being below the critical RH that promotes mould growth in buildings. In conclusion, through careful choice of (CT, RH), gaseous ozone is effective against SARS-CoV-2 and our results are of significance to a growing field where ozone is applied to control the spread of COVID-19.

Respiratory Safety Evaluation in Mice and Inhibition of Adenoviral Amplification in Human Bronchial Endothelial Cells Using a Novel Type of Chlorine Dioxide Gas Reactor

Since the onset of the COVID-19 pandemic, there has been a growing demand for effective and safe disinfectants. A novel use of chlorine dioxide (ClO2) gas, which can satisfy such demand, has been reported. However, its efficacy and safety remain unclear. For the safe use of this gas, the stable release of specific concentrations is a must. A new type of ClO2 generator called Dr.CLOTM has recently been introduced. This study aimed to investigate: (1) the effects of Dr.CLOTM on inhibiting adenoviral amplification on human bronchial epithelial (HBE) cells; and (2) the acute inhalation safety of using Dr.CLOTM in animal models. After infecting HBE cells with a recombinant adenovirus, the inhibitory power of Dr.CLOTM on the virus was expressed as IFU/mL in comparison with the control group. The safety of ClO2 gas was indirectly predicted using mice by measuring single-dose inhalation toxicity in specially designed chambers. Dr.CLOTM was found to evaporate in a very constant concentration range at 0-0.011 ppm/m3 for 42 days. In addition, 36-100% of adenoviral amplification was suppressed by Dr.CLOTM, depending on the conditions. The LC50 of ClO2 gas to mice was approximately 68 ppm for males and 141 ppm for females. Histopathological evaluation showed that the lungs of female mice were more resistant to the toxicity from higher ClO2 gas concentrations than those of male mice. Taken together, these results indicate that Dr.CLOTM can be used to provide a safe indoor environment due to its technology that maintains the stable concentration and release of ClO2 gas, which could suppress viral amplification and may prevent viral infections.

Risk of chlorine dioxide as emerging contaminant during SARS-CoV-2 pandemic: enzyme, cardiac, and behavior effects on amphibian tadpoles

Objective

The use of chlorine dioxide (ClO₂) increased in the last year to prevent SARS-CoV-2 infection due to its use as disinfectant and therapeutic human treatments against viral infections. The absence of toxicological studies and sanitary regulation of this contaminant represents a serious threat to human and environmental health worldwide. The aim of this study was to evaluate the acute toxicity and sublethal effects of ClO₂ on tadpoles of Trachycephalus typhonius, which is a common bioindicator species of contamination from aquatic ecosystems.

Materials and methods

Median lethal concentration (LC50), the lowest-observed effect concentration (LOEC), and the no-observed effect concentration (NOEC) were performed. Acetylcholinesterase (AChE) and glutathione-S-transferase (GST) activities, swimming behavior parameters, and cardiac rhythm were estimated on tadpoles of concentrations ≤ LOEC exposed at 24 and 96 h. ANOVA and Dunnett’s post-hoc comparisons were performed to define treatments significance (p ≤ 0.05).

Results

The LC50 of ClO₂ was 4.17 mg L⁻¹ (confidence limits: 3.73–4.66). In addition, NOEC and LOEC values were 1.56 and 3.12 mg L⁻¹ ClO₂, respectively, at 48 h. AChE and GST activities, swimming parameters, and heart rates increased in sublethal exposure of ClO₂ (0.78–1.56 mg L⁻¹) at 24 h. However, both enzyme activities and swimming parameters decreased, whereas heart rates increased at 96 h.

Conclusion

Overall, this study determined that sublethal concentrations of ClO₂ produced alterations on antioxidant systems, neurotoxicity reflected on swimming performances, and variations in cardiac rhythm on treated tadpoles. Thus, our findings highlighted the need for urgent monitoring of this chemical in the aquatic ecosystems.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s13530-021-00116-3.

Factors associated with the consumption of chlorine dioxide to prevent and treat COVID-19 in the Peruvian population: a cross-sectional study

BACKGROUND

Chlorine dioxide has been promoted as an alternative for the prevention and treatment of COVID-19, especially in Peru, despite the lack of evidence to support its efficacy. This study aimed to evaluate the factors associated with chlorine dioxide consumption in the Peruvian population.

METHODS

Analytical cross-sectional study. An adult Peruvian population was evaluated where chlorine dioxide consumption was divided into two groups according to the purpose of use: as prevention (individuals without COVID-19 history) and as treatment (individuals with COVID-19 history). The associated factors in each group were evaluated using Poisson regressions with the bootstrapping resampling method.

RESULTS

Of 3610 participants included, 3213 reported no history of COVID-19, and 397 had been infected. The prevalence of chlorine dioxide consumption to prevent or treat COVID-19 was 8 and 16%, respectively. Factors either positively or negatively associated with chlorine dioxide consumption for prevention were male sex (aPR: 1.36; 95% CI: 1.09-1.71), being an adult or older adult (aPR: 0.54; 95% CI: 0.35-0.82), having a health sciences student within the family unit (aPR: 1.38; 95% CI: 1.02-1.87), using medical information as the main source of information of COVID-19 (aPR: 0.57; 95% CI: 0.40-0.80), having comorbidities for COVID-19 (aPR: 1.36; 95% CI: 1.01-1.82), considering COVID-19 dangerous and deadly (aPR: 0.57; 95% CI: 0.45-0.74), using medications (aPR: 1.59; 95% CI: 1.25-2.06) and plants to prevent COVID-19 (aPR: 1.69; 95% CI: 1.21-2.36), considering chlorine dioxide ineffective (aPR: 0.18; 95% CI: 0.18-0.24), and being uninformed of its efficacy (aPR: 0.21; 95% CI: 0.16-0.28). In addition, factors associated with chlorine dioxide consumption for treatment were considering COVID-19 dangerous and deadly (aPR: 0.56; 95% CI: 0.33-0.96), considering chlorine dioxide ineffective (aPR: 0.22; 95% CI: 0.12-0.42), and being uninformed of its efficacy (aPR: 0.15; 95% CI: 0.07-0.32).

CONCLUSIONS

The prevalence of chlorine dioxide consumption to treat COVID-19 was higher than prevent. It is important to apply information strategies, prioritizing population groups with certain characteristics that are associated with a higher consumption pattern.

Intestinal perforation associated with chlorine dioxide ingestion: an adult chronic consumer during COVID-19 pandemic

COVID-19 pandemic is one of the most devastating worldwide crises in recent years. During this pandemic, people have been exposed to products that have not been proven to be safe and effective against COVID-19. We present an adult chronic consumer of chlorine dioxide, in which a fatal outcome is described. This case demonstrates that for people searching products to protect themselves from COVID-19, unregulated access to industrial disinfectants represents a dangerous alternative. To date, there is no scientific evidence to uphold the use of chlorine dioxide or chlorine derivatives as preventive or therapeutic agents against COVID-19. Researchers and general population must take into consideration the fatal possible consequences of not following communications and warnings from health authorities and government institutions.

ClO2-Loaded Aerogels with Biocide Effect

In this work, the mechanism of chlorine dioxide's (ClO₂) interaction with aerogel surfaces is described for the first time. To determine the mechanism, three types of aerogels (namely, silica, titania, and zirconia composites) were synthesized and characterized using N₂ sorption isotherm analysis, X-ray diffraction analysis, scanning electron microscopy, and X-ray photoelectron spectroscopy. The kinetics of the ClO₂ interaction mechanism was investigated via ClO₂-controlled sorption and desorption at different temperatures. The process was studied through the theoretical calculation of ClO₂ interaction with the aerogel surface. The biocide efficiency of the as-synthesized ClO₂-loaded aerogels on different bacteria strains was investigated, and efficient microorganism extermination was demonstrated. This system is a disinfectant that can find potential applications in various fields.

Effectiveness of Disinfection with Chlorine Dioxide on Respiratory Transmitted, Enteric, and Bloodborne Viruses: A Narrative Synthesis

A viral spread occurrence such as the SARS-CoV-2 pandemic has prompted the evaluation of different disinfectants suitable for a wide range of environmental matrices. Chlorine dioxide (ClO₂) represents one of the most-used virucidal agents in different settings effective against both enveloped and nonenveloped viruses. This narrative synthesis is focused on the effectiveness of ClO₂ applied in healthcare and community settings in order to eliminate respiratory transmitted, enteric, and bloodborne viruses. Influenza viruses were reduced by 99.9% by 0.5–1.0 mg/L of ClO₂ in less than 5 min. Higher concentration (20 mg/L) eliminated SARS-CoV-2 from sewage. ClO₂ concentrations from 0.2 to 1.0 mg/L ensured at least a 99% viral reduction of AD40, HAV, Coxsackie B5 virus, and other enteric viruses in less than 30 min. Considering bloodborne viruses, 30 mg/L of ClO₂ can eliminate them in 5 min. Bloodborne viruses (HIV-1, HCV, and HBV) may be completely eliminated from medical devices and human fluids after a treatment with 30 mg/L of ClO₂ for 30 min. In conclusion, ClO₂ is a versatile virucidal agent suitable for different environmental matrices.

Nebulized CLODOS Technology Shows Clear Virucidal Properties against the Human Coronavirus HCoV-229E at Non-Cytotoxic Doses

The emergent human coronavirus SARS-CoV-2 and its high infectivity rate has highlighted the strong need for new disinfection systems. Evidence has proven that airborne transmission is an important route of spreading for this virus. Therefore, this short communication introduces CLODOS Technology^®, a novel strategy to disinfect contaminated surfaces. It is a product based on stable and 99% pure chlorine dioxide, already certified as a bactericide, fungicide and virucide against different pathogens. In this study, CLODOS Technology^®, by direct contact or thermonebulization, showed virucidal activity against the human coronavirus HCoV-229E at non-cytotoxic doses. Different conditions such as nebulization, exposure time and product concentration have been tested to standardize and optimize this new feasible method for disinfection.

Outdoor disinfectant sprays for the prevention of COVID-19: Are they safe for the environment?

Due to the wide range of viability on inanimate surfaces and fomite transmission of SARS-CoV-2, hydrogen peroxide (0.5%, HP) and hypochlorite-based (0.1%, HC) disinfectants (common biocides) are proposed by World Health Organization to mitigate the spread of this virus in healthcare settings. They can be adopted and applied to outdoor environments. However, many studies have shown that these two disinfectants are toxic to fishes and aquatic non-target organisms (primary producers and macroinvertebrates). The global market of these disinfectants will increase in coming years due to COVID-19. Therefore, it is urgent to highlight the toxicities of these disinfectants. The main findings of this article allow the community to develop a new strategy to protect the environment against the hazardous effects of disinfectants. Therefore, we use the "toxicity calculated ratio (TC ratio)" that refers to the fold increase or decrease in the toxicities reported in the literature (NOEC, LOEC, LC50 and EC50) relative to the WHO-recommended dose of HP and HC. The calculated TC ratios are valuable for policy makers to formulate the regulations to prevent disinfectant exposure in the environment. Our results were collected via PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analysis) guidelines and showed that the TC ratios are from the single digits to several thousand-fold lower than the HP and HC recommended dose, which means these disinfectants are potentially dangerous to non-target organisms. The results also showed that HP and HC are toxic to the growth and reproduction of non-target organisms. Therefore, we recommend policymakers formulate protocols for critical assessment and monitoring of the environment-especially on non-target organisms in water bodies located in and around disinfectant-exposed areas to safeguard the environment in the future.

Considerations on water quality and the use of chlorine in times of SARS-CoV-2 (COVID-19) pandemic in the community

This review goal is to reflect on the challenges and prospects for water quality in the face of the pandemic caused by the new SARS-CoV-2 coronavirus (COVID-19). Based on the information available so far, the detection of SARS-CoV-2 RNA in wastewater has raised interest in using it as an early warning method, to detect the resurgence of infections and to report the risk associated with contracting SARS-CoV-2 in contact with untreated water or inadequately treated wastewater is discharged. The wastewater-based epidemiological approach can be used as an early indicator of infection within a specific population. On the other hand, it is necessary to collect information from the managers of drinking water supply companies and professionals who are related to water quality, to know SARS-CoV-2 data and information, and its influence on drinking water quality. The basic purpose of this review article is to try to provide a valuable and quick reference guide to COVID-19. Important topics were discussed, such as detection of SARS-CoV-2 in wastewater in various parts of the world; wastewater screening to monitor COVID-19; persistence of SARS-CoV-2 in aquatic systems; the presence of SARS-CoV-2 in drinking water; clean water as a mechanism to deal with the COVID-19 pandemic; chlorine as a disinfectant to eliminate SARS-CoV-2 and damage to ecosystems by the use of chlorine. Currently does not exist extensive literature on the effectiveness of water and wastewater treatment processes that ensure the correct elimination of SARS-CoV-2. Excessive use of disinfectants such as chlorine is causing effects on the environment. This document highlights the need for further research to establish the behavior of the SARS-CoV-2 virus in aquatic systems. This study presents an early overview of the observed and potential impacts of COVID-19 on the environment.