Importance of Disinfection in Breaking the Transmission Chain of Infectious Diseases
Infectious diseases pose a significant threat to public health, and their prevention and control are global challenges. Since the outbreak of coronavirus disease 2019 (COVID-19), the role of disinfection in breaking the transmission chain of infectious diseases has been increasingly recognized, and disinfection has been practiced in various settings, including healthcare facilities, public places, and residential buildings.
Chemical disinfection is the most common disinfection method, which is effective in quickly killing or inactivating microorganisms on abiotic surfaces. Among the commonly used chemical disinfectants, hydrogen peroxide (H₂O₂), chlorine dioxide (ClO₂), and chlorine-containing disinfectants, such as sodium dichloroisocyanurate (DCCNa), have gained significant attention due to their broad-spectrum antimicrobial efficacy.
Evaluation of Disinfection Efficiency in Real-World Settings
This study aimed to investigate the disinfection efficiency of commercial H₂O₂, ClO₂, and chlorine-based disinfectants on real-world surfaces and provide data for precise disinfection. Simulated field disinfection and field disinfection methods were conducted to quantitatively evaluate the disinfection efficiency of these three disinfectants.
Simulated Field Disinfection Experiments
The disinfection efficacy of the three commercial disinfectants was first evaluated using simulated field disinfection experiments. Escherichia coli (ATCC 8099) and Staphylococcus aureus (ATCC 6538) were used as biological indicators, representing gram-negative and gram-positive bacteria, respectively.
The results showed that all three disinfectants were effective against E. coli and S. aureus, with a reduction of more than 3.00 log₁₀ colony-forming units (CFU)/mL after an exposure time of 15 minutes. Specifically:
- 3.5% H₂O₂ was effective
- 100 mg/L ClO₂ was effective
- 250 mg/L sodium dichloroisocyanurate was effective
These findings indicate that the three disinfectants can efficiently inactivate indicator bacteria on surfaces under simulated field conditions.
Field Disinfection Evaluation
The disinfection efficiency of the three disinfectants was further evaluated in real-world settings, including a food production and processing workshop and a biosafety laboratory.
Food Production and Processing Workshop
In the food production and processing workshop, the natural bacterial load on the surfaces was assessed. The results showed that the use of 10.5% H₂O₂ with an exposure time of 30 minutes reduced the natural bacterial load by more than 90%.
Biosafety Laboratory
In the biosafety laboratory, the disinfection efficiency of ClO₂ and sodium dichloroisocyanurate was evaluated. The results indicated that:
- 500 mg/L ClO₂ with an exposure time of 60 minutes achieved a disinfection level of over 90%
- 450 mg/L sodium dichloroisocyanurate with an exposure time of 60 minutes also achieved a disinfection level of over 90%
These findings suggest that the disinfection efficiency of the three disinfectants can be influenced by factors such as the concentration of the disinfectant, exposure time, and the specific environment where disinfection is being conducted.
Factors Affecting Disinfection Efficiency
The disinfection efficiency of chemical disinfectants can be affected by various factors, including the type and concentration of the disinfectant, the exposure time, the nature and soiling of the surface to be disinfected, and the type and load of microorganisms present.
Disinfectant Concentration and Exposure Time
The study findings highlight the importance of adjusting the concentration of the disinfectant and the exposure time based on the specific conditions of the environment. In the food production and processing workshop, a higher concentration of H₂O₂ (10.5%) was required to achieve the desired disinfection level, compared to the simulated field disinfection experiments, where 3.5% H₂O₂ was effective.
Similarly, in the biosafety laboratory, higher concentrations of ClO₂ (500 mg/L) and sodium dichloroisocyanurate (450 mg/L) were needed, with an exposure time of 60 minutes, to achieve a disinfection level of over 90%.
Surface Characteristics and Microbial Load
The nature and cleanliness of the surfaces to be disinfected can also influence the disinfection efficiency. The food production and processing workshop had a rougher surface with visible organic matter, which likely contributed to the higher disinfectant concentration required. In contrast, the biosafety laboratory had smoother surfaces, but a higher natural microbial load due to its previous occupation and lack of regular cleaning.
Choosing the Appropriate Disinfectant
Each disinfectant has its own unique properties and considerations for use. Hydrogen peroxide is a versatile disinfectant with a broad spectrum of antimicrobial activity and minimal environmental impact, as its decomposition products are water and oxygen.
Chlorine dioxide is another effective disinfectant, with the advantage of producing fewer organic halogenated disinfection by-products compared to chlorine-based disinfectants. However, it can be more irritating to humans and corrosive to some materials.
Chlorine-containing disinfectants, such as sodium dichloroisocyanurate, are widely used due to their strong bactericidal and detoxifying abilities. They are suitable for disinfecting contaminated surfaces, objects, and fabrics, as well as water, fruits, and vegetables. However, they can be more corrosive to metals and have a bleaching effect on fabrics.
When choosing a disinfectant, it is essential to consider the specific conditions of the environment, the type and load of microorganisms present, and the safety and compatibility of the disinfectant with the materials and personnel involved.
Importance of Evaluating Disinfection Efficiency
Evaluating the disinfection efficiency of chemical disinfectants is crucial to ensure the effectiveness of disinfection efforts and avoid wastage of resources, health hazards, and environmental pollution. This study demonstrates the need to assess the disinfection efficiency in real-world settings, as the results can vary significantly from simulated experiments.
By understanding the factors that influence disinfection efficiency, such as disinfectant concentration, exposure time, and environmental conditions, organizations can develop and implement effective, standardized disinfection protocols. This will help ensure the successful prevention and control of infectious diseases, while minimizing the negative impacts of disinfection practices.
Conclusion
This study provides valuable insights into the disinfection efficiency of commercial H₂O₂, ClO₂, and chlorine-based disinfectants in real-world settings. The findings highlight the importance of considering various factors, such as disinfectant concentration, exposure time, surface characteristics, and microbial load, when developing effective disinfection strategies.
By sharing this information, the Joint Action for Water blog aims to empower water and sanitation professionals, community advocates, and policymakers with practical knowledge to enhance disinfection practices and contribute to the overall improvement of public health and environmental sustainability.
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