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Home>HOSPITAL HYGIENE>General Hospital Hygiene>‘E-water’ – a better solution for disinfection?

‘E-water’ – a better solution for disinfection?

21 October 2021

Traditionally, bleach and quaternary ammonium (Quats) disinfectants have been the most commonly employed by cleaning and disinfection companies. However, as Adrian Gee-Turner observed, the COVID-19 pandemic has re-focused attention on disinfectants and prompted users to start seeking assurance on issues such as effectivity against different pathogens, speed of action and handling safety. 

A CONNECTION between microorganisms and disease transmission was first established in a Vienna hospital in 1841, when the implementation of a hand-washing regimen resulted in a dramatic reduction in mortality rate among puerperal women. Today, the requirement for cleaning and disinfection is better understood, but the COVID-19 pandemic has heightened awareness of these important procedures. Nevertheless, it is important for cleaning staff to be aware of the difference between cleaning and disinfection. 

Cleaning is the physical removal of soil and microorganisms from surfaces, which may also involve the action of a surfactant, catholyte, detergent or water. Cleaning should be undertaken prior to disinfection because the presence of organic soil will reduce the effectiveness of disinfectants.

Disinfection is the process by which most or all of the pathogenic microorganisms are deactivated or killed. Internationally accepted standards have been created to define the levels of deactivation that are necessary for different microorganisms in different applications. Sterilisation refers to the process which kills all forms of microbial life, and is predominantly used for the decontamination of surgical instruments.

Professor Stephanie Dancer, a consultant microbiologist in NHS Lanarkshire and Professor of Microbiology at Edinburgh Napier University, advocates the physical removal of soil and pathogens rather than obliteration for routine cleaning, but accepts that there are circumstances where disinfectants are necessary. She said: “The challenge is to find a product that is effective, quick-acting, non-toxic to people and the environment; and, for the NHS in particular, it must be cheap. Electrolysed water (hypochlorous acid) is a potential choice for hospitals and other healthcare organisations.”

A wide variety of disinfectants are commercially available; the majority of which are toxic to both microorganisms and humans. This toxicity represents a safety hazard during use and storage, as well as, in some cases, an environmental threat. Interest is therefore growing rapidly in products that are able to deliver superior (verified) levels of efficacy, but without toxicity to users and the potential for environmental harm. Electrolysed water meets these requirements, but has not been universally adopted because past products quickly reverted to the original ingredients – salt and water. However, a small number of manufacturers have recently developed processes that have resolved this issue and it is now possible to purchase E-water with a 12-month shelf-life or longer.

E-water – what is it?
For the purposes of disinfection, the active ingredient of E-water is hypochlorous acid (HOCl) in an aqueous solution which is approximately pH neutral. It does not contain any substances that are hazardous to human health, so there are no COSHH requirements and no personal protective equipment (PPE) is necessary when handling the ready-to-use liquid. The end products from the practical deployment of HOCl are salt and water.

The Hypochlorous Acid solution is manufactured by the electrolysis of a mixture of salt and pure water. Shelf-life and pH stability have been designed into the process, but the details remain commercially sensitive for obvious reasons.

The effectiveness of the market’s leading e-Water products has been tested according to international standards such as EN 1276, EN 14476 and EN 13704 against the most common pathogens, with most demonstrating impressive Log-6 effectivity against bacteria, Log-4 against viruses and Log-3 against spore-forming bacteria.

Hand washing, masks, social distancing and ventilation all performed well during the COVID-19 pandemic. However, as enveloped viruses, coronaviruses are relatively easy to deactivate, so surface disinfection was also highly effective.

Comparison with traditional disinfectants
It is very important to differentiate between e-Water (Hypochlorous Acid) and household bleach (Sodium Hypochlorite). Bleach formulations dissolve in water to create a dilute aqueous chlorine solution in which undissociated hypochlorous acid (HOCl) is active as the antimicrobial compound.

Bleach denatures protein in micro-organisms and is therefore effective at killing bacteria, fungus and viruses. As an irritant to skin, bleach can cause burns and serious damage to eyes. Inhalation of its fumes can harm the respiratory tract, and the correct concentration of bleach must be used to achieve effective disinfection.

Most bleach manufacturers claim 99.9% kill (Log-3) of harmful micro-organisms, so e-Water can claim to be one thousand times more effective. This means that bleach could be expected (in the right conditions) to reduce 1million colony forming bacterial units (CFUs) to 1,000 CFUs whereas a Log-6 disinfectant (such as e-Water) would be expected to reduce the same size colony down to just one single CFU. Bleach is therefore mainly suitable for the low-cost disinfection of non-porous, unpainted surfaces such as floors and toilets.

The impact of Quats

Quats are widely used in cleaning and disinfection product formulations. Quats are positively-charged (cationic) surfactants that can be effective against bacteria, fungi and enveloped viruses. They also provide detergent activity, so they are suitable for cleaning purposes, and are frequently included in the formulations of household and industrial products. 

The primary bactericidal mechanism is the disruption of membranes, and Quats are generally active against enveloped viruses such as coronavirus but not against non-enveloped viruses. As lipophilic sanitisers Quats are not very effective against single-stranded, non-enveloped RNA viruses, such as Norovirus, because they lack a lipid envelope to attack. Quats permit the survival of many Gram-negative organisms and heavy use would encourage predominance of species such as Pseudomonas. 

The activity of Quats can be adversely affected by water hardness, fat-containing substances, absorbent materials and anionic surfactants.  The labels of Quat products generally contain health warnings and since they contain hazardous substances, Quats represent a threat to the environment, so used containers should be incinerated or disposed of in an acceptable permitted waste disposal facility. 

Quats have become popular because they provide an opportunity to formulate disinfectants to target specific pathogens in specific applications, especially where detergent action is also required. However, given the limitations outlined above, e-Water represents a superior alternative.

Hypochlorous Acid (HOCl) for disinfection
Towards the end of 2020, Dr. Eric Rasmussen, Briotech's chief medical officer, made an application to the World Health Organization proposing the inclusion of Hypochlorous Acid (HOCl) for disinfection, antisepsis, and wound care. In response, the WHO recommended further, larger clinical trials, but the submission contains information that is pertinent to this article:

HOCl has emerged in the current pandemic as the most potent and environmentally safe  disinfectant available and with a wide range of efficacy against many human pathogens, including  the SARS-CoV-2 coronavirus. In recent years compelling evidence of the potency of pure,  stable preparations of HOCl in the inactivation of even the most resistant infectious agents, such  as BSE Prions and HPV16 viruses (both of which are completely unaffected by  disinfectants currently on the EML list) has made it clear that HOCl deserves a place in every  public health program as a fundamental instrument of infectious disease control.

HOCl solutions are already included in the WHO list of coronavirus-effective biocides, and in the US EPA ‘N’ list of disinfecting agents able to control emerging pathogens like SARS-CoV-2 More than ten branded aqueous HOCl formulations have been cleared by the US FDA for topical use in wound management over the last decade. A Class III medical product approval for HOCl has been granted in the EU, and the Japanese Ministry of Health has approved use of HOCl for topical medical applications. The US FDA has approved HOCl for high level disinfection and sterilization of medical instruments, including those for use at critical (i.e., sterile) sites.   

Block and Rowan in 2020 reviewed surgeons’ needs for disinfection in the face of the coronavirus pandemic and concluded that HOCl comprises many of the desired effects of the ideal disinfectant: it is easy to use, is inexpensive, has a good safety profile, and can be used to disinfect large areas quickly and with a broad range of bactericidal and virucidal effects.

Further applications for e-Water have also been investigated by Professor Dancer. For example, in 2015 working with researchers from Hairmyres Hospital in Scotland, the in-use effect of E-water on reusable transcutaneous oxygen sensors2 was evaluated on the feet of healthy and diabetic volunteers. The work found that exposure to electrolysed water removed original skin commensals and alleviated the risk of transmitting microbial flora without affecting test results. The paper concluded that the product is non-toxic, inexpensive and may be useful for decontaminating a wide range of equipment. Good surface disinfection with E-water was shown in both care homes and an acute ward at Hairmyres.

During the COVID-19 pandemic, awareness and understanding of the measures required to prevent disease transmission improved markedly. However, a return to ‘normality’ should not mean that we should reinstate traditional cleaning and disinfection strategies. Instead, we should take advantage of this new opportunity and refine procedures to optimise the protection of indoor areas.

The COVID-19 pandemic has dramatically increased the use of HOCl in a wide variety of applications, and helped to raise the profile of this disinfectant. Infection control measures should maximise effectivity whilst minimising risks to cleaning staff and to the environment, therefore evidence is increasingly indicating that HOCl formulations with proven performance and a long shelf-life represent an excellent choice for cost-effective disinfection.

Adrian Gee-Turner is founder of L’Eau Limited. Adrian has a long career in healthcare equipment and managed the launch of the Nemesis eH2O brand of eWater prior to the COVID-19 pandemic.

For more information contact info@nemesis-eH2O.com