Good disinfection practices – what should we remember?

What are hand sanitisers?

According to the WHO, an alcohol-based hand sanitiser is an alcohol-containing preparation designed for application to the hands to inactivate microorganisms and/or temporarily suppress their growth. Such preparations may contain one or more types of alcohol, other active ingredients and ancillary substances.

Most alcohol-based preparations contain isopropyl alcohol, ethanol, n-propanol or their combinations. However, some hand sanitisers contain methanol^[1]. Unfortunately, they may cause adverse effects such as nausea, vomiting or headaches. More severe effects include blindness, seizures or damage to the nervous system if a sufficient amount of methanol is ingested^[2].

Due to the pandemic, the demand for hand sanitisers has grown, to prevent the spread of COVID-19. Since the CDC has recommended the use of alcohol-based hand sanitisers, many suppliers increased their production output or even moved their production lines to produce greater quantities of the above-mentioned products. The growing demand for such agents is due to the advantages they can provide in reducing the transmission of respiratory infections.

How to effectively disinfect your hands?

The effectiveness of a hand sanitiser depends on:

• the type of alcohol it contains,
• the alcohol concentration,
• the amount of preparation applied to the hands,
• the time of exposure to the product.

For virus disinfection, a 60% alcohol solution is usually recommended, with recent evidence suggesting ethanol and isopropyl alcohol efficiently inactivate the virus SARS-CoV-2 in 30s at >30% alcohol content^[3].

What if you cannot wash your hands with water and soap?

Alcohol-based disinfectants are one way to clean your hands after touching a surface or interacting with people, especially when hand washing is not an option. If soap and water are not available, the CDC recommends using an ethyl or isopropyl alcohol-based hand sanitizer.

What agents should we use for surface disinfection?

For large areas as well as places that we frequently touch, the procedure is different than for only disinfecting our skin. The WHO and CDC recommend washing frequently touched surfaces such as table tops, door handles or tables on a daily basis. You can use soap, a dishwashing liquid or dedicated cleaning agents. Then such surfaces should be disinfected with disinfectants. An interesting disinfection method is to use a 1% sodium hypochlorite solution by generating cold vapour with a nebulizer to disinfect large indoor spaces such as hospitals, care homes, isolation centres or quarantine facilities.The technology could be used both in peripheral primary care facilities and large health care centres dedicated to combating the COVID-19 pandemic. Such effective disinfection will help reduce the transmission of the disease and also largely reduce expenditure on disinfection and chemicals^[4].

Waste disinfection

Another important aspect is the treatment of particularly hazardous waste such as hospital wastewater with disinfectants, because the coronavirus enters wastewater in different ways, including hand washing, spit or vomit. As a consequence, viruses may enter the water systems via different channels such as wastewater drained from hospitals and quarantine facilities^[5]. For the disinfection of contagious wastewater, hospitals commonly use technologies such as:

• ozone disinfection,
• UV radiation,
• liquid chlorine,
• chlorine dioxide,
• sodium hypochlorite.

Ozone is a disinfecting agent with a strong bactericidal effect, widely used in water supply system engineering and wastewater treatment. As ozone disinfection has decolourising and deodorising effects, wastewater becomes clear, transparent and odourless after treatment.

Ultraviolet light (UV) is an electromagnetic wave with a length of 200nm to 400nm. As compared to chlorine disinfection, the investment and operational costs of UV disinfection are much lower. Such disinfection is sometimes insufficient though, as UV radiation does not penetrate obstacles and thus poses a threat to health.

Due to a relatively high risk of storage, the disinfection technology using liquid chlorine is not appropriate for disinfecting highly populated regions.

So far, chlorine dioxide has been one of the most effective disinfectants with a high oxidising capacity even in acidic conditions.

Chlorine dioxide destroys the anabolic pathways of protein and thus kills microorganisms, including bacteria, viruses, fungi, spores and Clostridium botulinum. Chlorine dioxide has the ability to decolorize, deodorize, oxidize and increase the oxide content in wastewater.

As compared to other disinfecting agents containing chlorine, the use of sodium hypochlorite is characterised by relatively lower toxicity, simpler equipment, stable operation, easier control and lower operational and preparation costs, which makes this disinfection method more feasible for smaller hospitals^[6].

Disinfection – hit or myth?

Disinfection has always been there in places where we did not pay much attention to it, such as dentist offices, beauty salons, hospitals, piercing or tattoo parlours. In recent years, it has also entered our lives and become our daily experience. It has protected many against becoming ill. At present, we can consider disinfection to be one of the hygiene and healthy lifestyle principles.

Monika Ciechanowicz
Junior R&D Specialist
PCC Rokita SA

Sources:
[1] Mahmood, A.; Eqan, M.; Pervez, S.; Alghamdi, H.A.; Tabinda, A.B.; Yasar, A.; Brindhadevi, K.; Pugazhendhi, A. COVID-19 and frequent use of hand sanitizers; human health and environmental hazards by exposure pathways. Sci. Total Environ. 2020, 742, 1405
[2] Holzman, S.D.; Larsen, J.; Kaur, R.; Smelski, G.; Dudley, S.; Shirazi, F.M. Death by hand sanitizer: Syndemic methanol poisoning in the age of COVID-19. Clin. Toxicol. 2021, 59, 1009–1014
[3] Neufeld, M.; Lachenmeier, D.W.; Ferreira-Borges, C.; Rehm, J. Is Alcohol an “Essential Good” During COVID-19? Yes, but Only as a Disinfectant! Alcohol. Clin. Exp. Res. 2020, 44, 1906–1909.
[4]Gupta, Arun, et al. “Disinfection by 1% sodium hypochlorite through cold fogging: an innovative appropriate technology against COVID-19 in public health.” International Journal of Research in Medical Sciences 10.1 (2022): 1.
[5] Giacobbo, Alexandre, et al. “A critical review on SARS-CoV-2 infectivity in water and wastewater. What do we know?.” Science of The Total Environment (2021): 145721.
[6] Jalali Milani, Sevda, and Gholamreza Nabi Bidhendi. “A Review on the Potential of Common Disinfection Processes for the Removal of Virus from Wastewater.” International journal of environmental research 16.1 (2022): 1-11.