Should we reduce our dependence on disinfection in order to create a healthier environment?

Dr. John Lear, Technical Director at BioHygiene, reports.

Disinfection is the process of eliminating or reducing numbers of undesirable micro-organisms such as bacteria, viruses and fungi, generally on surfaces, equipment and in water. Along with related processes such as sterilisation (the complete removal of all microbial life, including bacterial spores) and antisepsis (normally referring to the disinfection of living tissue), disinfection plays an essential role in our homes, the community, industry and in clinical settings. Disinfectants are critical in helping to create a healthier environment and in breaking the chain of infection, preventing the transmission of disease.

The global disinfectant market was valued at more than £24 billion in 2023 and is expected to grow at an annual rate of 10.49% until 2030 (Grand View Research 2024) – a trend driven by the COVID pandemic as well as industrial development, increasing incidences of hospital-acquired infections and general concerns over cleanliness and hygiene. However whereas it is clear that disinfection is a critical process in a number of fields, there are also significant concerns over the increasing use of chemical disinfectants in terms of their toxicity, environmental profiles, carbon footprint and possible links to antibiotic resistance. It is quite possible that in using disinfectants in an effort to create a healthier environment, we are actually doing the opposite in many cases.

Unfortunately most disinfectants are not particularly pleasant and many are potentially harmful to human health. Quaternary Ammonium Compounds, often referred to as QACs or QUATs, represent over 30% of the global disinfectant market (Grand View Research, 2024) being commonly used in disinfectant solutions, wipes, hand sanitisers, sprays and foggers, personal care products, textiles, paints and medical instruments. Studies have shown potential links to asthma, dermatitis, infertility and birth defects and more. Chlorine-based compounds such as sodium hypochlorite (used as household bleach), calcium hypochlorite (bleaching powder), sodium dichloroisocyanurate, chloramine, and chlorine dioxide tell a similar tale and even household bleach, which is perfectly safe when used as directed, can cause irritation to the eyes, skin and respiratory system. Similar concerns exist over other disinfectant types such as alcohols, peroxides, iodophors and aldehydes.

The desire to maintain a healthier environment should not be restricted to the immediate areas to which we are exposed – the wider environment must also be considered. Many disinfectants are environmentally hazardous, for example the QAC benzalkonium chloride at 50% strength and sodium hypochlorite at 14-15%, both concentrations commonly purchased by manufacturers for use as raw materials, carry the “dead fish and tree” hazard pictogram along with the hazard statement “Very toxic to aquatic life with long lasting effects”. As is the case with hazard ratings, the final concentrations employed in finished products may reduce the amount of information that must be stated on the product labels and Safety Data Sheets, or even remove the requirement to declare information altogether, so the content and potential repercussions are not always evident to the user. However the bottom line is that significant quantities of these materials are being released into the environment on a continuous basis. Global production of benzalkonium chloride alone stood at 300,000 tonnes in 2023 and that of sodium hypochlorite was 3,700,000 tonnes in 2022 (Chemanalyst, 2024).

It is therefore no surprise that disinfectant compounds appear at significant levels in wastewater treatment plants, where they may not be completely broken down or even be converted into more harmful disinfectant by-products (DBPs), a known property of chlorine-based disinfectants, for example. These materials then enter the wider environment and studies have demonstrated their presence in streams, rivers, lakes, soils and sediments, and in the tissues of animals that frequent those environments. Adverse ecotoxicological effects on animals including plankton, earthworms, fish, shellfish and amphibians have been observed.

There is also the question of carbon footprint. Most commercially available disinfectants are derived from the petroleum industry, which along with energy-intensive manufacturing processes, results in an extremely high carbon footprint. Quite apart from direct emissions, most of the carbon contained within these compounds themselves ends up being added to the atmosphere through biodegradation, further contributing to global warming. Taking one example, we have estimated the carbon dioxide equivalent (CO₂e) of benzalkonium chloride to be almost 2.5kg per kg of material. Given the figure above, this could mean that 750,000 tonnes of CO₂ were released into the atmosphere during 2023 as a result of benzalkonium chloride use alone, and this is before emissions associated with manufacture are even taken into account.

Finally there is the potential contribution of disinfectant over-use to the issue of antimicrobial resistance. We are currently facing a global antibiotic resistance crisis, as bacteria and other microbes have become resistant to the antibiotics and other antimicrobials that we rely on to treat infections. The development of antibiotic resistance is a natural process but has been greatly accelerated by our over-use and misuse of these agents in medicine, agriculture and horticulture. There are now bacterial species and strains that are resistant to our “last line of defence” antibiotics, and in the near future if not today, it will be impossible to treat infections caused by these organisms. Although true microbial resistance to disinfectants is rare, disinfectants and antibiotics can share mechanisms of action and resistance, and cross-resistance between disinfectants and antibiotics has been observed. Therefore there are ongoing concerns that disinfectant use could contribute to the issue of antibiotic resistance, and given the scale of the problem, it is essential that we continue to monitor this situation.

Given that disinfection is a critical process in many fields we could be forgiven for thinking that the disadvantages discussed above are a price that must be paid in order to break the chain of infection and prevent the transmission of disease. Yet there are increasing concerns and a growing body of evidence that over-use of disinfectants is resulting in adverse affects on our health and on our immediate and wider environment. It is clear that whereas we should continue to disinfect where necessary, we must also avoid the unnecessary use of disinfectants.

There are a number of ways in which we can reduce disinfectant use and to mitigate the health and environmental effects of these agents where their use is justifiably required. Disinfectants should always be used prudently and in a way which reflects necessity and evidence – do we actually need to disinfect in a given situation and are we confident that the product we are using will produce the desired results? In fact there may be many situations where effective cleaning, rather than disinfection, is perfectly sufficient. A shift towards naturally derived and sustainable disinfection will reduce human and environmental exposure to harmful disinfectants and reduce carbon footprint and greenhouse gas emissions. It is also possible to select agents that are less likely to contribute to the issue of antimicrobial resistance. We will further discuss these possibilities in future articles.

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