How our supermarket shelves are contributing to deadly antimicrobial resistance
Antimicrobial biocides are the disinfectant and antiseptic ingredients found in household, toilet and laundry cleaning products and other consumer goods such as cosmetics and personal hygiene products.
The first-ever survey of Australian consumer products from chemists, hardware stores and supermarkets, has found that these everyday products may be contributing to the global problem of antimicrobial resistance (AMR), until recently thought to be solely due to the overuse of antibiotics. In 2020 antimicrobial-resistant bacterial infections led to the direct death of 1031 Australians.
The study is important because it highlights that while the Therapeutic Goods Administration regulates anti-bacterial products for efficacy and safety, potential to drive microbial adaptation and AMR is not considered. The survey reveals both the widespread use and the lack of regulation of antimicrobial biocides in products available to the general public in Australia.
According to Dr Francesca Short from Monash University’s Biomedicine Discovery Institute, lead researcher of the study published in the journal, Access Microbiology, said that antimicrobial resistance “arises primarily from antibiotic use in medical and agricultural contexts.”
“Adaptation to biocides – such as those used in some personal hygiene products - can occur when bacteria are exposed to them at levels not enough to kill the bacteria, but enough to induce a stress response and select for fitter variants. Previous research from our group and others found that biocide adaptation can lead to antibiotic resistance as well, but it was impossible to judge the scale of the issue in Australia.”
While bacteria are unlikely to survive direct exposure to products such as hand sanitiser, according to the study, bacteria can be exposed to low concentrations of biocides in the environment due to the release of these molecules through wastewater streams, and when products are used that have reduced activity due to age or incorrect formulation.
Because of the widespread use of biocides it is difficult to determine how much real-world antimicrobial resistance results from their use. This is the first study to focus solely on direct-to-consumer products in Australia, “because they are likely to account for a large proportion of biocide exposure, particularly in the wake of the COVID pandemic,” Dr Short said. “In addition, this could be an easy area to make changes that will help protect us from AMR – there are many different biocides, and only some have the problematic follow-on effects.”
The scientists searched for products available through official websites of Australia’s leading supermarkets and pharmacies (Coles, Woolworths, Chemist Warehouse, Priceline Pharmacy, Terry White Chemmart, Pharmacy 4 Less) or Google Shopping, considered likely to contain antimicrobial biocides and to be used frequently.
These products included personal hygiene and care products, descriptors being: ‘hand sanitizers’, ‘eye drops’, ‘throat lozenges’, ‘mouthwash’, ‘soap’, ‘hand wash’, and ‘antiseptics’; and domestic cleaning products: ‘spray cleaning’, ‘toilet cleaning’, ‘wet wipes’, ‘laundry sanitizer’. ‘Disinfectants’ and ‘wet wipes’ were also searched, and included products used for personal or cleaning use.
The survey found that antimicrobial additives were present in personal hygiene products including hand sanitizers, soaps, skin antiseptics, hand wash, throat lozenges, mouthwash and eye drops.
While the survey found that many products contained alcohol or lactic/citric acid as biocides, which have limited impact on the development of antimicrobial resistance, “of greater concern is the broad use of QACs [Quaternary Ammonium Compounds], which have been strongly linked to antimicrobial resistance development,” first author Charles Nunez said.
Benzalkonium chloride (BAC) was the second most prevalent biocide identified, present in 22 % of surveyed products including spray cleaning products, antimicrobial wipes and mouthwashes, while 31 % of products contained either BAC or a different QAC. “Use of these biocides is predicted to increase the emergence of AMR bacteria, and there are additional concerns about its toxicity,” she said.
Another concerning finding was that an antibacterial agent, triclosan, was present in a few products, despite triclosan being banned in the USA and European Union (EU) in many products due to its potential to worsen the development of antimicrobial resistance.
In the USA, use of 19 biocides in household soap products was banned due to concerns about impacts on AMR pathogens and the environment, and a lack of evidence for improved efficacy. From 2012 in the EU, biocide-containing products must be registered for use under regulations requiring risk assessment regarding the development of resistance. The authors argue that Australia needs better regulation of biocides.
Read the full paper published in Access Microbiology, ‘Cleaning up our disinfectants: usage of antimicrobial biocides in direct-to-consumer products in Australia’.
See news coverage: ABC News, Channel 9 news, The Age (behind paywall)
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About the Monash Biomedicine Discovery Institute
Committed to making the discoveries that will relieve the future burden of disease, the Monash Biomedicine Discovery Institute (BDI) at Monash University brings together more than 120 internationally-renowned research teams. Spanning seven discovery programs across Cancer, Cardiovascular Disease, Development and Stem Cells, Infection, Immunity, Metabolism, Diabetes and Obesity, and Neuroscience, Monash BDI is one of the largest biomedical research institutes in Australia. Our researchers are supported by world-class technology and infrastructure, and partner with industry, clinicians and researchers internationally to enhance lives through discovery.