A common household chemical may be creating superbugs in our drains

A common household chemical may be creating superbugs in our drains

A common household chemical found in many products from your bathroom sink may be the main driver behind superbugs not being killed by antibiotics, according to a new study.

The University of Toronto research looked at triclosan – an antibacterial and antifungal agent often included in household items such as shampoos, soaps, deodorants, toothpastes and cleaning products – and its role in creating antibiotic resistance in Ontario’s sewers.

Wastewater treatment plants are huge swirling pools of microbes and antibacterial chemicals that are the perfect place for antibiotic resistance to thrive. A variety of antibiotics are washed down our drains along with many different strains of bacteria, which build up in sewage treatment plants and mix.

The researchers headed to an Ontario sewer and analyzed the sludge that contained this nasty cocktail of microbes and antimicrobial chemicals. They found that triclosan was the dominant antibacterial compound affecting E. coli and was likely to cause antibiotic resistance within pathogenic bacteria.

“Given that there are so many different antibiotics in sewage sludge, we were surprised to find that the majority of the antibacterial activity of the sludge could be directly linked to triclosan alone,” said Holly Barrett, lead author of the study and a PhD candidate in the University’s Department of Chemistry. Toronto, he said in a statement.

Diagram showing how triclosan can end up in wastewater treatment and create antibiotic-resistant bacteria.

Chemicals like triclosan enter sewage treatment plants after being washed down our drains. There, they can interact with bacteria and cause antibiotic resistance to develop. Image credit: Environ. Sci. Technol. 2022

When we think of antibiotic resistance, we often think of MRSA superbugs in hospitals and people taking over-prescribed antibiotics. Although these are real dangers, relatively few people are aware of the problem created by household chemicals entering the drain pipes beneath our feet.

Triclosan is banned for certain uses in some jurisdictions. For example, the FDA has tried to crack down on the use of the chemical in over-the-counter consumer antiseptic products in the US. But the chemical is apparently still finding its way into sewers in Canada, and the team behind this latest research says its findings show more needs to be done to regulate the chemical in other parts of the world.

“I think our results show that there is an urgent need for regulatory agencies in Canada to re-evaluate the use of triclosan,” Barrett explained.

“It’s still used in thousands of different household and cosmetic products in Canada, as well as in healthcare settings. While there are some regulations to limit the maximum amount of triclosan allowed in consumer products, even very low levels of this chemical can cause antibiotic-resistant bacteria to develop over time. More action needs to be taken,” he added.

Antibiotic resistance is considered one of the biggest threats to global health today. Around the world, a growing number of infections that were once easy to treat – such as pneumonia, tuberculosis, gonorrhea and salmonellosis – are becoming more difficult to treat as the antibiotics used become less effective.

Antibiotic-resistant probiotics have recently become one of the leading causes of death worldwide, and there is little sign that this trend will stop.

The study was published in the journal Environmental Science & Technology.

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