Study reveals the dirty truth about rubber duckies

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You’d be ‘quackers’ to keep rubber ducks and other plastic toys in the bath, according to new research.

A group of Swiss and US researchers have delved into “the dark side” of rubber ducks and found that they provide ideal conditions for bacteria growth.

The researchers from the Swiss Federal Institute of Aquatic Science and Technology, the Swiss Federal Polytechnic School and the University of Illinois revealed that diverse microbial growth is promoted by both the plastic materials and bath users themselves.

Any plastic materials dunked in bathwater provide ideal conditions for bacterial and fungal growth, according to the study. Dense growths of bacteria and fungi are found on the inner surface of toys and a “murky” liquid will often be released when they are squeezed by children.

Over a period of 11 weeks, experiments were carried out with new bath toys, under conditions simulating household use – some of the toys were exposed to clean water and others to dirty bath water, containing elements such as soap and body fluids.

When the toys were cut open, between five million and 75 million cells per square centimetre were observed on the inner surfaces. However, the researchers stressed that there was a big difference between the plastic toys exposed to different types of water.

Fungal species were detected in almost 60% of the real bath toys and in all the dirty-water control toys.

Potentially pathogenic bacteria were identified in 80% of all the toys studied, including Legionella and Pseudomonas aeruginosa, which is often implicated in hospital-acquired infections.

While the study found that tap water doesn’t typically promote microbial growth, the toys themselves provide a source of nutrients.

The main problem is that the plastic materials – often made of low-quality polymers – release organic carbon compounds that serve as nutrients to growing bacteria. During bathing, other key nutrients such as nitrogen and phosphorus, as well as additional bacteria, are contributed by the human body, external contaminants and personal care products. This allows bacteria and fungi to multiply inside of a toy children often enjoy using to squirt water into their faces.

Should we throw out our beloved rubber ducky?

Microbiologist Frederik Hammes is not surprised by the findings stating that “mouldy bath toys are widely discussed in online forums and blogs, but they have received little scientific attention to date.”

The vulnerable users in this problem are young children who may enjoy squirting water from bath toys into their faces.

“This could strengthen the immune system, which would be positive, but it can also result in eye, ear, or even gastrointestinal infections,” Mr Hammes said.

Should we toss the ducks out with the bathwater? Or as some suggest in online forums, simply plug their holes to prevent squirting? Mr Hammes suggests another approach – tighter regulations on the polymeric materials used to produce bath toys.

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