This article is more than 2 years old

This article is more than 2 years old

Rubber ducks used as bath-time toys are a haven for bacteria that could spread diseases, Swiss and American researchers have found.

The study by the Swiss Federal Institute of Aquatic Science and Technology, ETH Zurich and the University of Illinois, counted microbes swimming inside the yellow toys and found the murky liquid released when ducks were squeezed contained “potentially pathogenic bacteria” in four out of the five toys studied.

The bacteria found included Legionella and Pseudomonas aeruginosa, a bacterium that is “often implicated in hospital-acquired infections”, the authors said in a statement.

“We’ve found very big differences between different bath animals,” said microbiologist and lead study author Lisa Neu, alluding to other types of bath toys such as rubber crocodiles that also were examined. “One of the reasons was the material, because it releases carbon that can serve as food for the bacteria.”

The study, published on Tuesday in the journal Biofilms and Microbiomes, said the scientists discovered a strikingly high volume of up to 75m cells per square centimetre and a variety of bacteria and fungus in the ducks.

Tap water did not usually foster the growth of bacteria, the scientists said, but low-quality polymers in the plastic materials gave them the nutrients they needed.

Bodily fluids such as urine and sweat as well as contaminants and even soap in bathwater add microbes and nutrients such as nitrogen and phosphorus and create balmy brine for bacteria.

While certain amounts of bacteria can help strengthen children’s immune systems, they could also lead to eye, ear and intestinal infections, the researchers said.



The scientists, who received funding from the Swiss government as part of broader research into household objects, said using higher-quality polymers to make the ducks could prevent bacterial and fungal growth.