A new study shows that rubber ducks used as bath-time toys can be a reservoir of bacteria and fungi. The study showed that the liquid released when ducks were squeezed contained potentially pathogenic bacteria in 12 out of 19 toys studied. The bacteria found included Listeria spp, Legionella and Pseudomonas aeruginosa. Fungi were identified in 11 bath toys, some of which were potentially harmful strains. One of the reasons why some microbes can actually grow and form a permanent reservoir of these bacteria and fungi in this situation is that the plastic releases carbon that can serve as a food source for the microbes. Bodily fluids such as urine and sweat as well as contaminants and soap in bathwater add microbes and nutrients such as nitrogen and phosphorus which also help to support growth. The liquid also contained high levels of other species which are not considered harmful
Although the potentially pathogenic species identified are normally considered only harmful to people with lower immunity to infection, it must be remembered that this includes small babies whose immune system is relatively under developed. The study can be found at: Neu L, Bänziger C, Proctor CR, Zhang Y, Liu WT, Hammes F. Ugly ducklings—the dark side of plastic materials in contact with potable water. npj Biofilms and Microbiomes. 2018 Mar 27;4(1):7.