The rubber ducky you bring into your child's bath isn't as innocent as its smiling face suggests. New findings published in npj Biofilms and Microbiomes shows that bath toys made from flexible plastic materials can attract and spread harmful microbes during bath time.

Medical Xpress reports that for the study, researchers from the Swiss Federal Institute of Aquatic Science and Technology EAWAG, the Swiss Federal Polytechnic School, and the University of Illinois looked at two groups of toys: old bath toys collected from real homes, and new toys they exposed to clean water and bath water over the course of several weeks. What researchers found, after cutting the toys open, wasn't pretty. "All bath toys analyzed in this study had dense and slimy biofilms on the inner surface," the study reads. The old toys also contained dark patches suggesting mold growth, while the biofilms in the newer toys were transparent.

Potentially pathogenic bacteria, including Legionella (the cause of Legionnaires' disease) and Pseudomonas aeruginosa (associated with hospital-acquired infections), were found in 80 percent of all the toys studied. Fungi were also abundant: Fungal growth was detected in nearly 60 percent of the household bath toys and in all of the newer ones tested in dirty water.

When we take a bath, our bodies leach trace amounts of urine, sweat, and fecal matter into the water. Squeezing a bath toy like a rubber duck causes it to suck up that warm liquid and the gunk it contains. The interior of this toy is the ideal place for fungi and bacteria to flourish: The flexible polymer walls release organic carbon compounds which feed the new microbe populations. And when a kid squeezes a bath toy that's full of water, hopefully away from their face, all that bacteria comes squirting out and into the water they're bathing in.

If you want to make bath time a little cleaner, one solution is replacing your traditional rubber bath toys with alternative ones that aren't squeezable bacteria magnets. Unfortunately, that probably means retiring your rubber ducky.

[h/t Medical Xpress]