(CNN)A new study confirms what parents already know: the inside of a rubber ducky is gross.
Yes, those must-have pieces of the bath toy arsenal, look great in the store. They're brightly colored bits of joy the first time the little ones dunk 'em in the bathtub.
But what do they look like after a couple of weeks? They're usually caked with cruddy black stuff on the opening in the bottom and have a sticky, slimy substance on the insides. And that stuff is not harmless.
A new study published this week in the journal NPJ Biofilms and Microbiomes says that slimy stuff inside bath toys are teeming with bacteria with scary sounding names, like Bradyrhizobium, Agrobacterium, Caulobacter and Sphingomonas. Also found was Pseudomonas, which typically can cause eye and ear infections in humans.
In the study, researchers tested 19 different bath toys and found that plastic toys plus dirty bath water is a microbe's dream.
The main problem, says lead researcher Frederik Hammes, is what's in the plastic that make up rubber duckies and other bath toys.
"All these soft plastic materials have softeners called plasticizers in them to make them flexible," Hammes, who conducted the study with five other researchers at the Swiss Federal Institute of Aquatic Science and Technology, told CNN. "(The plasticizers) migrate out of the plastic into the water. The bacteria like to eat them"
But it's not just the chemicals leaking out of the toys that the microbes and bacteria like. The warm bath water itself is full of things they want too, like nitrogen and phosphates, supplied by soap and human body fluids. So the combination of plasticizers and dirty bath water creates almost a buffet for the bacteria to enjoy.
"It just gives them a nice amount of food to grow," Hammes said.
All this talk of bacteria and infections is definitely scary, but Hammes doesn't want people to freak out about it too much. We're exposed to microbes and bacteria all the time, he said, so "a bit of bacterial exposure is not that bad."
So while it's not so bad for healthy people, anyone with a compromised immune system may need to take more care.
So just what should a parent do to protect their children from the bacteria found in bath toys? Stop buying them? Give up bathing their kids?
No, nothing that dramatic, says Hammes. Some routine cleanliness will do just fine.
"The easiest answer is to wash the toy regularly with clean hot water and a bit of soap," he said. "Also, there are actually many toy ducks without a hole. Less fun, but certainly cleaner."
And that jibes with a trick that every good parent knows: put super glue in the bath toy's hole. Sure, it stops the squirting fun, but it does prevent the plague.