They bob around in bathtubs, but they are definitely not clean.

A new study has found ugly things lurking inside rubber ducky bath toys. "The dark side of plastic materials in contact with potable water" researched 19 plastic playthings that live in the tub.

A team from the Swiss Federal Institute of Aquatic Science and Technology and the University of Illinois collected five bath toys from different Swiss homes. They also purchased rubber ducks to be studied in adults-only households.

Researchers found that lying around in humid, warm and wet bathrooms creates bacteria and fungi in plastic toys that squirt water. They also exposed the toys to sweat, urine, water and soap over 11 days.

Then they cut them in half and studied the contents.

Study results showed bacteria such as drug-resistant Legionella, as well as E.coli and Listeria, were festering inside the toys' plastic guts. They also found mold. 

Those bacteria can lead to infections, researchers said.

Water isn't the only culprit, the study found. Plastic used in the toys is also to blame by releasing carbon compounds that nourish bacteria.

The researchers said using high-quality polymers to manufacture the toys would solve the problem. But that's not an immediate solution. Plugging the holes in the playthings would stop water from getting inside and creating a mess. Or, adults could wash and disinfect rubber duckies after bath time.

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