Rubber ducks might look sweet and innocent, but beneath their glazed-over smile, they harbor a terrible secret. Despite spending half of their lives in a soapy bath, their insides are filthy and pretty damn gross.  

New research by the Swiss Federal Institute of Aquatic Science and Technology, ETH Zurich, and the University of Illinois has found that bathtime toys are riddled with bacteria and fungi that could make you ill.

When you squeeze a rubber duck, you might notice a murky liquid seep out. This is actually a dense growth of bacteria and fungi that’s been thriving on the damp inner surface of the bath toys. The study, published the Nature journal Biofilms and Microbiomes, found between 5 and 75 million cells per square centimeter on the inner surfaces of toys that had been used for 11 weeks.

Over 80 percent of the toys studied also contained high numbers of harmful bacteria like Legionella and Pseudomonas aeruginosa, pathogens that could lead to a trip to the hospital. A further 60 percent also contained fungal species.

“Mouldy bath toys are widely discussed in online forums and blogs, but they have received little scientific attention to date,” Dr Frederik Hammes, study author, explained in a statement.

The risks involved with a dirty duck are relatively minimal and almost certainly not deadly. As many parents and doctors will tell you, exposing your kids to germs and dirt helps them to develop a sturdy immune system. However, Hammes added that children with a weaker immune system could be at risk if they squirt the murky water into their faces, as kids tend to do. “This could strengthen the immune system, which would be positive, but it can also result in eye, ear, or even gastrointestinal infections.”

Don’t worry, health-obsessed scientists are not going to take away your rubber ducky. They don't even think you should attempt to clean your bath toys after use. The researchers on the project insist that the best way resolve the problem is to push for higher-quality polymers to make bath toys and other plastics we keep in our bathroom.