BERN, Switzerland (AP) — Scientists now have the dirt on the rubber ducky: Those cute yellow bath-time toys are — as some parents have long suspected — a haven for nasty bugs.

Swiss and American researchers counted the microbes swimming inside the toys and say the murky liquid released when ducks were squeezed contained "potentially pathogenic bacteria" in four out of the five toys studied.

The bacteria found included Legionella and Pseudomonas aeruginosa, a bacterium that is "often implicated in hospital-acquired infections," the authors said in a statement.

The study by the Swiss Federal Ins...