
Can germs survive on a bar of soap?
Standard soap doesn’t kill bacteria, it just dislodges them - so where do they go?
Asked by: Shelly Lloyd, Canada
Yes. When you wash your hands, you transfer a thin film of bacteria, skin flakes and oils to the bar of soap. A 2006 study of 32 dental clinics found bacteria growing on the soap in all of them – after all, standard soap doesn’t kill bacteria, it just dislodges them. A 1988 study found that washing your hands with a dirty bar of soap doesn’t transfer any of the germs onto your hands – but then the study was conducted by a US soap manufacturer.
Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.
Authors

Luis trained as a zoologist, but now works as a science and technology educator. In his spare time he builds 3D-printed robots, in the hope that he will be spared when the revolution inevitably comes.
Subscription offer
Subscribe and try your first 3 issues for just £5. After your introductory period you will pay just £22.99 every 6 issues by Direct Debit. Receive every issue delivered direct to your door with FREE UK delivery.