Plague?

[Aquagility]

What causes the black spots on the white silicone sealant in my shower cabinet? And how can I get rid of them? Rubbing and scrubbing seem to have no effect at all.

[Catso]

I don't think there is a sure-fire way to remove it for any length of time. I believe it's a fungus or mould, that feeds on the silicone and the damp. Bleach will remove it, but it will soon return.

You can get sealer with that microban stuff in it now, which is supposed to prevent it (never tried it, so I don't know)

[anotheoldgit]

We have had some success with the following product, but can't guarantee it will not return, but then you could always give it another spray.
DETTOX Anti-Bacterial, Mould & Mildew Remover.

[Aquagility]

Thank you both. I have had no success with bleach - probably did not leave it on long enough. I will now try Dettox.
We old gits should stick together!

[alvin100]

Try replacing the silicone with a good quality bath silicone as this includes a mould inhibitor, make sure you wipe it down regularly with clean water.

[parkesquay]

In addition to all the good answers a lot of people fail to carry out simple daily maintenance, i.e.always keep your bathroom windows open as long as is practical and wipe off the excess wet areas immediately after a shower. Yes I know it adds a little time and is a small chore but it is worth it in the long run.

[Disco Fever]

This also probably means you do not have adequate ventilation in your bathroom that's why you have a build up of mildew and mould.