It seems no matter what you do in the bathroom you are spreading a fair amount of germs.  It makes you wonder if it's even safe to flush.

As proven by Myth Busters some time back when a toilet is flushed with the lid open a spray of nastiness is created by a difficult to see spray of filth.  The toilet expels 15 to 47 contaminated water droplets all around the lavatory upon flushing.  Yes, even on your toothbrush.

With so many lidless toilets out there, especially in hospitals a study was conducted to confirm these findings.  And what a confirmation it is.

C. difficile is distributed around your bathroom with each flush.  This is the bacteria that cause diarrhea.

People are encouraged to close the lid when they flush.  Of course now all this spray is contaminating the underside of the lid but you can't have it all.

And of course diligent hand washing is always recommended.

For more see this source article.