Yes it is true, but, each toilet would be different and there is no telling to what degree each toilet does it, if at all.
It has been going on ever since there were toilets.
Your body fights germs constantly, in or out of the bathroom.
If you practice sensible, realistic, cleanlyness and hygene I can't see a problem under normal circumstances.
I watched a program that showed that water out of a toilet had less bacteria than a kitchen counter top.
If you watched American Inventor they had a guy who invented a filter for the purpose of cleaning the germs, but, the germs still got out, fewer, but they got out, and the filter will bejust 1 more thing to change every so often and repair when it breaks.