I have no doubt that MMS would likely be effective topically and much safer than internal uses. Likewise I can see it as a water purifier. However, silver does the same thing in each case and despite all the mainstream bullcrap warnings, it is quite safe when properly made and administered.
I don't have a degree in chemistry, but it seems that the obvious question is whether or not MMS can be safe in any amounts that are also effective. I will simply pass and not take the chance.