I'm looking for one around the same price range in Tokyo as well....just not one with a lot of sulfur or other dangerous minerals.......Well, even in trace amounts, doesn't it have the potential of being harmful to the body
The human body is quite remarkable in the way that we have an excellent protection from exposure to most naturally occuring phenomina. Our skin is our first line of defense against all sorts of toxins and while it may seem frail to us when we compare it say the hide of an elephant or other animal, it actually does quite a remarkable job at keeping us safe.
The way this system is generally surmised to work is that while yes, trace elements minerals
can be absorbed by the body, usually they are only absorbed by the skin, coming to rest in the extracellular fluid compartment. This means that you could quite literally sweat and drool out any minerals your body absorbs
However it should be noted that this process also stops these minerals from actually ever entering your blood stream (which is the important thing!)
In any case, naturally occuring sulphur has for all intents and purposes no affect on your body chemistry (and isn't even all that dangerous when ingested orally, atleast the levels you would be exposed to). The only other minerals that one would have to worry about would be lead - which would be absorbed into the sweat and saliva as I stated before, and mercury - which is unlikely to be found in an onsen, you're more likely to ingest much more mercury from eating a fish actually.
In all these cases it would take prolonged exposure in order to even begin to have to worry about harboring more potentially toxic elements than your body can safely handle.
So, find someone nice to wash your back and enjoy your onsen, you have nothing to worry about
atsuiiiii
