Does the ash from burnt incense sticks contain poisonous substances?Heavy metals?
I can’t see how it could since it’s made up of common herbs and scents these folks can sell you everything you need to make non-poisonous ash.
It would be hard to see why it would contain heavy metals, especially since if the ash contained it, then some would be in the smoke as well. And that would not be very good.
However…I don’t know that incense is regulated or tested in any manner, so it is possible. Hard to see, given what goes into it, but a lot of common chemicals used in industry contain mercury or other heavy metals that could speciate into both the smoke and the ash.
It seems possible, but unlikely. Unless you can get a High School college-prep chem class to test for you, I think you might have a hard time getting solid proof one way or another.
Just curious (and certainly not meant as a snide comment) - where did you hear of this? News article? Friend? Website?