Those are all things that are present is dirt, except maybe the ethylenedwhatchamacallit, and none of them are dangerous in the levels you would be absorbing from smoke. Even organically grown things can absorb stuff like that. We all know the chemical addatives in cigarettes are bad, but the vast majority of cancer caused by cigarettes is most likely caused by Polonium 210, which as absorbed by tobacco straight from the earth's crust no matter if you grow it 100% organic or not. Most things that are toxic are beneficial or necessary in very small quantities, just like chlorine, which is totally toxic but we could not live without. Aside from meteors and comets and such, everything on earth comes from earth, we can synthesize things but we are only recreating what already exists, using what already exists. Human's don't have mysterious chemistry sets that come from the planet zargon that introduce brand new and never seen before toxins into the world, we just find ways to extract or recreate exactly what we want. And every year we get better and better at it. Every ten years science and technology advance more than they have in the entire history of humanity up to that point. Also, flushing doesn't actually remove ANYTHING from the plant itself, it removes excess buildup from the soil and forces the plant to use the reserves it has stored in the leaves, but you won't be flushing any salts or heavy metals that were previously absorbed out of the flowers or plant material itself. If it absorbed cadmium during the grow, it will have cadmium in it, washing its root system won't remove that from the flowers no mater how much water you run over them.