Sorry for correcting spelling, but it's *permethrin dust if you want to google it.
EDT: Sevin is pretty toxic. I wouldn't use that except in extreme circumstances--I'd have to have a really bad mite infestation for me to use it.
EDT2: and yeah, sorry that was unclear--permethrin is safe for...
I just googled it. Apparently, aluminum silicate's pretty beneficial as a litter, and pumice is also used, often as an absorbent. Either sounds good to me.
Some acidic wood ashes help retard mite growth, and some people add DE (personally, I think wood ashes are cheaper and just as effective, but if you don't have a furnace, I suppose it makes sense to buy DE.)
I don't know what's in your chinchilla dust bath, but I doubt it would hurt anything...