Will Falconer, DVM Moderator
Hi Virginia,
I've never been a fan of DE except in the garden. As it kills its insects by etching their chitin exoskeletons and causing dehydration, imagine how that might feel rubbed into skin. Ouch.
My understanding is this is not an inhalation risk, though concerns seems to persist on the internet. The old saw about "food grade" vs "pool grade" I think was even laid to rest some years back. Particle size is such that DE is cleared from the lungs normally, unlike asbestos fibers, for example. And borax is even larger, so I don't expect any lung issues at all with it.