I talked with a nice county extension agent today who said anything soft-bodied could be hurt by diatomaceous earth (DE) including toads, though being large and hopping they’ll be less so than a slug or earwig. But, I love my toads, so no more DE.
She did however suggest oil traps to reduce their population while I work to make the habitat less absurdly full of rotting wood (thanks past Claire for all the mulch).