Diatomaceous Earth is one of the very most potent killer of insect and insect like critters. Food grade can be safely be eaten in reasonable amounts and can be used as a wormer also. Don't eat a cupful a day, but small amounts are probably good for you.

The reason to NOT breath the dust is that it will eventually fill your lungs just as Portland cement will.

I always "dusted" our yard each year with diatomaceous earth and hardly ever had flea problems.

Can't think of any right now, but I would bet it will kill some beneficial insects also. Yea, lady bugs for one.

Bob