Now I can't say 100% its safe...I just know for the past 3 years I have used it.
I use it in my runs and coops.
I don't use tons of it a light dusting about twice a year or more if It seems like the bug population is building up.
It has kept my chickens bug free.
No lice/No mites and all...
I know it kills bugs and I'v used it in my runs to kill bugs out before with no ill affects before. I just didn't know if it be good for the eggs. I use it to kill out bugs in over 3 years of raising chickens iv used it and have had no problems with lice,mites or any other bug infestation.