Ricko,
I use it in all my snake enclosures, and I feed all my snakes on it also. Never had a problem with it. It some cases it can dry out the humidity in an enclosure and cause some shedding problems. If a snake is effected simply supply a wider water bowl.
As for lizards, I never use it with insect eating species for the reasons Simon stated. Its okay with herbavour lizards though, as friut salad has trouble digging tunnels
