Terrestrial isopods aren't capable of biting humans. Some hobbyists have reported their larger isopods attempting to chew on small, thin-skinned amphibians and invertebrates while looking for a high-protein snack. This isn't a common issue. If you're concerned, you can add fish flakes or freeze-dried minnows under the water bowl in your bioactive enclosure. That should meet your isopods' craving for protein.