Could it be possible that McCoy's xenopolycythemia was caused by the build-up of transporter re-materialization errors? (His fears confirmed.) It seems to me that materializology/replicatology/transporter medicine would be a medical specialty worth having. Dealing with transporter-related diseases as well as studying the effects on a body of eating replicated food (similar to how people are studying GMOs). I could see such a specialist being consulted in numerous cases.