Is it dangerous to handle PVC pipes on an 18 hour basis?

Depends on what you’re doing with the pipes

No, skin contact doesn’t appear to pose any hazards. PVC has plenty of issues, to be sure; incineration of PVC releases some very nasty componds, and heavy metals can leach out of PVC pipe into drinking water. But neither of these will happen during routine handling, even over a long time.

PVCs that have been softened by the addition of compounds called plasticizers, particularly phthalates, can be toxic via oral contact, but rigid PVC pipes don’t contain these compounds (and I’m guessing you’re not gonna be sucking on them anyway).

Here’s additional info.