The LHCOS official stance on PVC is: Use at your own risk
The safety of PVC is a hotly debated topic and without research on its effect on crustaceans we are not able to make a determination. Below are some arguments against and for PVC.
PVC isn’t a safe product to be used in a closed environment or with land hermits that tend to taste sample their surroundings, or really anywhere for that matter.
It’s production includes chlorine and lead and it leaches chemical gases into the air, especially in heated areas. In closed areas like crabitats these dangers are even more harmful.
My largest tank is a reef tank and removing the installed PVC plumbing opens two holes at the bottom of my tank. When I bought it 2 years ago I thought a wise way to address that was to wrap the PVC with sisal rope. It solved the problem and gave the crabs something tall and fun to climb and hang out on. Once I realized the dangers of it I removed the pipe and had the holes sealed with a small square of plexiglass.
Something I found on a bird forum:
So going off memory, basically the High Definition PVC (furniture grade) is the best. It’s been deemed safe and used to make items for children. It doesn’t contain dioxins, plasticizers or harmful metals.
What is Furniture Grade PVC?
CPVC (the cream colored PVC) is safe to use for hot and cold water, whereas PVC is only safe used for cold water. The CPVC doesn’t degrade in the sun like PVC does and CPVC also doesn’t off-gas if heated up. Heated PVC will off-gas a colorless, odorless fume which is toxic. CPVC is smaller than the PVC. CPVC goes by the outer diameter measurement whereas PVC uses the inner hollow hole size as it’s measurement.
I wouldn’t use the Schedule 40 white PVC to build anything that could possibly get too warm or be outside in the sun.
I also wouldn’t make something out of PVC that would be chewed on; like a hanging toy or foot toy. I made a shower stand out of PVC years ago, it serves it’s purpose and the birds don’t chew it.