Using polypropylene—considered a "cleaner" plastic than PVC—Polystar is a new imported piping being marketed as an alternative in commercial applications.
Fusiotherm is durable, recyclable, and free of PVC, heavy metals, and flame retardants. It's also far easier to install than copper at about the same price.
Plastics are made from petrochemicals whose environmental profiles are complicated at best. But some stand out as, if not cleaner, at least less dirty.