Grayline is right: PE and PVC are very different. You asked about the environmental issues with PVC. PVC is a rigid material (think: PVC pipe that your plumber uses). It's made flexible by adding a plasticizer. Flexible PVC is the same stuff that was used for seats in your 1967 Ford Galaxie. It's very soft and supple (and sticks to your legs when you wear shorts).
Most plasticizers use a family of chemicals called "phthalates". There has been some concern in recent years, linking phthalates with a variety of health and environmental issues. A few plastic tubing companies now are offering non-phthalate PVC. Look up that term and you'll find them. The material has all of the same properties as the old PVC, but just without the phthalates.