The Internet has articles saying anything you can imagine. I would look for scholarly articles from a university or peer reviewed source or pieces from regulatory (FDA/EPA/etc.) or consumer advocacy (Consumer Reports, etc.) agencies for reliable information.
I can tell you that PVC pipes are absolutely allowed in organic production. If you want to use something else, go for it. For piping you can use copper or stainless. Galvanized is considered very safe, but if you’re worried about PVC you might not feel comfortable with zinc plating either. For support/structure, just use wood. Bamboo is cheap and easy, can get dimensional lumber too.