The majority of shower curtains are made from polyvinyl chloride (PVC). That new shower curtain smell that you smell for months, even years, is toxic. PVC shower curtains contain volatile organic compounds (VOCs), phthalates, organotins and metals (lead, cadmium, mercury, chromium, and other metals). A study done in 2008 revealed that PVC shower curtains can release as many as 108 volatile organic chemicals into the air in your home. The chemicals that are being released have been know to cause liver damage, cancers, reproductive and fertility issues, and damage to the central nervous and respitory systems, just to name a few.
Here are some tables taken from the Center for Health, Environment and Justice's Volatile Vinyl report (I had a hard time picking a few, they were all so disturbing):
The minute I came across this report last year I ditched my shower curtain and went out and bought a safe one. Look for shower curtains that are PVC-free. EVA and Peva are some non-pvc shower curtain options. The absolute safest solution, however, will be an organic cotton (or other organic) fabric. I currently have an EVA shower curtain, but I am going to step it up to an organic cotton one soon. Not only will your shower be safe but you can use a fabric shower curtain forever!