They used to be. Nowadays, actually all new ceramic skillets are PFAS-free. PFAS is a collective term for all kinds of artificial substances that repel water, dust, dirt or grease. Best known are Teflon (PTFE) and PFOA, which was widely used for non-stick coatings. Since 2020, this has been banned in the EU. By the way, you can safely use old pans that are not PFAS-free, as long as you follow the manufacturer's instructions. The most important thing is not to let them get too hot.