PTC- element are safe if the ceramic is not PTFE-coated. And even if it is it needs to get above 260C/500F degrees to even start producing singular fume-molecules.
" PTC immersion heater technology is going to be proven as a great reducer of maintenace down time.Our ptc heaters are a valued asset in aquaculture and fish farming, we make submersible heaters that meet their needs.We sell heaters for plating,metal finishing, diesel exhaust fluid applications. We sell the only PTC heat exchangers.Our PTC heaters are available in 304 stainless,316 stainless, titanium and teflon* for all your chemical metal finishing requirements. "
This is from another site but just so you know!