By far the best cookware from a toxins perspective is earthenware. It is also the cheapest. You can find it in most Oriental markets. The only drawback is you have to be more careful with it because it is breakable. Can't let a pot boil dry or drop a lid.
The 2nd best thing is cast iron. Corningware or other glassware is also very good.
Stainless steel still leaches heavy metals, particularly nickel, tin, zinc.