OK you got me on the gold but silver is on the list as well as antimony, Beryllium, cadmium, chromium, copper, lead, manganese, nickel, selenium, vanadium and I would add zinc to that list just from personal experience. This is getting to be a big thing in the welding industry. After 49 years of welding I'm glad I took care of myself. Just welded some stainless pipe inside of the Hungry Horse Dam. A pile of paper 3 inches high just to prove that I knew how to do it safely. Plus cert's.