The temperatures reached in the GVG are insufficient to facilitate reactions with copper – mainly the formation of copper oxides. So when used with the GVG, copper is not hazardous. (Copper-clad cookware is heated to higher temperatures than the copper in the GVG without problems.)

Inhaling copper oxides or copper vapor could be hazardous to your health. The GVG doesn’t reach anywhere near the temperatures required to produce copper oxides or copper vapor.

If one were to “burn” copper with a torch and inhale the fumes produced, they might be subjecting themselves to harm.