This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
Both metal and copper oxidize when exposed to oxygen and this is a natural process. Copper that is exposed to the outside environment is more likely to turn green and that is why copper vases and decorative pieces in gardens are often green.
Each element give off a particular color when heated in a flame. (Some are colorless). Copper gives off a green flame but to do that there must be some copper compound IN the flame. (there are many other elements that also could be causing a green flame).