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.
Sterling Silver tarnishes much more easily due to the copper content because copper oxidizes easily. In addition to surface tarnish when heated to soldering temperatures sterling silver becomes permeable to oxygen which may allow the copper in the alloy to oxidize in the interior resulting in firescale or firestain.