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.
When people sweat, it reacts with the copper jewel resulting in the corrosion of copper and hence salt compounds are formed. The salt of copper is green in color which gets deposited on to the skin of that person. This would result in the formation of green patches, behind the neck of any person. Apart from the above two cases, the failure of certain organs within the body would sometimes result in the formation of green skin.