Approach

The physical hazard classifications presented in the report are applicable to both forms of copper metal evaluated. Although it is not an official GHS endpoint, Section 2.2 of the report discusses the combustible dust hazard of the copper metal forms, because an evaluation of this hazard is required in the preparation of a safety data sheet in the United States. The overall assessment of the available literature does not support listing copper metal as a combustible dust hazard.

Classifications

Copper massive and copper powder are not classified for the following applicable GHS physical hazards: explosiveness; flammable solid; self-reactive substances and mixtures; pyrophoric solids; self-heating substances and mixtures; substances and mixtures that, when in contact with water, emit flammable gases; oxidizing solids; corrosive to metals; or desensitized explosives. A summary of the endpoints and details on the hazard classification decisions are provided in Table 2.2 of the report. The remaining seven GHS physical hazard endpoints (flammable gases, aerosols, oxidizing gases, flammable liquids, pyrophoric liquids, oxidizing liquids, organic peroxides) were judged to be not applicable to these forms of copper metal.

Table 2.2  Summary of GHS Physical Hazard Classifications for Copper Metal and Justification

Endpoint	GHS Classification	Justification
Explosiveness	Not Classified	Absence of explosive functional groups/properties.
Flammable solid	Not Classified	Study with coated copper flakes found no burning when in contact with flame for 20 minutes (ECHA, 2018a). Supported by data for copper powder (ECHA, 2018a).
Chemicals under pressure	Not Classified	Study with coated copper flakes found no burning when in contact with flame for 20 minutes (ECHA, 2018). Supported by data for copper powder (ECHA, 2018).
Self-reactive substances and mixtures	Not Classified	Absence of self-reactive functional groups/properties.
Pyrophoric solids	Not Classified	Copper powder is used to extinguish some combustible metal fires (e.g., lithium).
Self-heating substances and mixtures	Not Classified	No data available. Experience with copper metal forms indicates a lack of self-heating properties.
Substances and mixtures that, when in contact with water, emit flammable gases	Not Classified	Copper is not a metalloid. Finely divided copper will not react with water at standard temperature and pressure.
Oxidizing solids	Not Classified	Copper contains no oxygen, chlorine, or fluorine.
Corrosive to metals	Not Classified	No data available. Experience with copper metal forms indicates that they are not corrosive to metals.
Desensitized explosives	Not Classified	Absence of explosive functional groups/properties.

Notes: GHS = Globally Harmonized System of Classification and Labelling of Chemicals (UN, 2019).