Approach

In the absence of toxicological data on copper massive and copper powder, the hazard assessments for these copper forms are based on read-across to the more data-rich soluble copper compounds (e.g., copper sulfate), less soluble copper compounds (e.g., copper oxide), and fine coated copper flakes (which are coated with substances – e.g., aliphatic acids – to increase the specific surface area of the flakes). Copper ions are assumed to be the toxic moiety responsible for effects observed in vivo, an assumption that is supported by the available database on copper substances. This assumption forms the basis of the read-across approach. For the hazard profiles of copper massive and copper powder, information on solubility and bioaccessibility was evaluated in combination with toxicological data on coated copper flakes and other copper compounds in the read-across approach.

When high-quality data were identified for multiple copper substances or forms (e.g., copper oxide, copper sulfate, and coated copper flakes), consideration was given to chemical properties such as particle size, bioaccessibility, and solubility to enable the selection of the most relevant surrogate, and thus the key study(ies), to read across to the copper form of interest. To evaluate potential systemic toxicity from repeated oral exposure, toxicological data from the more soluble copper forms may be read across to less soluble forms, when no toxicological data are available for the latter, as a conservative measure. To evaluate potential acute oral toxicity, in vivo toxicity data on several copper-containing substances were used in combination with oral bioaccessibility data to predict the oral toxicity of those copper forms without in vivo data. Bioaccessibility data are used to support the read-across rationale and help determine appropriate GHS hazard classifications for the forms of copper metal assessed herein without performing additional animal studies.

Classifications

No human health hazards are assigned to copper massive or copper powder. Table 3.4 of the report summarizes these hazard classifications. Tables 3.2 (copper massive) and 3.3 (copper powder) of the report also present summaries of the justifications for each classification.

Table 3.4  Summary of GHS Human Health Hazard Classifications for Copper Metal Forms

Copper Metal Form	GHS Hazard Classifications	GHS Hazard Statement Code
Copper Massive CAS: 7440-50-8, EC: 231-159-6	Not Classified	NA
Copper Powder CAS: 7440-50-8, EC: 231-159-6	Not Classified	NA

Notes: CAS# = Chemical Abstracts Service Registration Number; EC# = European Community Number; GHS = Globally Harmonized System of Classification and Labelling of Chemicals (UN, 2019); NA = Not Applicable.