Registration Dossier

Administrative data

Description of key information

Key value for chemical safety assessment

Additional information

Justification of the read-across from copper (II) oxide to copper sulphide:

In order to minimise animal testing, available data on copper(II) oxide have been read-across to copper sulphide (copper (II) oxide is unclassified on the basis of acute toxicity, irritation and sensitisation potential). These are both simple inorganic copper(II) compounds with very low water solubility and an anion of no toxicological concern. In fact, theoretical estimates for the solubility of copper sulphide are orders of magnitude lower than those of the oxide, ranging from 3.31E-11 µg/L to 2.4E-10 µg/L. It is generally accepted that lower water solubility can be equated to lower bioavailability and hence acute toxicity; an effect clearly seen by a comparison of copper(II) oxide toxicity with that of the more soluble copper(I) oxide. On this basis, it is considered that a read-across of the acute toxicological, irritation and sensitisation properties from copper(II) oxide to copper sulphide represents a reasonable worst-case approach, and leads to that conclusion that copper sulphide is similarly unclassified. This conclusion is supported by the fact that acute oral and irritation testing carried out with dicopper sulphide confirms that this marginally more soluble compound is also unclassified.

Acute oral toxicity:

A GLP-compliant acute oral toxicity study was conducted with the read-across compound copper (II) oxide using male rats, in accordance with OECD Guideline 423 (Sanders, 2002a). The LD50 value obtained was > 2500 mg/kg bw. It is therefore concluded that copper sulphide is not classified on the basis of acute oral toxicity.

Acute inhalation toxicity:

Copper sulphide has an extremely low calculated mass solubility in the range 3.31E-11 mg/L to 2.40E-10 mg/L.  Any inhaled material will also be insoluble in lung fluid, with negligible bioavailability or potential to cause toxicity.  Compounds with low solubility in lung fluid have been shown not to require classification on the basis of acute inhalation toxicity.  It is considered that copper sulphide aligns with this category of copper compounds and should therefore not be classified.  This approach is consistent with sound scientific principles and the obligation to avoid animal testing whenever possible.

 

Acute dermal toxicity:

A GLP-compliant acute dermal toxicity study was conducted with the read-across compound copper (II) oxide using male and female rats in accordance with OECD Guideline 402 (Sanders, 2002b). The LD50 value obtained was > 2000 mg/kg bw. It is therefore concluded that copper sulphide is not classified on the basis of dermal toxicity.

Justification for classification or non-classification