Copper sulphide

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

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.

Sensitisation:

A GLP-compliant guinea-pig maximisation test was carried out with the read-across compound copper (II) oxide in accordance with OECD Guideline 406 (Sanders, 2002). Discrete or patchy erythema was noted in 4/10 and 2/10 animals challenged with test material after 24 hours, at concentrations of 10% w/w and 5% w/w respectively. In all cases, the erythema disappeared after 48 hours. These reactions were, therefore, not associated with contact sensitisation. No local skin effects were observed in any animals of the control group. Under the conditions of the test, the test material produced a 0% (0/10) sensitisation rate in the guinea pig. On this basis it is concluded that copper sulphide is not a sensitiser.