Dicopper sulphide

Endpoint summary

Additional information

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

In order to minimise animal testing, data on the acute dermal toxicity, eye irritation and sensitisation potential of copper(II) oxide have been read across to dicopper sulphide (copper (II) oxide is unclassified on the basis of acute toxicity, irritation and sensitisation potential). These are both simple inorganic copper compounds with low water solubility and an anion of no toxicological concern. In fact, theoretical estimates for the solubility of dicopper sulphide are orders of magnitude lower than those of the oxide, ranging from 3.43E-10 µg/L to 1.36E-08 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 dicopper sulphide represents a reasonable worst-case approach, and leads to that conclusion that dicopper sulphide is similarly unclassified. This conclusion is supported by the fact that acute oral toxicity (Bradshaw, 2012) and skin irritation testing (Warren, 2012) carried out with dicopper sulphide confirms that this compound is unclassified for these endpoints.

Skin irritation/corrosion:

A GLP-compliant in-vitro skin irritation test was conducted in accordance with the requirements of OECD Guideline 439 and EU Method B.46 (Warren, 2012). Data were presented in the form of percentage viability. The relative mean viability of the test item treated tissues was 57.6% after a 15 minute exposure. On this basis it is concluded that dicopper sulphide is unclassified on the basis of skin irritation/corrosivity potential. This conclusion is supported by the results of a GLP-compliant skin irritation/corrosivity study conducted in the rabbit with the read-across compound copper (II) oxide in accordance with OECD Guideline 404 (Sanders, 2002c). No erythema or oedema was recorded in any animal at any time.

Eye irritation/corrosion:
A GLP-compliant eye irritation study was conducted in New Zealand White rabbits with the read-across compound copper (II) oxide in accordance with OECD Guideline 405 (Sanders, 2002d). Average scores for corneal opacity, iris, conjunctival redness and chemosis were 0.33, 0.22, 0.77 and 0.55 respectively. All effects were fully reversible. It is therefore concluded that dicopper sulphide is not classified on the basis of eye irritation/corrosivity.