Nickel sulphide

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

Ni sulphideis classified as Skin Sens. 1;H317 in the 1st ATP to the CLP Regulation. No animal or human studies were identified characterizing skin sensitization following exposure to nickel sulphide. The Ni²⁺ion is considered exclusively responsible for the immunological effects of nickel (Menné 1994). The results of a comprehensive bioaccessibility testing program evaluating release of Ni ion in synthetic sweat from various Ni compounds indicate that Ni sulphidereleases less nickel (II) ion compared to water soluble nickel substances known to be skin sensitizers (including nickel sulphate and nickel chloride), but releases more nickel ions compared to nickel metal, which is also a known skin sensitizer. This suggests that nickel sulphide is probably a skin sensitizer but with lesser potency than water soluble nickel compounds like nickel sulphate. Although the bioaccessibility method has not yet been validatedin vivo, the classification for skin sensitization for nickel sulphide is appropriate to be read-across from nickel sulphate, since it is a skin sensitizer. An explanation of the rationale and methodology is provided in Section 7.4.1 of IUCLID and asAppendix B3. New testing for dermal sensitization in animals is therefore waived for Ni sulphide.

In addition to animal data for nickel sulphate, copious information on human dermal sensitization to nickel sulphate is documented in theNickel and nickel compounds Background Document in support of individual RISK ASSESSMENT REPORTS of nickel compounds prepared in relation to Council Regulation (EEC) 793/9. Additional studies are summarized in the Nickel Sulphate IUCLID dossier Section 7.10.4. One of these studies, a meta-analysis of published patch test studies by Fischer et al. (2005) has been used as the basis for the derivation of a DNEL for dermal elicitation/sensitization with nickel sulphate as described in Section 5.11. The aim of the study by Fischer et al. (2005) was to assess thresholds of response by making a statistical analysis of available dose-response studies with a single occluded exposure and comparing the results to thresholds from other modes of exposure. Eight occluded Ni dose-response studies were selected based on statistical considerations. The statistical analysis showed that 5% of a sensitized population reacts to 0.44 µg Ni/cm²and 10% react to 1.04 µg Ni/cm². In another study with a single open application, 7.8% of sensitized persons responded to a dose 6x higher than the dose to which 10% reacted in occluded exposure. The NOAEL of 0.00044 mg Ni/cm²from the Fischer et al. (2005) study is carried forward as the basis for the derivation of DNELfor dermal elicitation/sensitization. The Ni ion release in synthetic sweat from Ni sulphide relative to that released from Ni sulphate were used to derive a DNEL for Ni sulphide that takes into account its lower Ni ion release in sweat. SeeAppendix B3.

The following information is taken into account for any hazard / risk assessment:

Ni subsulphideis classified as Skin Sens. 1;H317 in the 1st ATP to the CLP Regulation. This is supported by results of recent bioaccessibility testing suggesting that Ni subsulphidereleases less nickel (II) ion compared to water soluble nickel substances known to be skin sensitizers (including nickel sulphate and nickel chloride), but releases more nickel ions compared to nickel metal, which is also a known skin sensitizer. Although the bioaccessibility method has not yet been validatedin vivo, the classification for skin sensitization for nickel subsulphide is appropriate with read-across from nickel sulphate, since it is a skin sensitizer.An explanation of the rationale and methodology is provided in Section 7.4.1 of IUCLID and asAppendix B3in the accompanying CSR.

Value used for CSA:sensitizing

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

No animal or human studies were identified characterizing respiratory sensitization following exposure to nickel sulphide. While there is some evidence from exposure to indicate that some more water-soluble nickel compounds are a respiratory sensitiser in humans, the available data is not considered sufficient for classification of Ni sulphide.

The following information is taken into account for any hazard / risk assessment:

The available data are not considered sufficient for classification as a respiratory sensitizer.

Value used for CSA:not sensitizing

Justification for classification or non-classification

Ni sulphideis classified as Skin Sens. 1;H317 in the 1st ATP to the CLP Regulation. This is supported by results of recent bioaccessibility testing suggesting that Ni subsulphidereleases less nickel (II) ion compared to water soluble nickel substances known to be skin sensitizers (including nickel sulphate and nickel chloride), but releases more nickel ions compared to nickel metal, which is also a known skin sensitizer. Although the bioaccessibility method has not yet been validatedin vivo, the classification for skin sensitization for nickel subsulphide is appropriate with read-across from nickel sulphate, since it is a skin sensitizer.An explanation of the rationale and methodology is provided in Section 7.4.1 of IUCLID and asAppendix B3in the accompanying CSR.