Nickel oxalate

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Additional information:

Where data are not available for nickel oxalate, data for other inorganic nickel compounds (i.e. structurally related substances) that are expected to have similar toxicity can be used for read across. For human health local effects endpoints, the bioavailability of Ni²⁺at the target site determines the potential occurrence and severity of the local effects to be assessed for the read across of nickel substances. For local effects, inorganic nickel substances of similar nickel ion release and similar physical form can be used for read across. For nickel substances, the read-across strategy is predicated on the assumed presence and bioavailability of a common metal anion (e.g., Ni²⁺) at the target site. This is a reasonable assumption for the majority of inorganic compounds and some organic compounds (e.g., metal salts of some organic acids) (ICCM, 2007; OECD, 2007; and ECHA, 2008), provided no significant effect of the other constituents is expected. The oxalate ion is not of concern since oxalate is not known to cause skin sensitization, but only skin irritation (see IUCLID section 7.3).

Although it is not expected that all of the nickel or oxalate ion would be released and bioavailable (based on low water solubility and release of these ions in simulated human bodily fluids [Kirby Memorial Health Center, 2010), the worst-case approach can be taken where read across takes into account the soluble nickel substances and oxalic acid as the ions released from nickel oxalate.

Data for inorganic nickel substances of the highest toxicity for the endpoint being evaluated can be used as a worst-case approach. This approach is not considered to be as representative of nickel toxicity potential for nickel oxalate as read across from an inorganic nickel substance of similar bioavailability, but is worst-case since it represents the highest nickel ion concentration at the target sites based on the potential release of the common nickel ion. In the case of skin sensitization, the substance used for read across is nickel sulfate hexahydrate. Based on nickel sulfate hexahydrate data demonstrating skin sensitization, read across to nickel oxalate would also be a skin sensitizer.

References

ECHA. 2008. Guidance on Information Requirements and Chemical Safety Assessment, Chapter R.6: QSARs and Grouping of Chemicals (Available from ECHA website: http://guidance.echa.europa.eu/docs/guidance_document/information_requirements_r6_en.pdf?vers=20_08_08).

ICMM [International Council on Mining and Metals]. 2007. Health Risk Assessment Guidance for Metals (HERAG) (available from ICMM website: http://www.icmm.com/page/235/our-work/projects/articles/metals-risk-assessment).

Kirby Memorial Health Center. 2010. Bioaccessibility of nickel oxalate (soluble nickel analyses in simulated gastric, interstitial, and lysosomal fluids). Study Sponsor: Metallo-Chimique. Report Date: 2010-06-30.

OECD [Organisation for Economic Co-operation and Development]. 2007. Guidance on Grouping of Chemicals. Series on Testing and Assessment Number 80 (Available from the OECD website: http://www.olis.oecd.org/olis/2007doc.nsf/LinkTo/NT0000426A/$FILE/JT03232745.PDF).

Justification for classification or non-classification

No data are available for nickel oxalate; therefore, data for nickel sulphate and nickel sulphate hexahydrate are used as read-across. Four studies are presented, three of which demonstrate the skin sensitization potential of nickel compounds. In FDRL (1986), all ten guinea pigs developed positive reactions at 24 and 48 hours. In Lammintausta et al. (1985), the lowest frequency of positive reactions was 51.6% when guinea pigs were tested using three different methods (GPMT, open epicutaneous and open epicutaneous with Freund's Complete Adjuvant. In Nielsen et al. (1992), the lowest frequency of positive reactions was 25% when guinea pigs were tested with 3.0% nickel sulfate hexahydrate in hydroxypropyl cellulose. In Seidnari et al. (1996), presented in 7.10.4 "Sensitisation data (humans)", Individuals with no pre-existing history of Ni intolerance underwent patch testing with 5, 10, and 20% nickel sulphate solutions. Patches were removed after 24 hours and subjects were re-tested 30 days later. Nickel sulphate solutions at concentrations up to 20% are not irritant to the skin of non-nickel-sensitive subjects.

Taking all of the available information into consideration and a classification of Xn; R43 and Skin Sens. Cat 1:H317 in the 1st ATP to CLP, nickel oxalate is classified as Skin Sens. Cat 1:H317 and Xn; R43.