Slags, nickel smelting

Endpoint summary

Additional information

The nickel slag is a complex metal containing substance. It mainly contains iron silicate and silicates of aluminum and calcium. Traces of metals exist in metal, mineral form or included in silicate phases.

In vitro gene mutation studies in bacteria are available for the analogue substance copper slag.

In a reliable EU B13 study (Cantalejo and Catediano, 1997) the analogue substance copper slag was tested in a bacterial reverse mutation assay with Salmonella typhimurium(strains TA 98, TA 100, TA 1537 and TA 1538) both with and without metabolic activation. Negative results with respect to genotoxic activity observed.

Absence of mutagenic effects is predicted for the target substance ncikel slag based on read accross from the analogue substance.

In a reliable EU B13 study (Caballero and Alava, 2000) the analogue substance copper slag was tested in a bacterial reverse mutation assay with Escherichia coli WP2 uvrApKM 101with and without metabolic activation. In addition bacterial survival test was performed that measured the influence of the test substance on the growth of the strain that is used to evaluate the cytotoxicity of the sample No mutations occurred. Copper slag is therefore considered as non mutagenic and does not affect bacterial survival.

Absence of mutagenic effects is predicted for the target substance ncikel slag based on read accross from the analogue substance.

Furthermore classification of the nickel slag was derived based on rules for mixtures:

Germ cell mutagenicity: Not classified

Results from calculated classification are further supported (WoE) by consideration of physical chemical properties of the UVCB substance.

Chemistry and mineralogy of the slag (see IUCLID section 4.23 chemical and mineralogical characterization) were taken into account.

Water solubility (IUCLID section 4.8) and Sequential dissolutions (IUCLID 4.23 Chemical assays) furthermore confirmed species present and their solubility behavior.

Short description of key information:
Complex metal containing substance
Bacterial reverse mutation tests performed with Salmonela Thyphimurium and Escherichia coli.Copper slag is considered as non mutagenic
Classification derived based on mixture toxicity rules
Solubility of the metal constituents is poor

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

The available test data indicate that the analogue substance copper slag has no genotoxicity. Based on read accross it is concluded that the target substance nickel slag is non mutagenic and therefore does not warrant classification for mutagenicity.

Nickel slag does not contain any constituents classified as a Category 1 mutagen. It does contain minor constituents (Cd compounds and NiS) classified as a Category 2 mutagen at actual levels much lower than < 0.1% Therefore nickel slag does not trigger classification for germ cell mutagenicity.

The classification derived is applicable to all nickel slags.See end-point record and discussion above for detailed justifications. 

The assessed samples and derived classifications are representative for typical nickel slags, across the industry, and defined within the concentration ranges outlined under IUCLID section 1.2.

Self-classification of the UVCB substance (IUCLID Section 2.1 & 2.2) was performed based on the following outline:

1. Characterization

The substance is accurately described with elemental composition (typical concentrations and concentration ranges, IUCLID Section 1.2), and specific speciation data (mineralogical composition) obtained from the respective representative samples (IUCLID Section 4, in particular 4.23). This detailed information on the substance identity is used as a basis for the classification.

2. Classification by the rules for mixtures

The UVCB is considered as complex metal containing substance with number of discrete constituents (metals, metal compounds, non-metal inorganic compounds).

The classification is based on concentration thresholds referring to the classified constituents present in the UVCB substance. Specific concentration limits are taken into account.

This concept and classification rules are incorporated in easy to use IT tool which is used to classify the UVCB substance.

 3. Bridging or Read-Across

Toxicological data (gene mutation studies) are available for the analogue substance copper slag. Read accross from the analogue substance (copper slag) to the target substance (nickel slag) is applied (surrogates with similar chemical and mineralogical composition and physical/chemical properties). Considering variability in composition, read-across and bridging is applied by using representative mineralogical/speciation composition combined with the metal concentration ranges (see composition in section 1.2) as a basis for the classification of the UVCB substance -see IUCLID 1.4 for information on Sampling procedure).

4. Bioavailability consideration

No correction for bio-availability applied

 SeeArche Complex Metal Mixture classification calculator (copper version June 2010)

MeCLAS webpage: www. meclas. eu