Slags, nickel smelting

Carcinogenicity

Description of key information

complex metal containing substance
classification made based on CLP rules for mixtures
solubility of metal constituents is poor
in vitro bio-accessability tests, mimicking gastric fluids 

Justification for classification or non-classification

Nickel slag does contain minor constituents classified as a Category 1 carcinogen ( NiS ) at max actual levels of 0.04% thus much lower than the threshold of 0.1% triggering classification of the mixture for carcinogenicity Cat 1. It further does contain minor constituents classified as a Category 2 carcinogen but below 1.0 %. Therefore the nickel slag does not trigger classification for carcinogenicity.

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 across production sites –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 are not available for the specific UVCB being evaluated. Considering variability in composition, read-across and bridging is applied by using representative mineralogical/speciation composition combined with the typical metal concentration (across companies) as a basis for the classification of the UVCB substance (chemical and mineralogical surrogates with similar origin/production process and physical/chemical properties (SeeIUCLID 1.4 for information on Sampling procedure).

 

4. Bioavailability consideration 

Data from bio-accessibility test in solution that resembles gastric fluid are available and further confirm the classification.

See Arche Complex Metal Mixture classification calculator (copper version June 2010);MeCLAS webpage: www.meclas.eu

 

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.

Classification derived based on rules for mixtures:

Carcinogenicity: 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.

Nickel slag does contain minor constituents classified as a Category 1 carcinogen ( NiS ) at max actual levels of 0.04% thus much lower than the threshold of 0.1% triggering classification of the mixture for carcinogenicity Cat 1. It further does contain minor constituents classified as a Category 2 carcinogen but below 1.0 %. Therefore the nickel slag does not trigger classification for carcinogenicity.

 

In vitro measurements of bio-accessibility in solvent that resembles gastric fluid performed according to ASTM D5517.07.(pH 1.5) The fraction of metals that solubilize under these conditions can be considered as worst case determinant of bio-assesability of metals contained in the slag.Results demonstrate reduced relative bio-accesabilty of metals (Cu 0.04, Ni 0.05, Co 0.06, dissolved concentrations of Pb and As were below detection limit) thus further confirm the classification.