Slags, nickel smelting

Endpoint summary

Description of key information

Complex metal containing substance
In vivo skin and eye irritation studies indicate thatnickel slag is not irritating to the skin or eyes.
Solubility of constituents in water is poor
Classification based on rules for mixtures 
 

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

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.

Skin irritation

In a reliable EU B4 in vivo skin irritation study (Caballero and Alava, 2001) the analogue/surrogate substance copper slag was applied to the shaved skin of a New Zealand White rabbit under a semiocclusive patch. No formation of erythema and edema was observed after 72 h (score 0.0). Copper slag was found to be non-irritating to the skin in rabbits. The absence of irritation effects furthermore excluded the possibility of corrosion, defined as a serious destruction of tissues throughout the skin thickness.

Eye irritation 

In a reliable EU B5 in vivo eye irritation study (Caballero and Alava, 2001) the analogue/surrogate substance copper slag was instilled into the eye of a New Zealand White rabbit. No negative changes in cornea, iris, conjuctivae and chemosis were observed after 72 h (score 0.0 ) Copper slag was found to be not eye irritant.

 

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

Skin irritation/corrosion: Not classified

Eye irritation: 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. Nickle slag is a solid poorly soluble in water. pH of solution observed in the water solubility test is 7.4 thus outside the irritation range ≤ 2 or ≥ 11.5

Justification for classification or non-classification

In the in vivo skin and eye irritation studies the analogue /surrogate substance copper slag was non-irritant and therefore does not require classification for skin irritation/corrosion and eye irritation. Based on read accross it is concluded that the nickel slag is non irritant.

 

Nickel slag contains some minor ingredients classified as Skin Corrorsive and .Skin Irritant but these are all present at concentrations < 1% . Therefore nickel slag is not classified for skin corrosion and skin irritation.

Nickel slag does not contain any constituents classified as Eye Dam.1 . It contains some minor ingredients classified as Eye Irrit. 2 but these are all present at concentrations < 1% . Therefore nickel slag is not classified for eye effects.

 

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 summation (additivity) 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 available (in vivo skin and eye irritation tests) for analogue/surrogate 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 typical metal concentration (across companies) 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 bioavailability applied.

 

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

MeCLAS webpage: www.meclas.eu