Sodium bis[4-hydroxy-3-[(2-hydroxy-1-naphthyl)azo]benzenesulphonamidato(2-)]cobaltate(1-)

Endpoint summary

Description of key information

in vitro skin irritation (OECD 431 and OECD 439): not irritating
in vitro eye irritation (OECD 437 and OECD Draft guideline EpiOcular): not irritating

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)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Skin irritation:

The objective was to assess the potential for corrosive activity and skin irritation of Eukesolar Rubine EB Liquid; dried. Using the currently available methods a single in vitro assay may not always be sufficient to cover the full range of skin irritating/corrosion potential. Therefore, two in vitro assays were part of this in vitro skin irritation and corrosion test strategy: The Skin Corrosion Test (SCT) and Skin Irritation Test (SIT).

The potential of Eukesolar Rubine EB Liquid; dried to cause dermal corrosion/irritation was assessed by a single topical application of 25 μL bulk volume (about 12 mg) of the undiluted test substance to a reconstructed three dimensional human epidermis model (EpiDerm™).

For the corrosion test two EpiDerm™ tissue samples were incubated with the test substance for 3 minutes and 1 hour, respectively. The irritation test was performed with three EpiDerm™ tissue samples, which were incubated with the test substance for 1 hour followed by a 42-hours post-incubation period.

Tissue destruction was determined by measuring the metabolic activity of the tissue after exposure/post-incubation using a colorimetric test. The reduction of mitochondrial dehydrogenase activity, measured by reduced formazan production after incubation with a tetrazolium salt (MTT) was chosen as endpoint. The formazan production of the testsubstance treated epidermal tissues is compared to that of negative control tissues. The quotient of the values indicates the relative tissue viability.

The EpiDerm™ skin corrosion/irritation test showed the following results:

Due to the intense color of the test substance it could not be determined whether the test substance is able to reduce MTT directly. Therefore an additional MTT reduction control was introduced. However, the result of the control tissues inactivated by freezing (KC) did not indicate an increased MTT reduction.

In both tests minimal compound residues remained on the tissues after the washing procedure. However, this did not interfere with the colorimetric test as was demonstrated in a pretest.

Corrosion test:

The mean viability of the test-substance treated tissues determined after an exposure period of 3 minutes was 117%, and it was 101% after an exposure period of 1 hour.

Irritation test:

The mean viability of the test-substance treated tissues determined after an exposure period of 1 hour with about 42 hours post-incubation was 105%.

Based on the observed results and applying the evaluation criteria it was concluded, that Eukesolar Rubine EB Liquid; dried does not show a skin irritation potential in the EpiDerm™ in vitro skin irritation and corrosion test strategy under the test conditions chosen.

Eye irritation:

The objective of the present study was the determination of a possible eye irritating potential of Eukesolar Rubine EB Liquid; dried. Using the currently available methods a single in vitro assay may not always be sufficient to cover the full range of eye irritating potential.

Therefore, two in vitro assays were part of this in vitro eye irritation test strategy: The Bovine Corneal Opacity and Permeability Test (BCOP Test) and EpiOcular Eye Irritation Test.

However, in the current case for Eukesolar Rubine EB Liquid; dried the results derived with EpiOcular alone were sufficient for a final assessment. Therefore further testing in BCOP was waived.

The potential of Eukesolar Rubine EB Liquid; dried to cause ocular irritation was assessed by a single topical application of 50 μL bulk volume (about 15 mg) of the undiluted test substance to a reconstructed three dimensional human cornea model (EpiOcular™).

Two EpiOcular™ tissue samples were incubated with the test substance for 6 hours followed by a 18-hours post-incubation period.

Tissue destruction was determined by measuring the metabolic activity of the tissue after exposure/post-incubation using a colorimetric test. The reduction of mitochondrial dehydrogenase activity, measured by reduced formazan production after incubation with a tetrazolium salt (MTT) was chosen as endpoint. The formazan production of the testsubstance treated epidermal tissues is compared to that of negative control tissues. The ratio of the values indicates the relative tissue viability.

The EpiOcular™ eye irritation test showed the following results:

Due to the intense color of the test substance it could not be determined whether the test substance is able to reduce MTT directly. Therefore an additional MTT reduction control was introduced. The result of the control tissues inactivated by freezing (KC) indicated an increased MTT reduction.

Compound residues remained on the tissues after the washing procedure. However, this did not interfere with the colorimetric test as was demonstrated in a pretest.

The final mean viability of the test-substance treated tissues was 78%.

Based on the observed results for the EpiOcular™ Test alone and applying the evaluation criteria it was concluded, that Eukesolar Rubine EB Liquid; dried does not show an eye irritation potential under the test conditions chosen.

Justification for classification or non-classification

Based on the available in vitro data, no classification for skin and eye irritation is required.