Cobaltate(3-), bis[6-amino-5-[(2-hydroxy-3,5-dinitrophenyl)azo]-1-naphthalenesulfonato(3-)]-, sodium

Endpoint summary

Description of key information

Skin irritation: non irritant

Eye irritation: non irritant

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

The potential of irritation/corrosion to skin and eye was assessed based on available data on Acid Green 104, Similar Substance 01 and Similar Substance 02.

In particular, Acid Green 104 and read-across substances are cobalt complexes with 2 phenyl-azo-naphtyl ligands functionalised by similar groups. Details on the read across approach are attached in section 13.

Skin and eye irritation studies with Acid Green 104 were conducted in rabbits. The composition of test material was 85 % dye and 15 % Na₂SO₄. No detailed description of the study, possibly including irritation scores, was available. The substance was only reported as slightly skin irritant and non eye irritant. Due to the lack of data, both reliability and results of the studies could not be assessed. Thus, such studies were not used in the decision on classification.

Skin irritation/corrosion potential was assessed in an in vitro study on Similar Substance 01 using EpiDerm^TM model according to OECD guideline 431 and 439.

Tissue destruction was determined by measuring the metabolic activity of the tissue after exposure/post-incubation using a colorimetric test.

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

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

Based on evaluation criteria reported in OECD guidelines, Similar Substance 01 resulted as non skin irritant.

Eye irritation potential was assessed in an in vitro study on Similar Substance 01 according to a draft proposal for a new test guideline (EpiOcular^TM) of 2014.

Two 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 final mean viability of the treated tissues was 78 %.

Based on evaluation criteria reported in OECD guideline Similar Substance 01 resulted as non eye irritant.

A supporting evidence to in vitro findings was derived from in vivo tests on Similar Substance 02, which resulted as non irritant to the skin and eye of rabbits.

Additional studies on Similar Substance 02, tested in different FAT at different concentrations, were available. Slight signs of irritation to the eye or skin of rabbits were reversible within the observation period of 7 days. Therefore, the substance was considered as non irritant to the skin and eye of rabbits.

Skin irritation potential of Similar Subtance 02

FAT	% dye	outcome	date
FAT 20036/A	42%	non irritant	1974
FAT 20036/C	63%	non irritant	1980

Eye irritation potential of Similar Substance 02

FAT	% dye	outcome	date
FAT 20036/A	42%	non irritant	1974
FAT 20036/C	63%	non irritant	1980
FAT 20036/D	71.8%	non irritant	1982

Available information indicated each FAT as composed by dye and coupage, typically sodium lignosulfonate, water, sodium sulfate. Such species were expected to have no impact on the toxicological profile.

Justification for classification or non-classification

OECD guidelines for in vitro tests contain indications on how to interpret the results according to the UN GHS categories. There is a correspondence between categories 1 and 2 (not further specified) of the UN GHS and those of the CLP Regulation (EC 1272/2208).

Skin corrosion EpiDerm^TM model in vitro allows to decide on classification of a substance in cat. 1, based on viability (% of negative control) as follows:

< 50 % after 3 min: prediction is corrosive (optional sub-category 1A)

≥ 50 % after 3 min and < 15 % after 1 hour: prediction is corrosive (optional sub-category 1B and 1C)

≥ 50 % after 3 min and ≥ 15 % after 1 hour: prediction is non-corrosive

Skin irrititation EpiDerm^TMmodel in vitro allows to decide on classification of a substance in cat. 2, based on viability (% of negative control) as follows:

≤ 50 % prediction is irritant (category 2)

> 50 % prediction is non-irritant

Since a viability above 100 % was obtained in in vitro skin corrosion and irritation studies, no classification was applied.

Evaluation of results of EpiOcular^TM model in vitro allows to decide on the classification of a substance, based on mean tissue viability (% of negative control) as follows:

≤ 60 % prediction is corrosive or irritant (category 1 or 2)

> 60 % prediction is non-irritant

Since a viability of 78 % was obtained in in vitro eye irritation studies, no classification was applied.

In addition, skin corrosion/irritation and eye irritation in vivo studies were evaluatued according to the CLP Regulation (EC 1272/2008).

Skin irritation means the production of reversible damage to the skin following the application of a test substance for up to 4 hours. Classification as skin irritant is applied if gradings at 24, 48 and 72 h after exposure leads to reaction scores above the threshold values of 2.3 in at least 2 of 3 animals.

Since in all cases, observed effects were below these thresholds and fully reversible within the observation period no classification as skin irritant was applied according to the CLP Regulation (EC 1272/2008).

As for eye irritation, a positive response in at least 2/3 animals, in terms of corneal opacity ≥ 1 and/or iritis ≥ 1, and/or conjunctival redness ≥ 2 and/or conjunctival oedema (chemosis) ≥ 2, calculated as mean scores of gradings at 24, 48 and 72 hours after instillation, leads to a classification in category 2 (eye irritant), if such effects fully reverse within 21 -days.

Very slight to slight signs of irritation were noted upon application of test substance, in both rinsed and unrinsed eye. Considering that the eye irritation scores were all below the threshold values and the that all signs were fully reversible within a 7 -day observation period, no classification as eye irritant was applied according to the CLP Regulation (EC 1272/2008).