Reaction mass of Sodium [2,4-dihydro-4-[(2-hydroxy-5-nitrophenyl)azo]-5-methyl-2-phenyl-3H-pyrazol-3-onato(2-)][1-[(2-hydroxy-5-nitrophenyl)azo]-,Sodium bis[1-[(2-hydroxy-5-nitrophenyl)azo]naphthalen-2-olato(2-)]cobaltate(1-)and Sodium bis[2,4-dihydro-4-[(2-hydroxy-5-nitrophenyl)azo]-5-methyl-2-phenyl-3H-pyrazol-3-onato(2-)]cobaltate(1-)

Endpoint summary

Description of key information

Skin irritation/corrosion: The test item has no skin irritation potential in an in vitro study according OECD TG 431.

Eye irritation: The test item has no eye irritation potential in an in vitro study according OECD TG 492.

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/corrosion

The skin irritation and corrosion potential of the test substance was assessed in an in vitro test strategy. Two in vitro assays were part of this strategy: The Skin Corrosion Test (OECD TG 439, SCT) and Skin Irritation Test (OECD TG 431,SIT). However, in the current case the results derived with the Irritation test alone were sufficient for a final assessment. Therefore, further testing in SCT was waived.

In the study according OECD TG 431, the test item was applied using ca. 25 μL bulk volume (about 23 mg) of the undiluted test substance to a reconstructed three-dimensional human epidermis model (EpiDermTM). The irritation test was performed with three EpiDerm tissues which were incubated with the test substance for 1 hour followed by a 42-hour post-incubation period.

Tissue destruction was determined by measuring the metabolic activity of the tissue after exposure/post-incubation by 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 test substance treated epidermal tissues is compared to that of negative control tissues. The quotient of the values indicates the relative tissue viability.

 Due to the color of the test substance, it could not be determined whether the test substance can directly reduce MTT. Therefore, an additional MTT reduction control (freeze-killed control tissues (KC)) was introduced. Brownish discoloration was observed on all test-substance treated tissues after the washing procedure. However, in a pretest, it was demonstrated that the color of the test substance did not interfere with the colorimetric test.

The final mean viability of the tissues treated with the test substance determined after an exposure period of 1 hour with an about 42-hour post-incubation was 82.6%.

Based on the results observed, it was concluded that the test item does not show a skin irritation potential in the EpiDerm in vitro skin irritation and corrosion test strategy under the test conditions chosen (BASF, 2017).

Eye irritation/corrosion

The eye irritation and corrosion potential of the test substance was assessed in an in vitro test strategy. Two in vitro assays were part of this strategy: The Bovine Corneal Opacity and Permeability Test (OECD TG 437) and EpiOcular Eye Irritation Test (OECD TG 492). However, the results derived with EpiOcular alone were sufficient for a final assessment. Therefore, further testing in BCOP was waived.

In the study according OECD TG 492, the test item was applied using ca. 50 μL bulk volume (about 30 mg) of the undiluted test substance to a reconstructed three-dimensional, human cornea model (EpiOcular). Two EpiOcular tissues were incubated with the test substance for 6 hours followed by an18 hour post-incubation period. Tissue destruction was determined by measuring the metabolic activity of the tissue after exposure/post-incubation by 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 epidermal tissues treated with the test substance is compared to that of negative control tissues. The ratio of the values indicates the relative tissue viability.

Due to the color of the test substance, it could not be determined whether the test substance is able to directly reduce MTT. Therefore, an additional MTT reduction control (freeze-killed control tissues (KC)) was introduced. In a pretest, it was demonstrated that the color of the test substance interferes with the colorimetric test. Therefore, color controls (viable tissues CC) and freeze-killed control tissues (KC CC) were performed to differentiate formazan produced by the cells in the MTT test from color residues of the test substance in the colorimetric test.

Orange discoloration and minimal compound residues were observed on all test-substance treated tissues after the washing procedure. The values of the color control (CC) tissues indicate interference due to the color of the test substance (mean value 7.6% of NC). The results of the KC tissues indicate an increased MTT reduction also (mean value 1.2% of NC). Thus, for the test substance the final mean viability is given after CC and KC correction. The final mean viability of the tissues treated with the test substance was 70%.

Based on the results observed in the EpiOcular Test alone and by applying the evaluation criteria, it was concluded that the test item does not show an eye irritation potential in the in vitro eye irritation test strategy under the test conditions chosen (BASF, 2017).

Justification for classification or non-classification

Classification, Labeling, and Packaging Regulation (EC) No 1272/2008

The available experimental test data are reliable and suitable for the purpose of classification under Regulation (EC) No 1272/2008. Based on these information the test item is not considered to be classified for skin and eye irritation under Regulation (EC) No 1272/2008, as amended for the tenth time in Regulation (EU) No 2017/776.