Iron cobalt black spinel

Endpoint summary

Description of key information

Skin irritation: The test item showed no skin irritation potential in the EpiDerm™in vitro skin irritation test.

Eye irritation: The test item showed no eye irritation potential in the EpiOcular™in vitro eye irritation test.

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 potential of the test substance to cause dermal corrosion/irritation was assessed by a single topical application of ca. 25 µL bulk volume (about 17 mg) of the undiluted test substance to a reconstructed three-dimensional human epidermis model in vitro according OECD TG 439.

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. 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 76.7%. Minimal compound residues remained on the tissues treated with the test substance after the washing procedure.

Based on the results the test item does not show a skin irritation potential in the EpiDerm™in vitro skin irritation test under the conditions chosen (BASF SE, 2017).

Eye irritation

The potential of the test substance to cause ocular irritation was assessed by a single topical application of ca. 50 µL bulk volume (about 21 mg) of the undiluted test substance according to OECD TG 492.

Two test runs were performed. Two reconstructed three-dimensional, human cornea model EpiOcular™ tissues per test run were incubated with the test substance for 6 hours followed by an 18-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 did not interfere with the colorimetric test.

In the 1st test run non-concordant replicate measurements of the test-substance treated tissues was obtained (values for single tissues (without KC correction): 78.4% and 15.6%). The high inter-tissue variability of the test substance occurred because tissue 2 (viable tissue and KC tissue) was mechanically damaged during the washing procedure.

In the 2nd test run the final mean viability of the tissues treated with the test substance was 78.7% (values for single tissues (without KC correction): 68.9% and 89.3%).The value for inter-tissue variability of the test substance is 20.3% and therefore minimal out of the acceptance range. Since all other quality criteria of the test were met and the viability values of both tissues are well above the cut off for eye irritation this deviation is not considered to adversely affect the result of this study.

In both test runs slight to moderate compound residues remained on the test-substance treated tissues after the washing procedure and these tissues were black discolored.

Based on the results the test item does not show an eye irritation potential in the EpiOcular™ in vitro eye irritation test under the conditions chosen (BASF SE, 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.