3-Isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, oligomers, 2-Hydroxy-1(2)- methylethyl carbamate blocked

Endpoint summary

Description of key information

- not irritating to skin (in-vitro Epiderm)

- not corrosive (in-vitro Epiderm)

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 objective was to assess the skin irritation and corrosion potential of the test substance. By using the currently available methods a single in vitro assay is not 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 the test substance to cause dermal corrosion/irritation was assessed by a single topical application of ca. 25 μL bulk volume (about 9 mg) of the undiluted test substance to a reconstructed three-dimensional human epidermis model (EpiDerm™).

For the corrosion test, two EpiDerm™ tissues were incubated with the test substance for 3 minutes and 1 hour, each. 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.

The following results were obtained in the EpiDerm™ skin corrosion/irritation test:

The test substance is not able to directly reduce MTT.

Results of the Corrosion Test (SCT):

The final mean viability of the tissues treated with the test substance determined after an exposure period of 3 minutes was 108.5% and 109.5% after an exposure period of 1 hour.

Results of the Irritation Test (SIT):

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 99.8%.

Based on the results observed and by applying the evaluation criteria, it was concluded that the test substance 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 was to assess the eye irritating potential of the test substance. By using the methods currently available a single in vitro assay is not 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 case of the test substance, the results derived with EpiOcular alone were sufficient for a final assessment. Therefore, further testing in BCOP was waived.

The potential of the test substance to cause ocular irritation was assessed by a single topical application of ca. 50 μL bulk volume (about 15 mg) 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 a 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.

The following results were obtained in the EpiOcular™ eye irritation assay:

The test substance is not able to directly reduce MTT. The final mean viability of the tissues treated with the test substance was 99.6%. The inter-tissue variability of the two test item-treated tissues was 24.8%, whereby the viabilities of the individual tissues were 112.0 and 87.2%. Thus, the acceptance criterion of a variability < 20% was not met. However, as all other acceptance criteria were met in the test and due to the unambiguous result of the test substance (both obtained values for viability >80%), the test was considered valid despite this deviation and was not repeated.

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

Justification for classification or non-classification

Based on the available data, the test substance is not classified with regard to skin and eye irritation according to Directive 67/548/EEC (DSD) and Regulation (EC) No 1272/2008 (CLP), respectively.