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Endpoint summary

Description of key information

In vitro Skin Corrosion Test / Skin Irritation Test (OECD TG 431/439 and GLP): irritating to skin (BASF SE 2021; 69V0281/20B042).

In Vitro Eye Irritation Test (OECD TG 492 and GLP): non-irritating to eyes (BASF SE 2021; 62V0281/20B045).

Additional information

Skin Irritation

For the assessment of the skin irritation/corrosion potential of Santalol Oil, two assays (i.e. the Skin Corrosion Test (SCT) and the Skin Irritation Test (SIT) according to OECD TG 431/439 and GLP) were considered in an in vitro skin irritation and corrosion test strategy, since a single in vitro assay is not considered sufficient to cover the full range of a skin irritating/corrosion potential (BASF SE 2021; 69V0281/20B042).

In the SCT, the potential to cause skin corrosion was assessed by a single topical application of 50μL undiluted Santalol Oil to a reconstructed three-dimensional, human epidermis model (EpiDerm™). Two EpiDerm™ tissues were incubated with the test substance for 3 minutes and 1 hour, each. In addition, 50μL per tissue of a negative control (deionized water) and of a positive control (8 N KOH) were applied to two tissues each per exposure period. The relative mean viability of the tissues treated with Santalol Oil after an exposure period of 3 minutes was 107.9%, and 122.2% after an exposure period of 1 hour. The tissues treated with the positive control (8 N KOH) showed a relative mean viability of 7.5% (3-minute exposure) and 5.5% (1-hour exposure) reflecting the expected sensitivity of the tissues. Based on the results observed and by applying the evaluation criteria, it was concluded that Santalol Oil does not show a skin corrosion potential in the EpiDerm™ in vitro skin corrosion test method under the test conditions chosen.

In the SIT, the potential to cause dermal irritation was assessed by a single topical application of 30μL undiluted Santalol Oil to a reconstructed three-dimensional, human epidermis model (EpiDerm™). Three EpiDerm™ tissues were incubated with the test substance for 1 hour followed by a 42-hour post-incubation period. In addition, 30μL per tissue of a negative control (PBS) and of a positive control (5% SDS) were applied to three tissues each. The relative mean viability of the tissues treated with Santalol Oil determined after an exposure period of 1 hour with an about 42-hour post-incubation was 4.7%. The tissues treated with the positive control (5% SDS) showed a relative mean viability of 2.5% reflecting the expected sensitivity of the tissues.

The acceptance criteria for both assays were met and Santalol Oil was found to be unable to reduce MTT directly.

Based on the results observed and by applying the evaluation criteria, it was concluded that the Santalol Oil shows a skin irritation potential in the EpiDerm™ in vitro skin irritation and corrosion test strategy under the test conditions chosen.

Eye Irritation

In the chosen key study for eye irritation according to OECD TG 492 and GLP (BASF SE 2021; 62V0281/20B045), the potential of Santalol oil to cause ocular irritation was assessed by a single topical application of 50 μL undiluted test substance to a reconstructed three-dimensional human cornea model (EpiOcular™). Two EpiOcular™ tissues were incubated with the test substance for 30 minutes followed by a 2-hour post-incubation period. In addition, 50 μL per tissue of a negative control (deionized water) and a positive control (methyl acetate) were applied to two tissues each.

The relative mean viability of the tissues treated with Santalol oil was 95.4%. The variability between the results of the tissues is within the acceptance range. The tissues treated with the positive control methyl acetate showed a relative mean viability of 25.8%, reflecting the expected sensitivity of the tissues. The mean OD570 of the negative control (deionized water) fulfilled the acceptance criteria and demonstrated the validity of the assay.

The test substance is not able to reduce MTT directly.

When using the currently available methods to assess the eye irritation potential of Santalol Oil, a single in vitro assay may not sufficient to cover the full range of eye irritation potential. In line with the in vitro eye irritation test strategy, two assays are considered relevant, i.e. The Bovine Corneal Opacity and Permeability Test (BCOP) and the EpiOcularTM Eye Irritation Test. In the current case the results derived with EpiOcularTM alone were sufficient for a final assessment. Therefore, further testing with BCOP was waived.

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

Justification for classification or non-classification

The present data on skin irritation fulfill the criteria laid down in regulation (EU) 1272/2008, and a classification as "skin irritant" (category 2) is warranted.

The present data on eye irritation do not fulfill the criteria laid down in regulation (EU) 1272/2008, and therefore, a non-classification is warranted.