Cinnamomum zeylanicum, ext.

Endpoint summary

Description of key information

Skin sensitisation (GPMT, OECD TG 406): Sensitising (based on read across from its major constituent eugenol)

Skin sensitisation (LLNA, OECD TG 429): Sensitising (based on read across from its major constituent eugenol) 

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

The sensitising potential of cinnamon leaf oil was based on read across to its major constituent eugenol. Both an LLNA and a guinea pig maximisation test are available for eugenol, which are both included as key studies.

 

In the Local Lymph Node Assay (similar to OECD 429), lymph node proliferation was determined after exposure to 0%, 5%, 10% or 25% eugenol in vehicle, using beta-scintillation counting (dpm/node). A pooled approach (per test group) was used.

Under the conditions of this study, mice exhibited a significant proliferation in the lymph nodes as a result of exposure to Eugenol. A stimulation index (SI) of >3 was found only for the 25% dose group. It can be concluded that Eugenol is a sensitising substance at this concentration, based on EU-criteria.

In a second local lymph node assay was performed, following OECD TG 429, version from 2002. five times four female mice per experimental dosage (2.5%, 5.0%, 10.0%, 25,%, and 50%) were dosed topically on the dorsum of both ears for three days. After five days, the mice were euthanised and their lymph nodes tested. Eugenol was observed to result in dose-dependent induction of local lymph node cell proliferation and SI values of greater than 3 in three concentrations tested (10%, 25%, 50%), therefore eugenol can be regarded as a skin sensitizer.

In the Guinea Pig Maximisation Test (GPMT), intradermal induction was performed with 0.1% test article, epicutaneous induction with 100% test article and the final challenge exposure was done with 25% test article. A negative control group (n=5) was also included. Positive skin reactions were scored and sensitisation rates were calculated. Positive skin reactions were noted in 3 out of 10 guinea pigs treated with 25% eugenol at the challenge phase (mean score of 0.8). A corresponding sensitisation rate of 30% was calculated. No positive skin reactions were noted in the negative control animals. Based on the results of this study and considering the threshold value of 30% as mentioned in EU-criteria, the substance has to be classified as sensitising.

Justification for classification or non-classification

Based on the available results, cinnamon leaf oil needs to be classified as a skin sensitiser 1b, in accordance with the criteria outlined in Annex I of the CLP Regulation (1272/2008/EC).