Registration Dossier

Administrative data

Description of key information

In a study performed to OECD Guideline 429 with GLP compliance, female mice were exposed topically on the dorsum of both ears to the test item at concentrations of 1%, 10% and 25% in acetone/olive oil (AOO) for three consecutive days.Control mice were treated with AOO (vehicle control) or with the reference item hexyl cinnamic aldehyde (HCA) in AOO (positive control) at concentrations of 10% and 30%. Mice were sacrificed after three days, small pieces were stamped from each ear, and weighed. The draining lymph nodes were excised, weighed, and single cell suspensions were prepared. Cell counts of the lymph node cell suspensions were measured, and based on significant responses in ear swelling and increases in lymph node cell counts a differentiation index (DI) was calculated for test item and reference item. The DI describes the relation between skin-draining lymph node cell activation (lymph node cell count index) and skin inflammation (ear weight index), with a DI > 1 indicating a chemically induced allergic reaction (skin sensitization), whereas 0 < DI < 1 demonstrates an irritant potency of the tested substance.

HCA as reference item and dosed at 10% and 30% showed significant increases in lymph node weights and lymph node cell counts in comparison to vehicle controls and thus was tested as skin sensitizing (DI > 1).

The test item showed no increase at concentrations of 1% and 25%, but significant increases of cell counts and lymph node weights at a concentration of 10%. At 1% and 25% the DI was < 1, and 1.9 at 10%, which was mainly due to the response of one animal. Nevertheless, the DI was not as obviously increased as observed for the reference item and not confirmed at 1% and 25%. According to the OECD Guideline 429, other aspects such as the strength of the dose-response and the positive control responses may also be used when determining whether a borderline result is declared positive. In particular the proliferation of cells in the lymph node is considered to be proportional to the dose and to the potency of the applied allergen. In conclusion, as there was no dose-response the test item should is not assessed to be a skin sensitizer.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records
Reference
Endpoint:
skin sensitisation, other
Remarks:
skin sensitisation: in vivo (LLNA)
Type of information:
other: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
2013
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of study:
mouse local lymph node assay (LLNA)
Specific details on test material used for the study:
Lot no: 110825
Date of Expiration: 25.08.2014
Appearance: white powder
Species:
mouse
Strain:
Balb/c
Sex:
female
Details on test animals and environmental conditions:
strain: Balb/c:AnCrl
Positive control results:
HCA was confirmed as a skin sensitiser.
Key result
Parameter:
other: DI (differentiation index)
Remarks:
The DI describes the relation between skin-draining lymph node cell activation and skin inflammation, i.e. a DI > 1 indicates a chemically induced skin sensitization, whereas 0 < DI < 1 demonstrates an irritant potency of the test item.
Remarks on result:
other: The DI (differentiation index) was determined
Interpretation of results:
GHS criteria not met
Conclusions:
The test item showed no increase at concentrations of 1% and 25%, but a significant increase of cells counts and lymph node weights at a concentration of 10%. The DI was < 1 at 1% and 25% and 1.9 at 10%, which was mainly due to the response of one animal. Thus, the DI was not as clearly increased as observed for the reference item and not confirmed at 1% and/or 25% tested dose. In conclusion, as there was no dose-response the test item should is not assessed to be a skin sensitizer.
Executive summary:

In a study performed to OECD Guideline 429 with GLP compliance, female mice were exposed topically on the dorsum of both ears to the test item at concentrations of 1%, 10% and 25% in acetone/olive oil (AOO) for three consecutive days.Control mice were treated with AOO (vehicle control) or with the reference item hexyl cinnamic aldehyde (HCA) in AOO (positive control) at concentrations of 10% and 30%. Mice were sacrificed after three days, small pieces were stamped from each ear, and weighed. The draining lymph nodes were excised, weighed, and single cell suspensions were prepared. Cell counts of the lymph node cell suspensions were measured, and based on significant responses in ear swelling and increases in lymph node cell counts a differentiation index (DI) was calculated for test item and reference item. The DI describes the relation between skin-draining lymph node cell activation (lymph node cell count index) and skin inflammation (ear weight index), with a DI > 1 indicating a chemically induced allergic reaction (skin sensitization), whereas 0 < DI < 1 demonstrates an irritant potency of the tested substance.

HCA as reference item and dosed at 10% and 30% showed significant increases in lymph node weights and lymph node cell counts in comparison to vehicle controls and thus was tested as skin sensitizing (DI > 1).

The test item showed no increase at concentrations of 1% and 25%, but significant increases of cell counts and lymph node weights at a concentration of 10%. At 1% and 25% the DI was < 1, and 1.9 at 10%, which was mainly due to the response of one animal. Nevertheless, the DI was not as obviously increased as observed for the reference item and not confirmed at 1% and 25%. According to the OECD Guideline 429, other aspects such as the strength of the dose-response and the positive control responses may also be used when determining whether a borderline result is declared positive. In particular the proliferation of cells in the lymph node is considered to be proportional to the dose and to the potency of the applied allergen.

In conclusion, as there was no dose-response the test item should is not assessed to be a skin sensitizer.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

In a GLP study according to OECD Guideline 429 in mice there was no indication for a significant skin sensitizing potential. Therefore, there is no need for classification and labelling of the test item according to CLP Regulation 1272/2008/EG.