Registration Dossier

Administrative data

Description of key information

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion
Additional information:

The dermal sensitizing potential of the test article (colorless liquid, purity 100% CASRN 4303-67-7, batch 338724) was evaluated in a local lymph node assay (LLNA) in female CBA mice. This study was performed in compliance with the Chemicals Act of Germany (2002) and OECD GLP (1997). The study design was based on OECD Guideline 429 (2002). The test article was diluted in vehicle (Acetone/Olive Oil at 4:1 (v/v)) for the appropriate concentrations. A pre-test evaluated 10 and 25% test article on the ear of one mouse mice each for three consecutive days. Treatment with 25% or 10% led to the deaths of both mice after 3 days (25% test article) and 7 days (10% test article). Unintended ingestion following grooming was considered a possible source of the mortality given the known rat acute oral LD50 (641 mg/kg).  A second pre-test evaluated 2.5 and 5% test article for three consecutive days on one mouse each. The animals in the second pre-test did not show signs of irritation or systemic toxicity. Groups of animals (5/treatment) received vehicle, 1, 2.5 or 5% test article on three consecutive days by application on the ears. Three days after the last exposure all animals were subjected to a 3H-methyl thymidine treatment and the auricular lymph nodes were removed to measure the amount of proliferative DNA by disintegrations per minute (DPM). The stimulation index (SI) was calculated for each group and, if possible, the concentration at which the test article could elicit an SI greater than or equal to 3 was determined (EC3). Hexylcinnamic aldehyde (HCA) is tested in this study design every 6 months at the test facility as a positive control and the most recent results indicated that model was valid. Mean DPM/animal values were 1622.5, 4533.7, and 5609.6 for the 1, 2.5 and 5% test article groups, respectively. The mean DPM/animal value for the vehicle control group was 374.9. The SI values for the 1, 2.5 and 5% test article groups were 4.33, 12.09, and 14.96, respectively. The EC3 could not be calculated because all SI were > 3. However, the EC3 is clearly less than 2%, because 1% CASRN 4303-67-7 produced an SI value of 4.33 . Based on the results of this study, the test article is a dermal sensitizer.

Migrated from Short description of key information:
A Local Lymph Node Assay (LLNA) was conducted on Laurylimidazole. The result of the study was:

Sensitizing in a Local Lymph Node Assay (LLNA) conducted according to OECD 429.

Justification for classification or non-classification

Based on the results of the test, Laurylimidazole meets the CLP criteria for Skin Sensitizer 1A.