2,2-dimethyl-3-(3-methylpenta-2,4-dienyl)oxirane

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

The study was performed to GLP and the method followed OECD 429 to assess the skin sensitisation potential of the test material in the CBA/J strain mouse following topical application to the dorsal surface of the ear. In a preliminary screening test mice were treated by daily application of 25 μl of the undiluted and 50% v/v in acetone/olive oil 4:1 diluted test item to the dorsal surface of each ear for three consecutive days (Days 1, 2, 3). The mice was observed twice daily and local skin irritation was scored daily. Any clinical signs of toxicity, if present, were also recorded. The bodyweight was recorded on Day 1 (prior to dosing) and on Day 6. Ear thickness measurements were conducted using a digital thickness gauge prior to dosing on Days 1 and 3, and on Day 6. A mean ear thickness increase of equal to or greater than 25% and/or well-defined irritation at the most (maximum grade 2) was considered to indicate excessive irritation and limited biological relevance to the endpoint of sensitisation. Very slight erythema was scored for the animals in the 100% group on Days 1, 2 and 3 post-dosing however no signs of irritation were observed thereafter. No signs of systemic toxicity were observed in any of the animals examined. Variations in ear thickness during the observation period were less than 25% from Day 1 pre-dose values. Based on the preliminary test, the concentrations selected for the main test were 0%, 25%, 50% and 100% v/v. In the main test, three groups of five female CBA/J mice were treated with test substance concentrations of 25, 50 or 100% w/w on three consecutive days, by open application on the ears. Five vehicle control animals were similarly treated, but with vehicle alone (Acetone/Olive oil (4:1 v/v)). No irritation of the ears was observed in any of the animals examined. Body weights were within the range seen for historic control animals. The auricular lymph nodes of the vehicle control group and 25% group were considered normal in size. The nodes of the 50% and 100% groups were considered enlarged. The largest nodes were found in the highest dose group. No macroscopic abnormalities of the surrounding area were noted for any of the animals. Mean DPM/animal values for the experimental groups treated with test substance concentrations 25, 50 and 100% were 751, 2746 and 4101 DPM, respectively. The mean DPM/animal value for the vehicle control group was 403 DPM. The SI values calculated for the substance concentrations 25, 50 and 100% were 1.9, 6.8 and 10.2, respectively. These results indicate that the test substance could elicit a SI ≥ 3. The data showed a dose-response and an EC3 value of 29.0 %. Under the conditions of this study, the test substance would be considered to be classified as skin sensitizer (Category 1B) under Regulation (EC) No 1272/2008.

Migrated from Short description of key information:
Skin sensitisation: sensitising, EC3 29% female mice, OECD 429, Wil Research B.V. 2014

Justification for selection of skin sensitisation endpoint:
one GLP compliant Klimisch 1 LLNA study indicating positive reaction to dermal exposure representative of the lowest dose descriptor available.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

The substance meets classification criteria under EU Directive 67/548/EEC for skin sensitisation: R43.

The substance meets classification criteria under Regulation (EC) No 1272/2008 for skin sensitisation category 1B.

 

The weight of evidence indicates that the substance has a low frequency of occurrence in humans and/or low to moderate potency in animals (EC3 >2%) and can be presumed to have the potential to produce sensitisation in humans via the dermal route.