Isooctyl acrylate

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

Key Study:

The skin sensitization potential of two samples of CASRN 29590-42-9 (MTDID 7819CE and MTDID 7819LS) was evaluated in a local lymph node assay per OECD 429 and OECD GLP (1997). Based on the results of a pre-screen test, test article concentrations of 25, 50, and 100% were tested in the main test (vehicle: acetone:olive oil 4:1), along with a concurrent positive control (25% alpha-hexylcinnamaldehyde in acetone:olive oil). The dorsal surface of both ears of female mice (5/group) were topically treated (25 uL/ear) with the appropriate test article concentration (0, 25, 50, or 100%), at the same time on Days 1, 2, and 3. Three days after the final exposure, all animals were injected with 3H-methyl thymidine and after five hours the draining (auricular) lymph nodes were excised and pooled for each animal. After precipitating the DNA of the lymph node cells, radioactivity measurements were performed. The activity was expressed as the number of disintigrations per minute (DPM) and a stimulation index (SI) was subsequently calculated for each group. The stimulation indices of MTDID 7819CE at the three concentrations were 2.8, 5.0, and 6.0, and the EC3 was determined to be 27.3%. The stimulation indices of MTDID 7819LS at the three concentrations were 3.6, 3.6, and 9.6; an EC3 could not be determined, because all stimulation indices were >3. The stimulation index of the concurrent positive control was 4.7, which is very similar to the stimulation indices of the positive controls for the other two portions of this study (4.6 and 6.5), in which other acrylate monomers were tested. Based on the results of the study, the test article should be considered to be a skin sensitizer, and the weight of evidence indicates that classification as GHS Category 1B is appropriate. 

Supporting Study:

16/20 animals challenged with 25% test material exhibited scores of +/- (or equivocal responses demonstrating mild, barely perceptible erythema). A second challenge using 40% test material produced positive responses (scores of 1); however 7/8 irritation controls (animals challenged with 40% test material with no previous induction exposures) also showed positive responses (scores of 1), indicating that the responses were a result of irritation, rather than sensitization.

Migrated from Short description of key information:
A Local Lymph Node Assay (LLNA) and Buehler test in have been conducted on Isooctyl Acrylate (IOA) (CASRN 29590-42-9). The LLNA (key study) indicated that IOA is classified as a CLP Skin Sensitizer 1B (GHS Category 1B), while the Buehler test (supporting study) was equivocal for sensitization.

Justification for classification or non-classification

Isooctyl Acrylate meets the CLP criteria for Skin Sensitizer 1B (GHS Category 1B).