Registration Dossier

Administrative data

Description of key information

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion
Endpoint conclusion:
adverse effect observed (sensitising)
Additional information:

The key study was performed to assess the skin sensitization potential of the test item in the CBA/Ca strain mouse following topical application to the dorsal surface of the ear (LLNA, OECD 429).

The Stimulation Index expressed as the mean radioactive incorporation for each treatment group divided by the mean radioactive incorporation of the vehicle control group are as follows:

Concentration (%v/v) in acetone/olive oil 4:1 Stimulation Index Results
Vehicle na na
25 2.35 Negative
50 3.13 Positive
100 4.50 Positive

In conclusion:

Test item is to be considered as a sensitizer under the conditions of the test. The concentration of test item expected to cause a 3 -fold increase in 3HTdR incorporation (EC3 value) was calculated to be 46%.


Migrated from Short description of key information:
There is one key study (K1) available. The LLNA study was performed according to the OECD 429 and GLP guidelines without signification deviations.(Bradshaw J., 2016) .Based on the results of this study alpha-methylstyrene is considered to be a sensitizer. In addition there is human data available (of questionable quality (all K4) indicating the test substance might indeed cause skin sensitization in exposed workers.

Justification for selection of skin sensitisation endpoint:
The study has been performed according to OECD 429 guideline and under GLP without deviations.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available
Additional information:
Migrated from Short description of key information:
There is no data available.

Justification for classification or non-classification

According to Regulation 1272/2008 on Classification, Labelling and Packaging, a SI (stimulation index) of 3 or more is considered a positive response. The EC3 represents that concentration which is needed to produce an SI of 3. Based on this Regulation the following distinction is made:

- EC3 value ≤ 2 %: Sensitiser Category 1A

- EC3 value > 2%: Sensitiser Category 1B

As, the EC3 of the test item is 46%, it was concluded that alpha-methylstyrene is to be classified as Skin Sensitiser Category 1B according to Regulation 1272/2008 on Classification, Labelling and Packaging.