Sodium 4-propoxycarbonylphenoxide

Endpoint summary

Description of key information

In the absence of data on skin sensitisation on target substance sodium 4-propoxycarbonylphenoxide an analogue read-across approach was conducted on source substance propyl 4-hydroxybenzoate:

LLNA (OECD 429): not sensitising

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

Justification for read-across

No data on skin sensitisation are available for sodium 4-propoxycarbonylphenoxide. The skin sensitisation assessment was therefore based on studies conducted with an analogue substances as part of a read across approach, which is in accordance with Regulation (EC) No. 1907/2006, Annex XI, 1.5. For each specific endpoint the source substance(s) structurally closest to the target substance is/are chosen for read-across, with due regard to the requirements of adequacy and reliability of the available data. Structural similarities and similarities in properties and/or activities of the source and target substance are the basis of read-across. A detailed justification for the read across approach is provided in the technical dossier (see IUCLID Section 13).

propyl 4-hydroxybenzoate (CAS 94-13-3)

The skin sensitising potential of the source substance propyl 4-hydroxybenzoate was investigated in a Local Lymph Node Assay (LLNA) in mice according to OECD Guideline 429 (Basketter, 1992). Four CBA/Ca mice per test group were treated with the test substance at concentrations of 5, 10 and 25% in acetone/olive oil (4:1 v/v) or with vehicle alone for three consecutive days by open application on the ears (25 µL/ear). Three days after the last exposure, all animals were injected with 3H-methyl thymidine and approximately after five hours the draining (auricular) lymph nodes were excised and pooled for each test group. After precipitating the DNA of the lymph node cells, radioactivity measurements were performed. Treatment with test substance concentrations of 5, 10 and 25% resulted in SI values of 1.3, 1.6 and 1.3, respectively. No EC3 value was calculated. The reliability check with positive control mercaptobenzothiazole indicated that the LLNA is an appropriate model for testing for contact hypersensitivity. Based on the results, the test substance was not regarded as a skin sensitiser under the conditions of the test.

Additional studies were performed on source substance propyl 4-hydroxybenzoate (Basketter, 1994; Basketter, 1991; Marzulli, 1968):

The source substance propyl 4-hydroxybenzoate was investigated in a Local lymph node assay according to OECD 429 (Basketter, 1994). Four female CBA/Ca mice per test group were treated with the test substance at concentrations of 5, 10 and 25% in acetone/olive oil (4:1 v/v) or with vehicle alone for three consecutive days by open application on the ears (25 µL/ear). Three days after the last exposure, all animals were injected with 3H-methyl thymidine and approximately after five hours the draining (auricular) lymph nodes were excised and pooled for each test group. After precipitating the DNA of the lymph node cells, radioactivity measurements were performed. Treatment with test substance concentrations of 5, 10 and 25% resulted in SI values of 1.4, 1.0 and 1.3, respectively. No EC3 value was calculated. The reliability check with positive control mercaptobenzothiazole indicated that the LLNA is an appropriate model for testing for contact hypersensitivity. Based on the results, the test substance was not regarded as a skin sensitiser under the conditions of the test.

Further, the source substance propyl 4-hydroxybenzoate was investigated in a Local lymph node assay according to OECD 429 performed at 4 different laboratories for an interlaboratory trial under same conditions as reported before (Basketter, 1991). Treatment with test substance concentrations of 5, 10 and 25% resulted in SI values of 1.3, 1.6 and 1.3; 1.9, 2.2 and 1.3; 1.0, 1.2 and 1.5; 1.2, 0.5 and 2.0, for the 4 laboratories respectively. Based on the results obtained by the four different laboratories, the test substance was not regarded as a skin sensitiser in any case.

In addition, a skin sensitisation test in 23 guinea pigs according to the Draize protocol (similar to OECD 406) is available for source substance propyl 4-hydroxybenzoate (Marzulli, 1968). For induction exposure, a test substance concentration of 3% was intradermally applied 10 times (every second day) for a period of 20 days in total. On Day 34 challenge exposure was applied by one intradermal injection and epicutaneous application of test substance at 3%. Evaluation method was not further specified. After rechallenge none of the animals showed a positive reaction. Therefore, based on the results obtained, the test substance was not regarded as a skin sensitiser.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Based on the analogue read-across approach, the available data on skin sensitisation do not meet the classification criteria according to Regulation (EC) 1272/2008 and are therefore conclusive but not sufficient for classification.