Reaction product of 2-hydroxybenzoic acid, styrene and oxozinc

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

A Local Lymph Node Assay according to OECD 429 and Commission Regulation (EC) No 440/2008, 30 May 2008, B.42 was performed with CBA/J Rj mice in order to determine the skin sensitisation potential of Reaction product of 2-hydroxybenzoic acid, styrene and oxozinc. Vehicle compatibility was verified in a Preliminary Compatibility Test with Acetone: Olive oil 4:1 (v:v) mixture (AOO). The maximum concentration was 100% using this vehicle.

A Preliminary Irritation / Toxicity Test was performed with the test item at concentrations of 100 % and 50 % in the selected vehicle. The 100 % concentration was considered acceptable as maximum concentration in the main assay, where twenty-four female CBA/J Rj mice were allocated to six groups of four animals each:

- four groups received the appropriate formulation of Reaction product of 2-hydroxybenzoic acid, styrene and oxozinc at concentrations of 100, 50, 25 and 10 (w/v) %,

- the negative control group received the vehicle (AOO),

- the positive control group received 25 (w/v) % HCA in the relevant vehicle (AOO).

The test item solutions were applied on the dorsal surface of ears of experimental animals (25 µl/ear) for three consecutive days (Days 1, 2 and 3). There was no treatment on Days 4, 5 and 6. On Day 6, the cell proliferation in the local lymph nodes was measured by incorporation of tritiated methyl thymidine (3HTdR) and the values obtained were used to calculate stimulation indices (SI).

No mortality or systemic clinical signs were observed during the study. No treatment related effect on the body weights was observed. Dried test item and fixed or slightly fixed ears were observed in the animals of the 100 and 50 (w/v) % treated groups on Days 1-6. Alopecia was observed in the animals of the 100 and 50 (w/v) % treated groups on Days 2-6. Peeling was observed on the ears of the animals of the 50 (w/v) % treated groups on Days 5 and 6.

Significant lymphoproliferative response (SI >= 3) of Reaction product of 2-hydroxybenzoic acid, styrene and oxozinc was observed at the concentrations applied compared to the negative control. Stimulation index values of the test item were 6.4, 89.7, 56.8 and 17.9 at treatment concentrations of 100, 50, 25 and 10 (w/v) %, respectively. These stimulation index values were compatible and in line with the biological dose-related response. The low value obtained for the 100% dose is not unusual and can sometimes be observed in connection with strong sensitisers as cytotoxicity to the immunocytes cannot be excluded.

α-Hexylcinnamaldehyde (25 (w/v) % dissolved in AOO) was used as the positive control to demonstrate the appropriate performance of the assay. A significant lymphoproliferative response (stimulation index value of 21.5) was noted for the positive control chemical, this result confirmed the validity of the assay.

In conclusion, Reaction product of 2-hydroxybenzoic acid, styrene and oxozinc was shown to have sensitisation potential (sensitiser) in the Local Lymph Node Assay under the test conditions used in this study.

Migrated from Short description of key information:
Reaction product of 2-hydroxybenzoic acid, styrene and oxozinc was assessed for skin sensitisation in a Local Lymph Node Assay according to OECD 429 and Commission Regulation (EC) No 440/2008, 30 May 2008, B.42 with CBA/J Rj mice . Based on the results obtained the test substance proved to have sensitising potential.

Justification for classification or non-classification

Based on available data on sensitisation properties, Reaction product of 2-hydroxybenzoic acid, styrene and oxozinc was classified and labelled as a skin sensitiser R43, May cause sensitization by skin contact, according to Directive 67/548/EEC (DSD) and cat. 1 (H317: May cause an allergic skin reaction), signal word “Warning”), according to Regulation (EC) No 1272/2008 (CLP).