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Description of key information

Key value for chemical safety assessment

Skin sensitisation

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

The aim of this study was to determine the skin sensitization potential of Sika Hardener MH following dermal exposure in the Local Lymph Node Assay.

The test item was a liquid, hence the maximum concentration of 100 % (the undiluted test item) was tested. Solubility of the test item in Acetone: Olive oil 4:1 (v/v) mixture (AOO) was examined and found to be acceptable. Since AOO is the most preferred solvent according to OECD 429 guideline, no other solvents were examined. The 50 % and 25 % formulations of test item in AOO were real solutions. Applicability of the undiluted test item and the formulations on the ears of animals was acceptable. A preliminary irritation/toxicity test was performed showing that application of test item up to 100 % was acceptable.

In the main assay 20 female CBA/Ca mice were allocated to five groups of four animals each:

-    three groups received Sika Hardener MH at concentrations of 100 %, 50 % or 25 %,

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

-    the positive control groups receiveda-Hexylcinnamaldehyde (HCA) at concentration of 25 %.

Each substance was applied on the external surface of each ear (25 mL/ear) of the animals for three consecutive days (Day 1, 2 and 3). There was no treatment on Days 4, 5 and 6. On Day 6, the cell proliferation in local lymph nodes was determined by measuring incorporation of tritiated methyl thymidine (3HTdR) and the obtained values were used to calculate stimulation indices (SI).

No mortality or significant systemic clinical signs were observed during the study. In the 100 % test item treated group twitching (intermittent) of the animals was observed approximately 1 hour after the third treatment on Day 3, but all animals were normal approximately 8 hours after the treatment and remained normal (i.e. no signs of systemic toxicity observed) during the subsequent days. No significant treatment related effects were observed on animal body weights in any treatment groups. No cutaneous reactions were observed at the site of the treatment (on the ears) in any of the treated groups. Slight, but not significant erythema was observed in the test item treated groups (presumably because of the slight accumulation of the viscous test item) at the base of ears of animals. Slight loss of hair (1/4 animals) was observed in the 100 % dose group. The effect was local (on the top of the head) and not extensive. The above mentioned effects were considered not to be significant and could not have effect on the proliferation results.

Stimulation index values of the test item were 31.8, 24.8 and 23.4 at treatment concentrations of 100 %, 50 % and 25 %, respectively.The stimulation index values were compatible with a biological dose-related response.

Normally, the EC3 value (the theoretical concentration of the test item in the test solution, leading a three fold increase of lymph node cell proliferation over the control) is estimated by linear interpolation using the reported SI values and the corresponding concentrations immediately above and below the SI value of 3. Since no SI value below 3 was observed with the test item, no estimation of the EC3 value was performed in this LLNA.

α-Hexylcinnamaldehyde, dissolved in AOO at concentration of 25 % (w/v) was used as positive control to demonstrate the appropriate performance of the assay. A significant lymphoproliferative response was noted for the positive control chemical with a stimulation index value of 7.4. The positive control results obtained confirmed the validity of the assay.

In conclusion, the test item SIKA Hardener MH was determined to be skin sensitizing in the LLNA assay.


Migrated from Short description of key information:
SIKA Hardener MH was tested for skin sensitising properties in a local lymph node assay. Based on the results obtained from testing the substance was considered as a skin sensitiser.

Justification for selection of skin sensitisation endpoint:
Only one study available.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available
Additional information:
Justification for selection of respiratory sensitisation endpoint:
According to Annex VII Regulation (EC) No 1907/2008 no study has to be conducted.

Justification for classification or non-classification

Based on the results obtained from testing SIKA Hardener MH was classified and labled as R43 (may cause sensitisation by skin contact) and Skin Sensitiser cat. 1 (H317: may cause an allergic skin reaction) according to Directive 67/548/EEC (DSD) and to Regulation (EC) No. 1272/2008 (CLP), respectively.