Isobutyl (S)-2-chloropropionate

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Additional information:

In a GLP conform Murine local lymph node assay according to OECD guideline 429, 25 mL of the test substance (purity 99.8 area-%) was applied in MEK as vehicle to the dorsal part of the ears of five female CBA mice in concentrations of 0 (vehicle control), 3, 10 and 50% for three consecutive days. Three days after the last application the mice were injected intravenously with 20 μCi of 3H-thymidine in 250 μL of sterile saline into a tail vein. About 5 hours after the 3H-thymidine injection, the mice were sacrificed and the auricular lymph nodes were removed. The stimulation indices (fold of change as compared to the vehicle control) for cell count, 3H-thymidine incorporation, lymph node weight and ear weight were determined.

When applied as 50% preparation in MEK, the test substance induced a biologically relevant response (increase to 1.5 fold or above of control value = stimulation index (SI) ≥ 1.5) in the auricular lymph node cell counts. However, there was no concentration response relation. There was a definitive increase in lymph node weights as well, without clear cut concentration response relation. Contrary to the cell count, the concentration-dependent increase of 3H-thymidine incorporation into the cells was not biologically relevant (no increase above the cut off stimulation index of 3) at the high concentration. All test-substance preparations did not cause an increase in ear weights. Due to the biologically relevant increases in lymph node cell counts and due to the concentration-response relationship in 3H-thymidine incorporation all without the presence of ear skin reaction the results indicate that a skin sensitizing potential of the test substance cannot be excluded. Thus it is concluded that L-Chlorpropionsaeureisobutylester shows a skin sensitizing effect in the Murine Local Lymph Node Assay under the test conditions chosen. The estimated concentration that leads to the SI of 1.5 for cell count (EC 1.5) and the estimated concentration that leads to the SI of 3.0 for 3H-thymidine incorporation (EC 3) was calculated by linear regression from the results of the 3, 10% and 50% concentrations to be 43.8% and 65.0%, respectively.

Migrated from Short description of key information:
LLNA: sensitising (GLP, OECD 429; BASF 2008)

Justification for classification or non-classification

According to the conditions and results of the available test, the test substance has to be classifed as skin sensitiser (R43 and skin sensitisation Cat 1B following 76/548/EEC and GHS requirements, respectively).