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Description of key information

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records
Reference
Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Qualifier:
according to
Guideline:
EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)
Deviations:
not specified
GLP compliance:
yes (incl. certificate)
Type of study:
mouse local lymph node assay (LLNA)
Species:
mouse
Strain:
Balb/c
Sex:
female
Vehicle:
other: DAE433
Vehicle:
other: DAE433
Positive control substance(s):
yes
Remarks:
Dinitrochlorobenzene (DNCB)
Positive control results:
The positive control substance DNCB produced positive LLNA response at an exposure level expected to give an increase in the Stimulation Index SI ≥ 3 over the negative control group, which was in congruence with the expected mode of action of a contact allergen. The positive control also elicited a reaction pattern with statistically significant increase in ear weight. The negative control did not reveal any changes.

Under the given test conditions, the animals exposed to the tested concentrations of the test substance 2-methoxy-5-nitrophenyl acetate elicited sensitising response in LLNA. Positive results in cell proliferation revealed that the test substance 2-methoxy-5-nitrophenyl acetate could be a contact allergen in mice. Comparison of Stimulation Indexes between treated groups and control vehicle group revealed that the test substance 2-methoxy-5-nitrophenyl acetate caused a significant increase in radioisotope incorporation into the DNA of dividing lymphocytes. The Stimulation Index of the middle ant the lowest treated groups (3 and 0.3 % w/v) is less than 3 but the values of DPM are statistically significantly increased compared to negative control and overall dose-effect relationship is manifested. The test substance 2-methoxy-5-nitrophenyl acetate, provides positive sensitising response in LLNA assay.

Interpretation of results:
sensitising
Remarks:
Migrated information Criteria used for interpretation of results: not specified
Conclusions:
the test substance, 2-methoxy-5-nitrophenyl acetate, provides positive sensitising response in LLNA assay.
Executive summary:

The test substance, 2-methoxy-5-nitrophenyl acetate, was tested for the assessment of skin sensitisation potential with the murine local lymph node assay. This study is a part of the test substance health hazard evaluation.

The Local Lymph Node Assay (LLNA) with radionuclide was used. The testing was conducted according to the Method B.42 – Skin Sensitisation: Local Lymph Node Assay, Council Regulation (EC) No.640/2012, published in O.J. L 193, 2012.

In this study the contact allergenic potential of 2-methoxy-5-nitrophenyl acetate was evaluated after topical application to female BALB/c mice. Mice were exposed to three concentrations of test substance suspended in vehicle (DAE 433) for 3 consecutive days.

In pilot experiment the following concentrations of test substance in application forms were used: 30 %, 3 %, 0.3 % (w/v). According to the results of pilot experiment the doses were confirmed for main study.

Primary proliferation of lymphocytes in the lymph node draining the site of application was evaluated using radioactive labelling of proliferating cells. The ratio of the proliferation in treated groups to that in vehicular controls, termed the Stimulation Index, was determined. The evaluation of ear weight was performed for elimination of false positive findings with certain skin irritants.

Comparison of Stimulation Indexes between treated groups and control vehicle group revealed that the test substance 2-methoxy-5-nitrophenyl acetate caused a significant increase in radioisotope incorporation into the DNA of dividing lymphocytes. The Stimulation Index of the highest treated groups is > 3 (30% - 3.19). The value of DPM is statistically significantly increased compared to negative control. The Stimulation Index of the middle and the lowest treated groups (3 and 0.3 % w/v) is < 3 but the values of DPM are statistically significantly increased compared to negative control and overall dose-effect relationship is manifested.

The test substance did not cause statistically significant increase of ear weight and irritation to skin at all dose level – it means the test substance 2-methoxy-5-nitrophenyl acetate did not cause irritation to skin.

The animals exposed to the test substance at all concentrations showed no pathological and no other negative clinical symptoms of intoxication throughout the experiment.

The positive control item DNCB (concentration 0.5% (w/v) elicited a reaction pattern with statistically significant increase in Stimulation Index of cell proliferation and of ear weight, which was in congruence with his expected mode of action as a contact allergen. Appropriate performance of the assay in the test laboratory was then demonstrated.

Under the given test conditions, the test substance, 2-methoxy-5-nitrophenyl acetate, provides positive sensitising response in LLNA assay.

Endpoint conclusion
Endpoint conclusion:
adverse effect observed (sensitising)
Additional information:
Migrated from Short description of key information:
Comparison of Stimulation Indexes between treated groups and control vehicle group revealed that the test substance 2-methoxy-5-nitrophenyl acetate caused a significant increase in radioisotope incorporation into the DNA of dividing lymphocytes. The Stimulation Index of the highest treated group is > 3 (30% - 3.19). The value of DPM is statistically significantly increased compared to negative control. The Stimulation Index of the middle ant the lowest treated groups (3 and 0.3 % w/v) is < 3 but the values of DPM are statistically significantly increased compared to negative control and overall dose-effect relationship is manifested.
The test substance 2-methoxy-5-nitrophenyl acetate, provides positive sensitising response in LLNA assay.

Justification for classification or non-classification