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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:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
No data about GLP
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Deviations:
no
GLP compliance:
not specified
Type of study:
mouse local lymph node assay (LLNA)
Species:
mouse
Strain:
other: CBA/Ca
Sex:
not specified
Details on test animals and environmental conditions:
TEST ANIMALS
- Age at study initiation: 8 -12 weeks
Vehicle:
acetone/olive oil (4:1 v/v)
Concentration:
5, 10 and 25%
No. of animals per dose:
4
Details on study design:
MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Criteria used to consider a positive response: A chemical was regarded as a sensitizer in the LLNA if at least one concentration of the chemical resulted in a three-fold or greater increase in ³HTdR incorporation compared to the control values. Also the data had to be compatible with a biological dose response although an allowance was made, especially at high doses, for either local toxicity or immunological suppression.

TREATMENT PREPARATION AND ADMINISTRATION:
Groups of 4 mice were treated by a daily topical application of 25 µL of each test substance concentration on the dorsal surface of each ear for 3 consecutive days. The negative control group was treated with vehicle only. Four days after the first topical application, all mice were injected intraveniously through the tail vein with 20 µCi [³H]methyl thymidine (³HTdR) in 250 µL phosphate buffered saline (PBS). After 5 h, the mice were killed by carbon dioxide asphyxiation and the draining auricular lymph nodes were excised and pooled for each group. A single cell suspension of lymph node cells was prepared. ³HTdR incorporation was measured by β-scintillation counting.
Positive control substance(s):
mercaptobenzothiazole (CAS No 149-30-4)
Positive control results:
Stimulation Index:
10% positive control substance: 4.5
25% positive control substance: 4.6
50% positive control substance: 5.5
Key result
Parameter:
SI
Remarks:
proliferation response test/control ratio
Value:
1.3
Test group / Remarks:
5% test item
Remarks on result:
other:
Remarks:
A chemical was regarded as a sensitizer in the LLNA if at least one concentration of the chemical resulted in a three-fold or greater increase in the T/C ration
Key result
Parameter:
SI
Remarks:
proliferation response test/control ratio
Value:
1.6
Test group / Remarks:
10% test item
Remarks on result:
other:
Remarks:
A chemical was regarded as a sensitizer in the LLNA if at least one concentration of the chemical resulted in a three-fold or greater increase in the T/C ration
Key result
Parameter:
SI
Remarks:
proliferation response test/control ratio
Value:
1.3
Test group / Remarks:
25% test item
Remarks on result:
other:
Remarks:
A chemical was regarded as a sensitizer in the LLNA if at least one concentration of the chemical resulted in a three-fold or greater increase in the T/C ration
Interpretation of results:
not sensitising
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
CLP: not classified
DSD: not classified
Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

Propylparaben was examined in several reliable local lymph node assays in mice according to OECD 429 (Basketter and Scholes, 1992; Basketter et al., 1991, Basketter et al., 1994). Groups of mice were treated by topical applications of 5, 10 or 25% propylparaben in acetone/olive oil (4:1, v/v) on the dorsal surface of each ear for 3 consecutive days. On Day 5, all mice were injected intravenously with 20 µCi [³H]methyl thymidine (³HTdR). After 5 h, the mice were sacrificed and a single cell suspension of draining auricular lymph nodes was prepared for each group. ³HTdR incorporation was measured by β-scintillation counting. Stimulation indices for propylparaben were in all dose groups < 3. The used positive controls were valid. Under the test conditions, propylparaben was not considered to be a skin sensitizer.

 

Moreover, propylparaben was examined in a Guinea Pig Maximization Test according to OECD 406 (Basketter and Scholes, 1992). After intradermal and epicutaneous induction treatment with 0.5% and 25% propylparaben and a challenge application of 10% propylparaben, no positive response was observed at the 24 and 48 h reading time point in any animal. The used positive controls were valid. Under the test conditions, propylparaben was not considered to be a skin sensitizer.

 


Migrated from Short description of key information:
Skin (Local Lymph Node Assay): not sensitizing

Justification for selection of skin sensitisation endpoint:
The selected study is the most adequate and reliable study based on overall quality assessment (refer to the endpoint discussion for further details).

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

The available data on skin sensitisation of the test substance does not meet the criteria for classification according to Regulation (EC) 1272/2008 or Directive 67/548/EEC, and is therefore conclusive but not sufficient for classification.