Propyl 4-hydroxybenzoate

Endpoint summary

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

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.