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Administrative data

skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
key study
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: study performed in accordance with an official guideline; also a positive control test was performed with a known sensitzer that proved the validity of the test system; GLP-conformity is given

Data source

Reference Type:
study report

Materials and methods

Test guideline
according to guideline
OECD Guideline 406 (Skin Sensitisation)
GLP compliance:
yes (incl. QA statement)
Type of study:
guinea pig maximisation test

Test material

Constituent 1
Chemical structure
Reference substance name:
4-tert-butylbenzoic acid
EC Number:
EC Name:
4-tert-butylbenzoic acid
Cas Number:
Molecular formula:
4-tert-butylbenzoic acid
Details on test material:
- Name of test material (as cited in study report):
- Supplier: presumably the sponsor (Clariant)
- Analytical purity: 99.6 % (HPLC)
- Batch Nr.: 021004
- Stability: stable under storage conditions; expiration date Nov 2003
- Stability of test item dilution: unknown in PEG 300 and in a 1:1 (v/v) mixture of FCA/physiological saline; is excluded from the statement of compliance
- Storage conditions: at room temperature away from direct sunlight in original container

In vivo test system

Test animals

guinea pig
other: Ibm: GOHI; SPF-quality guinea pigs (synonym: Himalayan spotted)
Details on test animals and environmental conditions:
Number of animals for main study/pretest: 15 females / 3 females (nulliparous and non-pregnant)
Age at pretest start / beginning of acclimatization period: 5-7 weeks
Body weight at pretest start: pretest groups 411-442 g; Body weight at beginning of acclimatization period: control and test group 378-426 g
Identification: by unique cage number and corresponding ear tags.
Randomization: selected by hand at time of delivery; no computer randomization.

Acclimatization: one week for the control and test group under test conditions after health examination. No acclimatization for the animals of the pre-
test. Only animals without any visible signs of illness were used for the study.

- Housing: individually in Makrolon type-4 cages with standard softwood bedding ("Lignocel", Schill AG, CH-4132 Muttenz)
- Diet: ad libitum, pelleted standard Provimi Kliba 3418, batch no. 64/02, guinea pig breeding / maintenance diet, containing Vitamin C (Provimi Kliba AG, CH-4303 Kaiseraugst). Results of analyses for contaminants are archived at RCC Ltd, Itingen, CH.
- Water: ad libitum, community tap water from Füllinsdorf. Results of bacteriological, chemical and contaminant analyses are archived at RCC Ltd, Itingen.

Environmental conditions:
- Temperature (°C): 20 +/- 3
- Humidity (%): 30-70
- Air changes (per hr): 10-15
- Photoperiod (hrs dark / hrs light): 12 / 12 (music played during daytime light period)

Study design: in vivo (non-LLNA)

intradermal and epicutaneous
other: Polyethylene glycol 300 (PEG 300), Freund's Complete Adjuvant (FCA), physiological saline
epicutaneous, occlusive
other: Polyethylene glycol 300 (PEG 300), Freund's Complete Adjuvant (FCA), physiological saline
No. of animals per dose:
control group: 5
test group: 10
Positive control substance(s):
alpha-hexylcinnamaldehyde, purity 85 %, from Aldrich Chemicals Company Inc., USA

Study design: in vivo (LLNA)

Positive control substance(s):
hexyl cinnamic aldehyde (CAS No 101-86-0)

Results and discussion

Positive control results:
It is stated in the study report that based on the findings and in accordance with Commission Directive 96/54/EEC, alpha-hexylcinnamaldehyde does have to be classified and labelled as skin sensitizer and proved the sensitivity of the test system.

Any other information on results incl. tables

Results main study:

Skin effects after intradermal induction (Day 1):

Erythema, oedema, necrotizing dermatitis, encrustation and exfoliation of encrustation were observed as expected (effects of FCA)

Skin effects after epidermal induction (Day 8):

Control group: no erythematous or oedematous reaction was observed in the animals treated with PEG 300 only.

Test group: Discrete/patchy erythema (score = 1) was observed in six out of 10 animals at the 24- and 48-hour reading after treatment with the test item at 50 % in PEG 300.

Skin effects after the challenge (Day 22):

Control group: no skin reactions were observed in the animals when treated with PEG 300 only or when treated with the test item at 25 % in PEG 300.

Test group: no skin reactions were observed in the animals when treated with PEG 300 only or when treated with the test item at 25 % in PEG 300.

Applicant's summary and conclusion

Interpretation of results:
not sensitising
Migrated information
It was concluded in the study report:
Based on the findings of the study and in accordance with Commission Directive 96/54/EEC, p-tert-butyl benzoic acid does not have to be classified and labelled as a skin sensitizer.