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Toxicological information

Skin sensitisation

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Administrative data

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Academic study, well documented, acceptable for assessment

Data source

Reference
Reference Type:
publication
Title:
Simultaneous p-tert-butylphenol-formaldehyde resin and p-tert-butylcatechol contact allergies in man and sensitizing capacities of p-tert-butylphenol and p-tert-butylcatechol in guinea pigs.
Author:
Zimerson E, Bruze M, Goossens A
Year:
1999
Bibliographic source:
J Occupational Environmental Medicine, 41(1), 23-28

Materials and methods

Test guidelineopen allclose all
Qualifier:
equivalent or similar to
Guideline:
EU Method B.6 (Skin Sensitisation)
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 406 (Skin Sensitisation)
GLP compliance:
not specified
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
This study has been performed before the LLNA study and since it is a publication it is publicly available.

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
p-tert-butylcatechol (TBC) 99%, manufactured by Acros Organics (Geel, Belgium).
TBC was showed to be of high purity, and the highest possible contamination of this substance with the monomers of PTBP-F-R, 2-MPTBP and 2,6-MPTBP, was lower than 0.02% and 0.01% w/w, respectively.

In vivo test system

Test animals

Species:
guinea pig
Strain:
Dunkin-Hartley
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS:
- Strain: Dunkin-Hartley
- Sex: female
- Source: J.A. Sahlin, Malmö, Sweden
- Age at study initiation: no data
- Weight at study initiation: 300-400 g
- Acclimation period: no data
- Housing: no data
- Diet: no data
- Water: no data

ENVIRONMENTAL CONDITIONS
- Temperature (degrees C): no data
- Humidity (%): no data
- Air changes: no data
- Photoperiod: no data

In life dates: no data

Study design: in vivo (non-LLNA)

Induction
Route:
other: intradermal and topical
Vehicle:
other: propylene glycol/acetone 90/10% v/v (intradermal)
Challenge
Route:
epicutaneous, occlusive
Vehicle:
other: propylene glycol/acetone 90/10% v/v (intradermal)
No. of animals per dose:
24: test group
12: control group
Details on study design:
TOPICAL IRRITANCY:
It was studied by means of a 48-h closed patch test in 4-8 animals on the flank. Testing was performed 1 week after pretreatment of the animals with Freund's complete adjuvant (FCA).

INDUCTION / CHALLENGE SCHEDULE:
* Induction procedure:
For intradermal sensitisation, 3 injections were given in a row on each side of the shoulder: (I) 0.1 mL of FCA in water 50% v/v; (II)0.1 mL of TBC in propylene glycol/acetone 90/10% v/v; (III) 0.1 mL of a preparation consisting of a mixture of TBC and FCA in propylene glycol/acetone 90/10% v/v in which the concentration for FCA was the same as that in (I) and the concentration of TBC was the same as that in (II).
24h before the topical sensitisation, all animals were treated on 2x4 cm area on the shoulder with 200 µL of a preparation consisting of sodium lauryl sulphate 10% w/v in dimethylacetamide/acetone/ethanol 4/3/3 v/v/v.
Topical sensitisation on the same skin area was then performed with 20 µL of a solution of 16.7% TBC on a 2x4 cm patch of Munktell 1002 filter paper.
The patch was covered with overlapping, impermeable plastic adhesive tape. This in turn was firmly secured by adhesive bandage. The dressing was left in place for 48h.

* Challenge procedure:
Challenge I was performed 2 weeks after the end of the induction stage, and a 24-h occluded patch test was performed on the right flank with 25 µL of TBC 7.5% (w/v) on each of the 2 patches near the back.
The Al-test on Durapore was used for patch-testing and was firmly secured by Acrylastic and an outer layer of Durapore.
12 test animals received TBC on both patches; 6 test animals received TBC only on the cranially located patch, while the vehicle alone was applied to the other patch. 6 other test animals received the vehicle alone on the cranially located patch, while TBC was applied to the other patch.
Challenge II was performed at the same time as challenge I but on the left side of the flank. 6 patches were tested on 24 test and 12 control animals: 2 patches near the back, 2 near the abdomen, and 2 between the back and the abdomen. The animals were challenged with the sensitiser (TBC: 10%).
A challenge was performed with nonirritant solutions.

GRADING SYSTEM:
The reactions were evaluated in a blind manner 24h after the removal of the patches.
The minimal criterion of an allergic (positive) reaction was a confluent erythema. The number of positive animals in each test group was statistically compared with the number of positive animals in the corresponding control group and also with the number of positive test animals tested with the vehicle alone.
When both comparisons yielded significant values, the compound was considered to be a contact sensitiser.
For challenge II, a comparison was only made between the number of animals positive for each substance in the test and control groups.
Challenge controls:
Challenge I & II: 12 females
no more data available
Positive control substance(s):
yes
Remarks:
2-methylol phenol

Results and discussion

Positive control results:
Challenge I: 3/6 positive animals

In vivo (non-LLNA)

Resultsopen allclose all
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
7.5 %
No. with + reactions:
20
Total no. in group:
24
Clinical observations:
No data
Remarks on result:
positive indication of skin sensitisation
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
No data
No. with + reactions:
2
Total no. in group:
12
Clinical observations:
No data
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
No data
No. with + reactions:
3
Total no. in group:
6
Clinical observations:
No data
Key result
Reading:
2nd reading
Hours after challenge:
24
Group:
test group
Dose level:
10%
No. with + reactions:
18
Total no. in group:
24
Clinical observations:
No data
Remarks on result:
positive indication of skin sensitisation
Reading:
2nd reading
Hours after challenge:
24
Group:
negative control
Dose level:
No data
No. with + reactions:
1
Total no. in group:
12
Clinical observations:
No data

Any other information on results incl. tables

CHALLENGE I:

Group                        Number of positive animals
Negative control/vehicle        2/12
TBC (7.5%)               20/24

CHALLENGE II:

                        Nb positive animals after challenge
Challenge substance        TBC group (10%)        Control group
TBC                18/24                1/12


Applicant's summary and conclusion

Interpretation of results:
Category 1 (skin sensitising) based on GHS criteria
Conclusions:
In this study, TBC was shown to be a potent sensitizer in guinea pigs.

EU GHS classification: skin sensitisation Category 1 (H317)



Executive summary:

In a dermal sensitization study using the method of Maximization test (Zimerson et al., 1999) with 4 -tert-butylpyrocatechol (TBC) in propylene glycol / acetone (90/10%), Dunkin-Hartley guinea pigs (24 females) were tested under test conditions similar to the guideline OECD 406. The positive control group received 2 -methylol phenol.

On day 1, three intradermal injections were performed in a row on each side of the shoulder. 24 hours before the topical sensitization (day 7), all the animals were treated on the shoulder with a preparation consisting of sodium lauryl sulphate (SLS) 10% in dimethyl acetamide/acetone/ethanol. On day 8, topical sensitization on the same skin area was then performed with a solution of the suspected sensitizer. The patch was covered by an occlusive dressing for 48 hours. On day 22 (= Challenge I), a 24 -hour occluded patch was performed on the right flank with 25µl of TBC, 2 patches near the back. Challenge II was performed at the same time as challenge I but on the left side of the flank.

The concentrations used for induction phase were 3.40% (intradermal) and 16.7% (topical) and those used for challenge phase were 7.50% (challenge I) and 10% (challenge II).

In challenge I, 20/24 treated animals showed positive reactions. In challenge II, 18/24 treated animals showed positive reactions.

In this study, 4 -tert-butylpyrocatechol was a dermal sensitizer.