2,4-di-tert-butylphenol

Endpoint summary

Description of key information

Not sensitising

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

from 1990-04-30 to 1990-05-24

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study without detailed documentation

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Principles of method if other than guideline:

Magnusson & Kligman maximisation test (J. Invest. Dermatol. 52, 268-276, 1969)

GLP compliance:

no

Type of study:

Freund's complete adjuvant test

Justification for non-LLNA method:

The test was carried out before the Reach law was in force.

Specific details on test material used for the study:

Purity: 99.5%

Species:

guinea pig

Strain:

Dunkin-Hartley

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: F. Winkelmann, Borchen, Germany
- Age at study initiation: not mentioned
- Weight at study initiation: average 377 g (control group) and 368 g (test group)
- Housing: conventional, Makrolon Type IV cages (maximum 5 animals per cage)
- Diet (e.g. ad libitum): Ssniff G4 complete feed for guinea pigs ad libitum, supplied by Ssniff Spezialfutter GmbH, Soest, Germany
- Water (e.g. ad libitum): drinking water ad libitum
- Acclimation period: not mentioned

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 ± 1
- Humidity (%): 60 ± 5
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: not mentioned

Route:

intradermal

Vehicle:

corn oil

Concentration / amount:

- Concentrations used for induction: intradermal: 5% v/v in corn oil;
- Concentration in Freunds Complete Adjuvants (FCA): 5%; dermal: 50% v/v in corn oil.
- Challenge schedule: day 21: removal of patches after 24 hours, evaluation after 24 and 48 hours after patch removal.
- Concentrations used for challenge: 25% v/v in corn oil.

Route:

epicutaneous, occlusive

Vehicle:

corn oil

Concentration / amount:

- Concentrations used for induction: intradermal: 5% v/v in corn oil;
- Concentration in Freunds Complete Adjuvants (FCA): 5%; dermal: 50% v/v in corn oil.
- Challenge schedule: day 21: removal of patches after 24 hours, evaluation after 24 and 48 hours after patch removal.
- Concentrations used for challenge: 25% v/v in corn oil.

No. of animals per dose:

test animals: 20 (main experiment)
control animals: 10

Details on study design:

RANGE FINDING TESTS: was performed with 25% test substance in corn oil

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 1
- Exposure period: intradermal: 5% v/v in corn oil;
- Concentration in Freunds Complete Adjuvants (FCA): 5%
- Test group: dermal: test substance in corn oil (2 x 4 cm patch)
- Control group: corn oil (2 x 4 cm patch)
- Frequency of applications: day 0: intradermal treatment, day 6: pretreatment with sodium dodecyl sulphate (10% in vaseline) and day 7: dermal treatment
- Duration: removal of patches after 48 hours
- Concentrations: 25% v/v, test substance was melt and stored at 40 °C

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: on day 21
- Exposure period: dermal application for 24 hours
- Test groups: test substance in corn oil (2 x 2 cm patch)
- Control group: corn oil (2 x 2 cm patch)
- Site: left flanks
- Concentrations: 25% v/v
- Evaluation (hr after challenge): 24 and 48 hours after application

Challenge controls:

not performed

Positive control substance(s):

no

Key result

Reading:

1st reading

Hours after challenge:

48

Group:

test chemical

No. with + reactions:

0

Total no. in group:

20

Remarks on result:

no indication of skin sensitisation

RESULTS OF PILOT STUDY: no dermal irritation, no more details were mentioned

RESULTS OF TEST

- Sensitization reaction: All animals of the control group and of the test substance treated animals showed after 24 and 48 hours none specific findings (Score = 0).

- Clinical signs: 1 hour after i.c. injection: all animals of test substance and control groups showed erythema (E) and oedema (O) at the injection sites, except one animal treated with Freund¿s Adjuvant (FCA) and vehicle (H2O), which showed E, O and necrosis (N) at the injection site. 24 hours after i.c. injection: all animals of the control and test substance groups showed erythema and oedema, partly also necrosis. Reactions after dermal administration: 1 hour after patch removal: all animals of control and test substance groups showed E, O of the whole application area. 24 hours after patch removal: all animals showed E and O of the whole application area as well as eschar formation of the inflamed injection sites

- Body weights: The fluctuation in body weight observed in the test animals during the test are not regarded as related to the substance because comparable changes in bodyweight occurred for the control animals.

Interpretation of results:

GHS criteria not met

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

The test material was evaluated for its sensitisation potential to guinea pig skin in a Magnusson and Kligman maximisation test (Key study, Mürmann P. (1990)). The test material failed to elicit a delayed hypersensitivity response and therefore 2,4-di-tert-butylphenol should be classified as non-sensitising according to the EEC labelling regulations. No symbol and hazard phrase are required.

Test Method

The method used for the Magnusson and Kligman test followed that described in the OECD Guidelines for Guideline 406 (Skin Sensitisation). Ten female and ten male guinea pigs were subjected to intradermal injections of Freunds complete adjuvant, 5% v/v in corn oil, on day 0. On day 6 the animals were pre-treated with sodium dodecyl sulphate (10% in Vaseline) and on day 7 a dermal patch with 25% DTBP in corn oil was applied for 48 hours. A group of 10 control animals were treated in a similar way with vehicle only. On day 21 all animals were challenged by the application of 25% DTBP in corn oil on one flank and challenge sites were covered by an occlusive dressing. The occlusive dressing was removed after 24 hours and the degree of a hypersensitivity reaction was assessed 24 and 48 hours after the removal of test material.

Results - After 24 and 48 hours there were no specific findings (Score = 0) relating to a sensitizing reaction in DTBP treated or control animals.

Justification for classification or non-classification

The test material failed to elicit a delayed hypersensitivity response and therefore in accordance with EU CLP (Regulation (EC) No. 1272/2008) 2,4-di-tert-butylphenol should be classified as non-sensitising. No symbol and hazard phrase are required.