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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
Study period:
from 2003-01-14 to 2003-04-04
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2003
Report date:
2003

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Version / remarks:
(1992)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method B.6 (Skin Sensitisation)
Version / remarks:
(1996)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EPA OPPTS 870.2600 (Skin Sensitisation)
Version / remarks:
(August 1998)
Deviations:
no
Qualifier:
according to guideline
Guideline:
other: Japanese Ministry of Agriculture, Forestry and Fisheries (MAFF): Japanese Test Guidelines (draft). Test Reports accompanying an application for registration. Unauthorised English translation, July 2000.
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
One in vivo non-LLNA study is already available.

Test material

Constituent 1
Chemical structure
Reference substance name:
Di-tert-butyl 1,1,4,4-tetramethylbut-2-yn-1,4-ylene diperoxide
EC Number:
213-944-5
EC Name:
Di-tert-butyl 1,1,4,4-tetramethylbut-2-yn-1,4-ylene diperoxide
Cas Number:
1068-27-5
Molecular formula:
C16H30O4
IUPAC Name:
2,5-bis(tert-butylperoxy)-2,5-dimethylhex-3-yne
Test material form:
liquid

In vivo test system

Test animals

Species:
guinea pig
Strain:
Dunkin-Hartley
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Species: Dunkin Hartley strain, albino guinea pig (SPE-quality), females were nulliparous and non-pregnant.
- Source: Charles River Deutschland, Kisslegg, Germany
- Age at study initiation: Young adult animals (approx. 4 weeks old)
- Housing: Group housing of maximally 5 animals per labelled cage (74 cm x 54 cm x 25 cm geight) containing purified sawdust as bedding material (SAWI, Jelu Werk, Rosenberg, Germany).
- Identification: Ear tattoo
- Diet: Free access to standard guinea pig diet, including ascorbic acid (100 mg/kg); (Charles River Breeding and Maintenance Diet for Guinea Pigs, Altromin, Lage, Germany).
- Water: Free access to tap water. Vitamin C (Dopharma, Raamsdonkveer, Netherlands) 200 mg/L was added to the water of the animals of the main study to ensure sufficient availability.
- Acclimation period: At least 5 days before the start of treatment under laboratory conditions.

ENVIRONMENTAL CONDITIONS
- Temperature: 21 ± 3 °C
- Humidity: 30 - 70 %
- Air changes: 15 per hour
- Photoperiod: 12 hours artificial fluorescent light and 12 hours dark per day.

Study design: in vivo (non-LLNA)

Induction
Route:
intradermal and epicutaneous
Vehicle:
corn oil
Concentration / amount:
Induction:
- intradermal: 50%
- epidermal: 100%
Challange:
- epidermal. 50%
Challenge
Route:
epicutaneous, occlusive
Vehicle:
corn oil
Concentration / amount:
Induction:
- intradermal: 50%
- epidermal: 100%
Challange:
- epidermal. 50%
No. of animals per dose:
Experimental group: 10 females
Control group: 5 females
Details on study design:
RANGE FINDING TESTS: Practical feasibility of administration determined the highes starting-concentration for each route. The starting- and subsequent concentrations were taken from the series: 100 % (undiluted), 50 %, 20 %, 10 %, 5 %, 2 %, 1 % and if needed, further lower concentrations using the same steps.
The test system and procedures were identical to those used during the main study, unless otherwise specified. The four animals selected were between 4 and 9 weeks old. No body weights were determined.

A.1 INDUCTION EXPOSURE (intradermal, 0.1 mL/site; Day 1)
- No. of exposures: 1
- Exposure period: single treatment on day 1
- Test groups: A) A 1:1 w/w mixture of Freunds' Complete Adjuvant (Difco, Detroit, U.S.A.) with water for injection (Fresenius AG, Bad Homburg, Germany); B) The test substance at a 50% concentration; C) 1:1 w/w mixture of the undiluted test substance and Freunds' Complete Adjuvant.
- Control group: Treated with adjuvant and the vehicle
- Site: Scapular region
- Frequency of applications: Once
- Concentrations: 50 %

A.2 INDUCTION EXPOSURE (epidermal, 0.5 mL/site; Day 8)
- No. of exposures: 1
- Exposure period: 48 hours
- Test groups: The scapular region was treated with 0.5 mL of a 100 % test substance concentration.
- Control group: Treated with adjuvant and the vehicle
- Site: Scapular region (area between the injection sites)
- Concentrations: 100 %

B. CHALLENGE EXPOSURE (epidermal, 0.1 mL; Day 22)
- No. of exposures: 1
- Day(s) of challenge: 22 days after the epidermal exposure
- Exposure period: 24 hours
- Test groups: single treatment
- Control group: single treatment
- Site: Flank
- Concentrations: 50 %
- Evaluation: 24 and 48 hours
Positive control substance(s):
no

Results and discussion

In vivo (non-LLNA)

Resultsopen allclose all
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
50 %
No. with + reactions:
0
Total no. in group:
10
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
50 %
No. with + reactions:
0
Total no. in group:
10
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
50 %
No. with + reactions:
0
Total no. in group:
5
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
50 %
No. with + reactions:
0
Total no. in group:
5

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
Based on the results of this study, the test substance is not considered to be sensitising to the skin under the test conditions chosen.
Executive summary:

2,5-Bis(tert-butylperoxy)-2,5-dimethyl-3-hexyne (85% in mineral oil) was tested in a Maximisation Test in albino guinea pig according to OECD guideline 406.

Test substance concentrations selected for the main study were based on the results of a preliminary study. In the main study, ten experimental animals were intradermally injected with a 50 % concentration and epidermally exposed to a 100 % concentration. Five control animals were similarly treated, but with vehicle alone (corn oil). Two weeks after the epidermal application all animals were epidermal challenged with a 50 % test substance concentration and the vehicle. No skin reactions were evident after the challenge exposure in the experimental and control animals. There was no evidence that the test item had caused skin hypersensitivity in the guinea pig, since no responses were observed in the experimental animals in the challenge phase.

Based on these results and according to the EC criteria for classification and labelling, the test substance does not have to be classified and has no obligatory labelling requirement for sensitisation by skin contact.