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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:
1999-12-07 to 2000-01-13
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2000
Report Date:
2000

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
EU Method B.6 (Skin Sensitisation)
Version / remarks:
1996
Deviations:
no
Qualifier:
according to
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Version / remarks:
1992
Deviations:
no
GLP compliance:
yes
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
Adequate data from a guinea pig maximization test is available.

Test material

Reference
Name:
Unnamed
Type:
Constituent

In vivo test system

Test animals

Species:
guinea pig
Strain:
Dunkin-Hartley
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Deutschland, Kisslegg Germany
- Age at study initiation: approx. 4 weeks old
- Weight at study initiation: individual body weights < 500 grams
- Housing: group housing of 5 animals per labelled metal cage with wire-mesh floors and equipped with an automatic drinking system
- Diet: free access to standard guinea pig diet, including ascorbic acid (1000 mg/kg)
- Water: free access to tap water
- Acclimation period: at least 5 days

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

Study design: in vivo (non-LLNA)

Inductionopen allclose all
Route:
intradermal and epicutaneous
Vehicle:
propylene glycol
Concentration / amount:
Induction (intradermal): 100 %
Induction (epicutaneous): 100 %
Challange (epicutaneous): 100 %
Challengeopen allclose all
Route:
epicutaneous, semiocclusive
Vehicle:
propylene glycol
Concentration / amount:
Induction (intradermal): 100 %
Induction (epicutaneous): 100 %
Challange (epicutaneous): 100 %
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 highest starting-concentration for each route. The starting- and subsequent concentrations were taken from 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 six animals selected were between 4 and 9 weeks old. No bdy weights were determined at termination.

MAIN STUDY
A. INDUCTION EXPOSURE
a) First induction (intradermal)
- No. of exposures: 1
- Exposure period: single treatment on day 1
- Test groups: A. A 1:1 w/w mixture of Freunds`Complete adjuvant with water for injection; B. The test substance at a 100 % concentration.; C. A 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: 100 %

a) Second induction (epicutanous), 7 days after first induction
- No. of exposures: 1
- Exposure period: 48 hours
- Test groups: The scapular area was treated with 0.5 mL of a 100 % test substance concentration.
- Control group: treated with adjuvant and the vehicle
- Site: scapular region
- Frequency of applications: once
- Concentrations: 100 %

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: 13 days after the epidermal exposure
- Exposure period: 24 hours
- Test groups: single treatment
- Control group: single treatment
- Site: flank
- Concentrations: 100 %
- Evaluation (hr after challenge): 24, 48 hours
Challenge controls:
No
Positive control substance(s):
yes
Remarks:
Alpha-hexylcinnamic aldehyde, tech. 85 %; Realiability check

Results and discussion

Positive control results:
A reliability check is carried out at regular intervals to check the sensititivity of the test system and the reliability of the experimental techniques.
The skin reactions in eight experimental animals observed in response to the 10 % test substance concentration in the challenge phase were considered indicative of sensitisation, based on the absence of any response in the control animals. These results lead to a sensitisation rate of 80 per cent to the 10 % concentration.

In vivo (non-LLNA)

Resultsopen allclose all
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
100 %
No. with + reactions:
0
Total no. in group:
5
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: 100 %. No with. + reactions: 0.0. Total no. in groups: 5.0.
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
100 %
No. with + reactions:
0
Total no. in group:
5
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 100 %. No with. + reactions: 0.0. Total no. in groups: 5.0.
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
100 %
No. with + reactions:
9
Total no. in group:
10
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 100 %. No with. + reactions: 9.0. Total no. in groups: 10.0.
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
100 %
No. with + reactions:
8
Total no. in group:
10
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 100 %. No with. + reactions: 8.0. Total no. in groups: 10.0.

Applicant's summary and conclusion

Interpretation of results:
Category 1 (skin sensitising) based on GHS criteria
Conclusions:
Taking into account the intensity of the responses and comparing theses with the skin reactions seen in the control animals, it was considered that hypersensitivity had been induced in nine (of the ten) experimental animals. The skin reactions as observed in the control animals were considered to be non-specific signs of irritation. These results indicate a sensitisation rate of 90 per cent.
Executive summary:

Tert.butyl peroxyneodecanoate (75 % in solvent) was tested in a Maximisation Test in albino guinea pig according to EU method B.6 and OECD guideline no. 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 and epidermally exposed to a 100 % concentration. Five control animals were similarly treated, but with vehicle alone (water). Two weeks after the epidermal application all animals were challened with a 100 % test substance concentration and the vehicle.

In the challenge phase in response to the 100 % test substance concentration, skin reactions varying between grades 1 and 4 were observed in all experimental animals and skin reactions of grade 1 were observed in all control animals.

Eschar formulation was seen in the treated skin sites amoung the experimental animals.

Taking into account the intensity of the responses and comparing theses with the skin reactions seen in the control animals, it was considered that hypersensitivity had been induced in nine (of the ten) experimental animals. The skin reactions as observed in the control animals were considered to be non-specific signs of irritation. These results indicate a sensitisation rate of 90 per cent.