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Toxicological information

Skin sensitisation

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Administrative data

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
weight of evidence
Study period:
28 Apr - 29 May 1998
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP guideline study with acceptable restrictions, the analytical purity of the test substance was not specified.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1998
Report Date:
1998

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Version / remarks:
adopted in 1992
Deviations:
yes
Remarks:
analytical purity of test substance not specified
Qualifier:
according to
Guideline:
EU Method B.6 (Skin Sensitisation)
Version / remarks:
adopted in 1996
Deviations:
yes
Remarks:
analytical purity of test substance not specified
GLP compliance:
yes
Type of study:
guinea pig maximisation test

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): methyl laurate
- Physical state: colourless liquid
- Analytical purity: not indicated by the sponsor; nevertheless, the test item was considered as 100% pure
- Storage: at room temperature in the dark

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, Germany
- Age at study initiation: approx. 5 weeks
- Weight at study initiation: 381 g (mean value)
- Housing: groups of 5 animals in metal cages with wire mesh floors
- Diet: free access to standard guinea pig diet (LC 23-B, pellet diameter 4 mm; Hope farms, Woerden, The Netherlands), including ascorbic acid (1600 mg/kg); in addition, hay was provided once a week (B.M.I., Helmond, The Netherlands)
- Water: tap water, diluted with decalcified water, ad libitum (by automatic drinking system: ITL, Bergen, The Netherlands)
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21
- Humidity (%): 50%
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12 / 12

Study design: in vivo (non-LLNA)

Inductionopen allclose all
Route:
intradermal and epicutaneous
Vehicle:
corn oil
Concentration / amount:
Induction: 50% intradermally, 100% epicutaneously
Challenge: 20% epicutaneously
Challengeopen allclose all
Route:
epicutaneous, occlusive
Vehicle:
corn oil
Concentration / amount:
Induction: 50% intradermally, 100% epicutaneously
Challenge: 20% epicutaneously
No. of animals per dose:
10 females for the experiment group; 5 for control
Details on study design:
RANGE FINDING TESTS: Prior to the start of the main study the intradermal and epidermal irritancy of the test substance were investigated for selection of suitable test substance concentrations for induction and challenge of the main study. The selection was based on the absence of toxicity. For the Induction phase the highest possible concentration that produced moderate irritation should be determined (including slight necrosis with diameter <3 mm for intradermal application. The challenge concentration should be the maximum non-irritant concentration. Selection of this concentration depended on a number of factors and exact criteria did not always apply.
The test substance concentrations used were from the series: Undiluted, 50%, 20%, 10%, 5%, 2%, 1% and, if needed, further lower concentrations using the same steps.
The test system, procedures and techniques were identical to those used in the main study; Animals were between 5 and 9 weeks old; therefore, body weights could exceed 500 g. Body weights were determined prior to treatment.

Intradermal injections: A series of four test substance concentrations were used; the highest concentration being the maximum concentration that could technically be injected. Each of two animals received two different concentrations in duplicate (0.1 mL/site) in the clipped scapular region. The injection sites were assessed for irritation 24 and 48 hours after treatment.

Epidermal application: A series of four test substance concentrations was used; the highest concentration being the maximum concentration that could technically be applied. Two different concentrations were applied (0.5 mL each) per animal to the clipped flank, using Metalline patches (2x3 cm) mounted on medical tape, held in place with Micropore tape and subsequently Coban elastic bandage. The animals receiving intradermal injections were treated with the lowest concentrations and two further animals with the highest concentrations. After 24 hours the dressing was removed and the skin cleaned of residual test substance. The treated skin areas were assessed for irritation 24 and 48 hours after exposure

Based on the results of the preliminary study a 50% dilution of the test substance in corn oil was used for intradermal induction, and the undiluted substance was used for the epidermal induction exposure. A 20% test substance concentration was selected for the challenge exposure.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 2
- Exposure period: Intradermal induction on Day 1 and epidermal induction at Day 8 (for 48 h)
- Test groups: Intradermal: FCA with water (1:1 w/w), 50% TS in vehicle, undiluted TS with FCA (1:1 w/w); Epidermal: 0.5 mL undiluted test substance
- Control group: FCA with water (1:1 w/w), vehicle (corn oil), vehicle with FCA (1:1 w/w)
- Site: Three pairs of intradermal injections into the scapular region of both flanks; one of each pair injected on each side of the midline and from cranial to caudal)
- Frequency of applications: 7 days
- Duration: 10 days
- Concentrations: Intradermal: 50%; Epidermal: undiluted


B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: Day 22
- Exposure period: 24 h
- Test groups: TS
- Control group: TS
- Site: On one of the flanks (previously clipped)
- Concentrations: 20% in vehicle
- Evaluation (hr after challenge): 48 and 72 h (24 and 48 h after removal of the dressing)
Challenge controls:
none
Positive control substance(s):
yes
Remarks:
alpha-hexyl cinnamic aldehyde, tech. 85%

Results and discussion

Positive control results:
The skin reactions in the experimental animals observed in response to the 10% and 5% test substance concentration in the challenge phase of an independent control experiment were considered indicative of sensitisation, based on the absence of any response in the respective control animals. The test substance exposure lead to a sensitisation rate of 100% to both the 10% and the 5% concentrations. From these results it was concluded that the female guinea pig of the albino Dunkin Hartley strain is an appropriate animal model for the performance of sensitisation studies in a Maximisation type of test.

In vivo (non-LLNA)

Resultsopen allclose all
Reading:
1st reading
Hours after challenge:
48
Group:
test group
Dose level:
20%
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
none
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 48.0. Group: test group. Dose level: 20% . No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: none.
Reading:
1st reading
Hours after challenge:
48
Group:
negative control
Dose level:
20%
No. with + reactions:
0
Total no. in group:
5
Clinical observations:
none
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 20%. No with. + reactions: 0.0. Total no. in groups: 5.0. Clinical observations: none.
Reading:
2nd reading
Hours after challenge:
72
Group:
test group
Dose level:
20%
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
none
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 72.0. Group: test group. Dose level: 20% . No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: none.
Reading:
2nd reading
Hours after challenge:
72
Group:
negative control
Dose level:
20%
No. with + reactions:
0
Total no. in group:
5
Clinical observations:
none
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 72.0. Group: negative control. Dose level: 20%. No with. + reactions: 0.0. Total no. in groups: 5.0. Clinical observations: none.

Any other information on results incl. tables

Induction readings:

Animal number

Intradermal injection (reading at day 3)

Epidermal exposure (reading at day 10)

 

A

B

C

100%

Control

Erythema

Edema

31

E2

NA

E3

0

0

32

N2

NA

E4

0

0

33

E4

NA

E4

0

0

34

E2

NA

E3

0

0

35

E3

E1

E2

0

0

Experimental

36

E2

E1

E2

3

2

37

E3

NA

E3

3

2

38

E3

E2

E4a

4

3

39

E2

E1

E3a

3

1

40

E3

E1

E4a

4n

1

41

E3

E2

E3

4

1

42

E4

E3

E4

4

3

43

E4

E4

E4

4

3

44

E4

E3

E4a

4

3

45

E3

E2

E3a

4

1

A: 1:1 mixture of Freuds´complete adjuvant with water

B: Test substance (50%) in corn oil

C: 1:1 mixture of the undiluted test substance with Freuds´complete adjuvant

a: Moderate erythema visible approx. 2 cm caudally of the injection sites

n: Signs of necrosis

 

Skin effects intradermal injections:

NA: No abnormalities

E(.): Erythema (grade)

N(.): Signs of necrosis (mm in diameter)

Challenge readings

Animal No.

Day 24

Day 25

Comments

20%

Vehicle

20%

Vehicle

Control

31

0

0

0

0

 

32

0

0

0

0

 

33

0

0

0

0

 

34

0

0

0

0

 

35

0

0

0

0

 

Experimental

36

0

0

0

0

Not sensitized

37

0

0

0

0

Not sensitized

38

0

0

0

0

Not sensitized

39

0

0

0

0

Not sensitized

40

0

0

0

0

Not sensitized

41

0a

0a

0

0

Not sensitized

42

0

0

0

0

Not sensitized

43

0

0

0

0

Not sensitized

44

0

0a

0

0

Not sensitized

45

0

0

0

0

Not sensitized

 a: Skin reactions grade 1 noted at the edges of the application area are considered non-specific, possibly provoked by the edges of the patches.

No deaths occurred. No significant differences in the gain of body weight were observed between treatment and control group.

Applicant's summary and conclusion

Interpretation of results:
not sensitising
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
CLP: not classified
DSD: not classified