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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:
24 Mar - 24 Apr 1998
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study with acceptable restrictions. The epicutaneous induction and challenge were performed under semi-occlusive conditions.

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)
Deviations:
yes
Remarks:
epicutaneous induction and challenge performed under semi-occlusive conditions
Qualifier:
according to
Guideline:
EU Method B.6 (Skin Sensitisation)
Deviations:
yes
Remarks:
epicutaneous induction and challenge performed under semi-occlusive conditions
GLP compliance:
yes
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
Test was done before LLNA as first-choice method for in-vivo testing was set into force.

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): only trade name given
- Physical state: pale yellow liquid
- Analytical purity: 100% (UVCB)
- Lot/batch No.: N567701
- Storage condition of test material: at room temperature in the dark
- Other: density approximately 860 kg/m³

In vivo test system

Test animals

Species:
guinea pig
Strain:
Himalayan
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: BRL Ltd., Basel, Switzerland
- Age at study initiation: approximately 6 weeks
- Weight at study initiation: 416 ± 23 g (mean ± SD, control group); 434 ± 24 g (mean ± SD, treatment group)
- Housing: animals were housed in groups of 5 in labelled metal cages with wire-mesh floors (ITL, Bergen, the Netherlands)
- Diet: standard guinea pig diet (LC 23-B, pellet diameter 4mm, including ascorbic acid (1600 mg/kg); Hope farms, Woerden, the Netherlands), ad libitum
- Water: tap water, ad libitum
- Acclimation period: at least 5 days

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

IN-LIFE DATES: From: 24 March 1998 To: 24 April 1998

Study design: in vivo (non-LLNA)

Inductionopen allclose all
Route:
other: intradermal and epicutaneous, semi-occlusive
Vehicle:
corn oil
Concentration / amount:
Induction: undiluted (intradermal and epicutaneous)
Challenge: undiluted
Challengeopen allclose all
Route:
epicutaneous, semiocclusive
Vehicle:
corn oil
Concentration / amount:
Induction: undiluted (intradermal and epicutaneous)
Challenge: undiluted
No. of animals per dose:
10 (treatment group)
5 (control group)
Details on study design:
RANGE FINDING TESTS:
Prior to the start of the main study, the intradermal and epidermal irritancy of the test substance was investigated to select suitable concentrations for the induction and challenge phase of the main study. The selection was based on the absence of toxicity and on the following criteria for each route and/or study phase:
Induction (intradermal and epidermal): The highest possible concentration that produced moderate irritation (the intradermal reactions may include slight necrosis (< 3 mm in diameter)).
Challenge: The maximum non-irritant concentration.

A series of test substance concentrations were tested. The first and subsequent concentrations were selected 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 were 5-9 weeks old. The body weights were determined prior to treatment (results not shown).

Intradermal Injections:
A series of four test substance concentrations was used; the highest concentration was the maximum concentration that could technically be
injected (undiluted). One animal received 50 and 100% (undiluted), and the second animal received 10 and 20%, respectively, in duplicate (0.1 mL/site) in the clipped scapular region. The injection sites were assessed for irritation 24 and 48 hours after treatment. Slight erythema was observed at the injection site of the undiluted test substance 48 h after exposure. The udiluted test substance was selected for the induction phase in the main study.

Epidermal application:
A series of four test substance concentrations (10, 20, 50 and 100%) was used. All concentrations 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, which were held in place with Micropore tape and subsequently Coban elastic bandage (semi-occlusive covering). The animals receiving intradermal injections were treated with the lowest concentrations (10 and 20%) and two further animals with the highest concentrations (50 and 100%). 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. No skin irritation was observed at any of the treated sites at any of the reading time points. As the epidermal induction using the test substance did not cause any skin irritation, the test site of all animals was treated with 10% SDS approximately 24 hours before the epidermal induction in the main study, to provoke a mild inflammatory reaction. The udiluted test substance was selected for the challenge phase in the main study.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 2, intradermal and epicutaneous
- Exposure period: single injection (epidermal) and 48 h (epicutaneous)
- Test groups:
Intradermal, Day 1 (3 pairs of injections, 0.1 mL/site):
Injection 1: a 1:1 mixture (w/w) Freunds Complete Adjuvant (FCA)/water for injection
Injection 2: undiluted test substance
Injection 3: undiluted test substance in a 1:1 mixture (w/w) with FCA (final concentration is 50% test substance)
48 h after intradermal injection (Day 3), the degree of erythema and edema was evaluated.

On Day 7, the scapular area between the injection sites was clipped and subsequently rubbed with 10% sodium dodecyl sulfate in vaseline using a spatula. This concentration of SDS provoked a mild inflammatory reaction.

Epicutaneous, Day 8:
0.5 mL undiluted test substance was applied to the SDS-treated skin area. The semi-occlusive dressing was kept in place for 48 h. The degree of erythema and edema was evaluated directly after cleaning the skin area with water (Day 10).

- Control group:
Intradermal, day 1 (3 pairs of injections, 0.1 mL/site):
Injection 1: a 1:1 mixture (w/w) FCA/water
Injection 2: corn oil
Injection 3: corn oil (w/v) in a 1:1 mixture (w/w) FCA (final concentration is 50% corn oil)

On Day 7, the scapular area between the injection sites was clipped and subsequently rubbed with 10% sodium dodecyl sulfate (SDS, Boom, Meppel, the Netherlands) in vaseline using a spatula. This concentration of SDS provoked a mild inflammatory reaction.

Epicutaneous, Day 8: 0.5 mL corn oil

- Site: the shoulder region
- Frequency of applications: once (intradermal on Day 1 and epicutaneous on Day 8)
- Duration: Day 1 (intradermal), Day 8-10 (epicutaneous)
- Concentrations: undiluted (intradermal and epicutaneous)

B. CHALLENGE EXPOSURE
- No. of exposures: 1 (challenge)
- Day(s) of challenge: 21
- Exposure period: 24 hours
- Test groups: 0.5 mL test substance
- Control group: 0.5 mL test substance
- Site: approximately 20 mm x 30 mm, on one flank of the animals
- Concentration: undiluted
- Evaluation (hr after challenge): 24 and 48 hours after the challenge ended
Positive control substance(s):
yes
Remarks:
alpha-hexylcinnamicaldehyde, tech. 85%

Results and discussion

Positive control results:
A reliability check is carried out at regular intervals with alpha-hexylcinnamic aldehyde to check the sensitivity of the test system and the reliability of the experimental methods used by the test laboratory. In an independent study performed in 1998 (report No. 217812), alpha-hexylcinnamic aldehyde induced sensitisation in 80% (8/10) of the Himalayan guinea pigs challenged with a 10% solution, and in 70% (7/10) of the guinea pigs challenged with a 5% solution. A 5% solution was used for intradermal induction and undiluted test substance was used for topical induction.

In vivo (non-LLNA)

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

Any other information on results incl. tables

48 hours after intradermal induction, slight to severe erythema was noted at all of the sites injected with FCA/water and FCA/test substance in 10/10 treated and 5/5 control animals. 4/5 control animals also exhibited necrosis at the FCA/test substance injection site. In 3/10 treated animals slight to well-defined erythema was observed at the injection site of the test substance. Following the topical induction, severe erythema and scabs were observed at the test site in 3/10 treated animals. A further 4/10 (in total 7/10) treated and 4/5 control animals exhibited only scabs. No edema was observed (see Table 1).

48 and 72 hours after the challenge, no sensitisation was observed in the treated animals.

There was no mortality, no signs of toxicity and no treatment-related effects on body weight.

Table 1: skin irritation effects of intradermal and epidermal induction

 

Group/

animal No.

Intradermal induction (Day 3), undiluted test substance

Epidermal induction (Day 10), undiluted test substance

Control

A

B

C

Erythema

Edema

16

E2

NA

E3

0p

0

17

E2

NA

N2

0a

0

18

E3

NA

N3

0a

0

19

E3

NA

N3

0

0

20

E2

NA

N3

0a

0

Experimental

 

 

 

 

 

21

E4

NA

E2

0a

0

22

E1

NA

E1

0

0

23

E2

E2

E2

0a

0

24

E2

NA

E1

0a

0

25

E1

NA

E1

4k

0

26

E1

NA

E1

0

0

27

E3

E1

E2

0a

0

28

E2

E1

E2

4s

0

29

E2

NA

E2

4k

0

30

E3

NA

E2

0

0

A. 1:1 mixture of FCA and water for injection

B. undiluted test substance (experimental group) or vehicle (control group)

C. 1:1 mixture of FCA and undiluted test substance (experimental group) or vehicle (control group)

a. small scabs

k. scabs

p. scaliness

s. eschar formation

 

Skin effect intradermal injections:

NA. No abnormalities

E. erythema

N. signs of necrosis (mm in diameter)

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 classifed