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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:
12 March-18 April 1997
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1997
Report Date:
1997

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Version / remarks:
(Adopted: 17 July 1992)
Deviations:
no
Principles of method if other than guideline:
The method followed is also described by Magnusson, B. and Kligman, AM (1970): "Allergic Contact Dermatitis in the guinea pig: identification of contact allergens", Thomas, CC Springfield, Illinois, USA
GLP compliance:
yes
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
At the time of performance of the test the guinea pig maximisaton test was considered the most relevant test for this endpoint and this test item.

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Takenate 600 = 1,3-bis(isocyanatomethyl)cyclohexane
- Physical state: colourless/pale yellow clear liquid
- Storage conditions: Room temperature, dark, dry
- Expiry: Assumed stable for 6 months after receipt (date receipt = 9 December 1996)

In vivo test system

Test animals

Species:
guinea pig
Strain:
Dunkin-Hartley
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: D. Hall, Newchurch, Staffordshire, UK
- Age at study initiation: 6 to 7 weeks old
- Weight at study initiation: 455 to 534 g
- Housing: animals were housed in groups of five in suspended metal cages with mesh floors
- Diet: ad libitum (Vitamin C enriched guinea pig diet FD2; hay provided weekly)
- Water: ad libitum
- Acclimatisation period: twelve days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18.5-21
- Humidity (%): 24-61
- Air changes (per hr): approximately 15
- Photoperiod (hrs dark / hrs light): 12/12

Study design: in vivo (non-LLNA)

Inductionopen allclose all
Route:
intradermal
Vehicle:
other: Alembicol D
Concentration / amount:
0.01% v/v
Day(s)/duration:
Day 1
Adequacy of induction:
highest concentration used causing mild-to-moderate skin irritation and well-tolerated systemically
Route:
epicutaneous, occlusive
Vehicle:
other: Alembicol D
Concentration / amount:
20% v/v
Day(s)/duration:
Day 8, 48 hours
Adequacy of induction:
highest concentration used causing mild-to-moderate skin irritation and well-tolerated systemically
Challenge
No.:
#1
Route:
epicutaneous, occlusive
Vehicle:
other: Alembicol D
Concentration / amount:
2.5% and 5%
Day(s)/duration:
Day 21, 24 hours
Adequacy of challenge:
highest non-irritant concentration
No. of animals per dose:
Preliminary: 2 (intradermal injections), 8 (topical application);
Main: 10 (test), 5 (control)
Details on study design:
CONCENTRATIONS TESTED
Preliminary study:
For Intradermal concentrations 0.001%, 0.0025%, 0.005%, 0.01%, 0.025%, 0.05%, and 0.1% v/v;
For Topical concentrations: 7.5%, 10%, 15%, 20%, 30%, 50%, 70% and 100% v/v.
Main study:
Intradermal injection: 0.01% v/v;
Topical application: 20% v/v;
Challenge application: 5 and 2.5% v/v.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: three pairs of injections, 0.1 ml each: Freund's Complete Adjuvant plus water in ratio 1:1, a 0.01% v/v formulation of the test substance in Alembicol D, a 0.01% v/v formulation of the test substance in a 50:50 mixture of Freund's Complete Adjuvant plus Alembicol D.
- Exposure period: One week later day 7, same region was clipped again and treated with a topical application (0.4 ml) of a paper saturated with test material (20% v/v). An occlusive dressing was kept in place for 48 hours.
- Control group: Identical procedure as test animals, except test substance was omitted.
- Site: 40x60 mm area, hair was removed on the shoulder region
- Duration: 21 days

B. CHALLENGE EXPOSURE
- Day of challenge: day 21, two weeks after topical induction.
- Exposure period: A filter paper saturated with approx. 0.2 ml of 5% v/v test substance was applied to an anterior site of the flank. A filter paper saturated with 2.5% v/v test substance was applied to the posterior site. Patches were occluded. After 24 hours of occlusive dressing this was removed.
- Control group: All animals were treated the same.
- Site: An area on left flank of each animal was clipped free of hair.
- Evaluation (hr after challenge): 24 + 48 after removal of dressing
Positive control substance(s):
yes
Remarks:
historical control data of hexyl cinnamic aldehyde (HCA), benzocaine and 2-mercaptobenzothiazole (MBT)

Results and discussion

Positive control results:
Summary of positive control data from 1995 and 1996: 6/10 for benzocaine, 8/10 and 10/10 for HCA, 10/10 (twice) for MBT included.

In vivo (non-LLNA)

Resultsopen allclose all
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
0.01% intradermal, 20% epidermal, 2.5% and 5% challenge
No. with + reactions:
10
Total no. in group:
10
Clinical observations:
Necrotic effects (necrosis/ necrotic edges/ necrotic patches) in all animals, dryness and sloughinig of the epidermis in one animal, blanching in two animals.
Remarks on result:
positive indication of skin sensitisation
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
n.a.
No. with + reactions:
0
Total no. in group:
5
Clinical observations:
Localized dermal reaction (restricted to a small area of the challenge site) was seen in one animal at 24 and 48 hours; dryness and sloughing of the epidermis was observed at 72 hours for another animal.
Remarks on result:
no indication of skin sensitisation
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
not specified
No. with + reactions:
6
Total no. in group:
10
Clinical observations:
Not speicified
Remarks on result:
positive indication of skin sensitisation
Remarks:
Historical data

Any other information on results incl. tables

No signs of ill health or toxicity were noted. Bodyweight increases in test group animals were comparable to control group animals.

Intradermal injections resulted in necrosis at sites receiving Freund's Complete Adjuvant in test and control animals. Slight irritation was seen in test animals at sites receiving Takenate 600, 0.01% v/v in Alembicol D and slight irritation was observed in control animals receiving Alembicol D.

Slight erythema was observed in test animals following topical induction application with Takenate 600, 20% v/v in Alembicol D. Slight erythema was seen in the control guinea pigs.

After challenge, dermal reactions (erythema and oedema) were seen in all of the ten test animals at 24 and 48 hours after challenge, compared to none in the controls. Well-defined erythema was seen in 9/10 animals, in one animal slight erythema was seen.

Oedema formation was slight in one animal, well-defined (edges of area well-defined by definite raising) in 6 animals and moderate (raised approximately 1 mm) in 3 animals.

Applicant's summary and conclusion

Interpretation of results:
Category 1A (indication of significant skin sensitising potential) based on GHS criteria
Conclusions:
In a skin sensitising test in guinea pigs performed according to OECD guidance and GLP principles, Takenate 600 produced evidence of skin sensitisation (delayed contact hypersensitivity) in all of the ten test animals.
Executive summary:

A skin sensitising test in guinea pigs was performed according to OECD guidance and GLP principles. Based on a dose range finder experiment, concentrations for intradermal injection, topical application and challenge application were established at 0.01% v/v, 20% v/v and 2.5%/5% v/v Takenate 600. No signs of ill health or toxicity were noted. Bodyweight increases in test group animals were comparable to control group animals. After challenge, dermal reactions (erythema and oedema) were seen in all of the ten test animals at 24 and 48 hours after challenge, compared to none in the controls. Well-defined (or slight) erythema was seen in 10/10 animals. Oedema formation was slight in one animal, well-defined (edges of area well-defined by definite raising) in 6 animals and moderate (raised approximately 1 mm) in 3 animals. As the test substance produced evidence of skin sensitisation (delayed contact hypersensitivity) in all of the ten test animals, Takenate 600 was found to be a skin sensitiser (cat. 1A).