1,3-bis(isocyanatomethyl)benzene

Skin sensitisation

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

Justification for type of information:

The study was performed before non-animal tests or the local lymph node assay were available.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1997

Report date:

1997

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: 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:

The study was performed before the LLNA was available.

Test material

Test material information

Constituent 1

Reference substance name:

1,3-bis(isocyanatomethyl)benzene

EC Number:

222-852-4

EC Name:

1,3-bis(isocyanatomethyl)benzene

Cas Number:

3634-83-1

Molecular formula:

C10H8N2O2

IUPAC Name:

1,3-bis(isocyanatomethyl)benzene

Details on test material:

- Name of test material (as cited in study report): Takenate 500 = 1,3-bis (isocyanatomethyl)benzene
- Physical state: colourless/pale yellow clear liquid

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: 451 to 524 g
- Housing: animals were housed in groups of five in suspended metal cages with mesh floors.
- Diet (e.g. ad libitum): ad libitum (Vitamin C enriched guinea pig diet FD2)
- Water (e.g. ad libitum): ad libitum
- Acclimatisation period: twelve days

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

Study design: in vivo (non-LLNA)

Induction

Induction 1

Route:

intradermal and epicutaneous

Vehicle:

other: Alembicol D

Induction 2

Concentration / amount:

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: 0.5%, 1%, 2.5%, 5%, 7.5%, 10%, 15% and 20%, 30%, 50%, 70%, 100% v/v
Main study:
Intradermal injection: 0.01% v/v (highest concentration in preliminary study, causing irritation but not adversely affecting the animals)
Topical application: 100%
Challenge application: 15 and 7.5% v/v (15% was the highest concentration not giving rise to irritating effects)

Challenge

Challenge 1

Route:

epicutaneous, occlusive

Vehicle:

other: Alembicol D

Challenge 2

Concentration / amount:

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: 0.5%, 1%, 2.5%, 5%, 7.5%, 10%, 15% and 20%, 30%, 50%, 70%, 100% v/v
Main study:
Intradermal injection: 0.01% v/v (highest concentration in preliminary study, causing irritation but not adversely affecting the animals)
Topical application: 100%
Challenge application: 15 and 7.5% v/v (15% was the highest concentration not giving rise to irritating effects)

No. of animals per dose:

10 test and 5 control

Details on study design:

RANGE FINDING TESTS: Selection of concentrations for main study
Intradermal induction: 0.001%, 0.0025%, 0.005%, 0.01%, 0.025%, 0.05% and 0.1% were injected. The highest concentration causing only mild to moderate skin irritation, and which was well tolerated systemically was selected for intradermal induction.
Topical induction: 0.5%, 1%, 2.5%, 5%, 7.5%, 10%, 15%, 20%, 30%, 50%, 70% and 100% was applied, highest concentration producing only mild to moderate dermal irritation was selected.
Topical challenge: 15%, 7.5% were applied occlusively for a period of 24 hours. The highest non irritant concentration and one lower concentration were selected for the topical challenge.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: three 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 the undiluted test material. 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(s) of challenge: Day 21, two weeks after topical induction.
- Exposure period: A filter paper saturated with approx. 0.2 ml of 15% v/v test substance was applied to an anterior site of the flank. A filter paper saturated with 7.5% 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:

periodically checked with known sensitisers, 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

In vivo (non-LLNA)

Results

Results 1

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

7.5% and 15%

No. with + reactions:

10

Total no. in group:

10

Clinical observations:

Same results at 48 hours. Necrosis occured in one animal, necrotic patch in several animals, thickening, dryness and sloughinig of the epidermis occured also in one animal.

Remarks on result:

other: see Remark

Remarks:

Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 7.5% and 15%. No with. + reactions: 10.0. Total no. in groups: 10.0. Clinical observations: Same results at 48 hours. Necrosis occured in one animal, necrotic patch in several animals, thickening, dryness and sloughinig of the epidermis occured also in one animal. .

Results 2

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

7.5% and 15%

No. with + reactions:

0

Total no. in group:

5

Clinical observations:

Same results at 48 hours. No observations.

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: 7.5% and 15%. No with. + reactions: 0.0. Total no. in groups: 5.0. Clinical observations: Same results at 48 hours. No observations..

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. During induction, slight irritation was seen in test and control animals after intradermal injections, slight erythema was observed after topical application in test and control animals.

Applicant's summary and conclusion

Interpretation of results:

Category 1A (indication of significant skin sensitising potential) based on GHS criteria

Conclusions:

Takenate 500 produced evidence of skin sensitisation (delayed contact hypersensitivity) in all of the ten test animals. Classification with risk phrase R43 is warranted.