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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:
July - August, 1985
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1985
Report date:
1985

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Version / remarks:
adopted May 12, 1981
Deviations:
no
GLP compliance:
yes
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
Existing in vivo study dated 1985 available of good quality to meet this endpoint

Test material

Constituent 1
Chemical structure
Reference substance name:
1-(N,N-bis(2-ethylhexyl)aminomethyl)-1,2,4-triazole
EC Number:
401-280-0
EC Name:
1-(N,N-bis(2-ethylhexyl)aminomethyl)-1,2,4-triazole
Cas Number:
91273-04-0
Molecular formula:
C19 H38 N4
IUPAC Name:
bis(2-ethylhexyl)[(1H-1,2,4-triazol-1-yl)methyl]amine
Details on test material:
- Physical state: liquid
- Analytical purity: commercial grade
- Storage condition of test material: room temperature

In vivo test system

Test animals

Species:
guinea pig
Strain:
other: Pirbright White Strain (Tif: DHP)
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source:CIBA-GEIGY LTD. Tierfarm, 4334 Sisseln, Switzerland
- Age at study initiation: 10 weeks old
- Weight at study initiation: 299-416 g
- Housing: individually in Macrolon cages
- Diet: standard guinea pig pellets, NAFAG No.846, ad libitum
- Water: ad libitum
- Acclimation period: 8 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22+3°C
- Humidity (%): 30 to 70 %
- Photoperiod (hrs dark / hrs light): 12 hours light cycle day

Study design: in vivo (non-LLNA)

Induction
Route:
intradermal and epicutaneous
Vehicle:
other: Sesame oil and vaseline
Concentration / amount:
First induction: 1% in sesame oil
Second induction: 0.4 g paste of 30% test item
Challenge: 0.2 g paste of 30% test item
Challenge
Route:
epicutaneous, occlusive
Vehicle:
other: Sesame oil and vaseline
Concentration / amount:
First induction: 1% in sesame oil
Second induction: 0.4 g paste of 30% test item
Challenge: 0.2 g paste of 30% test item
No. of animals per dose:
20
Details on study design:
MAIN STUDY
A. INDUCTION EXPOSURE
The induction was a two-stage operation. First, intradermal injections (into the neck region); second, closed patch exposure over the injection sites one week later.
First induction:
Three pairs of intradermal injections (0.1 mL per injection) were made simultaneously into the shaved neck of the guinea pigs as follows: adjuvant and saline (1: 1), test item in sesame oil, test item in the adjuvant saline mixture.
- Control group: yes, treated with adjuvant and the vehicle
- Site: neck
- Concentrations: 1% solution (0.1 ml per injection)

Second induction:
One week after induction the test item was incorporated in vaseline and applied on a filterpaper patch to the neck of the animals (patch 2 x 4 cm; occluded administration for 48 hours).
The application sites were pretreated the day before with 10 % sodium lauryl sulfate (open application).
- No. of exposures: one
- Exposure period: 48 h
- Control group: yes, treated with adjuvant and the vehicle
- Site: neck
- Concentrations: 30% test item (approx. 0.4 g test item)

B. CHALLENGE EXPOSURE
Two weeks after the epidermal induction application the animals were tested on the flank with the test item in vaseline and the vehicle alone (patch 2 x 2 cm; occluded administration for 24 hours).
- No. of exposures: one
- Day(s) of challenge: Two weeks after the epidermal induction application
- Exposure period: 24 h
- Control group: yes, treated with the vehicle as well as with the test compound
- Site: flank
- Concentrations: 30% test item (approx. 0.2 g test item)
- Evaluation (hr after challenge): 24 h and 48 h

C. CONTROL GROUP
A control group was treated with adjuvant and the vehicle during the induction period. During the challenge period the group was treated with the vehicle as well as with the test compound (at least 10 animals) to control the maximal subirritant concentration of the test item in adjuvant treated animals.
Positive control substance(s):
no

Results and discussion

Positive control results:
The sensitivity of the strain was checked every six months with Paraphenylene-diamine or Potassium-dichromate.

In vivo (non-LLNA)

Resultsopen allclose all
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
30%
No. with + reactions:
19
Total no. in group:
20
Remarks on result:
positive indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
30%
No. with + reactions:
17
Total no. in group:
20
Remarks on result:
positive indication of skin sensitisation
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
30%
No. with + reactions:
0
Total no. in group:
20
Remarks on result:
no indication of skin sensitisation
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
30%
No. with + reactions:
0
Total no. in group:
20
Remarks on result:
no indication of skin sensitisation
Group:
positive control
Remarks on result:
not measured/tested

Applicant's summary and conclusion

Interpretation of results:
Category 1A (indication of significant skin sensitising potential) based on GHS criteria
Conclusions:
85 to 95% of the animals were sensitised by the test article under the experimental conditions employed. The test substance is therefore regarded a skin sensitizer.
Executive summary:

In a guinea pig maximization test according to OECD guideline No. 406, 10 male and 10 female animals were first induced and then challenged with the test article to investigate its sensitization potential. Induction was a two-stage operation: First, three pairs of intradermal injections (0.1 ml per injection) were made into the shaved neck of the animals with a 1:1 mixture (v/v) of adjuvant/saline, 1% of the test substance in sesame oil, and 1% of the test substance in a 1:1 mixture (v/v) of adjuvant/ saline. One week later the test article was incorporated in vaseline (30% concentration) applied on a filter paper patch to the neck of the animals (patch 2 x 4 cm; 0.4 g, occluded administration for 48 hours). The application sites were pretreated on the previous day with 10 % sodium lauryl sulfate (open application). Two weeks after the epidermal induction application the animals were tested on the flank with 30% test substance in vaseline and the vehicle alone (patch 2 x 2 cm; 0.2 g, occluded administration for 24 hours). A control group of 10 males and 10 females was treated with adjuvant and the vehicle during the induction period. During the challenge period the group was treated with the vehicle as well as with the test compound (at least 10 animals) to control the maximal subirritant concentration of the test compound in adjuvant treated animals. Twenty four hours after removing the dressings the challenge reactions were graded according the Draize scoring scale.

A second evaluation was made 48 hours after removing the dressings. At the 24 hour time point, 19/20 animals of the test group showed dermal irritation reactions. At the 48 hour time point, 17/20 animals were positive. None of the animals of the control group showed reactions either treated with the vehicle or with the test compound during challenge. In conclusion, under the experimental conditions employed, 85 to 95% of the animals of the test group showed skin reactions 24 and 48 hours after removing the dressings. The test article is therefore regarded as a skin sensitizer in albino guinea pigs and requires classification.