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Toxicological information

Skin sensitisation

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Administrative data

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Remarks:
In vivo study performed prior (1980) to REACH implementation and adoption of LLNA test guideline.
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1980-10-06 - 1980-11-12 (experimental phase)
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1980
Report Date:
1980

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Deviations:
not applicable
GLP compliance:
not specified
Type of study:
Buehler test
Justification for non-LLNA method:
In vivo guinea pig study was performed prior (1980) to REACH implementation and adoption of LLNA test guideline.

Test material

Reference
Name:
Unnamed
Type:
Constituent

In vivo test system

Test animals

Species:
guinea pig
Strain:
other: Albino
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Weight at study initiation: 300 - 400 g
- Housing: The animals were housed and maintained in compliance with the Animal Welfare Act (Pub. L-94-279) 9 CFR Part 3.
- Indication of any skin lesions: none stated

Study design: in vivo (non-LLNA)

Induction
Route:
epicutaneous, occlusive
Vehicle:
unchanged (no vehicle)
Concentration / amount:
0.5 g
Day(s)/duration:
10 application, every second day
Adequacy of induction:
other: highest possible concentration (undiluted material), non-irritant
Challenge
No.:
#1
Route:
epicutaneous, occlusive
Vehicle:
unchanged (no vehicle)
Concentration / amount:
0.5 g
Day(s)/duration:
24 h
Adequacy of challenge:
other: highest possible concentration (undiluted)
No. of animals per dose:
5 males & 5 females
Details on study design:
MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 10
- Exposure period: 24h exposure
- Test groups: group of ten (five male and five female rats)
- Control group: none stated
- Site: intact skin test sites
- Frequency of applications: every second day
- Duration: 19 days
- Concentrations: undiluted

B. CHALLENGE EXPOSURE
- No. of exposures: 2
- Day(s) of challenge: At the termination of the 2 week rest period a challenge application was put on skin sites differing from the original test sites. The challenge application remained on for 24 hours.
- Exposure period: 24h
- Test groups: group of ten (five male and five female rats)
- Site: skin sites differing from the original test sites
- Concentrations: undiluted
- Evaluation (hr after challenge): 24h & 48h
Challenge controls:
none stated
Positive control substance(s):
not required

Results and discussion

Positive control results:
n/a

In vivo (non-LLNA)

Resultsopen allclose all
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
undiluted
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
no effects stated
Remarks on result:
no indication of skin sensitisation
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
undiluted
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
no effects stated
Remarks on result:
no indication of skin sensitisation
Reading:
other: 1st & 2nd reading
Group:
negative control
Remarks on result:
other: information not given
Reading:
other: 1st & 2nd reading
Group:
positive control
Remarks on result:
other: information not given

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
Study was performed scientifically reasonable similar OECD TG 406 on 1,3,4-Thiadiazole-2,5-dithiole, is sufficiently documented, and taking into account the obtained results with acceptable restrictions. Hence, the results can be considered as reliable to assess the sensitizing potential of 1,3,4-Thiadiazole-2,5-dithiole in guinea pigs.
The undiluted test material was tested on 5 male and 5 female guinea pigs. According to OECD TG 406 regarding the Bühler test, “a minimum of 20 animals is used in the treatment group“. As the test item did not produce any sign of irritation, neither during induction nor challenge, in all the tested animals, the result can be nevertheless considered as unambiguous. Hence, the test item does not need to be classified as a skin sensitizer.
Executive summary:

In a dermal sensitization study (performed scientifically reasonable similar OECD TG 406) with unchanged 1,3,4-Thiadiazole-2,5-dithiole in 300-400 g albino guinea pigs (5/sex) were tested using the method of Bühler, irritation scoring according to Draize. 

A 0.5 gm portion of material was applied to the intact skin test sites on the guinea pigs. After a 24 hour contact period (occlusive) the patch was removed and the animals were allowed to rest for one day. Exposure was repeated 10 times. After the tenth application the animals were rested for a two week period. At the termination of the rest period a challenge application was put on skin sites differing from the original test sites. The challenge application remained on for 24 hours. Twenty-four hours after each induction stage application and twenty-four and forty-eight hours after the challenge (re-test) application, the sites were examined for irritation, if any.

In none of the animals any sign of systemic toxicity, irritation or sensitization was noted after any application.

In this study, 1,3,4-Thiadiazole-2,5-dithiole is not a dermal sensitizer, no classification is required.