1,3,4-thiadiazole-2,5-dithiol

Acute Toxicity: dermal

Administrative data

Endpoint:

acute toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2018-01-24 - 2018-02-14 (experimental phase)

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity)

Version / remarks:

OECD Guideline for the Testing of Chemicals No. 402 “Acute Dermal Toxicity” (2017)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test type:

fixed dose procedure

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

1,3,4-thiadiazole-2,5-dithiol

EC Number:

214-014-1

EC Name:

1,3,4-thiadiazole-2,5-dithiol

Cas Number:

1072-71-5

Molecular formula:

C2H2N2S3

IUPAC Name:

1,3,4-thiadiazole-2,5-dithiol

Test material form:

solid: particulate/powder

Remarks:

white

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: sponsor

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: approximately 4 °C in the dark

Test animals

Species:

rat

Strain:

Wistar

Remarks:

Wistar (RccHan(TM):WIST)

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Envigo RMS (UK) Limited, Oxon, UK
- Females (if applicable) nulliparous and non-pregnant: yes
- Age at study initiation: At the start of the study the animals were 8 to 12 weeks of age.
- Weight at study initiation: At the start of the study the animals weighed at least 200 g. The weight variation did not exceed ±20% of any previously treated animal.
- Fasting period before study: no
- Housing: The animals were individually housed throughout the study in suspended solid floor polypropylene cages furnished with woodflakes. The animals were provided with environmental enrichment items which were considered not to contain any contaminant of a level that might have affected the purpose or integrity of the study.
- Diet (e.g. ad libitum): 2014C Teklad Global Rodent diet supplied by Envigo RMS (UK) Limited, Oxon, UK ad libitum
- Water (e.g. ad libitum): mains drinking water ad libitum
The diet, drinking water and bedding were routinely analyzed and were considered not to contain any contaminants that could reasonably be expected to affect the purpose or integrity of the study.
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): The temperature was set to achieve limits of 19 to 25 °C.
- Humidity (%): The relative humidity was set to achieve limits of 30 to 70%
- Air changes (per hr): The rate of air exchange was at least fifteen changes per hour.
- Photoperiod (hrs dark / hrs light): The lighting was controlled by a time switch to give 12 hours continuous light and 12 hours darkness.

IN-LIFE DATES: From: To:

Administration / exposure

Type of coverage:

semiocclusive

Vehicle:

unchanged (no vehicle)

Remarks:

skin was moistened ahead with arachis oil BP

Details on dermal exposure:

TEST SITE
- Area of exposure: back and flanks
- % coverage: approximately 10% of the total body surface area
- Type of wrap if used: A piece of surgical gauze was placed over the treatment area and semi occluded with a piece of self adhesive bandage. Shortly after dosing the dressings were examined to ensure that they were securely in place.

REMOVAL OF TEST SUBSTANCE
- Washing (if done): After the 24 Hour contact period the bandage was carefully removed and the treated skin and surrounding hair wiped with cotton wool moistened with arachis oil BP to remove any residual test item.
- Time after start of exposure: 24h

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 2000 mg/kg bw
- For solids, paste formed: no

Duration of exposure:

24h

Doses:

2000 mg/kg bw

No. of animals per sex per dose:

3 in total

Control animals:

not required

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: The animals were observed for deaths or overt signs of toxicity 30 minutes, 1, 2, 4 and 6 hours after dosing and subsequently once daily for 14 days.
After removal of the dressings and subsequently once daily for 14 days, the test sites were examined for evidence of primary irritation
Individual body weights were recorded prior to application of the test item on Day 0 and on Days 7 and 14.
- Necropsy of survivors performed: yes
At the end of the study the animals were killed by cervical dislocation. All animals were subjected to gross necropsy. This consisted of an external examination and opening of the abdominal and thoracic cavities. The appearance of any macroscopic abnormalities was recorded. No tissues were retained.
- Other examinations performed: clinical signs, body weight, skin reactions

Results and discussion

Preliminary study:

no mortalities noted in the first female

Effect levels

Effect levels 1

Key result

Sex:

female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Effect levels 2

Key result

Sex:

female

Dose descriptor:

LD0

Effect level:

>= 2 000 mg/kg bw

Based on:

test mat.

Remarks on result:

other: none of the three animals died

Mortality:

There were no deaths.

Clinical signs:

other: No signs of systemic toxicity were noted during the observation period.

Gross pathology:

No abnormalities were noted at necropsy.

Other findings:

Dermal reactions:
Signs of dermal irritation noted included very slight to well defined erythema and very slight edema. Crust formation, small superficial scattered scabs and scab lifting to reveal glossy skin were also noted. Yellow staining of the treatment sites was also noted.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Remarks:

EU implementation

Conclusions:

The study was conducted under GLP according to OECD guideline 402 on the registered substance itself. The method is to be considered scientifically reasonable with no deficiencies in documentation. Hence, the results can be considered as reliable to assess the acute oral toxicity in rats. The acute dermal median lethal dose (LD50) of the test item in the female Wistar strain rat was found to be greater than 2000 mg/kg body weight.

Executive summary:

The study was performed to assess the acute dermal toxicity of the test item in the Wistar strain rat according to OECD TG 402 under GLP.

Methods: Initially, one female animal was given a single, 24 hour, semi‑occluded dermal application of the undiluted test item to intact skin at a dose level of 2000 mg/kg body weight. Based on the results of the initial test, a further two female animals were similarly treated. Clinical signs and body weight development were monitored during the study. All animals were subjected to gross necropsy.

Results:

Mortality. There were no deaths.

Clinical Observations. There were no signs of systemic toxicity.

Dermal Irritation. Signs of dermal irritation noted included very slight to well defined erythema and very slight edema. Crust formation, small superficial scattered scabs and scab lifting to reveal glossy skin were also noted. Yellow staining of the treatment sites was also noted. 

Body Weight. One animal showed body weight loss during the first week with expected gain in body weight during the second week. The remaining animals showed expected gains in body weight.

Necropsy. No abnormalities were noted at necropsy.

Conclusion: The acute dermal median lethal dose (LD50) of the test item in the female Wistar strain rat was found to be greater than 2000 mg/kg body weight.