Imidazolidine-2-thione

Endpoint summary

Description of key information

Acute oral toxicity studies indicated that rats are more susceptible to ETU than mice. The reported LD50 for ethylene thiourea given orally to rats is between 545 and 1832 mg/kg body weight. For oral doses to mice, the LD50 is more than 4000 mg/kg body weight. Ethylene thiourea is of low toxicity by the dermal route, with a dermal LD0 higher than 2000 mg/kg bw in rats. 

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

other: Documentation insufficient for assessment

Principles of method if other than guideline:

No data

GLP compliance:

not specified

Test type:

standard acute method

Species:

rat

Strain:

Wistar

Sex:

not specified

Details on test animals or test system and environmental conditions:

no

Route of administration:

oral: gavage

Vehicle:

not specified

Details on oral exposure:

no

Doses:

no data

No. of animals per sex per dose:

No data

Control animals:

not specified

Details on study design:

no

Statistics:

no data

Preliminary study:

No data

Sex:

not specified

Dose descriptor:

LD50

Effect level:

545 mg/kg bw

Mortality:

no data

Clinical signs:

other: no data

Gross pathology:

no data

Other findings:

no data

Interpretation of results:

harmful

Remarks:

Migrated information category 4 Criteria used for interpretation of results: other: REGULATION (EC) No 1272/2008

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

940 mg/kg bw

Quality of whole database:

All three study have a klimisch score of 4.

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

Acute toxicity: via dermal route

Link to relevant study records

Reference

Endpoint:

acute toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2001/02/26 - 2001/08/03

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study (OECD 402)

Qualifier:

according to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.3 (Acute Toxicity (Dermal))

Deviations:

not specified

GLP compliance:

not specified

Test type:

standard acute method

Limit test:

yes

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Deutschland GmbH
- Age at study initiation: males = 42 days, females = 54 days
- Weight at study initiation: males = 203-235g, females = 208-227g
- Fasting period before study: 16 hours before administration
- Housing: singly in makrolon cages (type III)
- Diet (e.g. ad libitum): Altromin 1324, available before fasting period
- Water (e.g. ad libitum): yes, ad libitum
- Acclimation period: 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22+/-3°C
- Humidity (%):55+/-15%
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light):12/12

Type of coverage:

occlusive

Vehicle:

other: sesame oil

Details on dermal exposure:

TEST SITE
- Area of exposure: onto the shaved intact dorsal skin
- % coverage: 10% (5x6 cm, 1/10 of body surface)
- Type of wrap if used:
The tes suspension was applied to the shaved skin and the covered with 8 layers of gauze. The gauze was covered with a plastic sheet and secured with adhesive plaster on the application site.

REMOVAL OF TEST SUBSTANCE
At the end of the exposure period, possible residual substance was removed.

TEST MATERIAL
Administration : 10 ml ETU sesam oil suspension/ kg bw

VEHICLE
- Lot/batch no. (if required): 00D28FN
- Purity: no data

Duration of exposure:

24 hours

Doses:

2000 mg/kg bw

No. of animals per sex per dose:

5 rats/ sexe /dose

Control animals:

no

Details on study design:

Observation period: 14 days
At the start of the experiment, the rats were weighed.
Observations of clinical signs were performed before and immediately, 5, 15, 30 and 60 min, as well as 3, 6 and 24 hours after administration.
During the follow-up period, changes of skin and fur, eyes and mucous menbranes, respiratory and the circulatory, autonomic and central nervous system and somatomotor activity as well as behaviour pattern were observed at least once day until all symptoms subsided, thereafter each working day. Attention was also paid to possible tremor, convulsions, salivation, diarrheoea, lethargy, sleep and coma.
Observations on mortality were made at least once daily with appropriate actions taken to minimize loss of animals during the study. Individual body weights were recorded before administration of the substance and thereafter in weekly intervals up to the end pf the study, and at death.
The skin was observed for the development of erythema and oedema.
At the end of the experiments all surviving animals were sacrified, dissected and inspected macroscopically. all gross pathological changes were recorded. From animals which survived 24 hours or longer a microscopic examination of all organs which showed evident lesions was performed, if necessary. Autopsy and macroscopic inspection of animals which died prematurely were carried out as soon as possible after exitus.

Statistics:

no

Preliminary study:

No preliminary test was performed as it was known that the test substance possesses little toxicity.

Sex:

male/female

Dose descriptor:

LD0

Effect level:

>= 2 000 mg/kg bw

Based on:

test mat.

Mortality:

no mortality were observed.

Clinical signs:

other: Any clinical signs was observed. No influence on animal behaviour or premature mortality was noted. No skin reaction was observed (erythema score and edema score were equal to 0 at any test day).

Gross pathology:

The macroscopic examination of the internal organs did not reveal any changes.

Interpretation of results:

not classified

Remarks:

Migrated information Criteria used for interpretation of results: other: Regulation EC no.1272/2008

Conclusions:

Under the present test conditions a single dermal administration of 2000 mg/kg bw to rats revealed no toxic symptoms. The animals gained he expected body weight throught the test study period.

Executive summary:

The test substance was applied to rats dermally to obtain information on the possible effects in humans following overdosing with ETU.

Under the present test conditions a single dermal administration of 2000 mg/kg bw to rats revealed no toxic symptoms. The animals gained the expected body weight throught the test study period.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

discriminating dose

Value:

2 000 mg/kg bw

Quality of whole database:

This key study is reliable with a klimisch score of 1.

Additional information

Acute oral

Lewerenz et al. (1984) reported an acute oral LD50 for the rat of 940 mg/kg body weight. The values determined by Graham & Hansen (1972) and Teramoto et al. (1978) were 1832 mg/kg and 545 mg/kg body weight, respectively. Hasegawa et al. (1989) reported values of 4150 -4350 mg/kg body weight for the mouse.

Acute dermal

In an OECD guideline # 402 study, ethylene thiourea was applied to rats dermally to obtain information on the possible effects in humans following overdosing with ethylene thiourea. A single dermal administration of 2000 mg/kg bw to rats revealed no toxic symptoms. The animals gained he expected body weight throught the test study period.

Justification for classification or non-classification

Mandatory classification

Regulation (EC) No 1272/2008 : Annex VI Table 3.1: Acute tox 4 (H302: Harmful if swallowed)