Imidazolidine-2-thione

Endpoint summary

Description of key information

Ethylene thiourea is not irritating to the eyes or the skin of rabbits and the respiratory tract of rats.

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Endpoint:

skin irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2001/02/26 - 2001/05/08

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study (OECD 404)

Qualifier:

according to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.4 (Acute Toxicity: Dermal Irritation / Corrosion)

Deviations:

not specified

GLP compliance:

no

Species:

rabbit

Strain:

Himalayan

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: LPT Laboratory of Pharmacology and toxicology kg
- Age at study initiation: 5-6 months
- Weight at study initiation: 2.2-2.5 kg
- Housing: singly in special restrainers with dimensions of 425 mm x 6000 mm x 380 mm which allowed free movement of the head but prevented a complete body turn.
- Diet (e.g. ad libitum): altromin 2023, available before and after the exposure period.
- Water (e.g. ad libitum): tap water, ad libitum
- Acclimation period: At least 20 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 +/- 3°C
- Humidity (%): 55+/-15%
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: To:

Type of coverage:

occlusive

Preparation of test site:

shaved

Vehicle:

water

Controls:

no

Amount / concentration applied:

500 mg ETU per patch per animal, once epicutaneous

Duration of treatment / exposure:

4 hours

Observation period:

60 minutes, 24-48-72 hours

Number of animals:

3 rabbits (males)

Details on study design:

TEST SITE
- Area of exposure: dermal application to the shaved intact dorsal skin
- % coverage: 6 cm²
- Type of wrap if used: a gauze patch

REMOVAL OF TEST SUBSTANCE
- Washing (if done): no
- Time after start of exposure: 4 hours

Irritation parameter:

erythema score

Basis:

mean

Remarks:

3 rabbits

Time point:

24/48/72 h

Score:

0

Max. score:

4

Remarks on result:

no indication of irritation

Irritation parameter:

edema score

Basis:

mean

Remarks:

3 rabbits

Time point:

24/48/72 h

Score:

0

Max. score:

4

Remarks on result:

no indication of irritation

Irritant / corrosive response data:

Any reaction was observed: erythema score and edema score were equal to 0 at all time.

Interpretation of results:

not irritating

Remarks:

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

Conclusions:

Under the present test conditions none of the three rabbits exposed for 4 hours to 500 mg ETU per patch and animal showed any substance-related lesions at the examination time-points 60 min and 24, 48 and 72 hours after patch removal. There were no systemic intolerance reactions.
ETU was non-irritating to skin, hence, no labelling is required.

Executive summary:

The aim of this examination was to examine ETU for acute skin irritation in rabbits (patch test). After the 4 -hour exposure period, the patch was removed and the skin sites of the three animals were evaluated.

Under the present test conditions none of the three rabbits exposed for 4 hours to 500 mg ETU per patch and animal showed any substance-related lesions at the examination time-points 60 min, and 24, 48 and 72 hours after patch removal. There were no systemic intolerance reactions.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Link to relevant study records

Reference

Endpoint:

eye irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with acceptable restrictions. Restriction : no data on purity, no quantitative data for ETU

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

Deviations:

yes

Remarks:

no score are available.

GLP compliance:

not specified

Species:

rabbit

Strain:

other: Japanese white (females)

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
- Source: Shizuoka, Japan
- Age at study initiation: no data
- Weight at study initiation: 2.0-2.2 kg
- Housing: in metal cages (39 x40x44 cm)
- Diet (e.g. ad libitum): RC4 diet (Oriental Yeast Co., Tokyo Japan), ad libitum
- Water (e.g. ad libitum): not precised, ad libitum
- Acclimation period: no data

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 25 +/-1°C
- Humidity (%): 55+/-5%
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light): 12/12

Vehicle:

not specified

Controls:

yes

Amount / concentration applied:

The chemical (Solid = 100 mg ; liquid = 0.1 ml) was placed into conjunctival sac of the left eye.
The right eye was served as a blank.

Duration of treatment / exposure:

1 single administration

Observation period (in vivo):

1, 4, 24, 48, 72, 96 hr, and 7, 14, 21 days after the treatment of chemical.

Number of animals or in vitro replicates:

3 animals/ group

Details on study design:

REMOVAL OF TEST SUBSTANCE : no data
SCORING SYSTEM: Corneal opacity, erythema, chemosis, secreta and iritis were classified according to the Draize score (1944).

Irritation parameter:

overall irritation score

Remarks:

Draize score

Basis:

mean

Time point:

24/48/72 h

Score:

<= 7

Max. score:

110

Reversibility:

fully reversible within: 24 h

Remarks on result:

other: Minimal irritation

Irritation parameter:

cornea opacity score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Remarks on result:

other: data not reported

Irritation parameter:

iris score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Remarks on result:

other: data not reported

Irritation parameter:

conjunctivae score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Remarks on result:

other: data not reported

Irritation parameter:

chemosis score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Remarks on result:

other: data not reported

Irritant / corrosive response data:

There was no quantitative data for ETU.
It was a chemical which inducing no or mild damage recovering within 24 hr. This score distributed from 0 up to 7.0 .

Other effects:

no

Interpretation of results:

not irritating

Remarks:

Migrated information Criteria used for interpretation of results: expert judgment

Conclusions:

ETU was in class I, it was a non or mild irritant.

Executive summary:

The Draize eye irritation test has been used as an attempt to predict ocular irritancy of chemicals.The eye irritation ratings were made in three classes on the basis of the recovery time of corneal and conjunctival damages. A three-class discrimination was made as follows; class I included chemicals which induced the damages recovering within 24 hr, class II included chemicals which induced the damages persisting for more than 24 hr but recovering within 21 days, class III included chemicals which induced the damages not recovering within 21 days. ETU was a non or mild irritant (class 1).

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Additional information

Skin irritation

 

The acute skin irritation in rabbits (patch test) of ethylene thiourea was evaluated in an OECD guideline # 404 study (Leuschner, 2003). After the 4 -hour exposure period, the patch was removed and the skin sites of the three animals were evaluated. None of the three rabbits exposed for 4 hours to 500 mg ethylene thiourea per patch and animal showed any substance-related lesions at the examination time-points 60 min, and 24, 48 and 72 hours after patch removal. There were no systemic intolerance reactions.

 

Eye irritation

 

A Guideline study with acceptable restrictions was available for eye irritation (Sugai 1990). This study used 3 rabbits and one dose of ethylen e thiourea (100 mg / 1 ml). The Draize eye irritation test has been used as an attempt to predict ocular irritancy of chemicals. Score of ethylene thiourea distributed from 0 up to 7.0 , but there were no quantitative data.

 

Respiratory irritation .

 

In the 28-day inhalation toxicity study performed according to the OECD guideline # 412 (Duchosal et al., 1988), no clinical and histological sign of nasal and lung irritation was observed up to the concentration of 0.197 mg/l.

Justification for classification or non-classification

No classification is warranted for skin and eye irritation according to Regulation (EC) No 1272/2008.