Registration Dossier

Administrative data

Description of key information

Ethylene thiourea was not a skin sensitizer in a mouse ear swelling test.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records
Reference
Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study well documented, meets generally accepted scientific principles, acceptable for assessment.
Qualifier:
no guideline followed
Principles of method if other than guideline:
Mice were exposed by dermal route (epicutaneous, open) to ETU. After induction and challenge phase, the sensibilisant power of ETU was studied.
GLP compliance:
yes
Type of study:
mouse ear swelling test
Justification for non-LLNA method:
An old study to evaluate the skin sensitisation was available before the REACH regulation ; no new study was performed.
Species:
mouse
Strain:
B6C3F1
Sex:
female
Details on test animals and environmental conditions:
no data
Route:
epicutaneous, open
Vehicle:
other: ethylene glycol
Concentration / amount:
Induction : 1.0%, 3.0%, 10.0% ETU
Challenge : 10% ETU
Route:
epicutaneous, open
Vehicle:
other: ethylene glycol
Concentration / amount:
Induction : 1.0%, 3.0%, 10.0% ETU
Challenge : 10% ETU
No. of animals per dose:
8 mice per group
Details on study design:
RANGE FINDING TESTS:
Primary irritancy studies indicated that all concentrations of ETU tested (up to 30%) were non-irritating.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 1
- Exposure period: 5 consecutive days
- Site: Dorsal surface site
- Frequency of applications: in continuously
- Concentrations: 1.0%, 3.0% or 10.0% ETU

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: no data
- Exposure period: no data
- Site: on the dorsal and ventral sites on the left ear.
- Concentrations: 10% ETU
- Evaluation (hr after challenge): 24 and 48hr


OTHER: Between Induction exposure and challenge exposure, there were 7 days.
Site preparation included intradermal injection of Freud's complete adjuvant in some mice.
The irritancy response was determined by monitoring the extravasation of 125 I- bovine serum albumin into the treated area. The contact hypersensitivity response was determined by monitoring the infiltration of 125 I-iododeoxyuridine laabeled cells into the challenge site in addition to the mouse ear swelling test.
Challenge controls:
yes, vehicle control. see table.
Positive control substance(s):
yes
Remarks:
DNFB
Positive control results:
The positive response with 0.5% DNFB was observed 24 hr after challenge.
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
10%
No. with + reactions:
0
Total no. in group:
8
Remarks on result:
no indication of skin sensitisation
Reading:
1st reading
Hours after challenge:
48
Group:
test group
Dose level:
10%
No. with + reactions:
0
Total no. in group:
8
Remarks on result:
no indication of skin sensitisation
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
100%
No. with + reactions:
0
Total no. in group:
8
Remarks on result:
no indication of skin sensitisation
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
100%
No. with + reactions:
8
Total no. in group:
8
Remarks on result:
positive indication of skin sensitisation

There were no treatment-related effects on survival or body weights. There was no evidence of skin irritation in the form of erythma or edema in any of the treatment groups. No statistically significant or dose-related hypersensitivity response was observed in mice sensitized with 1%, 3% or 10% ETU and challenge with 10% ETU.

Interpretation of results:
not sensitising
Remarks:
Migrated information
Conclusions:
Under these experimental conditions, no statistically significant or dose-dependent contact hypersensitivity responses to ETU were observed in mice following dermal exposure.
Executive summary:

ETU was tested in his sensibility with a mouse ear swelling test. The induction was made with 1.0%, 3.0%, 10.0% ETU, and the challenge with 10% ETU. There were no statistically significant or dose-dependent contact hypersensitivity responses with ETU.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

Human data

Rudzki et al. (1976) performed patch tests on 200 patients with contact dermatitis in Poland. ETU was diluted in yellow soft paraffin and applied to the skin at a concentration of 2%. Only one person out of the 200 (0.50%) exhibited a positive reaction to ETU.

Animal study One study was available and reliable for this endpoint (Munson, 1992). Ethylene thiourea was tested in its sensitizing potential with a mouse ear swelling test. The induction was made with 1.0%, 3.0%, 10.0% ETU, and the challenge with 10% ETU. There was no evidence of skin irritation in the form of erythma or oedema in any of the treatment groups. No statistically significant or dose-related hypersensitivity response was observed in mice sensitized with 1%, 3% or 10% ETU and challenge with 10% ETU. Under these experimental conditions, no statistically significant or dose-dependent contact hypersensitivity responses to ETU were observed in mice following dermal exposure.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

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