1-amidino-2-thiourea

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2015

Report date:

2015

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

1-amidino-2-thiourea

EC Number:

218-308-0

EC Name:

1-amidino-2-thiourea

Cas Number:

2114-02-5

Molecular formula:

C2H6N4S

IUPAC Name:

1-(Diaminomethylidene)thiourea

Test material form:

solid: crystalline

Specific details on test material used for the study:

Supplier: Changzou Foreign Trade Corp.Batch No.: 0041A25 (20141211)Physical state: solid substance, crystalline powderColour: whiteStorage: in a cool, dry place, protected from light

In vivo test system

Test animals

Species:

mouse

Strain:

CBA/Ca

Sex:

female

Details on test animals and environmental conditions:

Species and strain: CBA/Ca Ola Hsd miceSource: TOXI-COOP ZRT.Hygienic level duringthe study: Good conventionalNumber of animals: 28 animals/main testSex: Female, nulliparous, non-pregnantAge of animals: Young adult mice;11-12 weeks old (at start of the main test)Body weight range at starting: 18.5-23.4 gThe weight variation in animals involved in the study did not exceed ± 20 % of the mean weight.Acclimatization time: 7 daysAnimal health: Only healthy animals were usedHousing during acclimatization period: Grouped caging in small groupsHousing during the test: Grouped caging (4 animals/cage)Cage type: Type II. Polypropylene / polycarbonateBedding: Laboratory beddingLight: 12 hours daily, from 6.00 a.m. to 6.00 p.m.Temperature: 22 ± 3 °CRelative humidity: 30 – 70 %Housing/Enrichment: Mice were group-housed to allow social interaction, and with deep wood sawdust bedding, to allow digging and other normal rodent activities.

Study design: in vivo (LLNA)

Vehicle:

dimethylformamide

Concentration:

Based on the preliminary test results the test item was examined in the main test at 25 %, 10 %, 5 % and 2.5 % (w/v) concentrations as formulations in N,N-Dimethylformamide (DMF).

No. of animals per dose:

4 animals/treatment group

Details on study design:

Animals in the treatment groups were treated with the relevant vehicles (DMF or AOO), appropriate formulations of the test item or 25 % (w/v) concentration of the positive control substance. The test item was administered at four different concentrations according to the results of the dose range finding test. For detailed data see the table below.Each mouse was topically treated with 25 μL of the appropriate formulations of the test item, the positive control substance or the vehicles (see Table 3) using a pipette, on the dorsal surface of each ear. After the treatments animals were returned to their cages. Each animal was dosed once a day for three consecutive days (Days 1, 2 and 3). There was no treatment on Days 4, 5 and 6.All animals have been monitored daily for systemic toxicity or excessive skin irritation. In case of failed treatment, systemic toxicity or excessive irritation the respective dose-group is excluded from evaluation.

Positive control substance(s):

hexyl cinnamic aldehyde (CAS No 101-86-0)

Results and discussion

Positive control results:

The positive control group animals were treated with 25 % (w/v) HCA solution (dissolved in AOO) concurrent to the test item groups. No mortality, cutaneous reactions or signs of toxicity were observed in the positive control group.Significant lymphoproliferative response (SI ≥ 3) was noted for HCA (SI = 6.9). The results of the positive control item demonstrated appropriate performance of the test in accordance with the relevant guidelines and confirmed validity of the assay.

In vivo (LLNA)

Results

Remarks on result:

other: no skin sensitization potential

Any other information on results incl. tables

Test GroupName	Measured DPM/group	Group* DPM	DPN (DPM/Node)	Stimulation IndexValues
Vehicle control for the positive control: AOO	8610	8585.0	1073.1	1.0
Positive control: 25 % HCA in AOO	59201	59176.0	7397.0	6.9
Amidinothiourea (CAS No. 2114-02-5) 25% in DMF	16022	15997.0	1999.0	2.2
Amidinothiourea (CAS No. 2114-02-5) 10% in DMF	3694	3669.0	458.6	0.5
Amidinothiourea (CAS No. 2114-02-5) 5% in DMF	6502	6477.0	809.6	0.9
Amidinothiourea (CAS No. 2114-02-5) 2,5% in DMF	7503	7478.0	934.8	1.0
Vehicle control for the test item: DMF	7184	7159.0	894.9	1.0

*Group DPM = measured DPMgroup- average DPMbackground

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

In conclusion, under the conditions of the present Local Lymph Node Assay, AMIDINOTHIOUREA (CAS No. 2114-02-5) tested at the maximum attainable concentration of 25 % (based on solubility) and at concentrations of 10 %, 5% and 2.5 % (w/v) as formulations in an appropriate vehicle (DMF) was shown to have no skin sensitization potential.