Tricobalt dicitrate

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Acceptable, well documented publication which meets basic scientific principles.

Data source

Reference

Reference Type:

publication

Title:

Detection of contact sensitivity of metal salts using the murine local lymph node assay.

Author:

Ikarashi, Y. et al.

Year:

1992

Bibliographic source:

Toxicology Letters 62: 53-61

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

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

Deviations:

yes

Remarks:

- Radiolabelling of cells was performed ex vivo, different vehicles and various vehicle concentrations were compared.

GLP compliance:

not specified

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

7791-13-1

EC Number:

616-574-6

Cas Number:

7791-13-1

IUPAC Name:

7791-13-1

Constituent 2

Reference substance name:

cobalt(II)chloride hexahydrate

IUPAC Name:

cobalt(II)chloride hexahydrate

Details on test material:

- Name of test material (as cited in study report): cobalt(II)chloride hexahydrate
- Molecular formula (if other than submission substance): CoCl2*6H2O
- Molecular weight (if other than submission substance): 237.84 g/mol
- Analytical purity: no data
- Other: Source: Wako Pure Chemical Industries, Ltd., Osaka, Japan

In vivo test system

Test animals

Species:

mouse

Strain:

Balb/c

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Japan SLC Inc., Shizuoka, Japan
- Age at study initiation: 6-8 weeks

Study design: in vivo (LLNA)

Vehicle:

other: DMSO or 70% ethanol

Concentration:

5% of CoCl2*6H2O in DMSO, 5% of CoCl2*6H2O in ethanol

No. of animals per dose:

3

Details on study design:

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Criteria used to consider a positive response: SI > 2

TREATMENT PREPARATION AND ADMINISTRATION:
Exp 1: Groups of mice were treated with 5% of CoCl2*6H2O in DMSO or DMSO alone by applying 25 µL to the dorsum of both ears for three consecutive days. Four days following the initial application, draining lymph nodes were excised. After preparation of a single cell suspensions, the incorporation of [³H]TdR was performed for 18 hours ex vivo.

Exp 2: Groups of mice were treated with 5% of CoCl2*6H2O in DMSO or with 70% ethanol alone by applying 25 µL to the dorsum of both ears for three consecutive days. Prior to the treatment, the ears of each mouse were gently abraded using a 19-g needle. Four days following the initial application, draining lymph nodes were excised. A single cell suspension of LNC was prepared and incorporation of [³H]TdR was measured.

In both experiments a single cell suspension of lymph node cells was prepared and incorporation of [³H]TdR was measured after 18 hours incubation.

Positive control substance(s):

not specified

Statistics:

[³H]TdR incorporation was calculated as mean cpm ± SD. Stimulation indices of lymph node cell proliferation between substance-treated and vehicle-treated groups were calculated.

Results and discussion

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Remarks on result:

other: see Remark

Remarks:

Exp 1: 5.23% in DMSO (recalculated value, equivalent to 5% CoCl2*6H2O): 4.54 Exp 2: without abration: 5.23% in 70% ethanol (recalculated value, equivalent to 5% CoCl2*6H2O): 2.2 with abration: 5.23% in 70% ethanol (recalculated value, equivalent to 5% CoCl2*6H2O): 4.58

Results 2

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: see Remark

Remarks:

In mean cpm ± SD (x0.001) per node of 3 animals: Exp 1: DMSO: 1.71 ± 0.68 mean cpm ± SD (x0.001); 7.77 mean cpm (x0.001) in DMSO (recalculated value, equivalent to 5% CoCl2*6H2O in DMSO: 7.42 ± 1.00 mean cpm ± SD (x0.001)) Exp 2: 70% ethanol: 2.25 ± 0.30 mean cpm ± SD (x0.001); without abration: 4.94 mean cpm (x0.001) in 70% ethanol (recalculated value, equivalent to 5% CoCl2*6H2O in 70% ethanol: 4.72 ± 0.52 mean cpm ± SD (x0.001)) with abration: 10.3 mean cpm (x0.001) in 70% ethanol (recalculated value, equivalent to 5% CoCl2*6H2O in 70% ethanol: 9.84 ± 2.76 mean cpm ± SD (x0.001))

Any other information on results incl. tables

Exp 1:

Repeated exposure for three consecutive days induced an increase of LNC proliferative response in the draining lymph node (SI=4.54).

Exp 2:

Dissolution in 70% ethanol resulted in a greater proliferative response in the abrasion group (SI=4.58) than in the non-abrasion group (SI=2.2). The ear abrasion is effective in enhancing the penetration of the metal ion and to increase the LNC proliferation. However, the abrasion technique does not affect the LNC response in the vehicle or non-sensitiser-treated group.

Applicant's summary and conclusion

Interpretation of results:

sensitising

Remarks:

Migrated information