Registration Dossier

Data platform availability banner - registered substances factsheets

Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Toxicological information

Sensitisation data (human)

Currently viewing:

Administrative data

sensitisation data (humans)
Type of information:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
key study
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study meets generally accepted scientific principles, acceptable for assessment. Restrictions: no individual information provided.

Data source

Reference Type:
Cobalt contact dermatitis.
Camarasa JMG
Bibliographic source:
Acta Dermato-Venereologica 47(5):

Materials and methods

Type of sensitisation studied:
Study type:
study with volunteers
Test guideline
no guideline followed
Principles of method if other than guideline:
1000 patients of the Department of Allergy, Faculty of Medicine, Barcelona, were patch tested with 2 % cobalt nitrate solution with the occlusive technique.

For intra-dermal administrations, the patients were injected with 0.1 ml of a 0.01 % aqueous solution of Co(NO3)2 6H2O into the skin of the outer side of the upper arm. Injections were performed with a glas syringe and a disposable platinum needle. Reading intervals were 30 minutes, 24 and 48 hours, in some cases 8 to 15 days. Individual readings were not reported. Biopsies of intra-dermal delayed responses were taken 48 and 72 hours after injection, fixed in Bouin solution and stained with hematoxilin.
GLP compliance:

Test material

Constituent 1
Reference substance name:
EC Number:
Cas Number:
Details on test material:
- Name of test material (as cited in study report): cobalt nitrate
- Molecular formula (if other than submission substance): Co(NO3)2 6H2O
- Molecular weight (if other than submission substance): 291.03 g/mol
- Analytical purity: not reported
- Other: test compound identical to CAS 10141-05-6 apart from chemically combined water


Type of population:
other: general and occupational
- Number of subjects exposed: 1000
- Sex: male/female
Clinical history:
- History of allergy or casuistics for study subject or populations: patients of the department of allergy
- Exposure history: 126 of the individuals occupationally exposed
Route of administration:
other: epicutaneous and intradermally, respectively
Details on study design:
TYPE OF TEST(S) USED: patch test (epicutaneous test) ; other immunological tests: intra-dermal injection

- Type of application: occlusive
- Vehicle / solvent: water
- Concentrations: 2 % epicutaneous; 0.01 % intradermal
- Volume applied: 0.1 ml (intradermal)
- Testing/scoring schedule:
- Removal of test substance: yes

- Statistical analysis: yes
- Other: histology

Results and discussion

Results of examinations:
In the epicutaneous patch tests, 100 patients (of 1000) showed positive allergic responses to the cobalt salts (cobalt nitrate and/or cobalt chloride) attempted. 126 patients demonstrated cement eczema. Among those, 84 (66.4 %) showed sensitization to cobalt nitrate and cobalt chloride, or cobalt nitrate alone.

In the intradermal tests, 77 patients (of 1000) showed intra-dermal responses with cobalt salts. Among the 126 patients with cement eczema, 72 demonstrated intra-dermal hypersensitivity to an aqueous solution of cobalt nitrate and cobalt chloride, or cobalt nitrate alone.

Two types of reactions were observed:
1. Immediate erythema, slightly edematous, irregular borders, 2 cm in diameter.
2. Delayed tuberculin-like response, appearing 24 to 48 hours later; red papule with more or less defined borders, 0.5-1 cm diameter, remaining for 2-3 days more, gradually receding and disappearing completely in 6-8 days.

The most characteristic lesions were located in the lower dermis, infiltrates appeared in islands deposited around vessels of the papilar dermis, occasionally distributed around pilosebacious follicles or a sweat gland. The rest of the dermis was free of infiltrate, although small foci of methacromasia were present near edema areas.
Histological examinations of the papules demonstrated a non-specific infiltrate of greater or lesser intensity. Infiltrates were mainly composed of small lymphocytes, histiocytes were abundant. There was a small amount of granulocytic infiltrate as well as some eosinophils and some plasma cells. In some cases leucocytoklasis areas occured.

Any other information on results incl. tables

Positive allergic responses towards cobalt nitrate among patients with cement eczema (epicutaneous test):

 Sensitive to  potassium bichromate, cobalt chloride, cobalt nitrate  potassium bichromate, cobalt nitrate  cobalt nitrate, cobalt chloride
 Number of cases  74 (58.7 %)  6 (4.7 %)  4 (3 %)

Positive intradermal responses towards cobalt nitrate among patients with cement eczema (intradermal test):

 Sensitive to  potassium bichromate, cobalt chloride, cobalt nitrate  potassium bichromate, cobalt nitrate  cobalt nitrate, cobalt chloride
 Number of cases  58 (45.31 %)  14 (11 %)  0

Applicant's summary and conclusion