Zinc glycinate sulfate

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Data source

Reference

Reference Type:

publication

Title:

Identification of Metal Allergens in the Local Lymph Node Assay

Author:

David A. Basketter, Linda J. Lea, Karen J. Cooper, Cindy A. Ryan, G. Frank Gerberick, Rebecca J. Dearman, and Ian Kimber

Year:

1999

Bibliographic source:

American Journal of Contact Dermatitis, Vol IO, No 4 (December), 1999:pp 207-212

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

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

Version / remarks:

adopted 22 July, 2010

Principles of method if other than guideline:

- Principle of test:
Test conducted similar to OECD guideline 429
- Short description of test conditions:
Groups of 4 CBAKa mice were treated with 25 µL of test material, or with an equal volume of the vehicle alone, on the dorsum of both ears. Treatment was performed once daily for 3 consecutive days. Five days after the initiation of exposure, all mice were injected by the tail vein with 250 µL of phosphate buffered saline (PBS) containing 20 µCi of tritiated thymidine. Mice were killed 5 hours later and the draining lymph nodes excised and pooled for each experimental group. A single-cell suspension of lymph node cells was prepared by mechanical disaggregation. The lymph node cell suspension was washed twice in an excess of PBS and then precipitated with 5% trichloroacetic acid (TCA) at 4°C for 18 hours. Pellets were resuspended in TCA and the incorporation of tritiated thymidine measured by β-scintillation counting.
- Parameters analysed / observed: cell proliferation measured by incorporation of tritiated thymidine

GLP compliance:

not specified

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

Zinc sulphate

EC Number:

231-793-3

EC Name:

Zinc sulphate

Cas Number:

7733-02-0

Molecular formula:

H2O4S.Zn

IUPAC Name:

zinc sulfate

Details on test material:

ZnSO4 is soluble in water, toxicity based on free ion concentration

Specific details on test material used for the study:

Source: Sigma, Poole, UK.
Purity: 99 %

In vivo test system

Test animals

Species:

mouse

Strain:

CBA/Ca

Sex:

not specified

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Harlan Olac, Bicester, United Kingdom)
- Age at study initiation: 7- 12 weeks
- Housing: in groups of four animals

Study design: in vivo (LLNA)

Vehicle:

dimethyl sulphoxide

Concentration:

5, 10, 25%

No. of animals per dose:

4

Details on study design:

MAIN STUDY

Groups of 4 CBA/Ca mice were treated with 25 µL of test material, or with an equal volume of the vehicle alone, on the dorsum of both ears. Treatment was performed once daily for 3 consecutive days. Five days after the initiation of exposure, all mice were injected by the tail vein with 250 µL of phosphate buffered saline (PBS) containing 20 µCi of tritiated thymidine (2 Ci mmol/L; Amersham International, Amersham, UK). Mice were killed 5 hours later and the draining lymph nodes excised and pooled for each experimental group. A single-cell suspension of lymph node cells was prepared by mechanical disaggregation. The lymph node cell suspension was washed twice in an excess of PBS and then precipitated with 5% trichloroacetic acid (TCA) at 4°C for 18 hours. Pellets were resuspended in TCA and the incorporation of tritiated thymidine measured by B-scintillation counting.

- Criteria used to consider a positive response:
A substance was regarded as a skin sensitizer if, at any test concentration, the proliferation in treated lymph nodes was threefold or greater than that in the concurrent vehicle treated controls.

Positive control substance(s):

other: see 'Remarks'

Statistics:

Not reported

Results and discussion

Positive control results:

From the positive control substances, mercury and cobalt resulted in a SI value of over 3 at least in two of three concentrations and were thus considered as dermal sensitisers.

In vivo (LLNA)

Results

Results 1

Key result

Parameter:

SI

Value:

1.3

Test group / Remarks:

at 5 % zinc sulfate

Results 2

Key result

Parameter:

SI

Value:

2

Test group / Remarks:

at 10% zinc sulfate

Results 3

Key result

Parameter:

SI

Value:

2.3

Test group / Remarks:

at 25 % zinc sulfate

Cellular proliferation data / Observations:

CLINICAL OBSERVATIONS: none reported

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

In this study similar to OECD guideline 429 (LLNA), zinc sulfate is not considered to be a dermal sensitiser.

Executive summary:

In a dermal sensitization study similar to OECD guideline 429 (22 July, 2010) with zinc sulfate in DMSO, young adult CBA/CA mice (4/group) were tested in an LLNA. Additionally, besides zinc sulfate, other metal salts were investigated in the LLNA which are known dermal sensitizers and these metal salts are considered to be the positive controls.

No adverse clinical signs or mortality was observed during the study. Stimulation Indices (S.I.) of 1.3, 2.0 and 2.3 were determined with the test item at concentrations of 5, 10 and 25 % in DMSO, respectively. These results indicate that the test substance could not elicit an SI ≥ 3 and is therefore not regarded as skin sensitizer under the conditions of this study.

Proliferation of the treated lymph nodes was in no concentration increased to over 3-fold of that of the vehicle control lymph nodes. Thus, in this study, zinc sulfate is not a dermal sensitizer and does not need to be classified as dermal sensitizer according to Regulation (EC) No 1272/2008 (CLP) and the Globally Harmonized System for Classification and Labelling of Chemicals (GHS).