Silicic acid, aluminum magnesium sodium salt

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

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)

GLP compliance:

yes (incl. QA statement)

Remarks:

Hessisches Ministerium für Umwelt, Energie, Landwirtschaft und Verbraucherschutz

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

Silicic acid, aluminum magnesium sodium salt

EC Number:

234-919-5

EC Name:

Silicic acid, aluminum magnesium sodium salt

Cas Number:

12040-43-6

Molecular formula:

Na(0.017-1.739)Mg(0.008-0.823)Al(0.002-0.2473)SiO(2.018-3.837)

IUPAC Name:

aluminium(3+) magnesium(2+) sodium tris(oxosilanebis(olate))

Test material form:

solid: particulate/powder

Specific details on test material used for the study:

Identification: Silicic acid Aluminium Magnesium Sodium Salt
Batch: code # 1107274003
Purity: > 99%
Appearance: White powder
Expiry Date: November 01, 2018
Storage Conditions: (provided by the Sponsor) At room temperature, moisture protected
Stability: Stable a room temperature
Stability in Solvent: Stable in DMSO

In vivo test system

Test animals

Species:

mouse

Strain:

other: CBA/CaOlaHsd

Sex:

female

Details on test animals and environmental conditions:

The animals were kept conventionally. The experiment was conducted under standard laboratory conditions.
Housing: group
Cage Type: Makrolon Type II (pre-test) / III (main study), with wire mesh top
Bedding: granulated soft wood bedding
Feed: 2018C Teklad Global 18% protein rodent diet (certified), ad libitum
Water: tap water, ad libitum
Environment: temperature 22 ± 2°C relative humidity approx. 45-65% artificial light 6.00 a.m. - 6.00 p.m.

Study design: in vivo (LLNA)

Vehicle:

dimethyl sulphoxide

Concentration:

0.5, 1, and 2.5% (w/w)

No. of animals per dose:

4

Details on study design:

In order to study a possible skin sensitising potential of Silicic acid Aluminium Magnesium Sodium Salt, three groups each of four female mice were treated once daily with the test item at concentrations of 0.5, 1, and 2.5% (w/w) in DMSO by topical application to the dorsum of each ear for three consecutive days. The highest concentration tested was the highest concentration that could be achieved whilst avoiding systemic toxicity and excessive local skin irritation as confirmed by two pre-experiments. A control group of four mice was treated with the vehicle (DMSO) only. Five days after the first topical application the mice were injected intravenously into a tail vein with radio-labelled thymidine (3H-methyl thymidine). Approximately five hours after intravenous injection, the mice were sacrificed, the draining auricular lymph nodes excised and pooled per group. Single cell suspensions of lymph node cells were prepared from pooled lymph nodes, which were subsequently washed and incubated with trichloroacetic acid overnight. The proliferative capacity of pooled lymph node cells was determined by the incorporation of 3H-methyl thymidine measured in a β-scintillation counter.

Positive control substance(s):

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

Statistics:

A test item is regarded as a sensitiser in the LLNA if the exposure to one or more test concentration resulted in a 3-fold or greater increase in incorporation of 3HTdR compared with concurrent controls, as indicated by the Stimulation Index (S.I.). The estimated concentration of test item required to produce a S.I. of 3 is referred to as the EC3 value.
In this study Stimulation Indices of 1.13, 1.16, and 0.96 were determined with the test item at concentrations of 0.5, 1, and 2.5% (w/w) in DMSO.
The EC3 value could not be calculated, since none of the tested concentrations induced a S.I. greater than the threshold value of 3.

Results and discussion

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Value:

1

Test group / Remarks:

0.0 % (w/w) (control group)

Results 2

Key result

Parameter:

SI

Value:

1.13

Test group / Remarks:

0.5 % (w/w)

Results 3

Key result

Parameter:

SI

Value:

1.16

Test group / Remarks:

1.0 % (w/w)

Results 4

Key result

Parameter:

SI

Value:

0.96

Test group / Remarks:

2.5 % (w/w)

Results 5

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: see Remark

Remarks:

Test item concentration % Measurement DPM DPM per lymph node 0 9914 1236.9 0.5 11222 1400.4 1 11523 1438.1 2.5 9512 1186.1

Applicant's summary and conclusion

Interpretation of results:

not sensitising

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

The test item Silicic acid Aluminium Magnesium Sodium Salt was not a skin sensitiser under the test conditions of this study.