Silicic acid, aluminum magnesium sodium salt

Endpoint summary

Description of key information

Skin sensitisation

Silicic acid Aluminium Magnesium Sodium Salt was not a skin sensitiser under the test conditions of OECD 429. (Key, Roth, 2015, OECD 429, SMAS, RL1)

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

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

Qualifier:

according to guideline

Guideline:

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

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)

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

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.

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.

Parameter:

SI

Value:

1

Test group / Remarks:

0.0 % (w/w) (control group)

Key result

Parameter:

SI

Value:

1.13

Test group / Remarks:

0.5 % (w/w)

Key result

Parameter:

SI

Value:

1.16

Test group / Remarks:

1.0 % (w/w)

Key result

Parameter:

SI

Value:

0.96

Test group / Remarks:

2.5 % (w/w)

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

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.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

The study performed with SMAS (Roth, 2015, OECD 429, SMAS) did not sensitize any animals, therefore the substance was considered not skin sensitizing.

Respiratory sensitisation

Link to relevant study records

Reference

Endpoint:

respiratory sensitisation

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

Although no study specifically on respiratory sensitisation is available, one on acute inhalation did not found any item-related effects during the inhalation exposure and observation period in the male and female test animals. (Stahl, 2012, sim. OECD 403, SMAS)

Furthermore, due to the mass median aerodynamic diameter (MMAD) of the test item Silic acid Aluminium Magnesium Sodium Salt of more than 10µm no respiration is expected.

Experimental studies/investigations about the exposure during the application/production give no hint that dust of the test item is respired by the applicants/workers

Justification for classification or non-classification

As no hazard was identified, there is no need for classification or labelling as skin or respiaratory sensitising agent.