Silicic acid, aluminum magnesium sodium salt

Endpoint summary

Description of key information

Skin irritation (Key, Andres, 2015, OECD 435, SMAS, RL1):

Silicic acid Aluminium Magnesium Sodium Salt was considered as not corrosive in the Corrositex® - Test.

Eye irritation (Key, Geitlinger, 2019, OECD 492, SMAS, RL1):

Under the conditions of the test, Silicic acid, magnesium aluminium sodium salt is considered non-eye irritant in the EpiOcular(TM) Eye Irritation Test.

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Endpoint:

skin corrosion: in vitro / ex vivo

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 435 (In Vitro Membrane Barrier Test Method for Skin Corrosion)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Rheinland-Pfalz, Landesamt für Umwelt, Wasserwirtschaft und Gewerbeaufsicht

Specific details on test material used for the study:

Name Silicic acid Aluminium Magnesium Sodium Salt
Batch no. code # 1107274003
Appearance white powder
Composition Silic acid Aluminium Magnesium Sodium Salt
CAS No. 12040-43-5
EINECS-No. 234-919-5
Purity > 99 %
Homogeneity homogeneous
Stability stable at room temperature
Solubility poorly soluble
Expiry date 01. Nov. 2018
Storage room temperature (20 ± 5 °C), dry

Test system:

artificial membrane barrier model

Source species:

other: synthetic macromolecular bio-barrier

Control samples:

yes, concurrent negative control

Species:

other: synthetic biobarrier

Details on test animals or test system and environmental conditions:

The Corrositex® test is an in vitro procedure by which the assessment of corrosivity is not carried out in live animals.
The Corrositex® test refers to the penetration of the membrane barrier which is measured by a change in the colour of a pH indicator dye.

Controls:

yes, concurrent positive control

Duration of treatment / exposure:

60 min

Irritation / corrosion parameter:

penetration time (in minutes)

Run / experiment:

negative control

Value:

> 60

Negative controls validity:

valid

Irritation / corrosion parameter:

penetration time (in minutes)

Run / experiment:

positive control

Value:

ca. 12

Positive controls validity:

valid

Irritation / corrosion parameter:

penetration time (in minutes)

Run / experiment:

test item

Value:

> 60

Remarks on result:

no indication of irritation

The controls showed the following results: The negative control showed no break-through within the observation time of 60 min.

The positive control showed clear corrosive effects after 12 minutes and is consequently classified as a corrosive substance belonging to UN Packing Group II.

Therefore the test item (substance category 2 according to the categorisation) is classified as a non-corrosive substance.

Interpretation of results:

not classified

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

Silicic acid Aluminium Magnesium Sodium Salt is considered as not corrosive in the Corrositex® - Test.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Link to relevant study records

Reference

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Sep. 6-18, 2019, experimental phase: Sep. 9-12, 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 492 (Reconstructed Human Cornea-like Epithelium (RhCE) Test Method for Identifying Chemicals Not Requiring Classification and Labelling for Eye Irritation or Serious Eye Damage)

Version / remarks:

2019

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Name: Silicic acid, magnesium aluminium sodium salt
Batch no.: 1901274010
Appearance: white fluffy powder
Composition: Sodium; Magnesium; Aluminium; Silica
Purity: >95%
Homogeneity: homogeneous

Controls:

yes, concurrent positive control

yes, concurrent negative control

Duration of treatment / exposure:

6 h

Duration of post- treatment incubation (in vitro):

18 h

Number of animals or in vitro replicates:

2

Details on study design:

- Negative Control: Sterile demineralised water, prepared by LAUS GmbH using an ion exchanger and membrane filtration through sterile filters, batch no.: T20190717.
- Positive Control: Methyl acetate (C3H6O2, CAS No. 79-20-9), procured from MatTek, batch no.: 021319ISC.
- Test System: Commercially available EpiOcular(TM) kit.
The EpiOcular tissue consists of normal, human-derived keratinocytes which have been cultured to form a stratified squamous epithelium similar to that found in the human cornea. It consists of highly organized basal cells. These cells are not transformed or transfected with genes to induce an extended life span. The EpiOcular tissues are cultured in specially prepared cell culture inserts with a porous membrane through which nutrients can pass to the cells. The tissue surface is 0.6 cm².
- MTT solution: 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (=MTT), which can be reduced to a blue formazan, prepared by LAUS GmbH.
A MTT stock solution of 5 mg/mL in DPBS buffer was prepared and stored in aliquots of 2 mL at – 20 ± 5 °C. 2 mL of the stock solution were thawed and diluted with 8 mL of assay medium (resulting in 1 mg/mL). This MTT-solution with the concentration of 1 mg/mL was used in the test.

Irritation parameter:

in vitro irritation score

Run / experiment:

relative tissue viability

Value:

ca. 86.3 - ca. 91

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Measured Values

As blank, the optical density of isopropanol was measured in eight wells of the 96-well-plate. The measured values and their mean are given in the following table:

Table 9.1-a : Absorbance Values Blank Isopropanol (OD at 570 nm)

Replicate              1              2               3               4             5             6             7             8              Mean

Absorbance       0.032       0.033       0.033       0.034       0.034       0.034       0.033       0.035       0.034

The absorbance values of negative control, test item and positive control are given in the following table:

Table 9.1-b: Absorbance Values Negative Control, Positive Control and Test Item (OD at 570 nm)

Designation        Measurement        Negative Control        Positive Control       Silicic acid, magnesium aluminium                                                                                                                                                   sodium salt

Tissue 1                    1                            1.878                     0.791                                          1.671

2                            1.889                     0.772                                          1.658

Tissue 2                    1                            1.771                     0.866                                          1.586

2                            1.761                     0.859                                          1.574

From the measured absorbances, the mean of each tissue was calculated, subtracting the mean absorbance of isopropanol as given in table 9.1-a (= corrected values).

Table 9.1-c: Mean Absorbance Negative Control, Positive Control and Test Item

Designation                     Negative Control        Positive Control        Silicic acid, magnesium aluminium sodium salt

Mean – blank (Tissue 1)       1.850                            0.748                                          1.631

Mean – blank (Tissue 2)       1.732                            0.829                                          1.546

Comparison of Tissue Viability

For the test item and the positive control, the following percentage values of tissue viability were calculated in comparison to the negative control:

Table 9.2-a: % Viability Positive Control and Test Item

Designation                     Positive Control               Silicic acid, magnesium aluminium sodium salt

% Viability (Tissue 1)              41.7%                                                 91.0%

% Viability (Tissue 2)              46.3%                                                 86.3%

% Viability Mean                     44.0%                                                88.7%

Eye hazard potential was assessed using the criteria given in the following table:

Table 9.3-a: Assessment of Eye Hazard Potential

% Viability               Assessment               UN GHS classification

> 60 %                    Non eye irritant              No Category

≤ 60 %                   At least eye irritant         No prediction can be made (category 1 or 2)

Validity criteria and results are stated in the following table:

Table 9.4 -a:

Validity                                           CriterionDemanded                                           Found    

Mean OD of negative control              > 0.8 and < 2.8                                                 1.8

% mean relative viability of

positive control                                   < 50% of negative control                                 44.0%

Variation within replicates                   < 20%                                                              6.6% (negative control)

4.5% (positive control)

4.7% (test item)

Values for negative control and for positive control were within the range of historical data of the test facility.

Therefore, the experiment was considered valid.

Interpretation of results:

GHS criteria not met

Conclusions:

Under the conditions of the test, Silicic acid, magnesium aluminium sodium salt is considered non-eye irritant in the EpiOcular(TM) Eye Irritation Test.

Executive summary:

The test item Silicic acid, magnesium aluminium sodium salt was applied to a three-dimensional human cornea tissue model in duplicate for an exposure time of 6 hours.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Skin irritation / corrosion

The in vitro study performed with SMAS (Andres, 2015, OECD 435, SMAS) was considered as not corrosive in the Corrositex®-Test.No signs of irritation observed at limit concentration ofLD50 > 2000 mg/kg bw in acute dermal toxicity study on SMAS. Skin irritation was also not observed in an acute dermal toxicity study (Hozova, 2016, OECD 402, SMAS) in SMAS at a limit dose of 2000 mg/kg bw.

Eye irritation

The study performed with SMAS (Geitlinger, 2019, OECD 492, SMAS) was considered as non-eye irritant in the EpiOcular® Eye test. The result is supported by another study in NAS (Woltjen/Calkins, 1978, NAS) which showed no lasting irritation to the eyes.

Justification for classification or non-classification

Based on the studies no irritating effects are expected from the exposure to silicic acid, aluminium magnesium sodium salt. No need for classification as skin or eye irritant.

However, depending on the variable composition of SMAS, the potential to cause irritating effects to the eyes and the skin have to be considered and precautions are required to protect the eyes and the skin.