1,1,1"((methylsilanetriyl)tris)(oxy))tris(2-methylpropan-2-amine)

Endpoint summary

Description of key information

On the basis of the experimental studies of the structurally and functionally similar read across chemical and applying the weight of evidence approach and by evaluating the effect of the test item can be classified as Corrosive: a combination of optional Subcategories 1B-and-1C.

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:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Remarks:

experimental data of read across substances

Justification for type of information:

Data for the target chemical is summarized based on the read across chemicals

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

other: as mentioned below

Principles of method if other than guideline:

WoE report is based on two toxicity to skin corrosion/irritation studies as-
WoE 2 and WoE 3.

GLP compliance:

not specified

Test system:

artificial membrane barrier model

Source species:

human

Cell type:

non-transformed keratinocytes

Justification for test system used:

WoE 2 and WoE 3
The EPISKIN model has been validated for corrosivity testing in an international trial; it is considered to be suitable for this study (STATEMENT ON THE SCIENTIFIC VALIDITY OF THE EPISKINTM TEST (AN IN VITRO TEST FOR SKIN CORROSIVITY); ECVAM JRC Environment Institute, European Commission; Ispra; 03 April 1998).

Vehicle:

unchanged (no vehicle)

Details on test system:

WoE 2
RECONSTRUCTED HUMAN EPIDERMIS (RHE) TISSUE
- Model used: EpiSkin, EPISKIN SNC Lyon, France
- Tissue batch number: 20-EKIN-008

TEMPERATURE USED FOR TEST SYSTEM
- Temperature used during treatment / exposure: room temperature

REMOVAL OF TEST MATERIAL AND CONTROLS
- Volume and number of washing steps: 25 mL PBS 1 x solution
- Observable damage in the tissue due to washing: no

MTT DYE USED TO MEASURE TISSUE VIABILITY AFTER TREATMENT / EXPOSURE
- MTT concentration: 0.3 mg/mL in saline buffer
- Incubation time: 3 hours (± 15 min) at 37±1°C in an incubator with 5±1 % CO2, protected from light, ≥95 % humidified atmosphere.
- Spectrophotometer: Thermo Scientific; Multiscan FC
- Wavelength: 570 nm

FUNCTIONAL MODEL CONDITIONS
- Morphology: Adult human-derived epidermal keratinocytes are seeded on a dermal substitute consisting of a collagen type I matrix coated with type IV collagen. A highly differentiated and stratified epidermis model is obtained after a 13-day culture period comprising the main basal, supra basal, spinous and granular layers and a functional stratum corneum
- Contamination: All biological components of the epidermis and the kit culture medium have been tested for the presence of viruses, bacteria and mycoplasma.

NUMBER OF REPLICATE TISSUES: 2

CONTROL TISSUES USED IN CASE OF MTT DIRECT INTERFERENCE
- killed tissues
- Procedure used to prepare the killed tissues: Water-killed epidermis
Place the living epidermis in a 12 well plate with 2 mL of distilled water (replacing the culture medium).Incubate at 37 °C, 5 % CO2, ≥ 95 % humidified atmosphere for 48 hrs +/- 1 hour. At the end of the incubation, discard the water. Keep dead epidermis frozen (dry) in freezer at -15 °C to -30 °C (killed epidermis can be stored and used up to 6 months). Before use, the killed tissues are de-frozen at room temperature (approx. 1 hour in 2 mL of maintenance medium).
- N. of replicates: 2
- Method of calculation used: As indictaed in guideline.

NUMBER OF INDEPENDENT TEST SEQUENCES / EXPERIMENTS TO DERIVE FINAL PREDICTION: 1

PREDICTION MODEL / DECISION CRITERIA

WoE 3
RECONSTRUCTED HUMAN EPIDERMIS (RHE) TISSUE
- Model used: EpiSkin, EPISKIN SNC Lyon, France
- Tissue batch number(s): 20-EKIN-008

TEMPERATURE USED FOR TEST SYSTEM
- Temperature used during treatment / exposure: room temperature

REMOVAL OF TEST MATERIAL AND CONTROLS
- Volume and number of washing steps: 25 mL PBS 1 x solution
- Observable damage in the tissue due to washing: no

MTT DYE USED TO MEASURE TISSUE VIABILITY AFTER TREATMENT / EXPOSURE
- MTT concentration: 0.3 mg/mL in saline buffer
- Incubation time: 3 hours (± 15 min) at 37±1°C in an incubator with 5±1 % CO2, protected from light, ≥95 % humidified atmosphere.
- Spectrophotometer: Thermo Scientific; Multiscan FC
- Wavelength: 570 nm

FUNCTIONAL MODEL CONDITIONS
- Morphology: Adult human-derived epidermal keratinocytes are seeded on a dermal substitute consisting of a collagen type I matrix coated with type IV collagen. A highly differentiated and stratified epidermis model is obtained after a 13-day culture period comprising the main basal, supra basal, spinous and granular layers and a functional stratum corneum
- Contamination: All biological components of the epidermis and the kit culture medium have been tested for the presence of viruses, bacteria and mycoplasma.

NUMBER OF REPLICATE TISSUES: 2

CONTROL TISSUES USED IN CASE OF MTT DIRECT INTERFERENCE
- killed tissues
- Procedure used to prepare the killed tissues: Water-killed epidermis
Place the living epidermis in a 12 well plate with 2 mL of distilled water (replacing the culture medium).
Incubate at 37 °C, 5 % CO2, ≥ 95 % humidified atmosphere for 48 hrs +/- 1 hour. At the end of the incubation, discard the water.
Keep dead epidermis frozen (dry) in freezer at -15 °C to -30 °C (killed epidermis can be stored and used up to 6 months).
Before use, the killed tissues are de-frozen at room temperature (approx. 1 hour in 2 mL of maintenance medium).
- N. of replicates : 2
- Method of calculation used: As indictaed in guideline.

NUMBER OF INDEPENDENT TEST SEQUENCES / EXPERIMENTS TO DERIVE FINAL PREDICTION: 1

PREDICTION MODEL / DECISION CRITERIA

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Amount/concentration applied:

WoE 2
TEST MATERIAL
- Amount(s) applied: 50 µL

NEGATIVE CONTROL
- Amount(s) applied: 50 µL
- Concentration: 0.9%

POSITIVE CONTROL
- Amount(s) applied: 50 µL

WoE 3
TEST MATERIAL
- Amount(s) applied: 50 µL

NEGATIVE CONTROL
- Amount(s) applied: 50 µL
- Concentration: 0.9%

POSITIVE CONTROL
- Amount(s) applied: 50 µL

Duration of treatment / exposure:

WoE 2 and WoE 3
exposure times of 4 hours (±10 min), 1 hour (±5 min) and 3 min at room temperature

Number of replicates:

2

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

1st experiment (4 hours exposure)

Value:

24

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: WoE 2

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

1st experiment (1 hours exposure)

Value:

57

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: WoE 2

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

1st experiment (3 min exposure)

Value:

40

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: WoE 2

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

1st experiment (4 hours exposure)

Value:

10

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: WoE 3

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

1st experiment (1 hour exposure)

Value:

72

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: WoE 3

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

1st experiment (3 min exposure)

Value:

49

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Other effects / acceptance of results:

WoE 2
- OTHER EFFECTS:
- Direct-MTT reduction: The test item interacted with the MTT, therefore additional controls and data calculations were necessary. The non-specific MTT reduction (NSMTT) was determined to be 20.67 %, 18.60 % and 39.02 % at the 4h, 1h and 3 min exposure respectively. As the NSMTT were below 50 % in each case the true MTT metabolic conversion in all occasions and the correction of viability percentages were undertaken.
- Colour interference with MTT: The test item is colourless, furthermore showed no ability to become coloured in contact with water. Therefore, considered not to be able to significantly stain the tissues and lead to false estimate of viability. Additional controls and data calculations were not necessary.

DEMONSTRATION OF TECHNICAL PROFICIENCY: The routine use of the method TOXI-COOP ZRT. demonstrated the technical proficiency in a separate study (study no.: 392-431-4224) using the twelve Proficiency Chemicals according to OECD Test Guideline No. 431.

ACCEPTANCE OF RESULTS:
- Acceptance criteria met for negative control: yes
- Acceptance criteria met for positive control: yes
- Acceptance criteria met for variability between replicate measurements: yes

WoE 3
- OTHER EFFECTS:
- Direct-MTT reduction: yes
The non-specific MTT reduction (NSMTT) was determined to be 8.53 %, 29.55 % and 30.80 % at the 4h, 1h and 3 min exposure respectively. As the NSMTT were below 50 % in each case the true MTT metabolic conversion in all occasions and the correction of viability percentages were undertaken.
- Colour interference with MTT: no

DEMONSTRATION OF TECHNICAL PROFICIENCY: The routine use of the method TOXI-COOP ZRT. demonstrated the technical proficiency in a separate study (study no.: 392-431-4224) using the twelve Proficiency Chemicals according to OECD Test Guideline No. 431.

ACCEPTANCE OF RESULTS:
- Acceptance criteria met for negative control: yes
- Acceptance criteria met for positive control: yes
- Acceptance criteria met for variability between replicate measurements: yes

Interpretation of results:

Category 1B (corrosive) based on GHS criteria

Conclusions:

On the basis of the experimental studies of the structurally and functionally similar read across chemical and applying the weight of evidence approach and by evaluating the effect of the test item can be classified as Corrosive: a combination of optional Subcategories 1B-and-1C.

Executive summary:

Data available of the read across chemicals has been reviewed to determine the effect of the test chemical for skin corrosion and irritation studies. The studies are as mentioned below:

A study according OECD TG 431 was conducted to predict the corrosion potential of the test item by measurement of its cytotoxic effect, as reflected in the MTT assay according to the OECD Test Guideline No. 431 (adopted 14 June 2019).

Disks of EPISKIN (two units / chemical / incubation time) were treated with test item and incubated for 4 hours (±10 min), 1 hour (±5 min) and 3 min at room temperature. Exposure of test material was terminated by rinsing with PBS 1x solution. The viability of each disk was assessed by incubating the tissues for 3 hours (±15 min) with MTT solution at 37±1 °C in an incubator with 5±1 % CO2 in a ≥ 95 % humidified atmosphere and protected from light. The formazan precipitated was then extracted using acidified isopropanol and quantified spectrophotometrically. NaCl (9 g/L saline) and glacial acetic acid treated epidermis were used as negative and positive controls, respectively. The test item is a MTT-reducer, therefore additional controls (test item treated killed tissues and negative control treated killed tissues) were used to detect and correct for test item interference with the viability measurement.

For each treated tissue viability was expressed as a % relative to negative control. The test item is considered to be non-corrosive to skin, if the mean relative viability after 4 hours of exposure is above or equal 35 % of the negative control.

The test item treated tissue viabilities were below 35 % of the mean negative control value after 4 hours exposure and above 35 % of the mean negative control value after 1 hour and 3 min of exposure. The average test item treated tissue relative viabilities were 24 % at 4 hours, 57 % at 1 hour and 40 % at 3 minutes of exposure.

Positive and negative controls showed the expected cell viability values within acceptable limits. All assay acceptance criteria were met, the experiment was considered to be valid.

The results obtained from this in vitro skin corrosion test, using the EPISKIN model, indicated that the test item reveals skin corrosion potential after 4 hours and no skin corrosion potential after 1 hour and 3 min of exposure under the utilised testing conditions.

A study according OECD TG 431 was conducted to predict the corrosion potential of the test item by measurement of its cytotoxic effect, as reflected in the MTT assay according to the OECD Test Guideline No. 431 (adopted 14 June 2019).

Disks of EPISKIN (two units / chemical / incubation time) were treated with test item and incubated for 4 hours (±10 min), 1 hour (±5 min) and 3 min at room temperature. Exposure of test material was terminated by rinsing with PBS 1x solution. The viability of each disk was assessed by incubating the tissues for 3 hours (±15 min) with MTT solution at 37±1 °C in an incubator with 5±1 % CO2 in a ≥ 95 % humidified atmosphere and protected from light. The formazan precipitated was then extracted using acidified isopropanol and quantified spectrophotometrically.

NaCl (9 g/L saline) and glacial acetic acid treated epidermis were used as negative and positive controls, respectively.

The test item is a MTT-reducer, therefore additional controls (test item treated killed tissues and negative control treated killed tissues) were used to detect and correct for test item interference with the viability measurement. For each treated tissue viability was expressed as a % relative to negative control. The test item is considered to be non-corrosive to skin, if the mean relative viability after 4 hours of exposure is above or equal 35 % of the negative control.

The test item treated tissue viabilities were below 35 % of the mean negative control value after 4 hours exposure and above 35 % of the mean negative control value after 1 hour and 3 min of exposure. The average test item treated tissue relative viabilities were 10 % at 4 hours, 72 % at 1 hour and 49 % at 3 minutes of exposure.

Positive and negative controls showed the expected cell viability values within acceptable limits. All assay acceptance criteria were met, the experiment was considered to be valid. The results obtained from this in vitro skin corrosion test, using the EPISKIN model, indicated that the test item reveals skin corrosion potential after 4 hours and no skin corrosion potential after 1 hour and 3 min of exposure under the utilised testing conditions.

Therefore, on the basis of the experimental studies of the structurally and functionally similar read across chemical and applying the weight of evidence approach and by evaluating the effect of the test item can be classified as Corrosive: a combination of optional Subcategories 1B-and-1C.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (corrosive)

Eye irritation

Link to relevant study records

Reference

Endpoint:

eye irritation: in vitro / ex vivo

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

the study does not need to be conducted because the substance is classified as skin corrosion, leading to classification as serious eye damage (Category 1)

Additional information

Data available of the read across chemicals has been reviewed to determine the effect of the test chemical for skin corrosion and irritation studies. The studies are as mentioned below:

A study according OECD TG 431 was conducted to predict the corrosion potential of the test item by measurement of its cytotoxic effect, as reflected in the MTT assay according to the OECD Test Guideline No. 431 (adopted 14 June 2019).

Disks of EPISKIN (two units / chemical / incubation time) were treated with test item and incubated for 4 hours (±10 min), 1 hour (±5 min) and 3 min at room temperature. Exposure of test material was terminated by rinsing with PBS 1x solution. The viability of each disk was assessed by incubating the tissues for 3 hours (±15 min) with MTT solution at 37±1 °C in an incubator with 5±1 % CO2 in a ≥ 95 % humidified atmosphere and protected from light. The formazan precipitated was then extracted using acidified isopropanol and quantified spectrophotometrically. NaCl (9 g/L saline) and glacial acetic acid treated epidermis were used as negative and positive controls, respectively. The test item is a MTT-reducer, therefore additional controls (test item treated killed tissues and negative control treated killed tissues) were used to detect and correct for test item interference with the viability measurement.

For each treated tissue viability was expressed as a % relative to negative control. The test item is considered to be non-corrosive to skin, if the mean relative viability after 4 hours of exposure is above or equal 35 % of the negative control.

The test item treated tissue viabilities were below 35 % of the mean negative control value after 4 hours exposure and above 35 % of the mean negative control value after 1 hour and 3 min of exposure. The average test item treated tissue relative viabilities were 24 % at 4 hours, 57 % at 1 hour and 40 % at 3 minutes of exposure.

Positive and negative controls showed the expected cell viability values within acceptable limits. All assay acceptance criteria were met, the experiment was considered to be valid.

The results obtained from this in vitro skin corrosion test, using the EPISKIN model, indicated that the test item reveals skin corrosion potential after 4 hours and no skin corrosion potential after 1 hour and 3 min of exposure under the utilised testing conditions.

A study according OECD TG 431 was conducted to predict the corrosion potential of the test item by measurement of its cytotoxic effect, as reflected in the MTT assay according to the OECD Test Guideline No. 431 (adopted 14 June 2019).

Disks of EPISKIN (two units / chemical / incubation time) were treated with test item and incubated for 4 hours (±10 min), 1 hour (±5 min) and 3 min at room temperature. Exposure of test material was terminated by rinsing with PBS 1x solution. The viability of each disk was assessed by incubating the tissues for 3 hours (±15 min) with MTT solution at 37±1 °C in an incubator with 5±1 % CO2 in a ≥ 95 % humidified atmosphere and protected from light. The formazan precipitated was then extracted using acidified isopropanol and quantified spectrophotometrically.

NaCl (9 g/L saline) and glacial acetic acid treated epidermis were used as negative and positive controls, respectively.

The test item is a MTT-reducer, therefore additional controls (test item treated killed tissues and negative control treated killed tissues) were used to detect and correct for test item interference with the viability measurement. For each treated tissue viability was expressed as a % relative to negative control. The test item is considered to be non-corrosive to skin, if the mean relative viability after 4 hours of exposure is above or equal 35 % of the negative control.

The test item treated tissue viabilities were below 35 % of the mean negative control value after 4 hours exposure and above 35 % of the mean negative control value after 1 hour and 3 min of exposure. The average test item treated tissue relative viabilities were 10 % at 4 hours, 72 % at 1 hour and 49 % at 3 minutes of exposure.

Positive and negative controls showed the expected cell viability values within acceptable limits. All assay acceptance criteria were met, the experiment was considered to be valid. The results obtained from this in vitro skin corrosion test, using the EPISKIN model, indicated that the test item reveals skin corrosion potential after 4 hours and no skin corrosion potential after 1 hour and 3 min of exposure under the utilised testing conditions.

Justification for classification or non-classification

On the basis of the experimental studies of the structurally and functionally similar read across chemical and applying the weight of evidence approach and by evaluating the effect of the test item can be classified as Corrosive: a combination of optional Subcategories 1B-and-1C.