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Description of key information

The potential of Decyltrimethoxysilane to induce skin irritation was evaluated during an in vivo study according to a method similar to the OECD Testing Guideline 404 with deviations. Animals were exposed for 24 hours to the test substance on abraded and non-abraded skin and scoring was performed according to Draize 24 and 72 hours following the application of Decyltrimethoxysilane. Irritation was observed in all animals with an erythema formation ranging from 1 (very slight erythema) to 2 (well-defined erythema) and an oedema formation ranging from 0 (no oedema) to 2 (slight oedema).

The exposure of 24 hours instead of the 4 hours currently recommended along with the abrasion of the skin can be expected to increase the skin irritant properties of Decyltrimethoxysilane. These are significant methodological deficiencies therefore the study cannot be used in order to classify the substance for its potential to induce skin irritation in accordance with Regulation (EC) No.1272/2008.

 

Despite a methodology expected to increase the hazardous properties of Decyltrimethoxysilane, a maximum score of 2 (on 4) was observed for both oedema and erythema formation and the authors of the study concluded that the substance was not corrosive to the skin. It was therefore required to perform a GLP-compliant in vitro skin irritation study according to the OECD Testing Guideline 439 to determine if the substance should be classified as irritant to the skin.

As a result of this in vitro study Decyltrimethoxysilane reduced the tissue viability to 3.03%. It can therefore be concluded that the substance meets the criteria for classification as irritant to the skin according to Regulation (EC) No.1272/2008.

The in vivo eye irritation of Decyltrimethoxysilane was evaluated during a GLP-compliant study using a method similar to the OECD Testing Guideline 405.

Six New Zealand white rabbits received a single intraocular application of 0.1 mL of the undiluted test article in one eye. The contralateral eye, remaining untreated, served as a control. The eyes of all animals remained unwashed for 24 hours. Observations of corneal opacity, iritis, and conjunctivitis were recorded 24, 48, and 72 hours after treatment, and at four and seven days if irritation persisted.

No effects on cornea and iris were observed in any animal. Conjunctivae were observed in all animals on Day 1 with a maximum score of 3. On Day 3, conjunctivae were still observed 5/6 animals with a maximum score of 2.

Based on these results, it is concluded that Decyltrimethoxysilane meets the criteria for classification as Eye Irrit. 2; H319 in accordance with Regulation (EC) N°1272/2008.

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records
Reference
Endpoint:
skin irritation: in vitro / ex vivo
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From 06 November 2017 to 06 December 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 439 (In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Test system:
human skin model
Vehicle:
unchanged (no vehicle)
Details on test system:
RECONSTRUCTED HUMAN EPIDERMIS (RHE) TISSUE
- Model used: EpiDerm (EPI-200) Reconstituted Human Epidermis
- Tissue batch number(s): 25859

TEMPERATURE USED FOR TEST SYSTEM
- Temperature used during treatment / exposure: 37°C

NUMBER OF REPLICATE TISSUES:
Triplicate
Control samples:
yes, concurrent negative control
yes, concurrent positive control
Amount/concentration applied:
TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 30 µL

NEGATIVE CONTROL
- Amount(s) applied (volume or weight): 30 µL

POSITIVE CONTROL
- Amount(s) applied (volume or weight): 30 µL
Duration of treatment / exposure:
60 ± 1 minute (25 minutes at room temperature and 35 minutes at 37°C, 5% CO2, ≥95% RH)
Duration of post-treatment incubation (if applicable):
42 ± 4h post-treatment incubation (at 37°C, 5% CO2, ≥ 95% RH)
Number of replicates:
Triplicate
Irritation / corrosion parameter:
% tissue viability
Run / experiment:
Mean value
Value:
3.03
Vehicle controls validity:
not applicable
Negative controls validity:
valid
Positive controls validity:
valid
Other effects / acceptance of results:
Optical Density (OD) values obtained with blanks were higher than 0.1 (0.152). However, the spectrophotometer was fully validated and had passed all required tests. The OD values for blanks observed in this study are consistent with historical data using this spectrophotometer in the laboratory and meet our current internal acceptance criteria of blank OD values <0.194. Therefore this deviation is not considered significant.
Interpretation of results:
Category 2 (irritant) based on GHS criteria
Conclusions:
Decyltrimethoxysilane reduced the tissue viability to 3.03% and therefore meets the criteria for classification as irritant to the skin according to Regulation (EC) No.1272/2008.
Executive summary:

The in vitro skin irritation of Decyltrimethoxysilane was determined in accordance with the OECD Guideline for Testing of Chemicals 439 during a GLP-compliant study. This in vitro risk assessment assay predicts the Skin irritation potential of a chemical by measurement of its cytotoxic effect on the EpiDerm™ tissue model.

Prior to testing, the test substance was checked for interference with water and/or MTT. No interference was identified.

Skin irritation of the test substance and controls was evaluated in triplicate. After 60 ± 1 minutes exposure on the surface of the EpiDerm™ reconstructed human epidermis and a 42 ± 4h post-exposure incubation time, viability of the tissues was assessed and compared to the negative control.

The percentage of viability obtained with Decyltrimethoxysilane was 3.03%, therefore it has to be considered as irritant to the skin according to the criteria laid down in the OECD Guideline for Testing of Chemicals 439.

The test item met the criteria for classification as irritant to the skin according to Regulation (EC) No.1272/2008 on the Classification, Labelling and Packaging of Substances and Mixtures.

Endpoint conclusion
Endpoint conclusion:
adverse effect observed (irritating)

Eye irritation

Link to relevant study records
Reference
Endpoint:
eye irritation: in vivo
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From 18 October 2004 to 25 October 2004
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 405 (Acute Eye Irritation / Corrosion)
Deviations:
yes
Remarks:
Observation period ended after seven days
GLP compliance:
yes (incl. QA statement)
Species:
rabbit
Strain:
New Zealand White
Details on test animals or tissues and environmental conditions:
TEST ANIMALS
- Source: Suitable licensed provider (not specified)
- Age at study initiation: 3 months
- Weight at study initiation: 2 kg
- Housing: Stainless steel cages
- Diet: Certified Rabbit Diet #5322 at 100 gm/day/animal
- Water: water (source not specified) ad libitum
- Acclimation period: 12 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 65 to 75°F (equivalent to 18.33 to 23.89°C)
- Humidity (%): Monitored (variations not specified)
- Photoperiod (hrs dark / hrs light): 12h/12h
Vehicle:
unchanged (no vehicle)
Amount / concentration applied:
0.1 mL
Duration of treatment / exposure:
24 hours
Observation period (in vivo):
7 days
Number of animals or in vitro replicates:
6 animals
Details on study design:
REMOVAL OF TEST SUBSTANCE
- Washing (if done): room temperature distilled water
- Time after start of exposure: 24h

SCORING SYSTEM: Draize
Irritation parameter:
conjunctivae score
Basis:
mean
Time point:
24 h
Score:
2
Max. score:
3
Irritation parameter:
conjunctivae score
Basis:
mean
Time point:
48 h
Score:
1.5
Max. score:
3
Irritation parameter:
conjunctivae score
Basis:
mean
Time point:
72 h
Score:
1.33
Max. score:
2
Irritation parameter:
cornea opacity score
Basis:
mean
Time point:
24/48/72 h
Score:
0
Max. score:
0
Irritation parameter:
iris score
Basis:
mean
Time point:
24/48/72 h
Score:
0
Max. score:
0
Interpretation of results:
Category 2 (irritating to eyes) based on GHS criteria
Conclusions:
Decyltrimethoxysilane meets the criteria for classification as Eye Irrit. 2; H319 in accordance with Regulation (EC) N°1272/2008.
Executive summary:

The in vivo eye irritation of Decyltrimethoxysilane was evaluated during a GLP-compliant study using a method similar to the OECD Testing Guideline 405.

Six New Zealand white rabbits received a single intraocular application of 0.1 mL of the undiluted test article in one eye. The contralateral eye, remaining untreated, served as a control. The eyes of all animals remained unwashed for 24 hours. Observations of corneal opacity, iritis, and conjunctivitis were recorded 24, 48, and 72 hours after treatment, and at four and seven days if irritation persisted.

No effects on cornea and iris were observed in any animal. Conjunctivae were observed in all animals on Day 1 with a maximum score of 3. On Day 3, conjunctivae were still observed 5/6 animals with a maximum score of 2.

Based on these results, it is concluded that Decyltrimethoxysilane meets the criteria for classification as Eye Irrit. 2; H319 in accordance with Regulation (EC) N°1272/2008.

Endpoint conclusion
Endpoint conclusion:
adverse effect observed (irritating)

Respiratory irritation

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

Justification for classification or non-classification

An in vivo skin irritation study was performed on Decyltrimethoxysilane and showed that the substance was not corrosive to the skin. However it did not allow to determine if the substance meets the criteria for classification as irritant to the skin.

An in vitro skin irritation study was performed on the substance that concluded that Decyltrimethoxysilane meets the criteria for classification as Skin Irrit. 2, H315 in accordance with Regulation (EC) No.1272/2008.

An in vivo eye irritation was performed on the substance that concluded that Decyltrimethoxysilane meets the criteria for classification as Eye Irrit. 2; H319 in accordance with Regulation (EC) No.1272/2008.

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