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Toxicological information

Skin sensitisation

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Administrative data

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2017-01-31 to 2017-03-31
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2017
Report date:
2017

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Version / remarks:
17 July 1992
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Remarks:
OGYÉI National Institute of Pharmacy and Nutrition, Budapest, Hungary
Type of study:
Buehler test
Justification for non-LLNA method:
The Buehler study was selected as the type of sensitization test since the test substance is a functional silane and the Local Lymph Node Assay as the preferred alternative has shown to provide false positive results for silicone substances.

Test material

Constituent 1
Chemical structure
Reference substance name:
Ethoxytrimethylsilane
EC Number:
217-370-6
EC Name:
Ethoxytrimethylsilane
Cas Number:
1825-62-3
Molecular formula:
C5H14OSi
IUPAC Name:
ethoxytrimethylsilane
Test material form:
liquid
Details on test material:
- Name of test material (as cited in study report): Trimethyl ethoxy silane
- Physical state: Colourless liquid

In vivo test system

Test animals

Species:
guinea pig
Strain:
other: LAL/HA/BR
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: LAB-ÁLL Bt., Budapest, Hungary
- Females nulliparous and non-pregnant: yes
- Age at study initiation: young adult
- Weight at study initiation: 272 – 340 g
- Housing: 5/cage in in macrolon cages size IV
- Diet: Cunigra Diet for Rabbits (produced by Bonafarm-Bábolna Takarmány Ltd., Hungary) provided ad libitum
- Water: tap water from municipal supply containing at least 50 mg/100 mL ascorbic acid provided ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 17.9 – 22.5
- Humidity (%): <20 – 49
- Air changes (per hr): 15-20
- Photoperiod (hrs dark / hrs light): 12/12

Study design: in vivo (non-LLNA)

Induction
Route:
epicutaneous, occlusive
Vehicle:
other: sesame oil
Concentration / amount:
100%
Day(s)/duration:
Animals were treated on Days 1, 8, and 15 for 6 hours
Challenge
No.:
#1
Route:
epicutaneous, occlusive
Vehicle:
other: sesame oil
Concentration / amount:
100%
Day(s)/duration:
Day 29 for 6 hours
No. of animals per dose:
20 per test group, 10 per control group
Details on study design:
RANGE FINDING TESTS: The concentrations used in the preliminary test were 25, 50 (w/v) and 100% (undiluted). Two animals were used to test each dermal concentration. One concentration was used on the right side and another concentration on left side of the animals. No reaction was produced during the range finding test; therefore, animals in the main test were exposed to 100% test item (undiluted) during the induction and 100% test item (undiluted) as a challenge exposure and with 50% (w/v) test item formulated in sesame oil as a safeguard dose.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 3
- Exposure period: 6 hr/day
- Test groups: treated areas were covered for 6 hours with a fully occlusive foil.
- Control group: 0.5 mL of vehicle
- Site: scapular of animals
- Frequency of applications: single application on Days 1, 8, 15
- Duration: 15 days
- Concentrations: 100% (undiluted) test item

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: 1
- Exposure period: 6 hours on Day 29
- Test groups: treated areas were covered for 6 hours with a fully occlusive foil; 0.5 mL of 100% (undiluted) test item was applied to the left side of animals and a 50% (w/v) dilution of the maximum dermal challenge was applied on the right side
- Control group: treated areas were covered for 6 hours with a fully occlusive foil; 0.5 mL of 100% (undiluted) test item was applied to the left side of animals and a 50% (w/v) dilution of the maximum dermal challenge was applied on the right side
- Site: scapular of animals
- Concentrations: 100% (undiluted) test item with 50% (w/v) test item formulated in sesame oil as a safeguard dose
- Evaluation (hr after challenge): 24 (±2) and 48 (±2) hours after the end of the exposure period
Positive control substance(s):
yes
Remarks:
2-Mercaptobenzothiazole at concentration of 50% (w/v)

Results and discussion

Positive control results:
A positive response was seen in 16/20 animals at 24 hours observation, and in 15/20 at 48 hours observation. The mean scores were 0.80 and 0.75 according to the 24 and 48 hour results.

In vivo (non-LLNA)

Resultsopen allclose all
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
100% (undiluted)
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
No signs of systemic toxicity
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
100% (undiluted)
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
No signs of systemic toxicity
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
100% (undiluted)
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
No signs of systemic toxicity
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
100% (undiluted)
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
No signs of systemic toxicity
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
50% (w/v)
No. with + reactions:
16
Total no. in group:
20
Clinical observations:
Mean erythema score was 0.80.
Remarks on result:
positive indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
positive control
Dose level:
50% (w/v)
No. with + reactions:
15
Total no. in group:
20
Clinical observations:
Mean erythema score was 0.75.
Remarks on result:
positive indication of skin sensitisation

Applicant's summary and conclusion

Interpretation of results:
other: CLP/EU GHS criteria are not met, no classification required according to Regulations (EC) No 1272/2008.
Conclusions:
In a Buehler test conducted to GLP and OECD 406 ethoxy(trimethyl)silane was not sensitising to the skin.