2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

24/08/200-04/04/2001

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2001

Report date:

2001

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

GLP compliance:

yes (incl. QA statement)

Type of study:

Buehler test

Justification for non-LLNA method:

The current accepted and preferred method for skin sensitisation testing according to the REACH legislation and CLP Regulation (EC Nos 1907/2006 and 1272/2008) is the murine local lymph node assay (LLNA). A validated test method, OECD TG 429 (OECD 2002) is available for the LLNA.
The guideline acknowledges the limits of the LLNA, and states that there are instances where ‘test substance classes or substances containing functional groups shown to act as potential confounders’ make the use of guinea pig tests more appropriate. It is concluded that the LLNA is not applicable where the properties of the test material cause interference in the accuracy of the LLNA (OECD 2002). The statement in the OECD TG 429 is given with reference to the findings of Basketter et al. (2009a), who demonstrated false positives in silicone based substances which had previously been demonstrated to be non-sensitisers in the guinea pig maximisation test (GPMT).
The importance of available evidence from guinea pig results, consideration of chemical reactivity, epidermal bioavailability and clinical and experimental human data are emphasised as central to reaching appropriate regulatory decisions for substances which have been shown to fall outside the specificity of the LLNA (Basketter et al., 2009b). The non-applicability of the LLNA for silicone based substances has also been demonstrated by Petry et al. (2012).
The sensitisation potential of polyfunctional silicone materials was tested in a comparative study investigating the GPMT and the LLNA assays, which found the five tested substances to be negative in the GPMT whereas they were concluded to be weak to moderate skin sensitisers in the LLNA (Petry et al., 2012).
Basketter D, Ball N, Cagen S, Carillo JC, Certa H, Eigler D, Garcia C, Esch H, Graham C, Haux C, Kreiling R, Mehling A (2009a). Application of weight of evidence approach to assessing discordant sensitisation datasets: implication for REACH. Reg. Toxicol. Pharmacol., 55, 90-96.

Test material

Test material information

Constituent 1

Reference substance name:

10217-34-2

Cas Number:

10217-34-2

IUPAC Name:

10217-34-2

Constituent 2

Reference substance name:

-

EC Number:

425-050-4

EC Name:

-

IUPAC Name:

425-050-4

Constituent 3

Reference substance name:

[2-(3,4-epoxycyclohexyl)ethyl]triethoxysilane

IUPAC Name:

[2-(3,4-epoxycyclohexyl)ethyl]triethoxysilane

Details on test material:

- Name of test material (as cited in study report): Y-11870

- Physical state: clear colourless liquid

- Storage condition of test material: original container at room temperature. Once opened, the test article was blanketed under nitrogen prior to being resealed.

In vivo test system

Test animals

Species:

guinea pig

Strain:

Hartley

Sex:

male/female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Charles River Labs, Raleigh, NC
- Age at study initiation: young adult
- Weight at study initiation: 292 to 335 grams (males) and 290 to 332 grams (females) on study day -1
- Housing: individual suspended wire mesh cages
- Diet: PMI Nutrition Internationa Certified Guinea Pig LabDiet 5026, ad libitum
- Water: municipal water, ad libitum
- Acclimation period: minimum of 7 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-23.3
- Humidity (%): 30-62
- Photoperiod (hrs dark / hrs light): 12/12

Study design: in vivo (non-LLNA)

Induction

Route:

epicutaneous, occlusive

Vehicle:

unchanged (no vehicle)

Concentration / amount:

Primary irritation phase: 2.5%, 5%, 10%, 25% and 50%, 100%
Induction: 100% test article, negative controls untreated, positive controls 100% HCA
Challenge: 100% test article, negative controls 100% , positive controls 50% HCA

Challenge

No.:

#1

Route:

epicutaneous, occlusive

Vehicle:

unchanged (no vehicle)

Concentration / amount:

Primary irritation phase: 2.5%, 5%, 10%, 25% and 50%, 100%
Induction: 100% test article, negative controls untreated, positive controls 100% HCA
Challenge: 100% test article, negative controls 100% , positive controls 50% HCA

No. of animals per dose:

4M, 4F (range finding test), 10M, 10F (actual test), 5M, 5F (negative control), 5M, 5F (positive control)

Details on study design:

RANGE FINDING TESTS: Single applications of multiple concentrations of the test article to determine an irritation threshold.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 3
- Exposure period: 3 weeks
- Test groups: yes
- Control group: positive, yes
- Site: anterior left flank
- Frequency of applications: once per week
- Duration: 6 h
- Concentrations: 0.4 ml/site, undiluted

B. CHALLENGE EXPOSURE

- Exposure period: 6 hours
- Test groups: yes
- Control group: naive, yes
- Site: anterior right flank
- Concentrations: 0.4 ml/site, undiluted
- Evaluation (hr after challenge): 24 and 48 hours

Challenge controls:

A positive control group of five female and five male guinea pigs was included to demonstrate the reliability of the experimental design. The positive control group was induced and challenged on a similar regimen as the test group with alpha-hexylcinnamaldehyde. A negative control group of five female and five male guinea pigs was dosed only at challenge in the same manner as the test group and served as irritation control.

Positive control substance(s):

yes

Remarks:

alpha-hexylcinnamaldehyde

Results and discussion

In vivo (non-LLNA)

Results

Results 1

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

undiluted

No. with + reactions:

12

Total no. in group:

20

Remarks on result:

positive indication of skin sensitisation

Results 2

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

undiluted

No. with + reactions:

14

Total no. in group:

20

Remarks on result:

positive indication of skin sensitisation

Results 3

Reading:

1st reading

Hours after challenge:

24

Group:

positive control

Dose level:

100% HCA

No. with + reactions:

10

Total no. in group:

10

Remarks on result:

positive indication of skin sensitisation

Results 4

Reading:

2nd reading

Hours after challenge:

48

Group:

positive control

Dose level:

100% HCA

No. with + reactions:

10

Total no. in group:

10

Remarks on result:

positive indication of skin sensitisation

Results 5

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

undiluted

No. with + reactions:

0

Total no. in group:

10

Remarks on result:

no indication of skin sensitisation

Results 6

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

undiluted

No. with + reactions:

0

Total no. in group:

10

Remarks on result:

no indication of skin sensitisation

Any other information on results incl. tables

There were no deaths during the study. There were no clinical findings noted during the study. There were no remarkable body weight changes observed during the study.

The sensitization incidence index for the test group was 70% (14/20) following challenge dosing.

Applicant's summary and conclusion

Interpretation of results:

Category 1A (indication of significant skin sensitising potential) based on GHS criteria

Conclusions:

The test material was sensitising to skin in a study conducted according to an appropriate OECD test guideline and compliant with GLP.