Octanethioic acid, S-[3-(triethoxysilyl)propyl] ester, reaction products with 2-methyl-1,3-propanediol and 3-(triethoxysilyl)-1-propanethiol

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

19 Apr 2007 (Date of Project Protocol) - 09 Jul 2007 (Date of Report)

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2007

Report date:

2007

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)

Version / remarks:

adopted 24 April 2002

Test guideline 2

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2600 (Skin Sensitisation)

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Test material form:

liquid: viscous

Details on test material:

Colour: Light yellow

Specific details on test material used for the study:

Storage conditions: at room temperature

In vivo test system

Test animals

Species:

mouse

Strain:

CBA/Ca

Remarks:

CBA/Ca01aHsd

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: HArlan Winkelmann GmbH, D-33178 Borchen, Germany
- Females (if applicable) nulliparous and non-pregnant: not specified
- Age at study initiation: 6-12 weeks
- Weight at study initiation: 16 - 19g
- Housing: The animal were kept in groups in Macrolon-cages on Altromin saw fiber bedding
- Diet: ad libitum, Altromin 1324 maintenance diet for rat and mice (TPF)
- Water: free access to tap water
- Acclimation period: adequate acclimatisation period (at least 5 days)
- Indication of any skin lesions: Proir to the application and once a day thereafter all animals were observed in order to detect special clinical signs or reactions to treatment.

ENVIRONMENTAL CONDITIONS
- Temperature: 22±3°C
- Humidity: 55±10%
- Air changes: at least 10x / hour
- Photoperiod (hrs dark / hrs light): 12 / 12

Study design: in vivo (LLNA)

Vehicle:

other: AOO (3+1 (v/v) Acetone/ Olive Oil)

Remarks:

Vehicle served as negative control.

Concentration:

25%, 50%, 100%

No. of animals per dose:

5

Details on study design:

The preparations were made immediately prior to each dosing.

TREATMENT PREPARATION AND ADMINISTRATION
Topical applicaiton: Each mouse was treated by topical application of 25µL of the selected solution to the entire dorsal surface of each ear.
Topical applications were performed once daily over three consecutive days.

Administration of ³H-methyl thymidine: Five days after the first topical application treatment all mice were dosed with 20µCi ³H-methyl thymidine by intravenous injection (tail vein) of 250µL of ³H-methyl thymidine, diluted to a working concentration of 80µCi/mL.

Preparation of cell suspension: Approcimately 5 Hours after ³H-methyl thymidine-injection all mice were sacrificed. The draining "auricular lymph nodes" were excised, individually pooled for each animal (2 lymph nodes per animal) and collected in PBS. A single cell suspension of pooled lymph node cells was prepared by gentle mechanical disaggregation through polyamide gauze (200 mesh size). After washing the gauze with PBS the cell suspension was pelleted in a centrifuge. The supernatant was discarded and the pellets were resuspended with PBS. This washing procedure was repeated.
After the final wash each pellet was resuspended in approx. 1 mL 5% TCA at approx. 4°C overnight for precipitation of macromolecules. Each precipitate was once washed again, resuspended in 1 mL 5% TCA and 10 mL scintillation fluid was added. Then this solution was transferred into scintillation vials.

Determination of incorporated ³H-methyl thymidine: The ³H-methyl thymidine - incorporation was measured in a ß-counter and expressed as the number of disintegrations per minute (DPM). Similarly, background ³H-methyl thymidine levels were also measured (5% TCA). Determination of radioactivity was performed individually for each animal.

Results and discussion

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Value:

14.6

Test group / Remarks:

at a concentration of 25%

Results 2

Parameter:

SI

Value:

21.6

Test group / Remarks:

at a concentration of 50%

Results 3

Parameter:

SI

Value:

19.1

Test group / Remarks:

at a concentration of 100%

Cellular proliferation data / Observations:

The average DPM was 871.6 for the controls and 12772.2, 18786.2 and 16639.6 for the animals tested at 25%, 50% and 100%, respectively.

Any other information on results incl. tables

Weight development of all animals was within the expected range, which includes a weight loss of up 2 g throughout the study.

At the daily clinical observations the animals did not show any visible clinical symptoms.

Applicant's summary and conclusion

Interpretation of results:

Category 1 (skin sensitising) based on GHS criteria

Conclusions:

The skin sensitising properties of the substance were assessed in an LLNA, performed according to OECD/EC guidelines and GLP principles. All three tested concentrations of the test item exceeded the stimulation index of 3, therefore the substance was concluded to be a skin sensitiser.
The potency of the substance could not be determined, as no dose response relationship was found and extrapolation to derive an EC3 value was thus not possible. However, taking into account the high SI values found, it is highly likely the substance is a strong sensitiser (cat. 1A).