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Administrative data

skin sensitisation: in vivo (LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From December 11, 2007 to January 15, 2008
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP compliant with international guideline

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
according to guideline
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
GLP compliance:
yes (incl. QA statement)
Type of study:
mouse local lymph node assay (LLNA)

Test material

Constituent 1
Chemical structure
Reference substance name:
EC Number:
EC Name:
Cas Number:
Molecular formula:
Trisiloxane, 1,1,1,3,5,5,5-Heptamethyl-3-Tetradecyl-
Test material form:
liquid: viscous
Details on test material:
- Name of test material: Myristyl Trisiloxane
- Molecular formula:C21H50O2Si3
- Molecular weight: 419 g/mol
- Smiles notation: CCCCCCCCCCCCCC[Si](O[Si](C)(C)C)(O[Si](C)(C)C)C
- InChI=1/C21H50O2Si3/c1-9-10-11-12-13-14-15-16-17-18-19-20-21-26(8,22-24(2,3)4)23-25(5,6)7/h9-21H2,1-8H3
- Substance type:organic
- Physical state:viscous liquid

In vivo test system

Test animals

Details on test animals and environmental conditions:
- Source:Harlan Netherlands
- Age at study initiation:8 - 10 weeks
- Weight at study initiation:
- Housing:Single caging. The animals were distributed into the test groups at random and identified by cage number. Makrolon Type l, with wire mesh top; with granulated soft wood bedding.
- Diet: pelleted standard diet, ad libitum.
- Water: tap water, ad libitum.
- Acclimation period:5 days

- Temperature (°C):22 ± 3°C
- Humidity (%):30-70%
- Air changes (per hr):no data
- Photoperiod (hrs dark / hrs light):12 hours cycle dark/light from 6:00 to 18:00


Study design: in vivo (LLNA)

acetone/olive oil (4:1 v/v)
The test item in the main study was assayed at 0,25, 50, and 100%.
No. of animals per dose:
4 mice per doses
Details on study design:
- Compound solubility:A solubility experiment was performed according to the recommendations given by OECD 429. The highest test item concentration, which can be technically used was a 100% of the undiluted test item. The solutions will be formulated in acetone:olive oil (4+1).
- Irritation:To determine the highest non-irritant test concentration, a pre-test was performed in two animals.At concentratíons of 50 and 100% the animals showed redness of the ear skin after the third application only. At lower concentrations signs of toxicity or local Irritation were not observed.
- Lymph node proliferation response:


Topical Application:
Each test group of mice was treated by topical (epidermal) application to the dorsal surface of each ear lobe (left and right) with different test item concentrations of 25, 50, and 100% (w/v) in acetone:olive oil (4+1). The application volume, 25 µl, was spread over the entire dorsal sudate (Ø ~ 8 mm) of each ear lobe once daily for three consecutive days. A further group of mice was treated with an equivalent volume of the relevant vehicle alone (control animals).

Administration of 3H-Methyl Thymidine
3H-methyl thymidine (3HTdR) was purchased from GE Heaithcare (GE Healthcare product code no. TRA 310; specific activity, 2 Ci/mmol; concentration, 1 mCi/ml).
Five days after the first topical application, all mice were administered with 250 µl of 81.1 µCi/ml 3HTdR (corresponds to 20.0 µCi 3HTdR per mouse) by intravenous injection via a tail vein.

Determination of Incorporated 3HTdR
Approximately five hours after treatment with 3HTdR all mice were euthanised by intraperitoneal injection of Pentobarbital-Natrium.
The draining Iymph nodes were rapidly excised and pooled per group (8 nodes per group). Single cell suspensions (in phosphate buffered saline) of pooled lymph node cells were prepared by gentle mechanical disaggregation through stainless steel gauze (200 µm mesh size). After washing two times with phosphate buffered saline (approx. 10 ml) the Iymph node cells were resuspended in 5 % trichloroacetic acid (approx. 3 ml) and incubated at approximately +4 °C for at least 18 hours for precipitation of macromolecules. The precipitates were then resuspended in 5 % trichloroacetic acid (1 ml) and transferred to plastic scintillation vials with 10 ml of “Ultima Gold” scintillation liquid (Perkin Eimer (LAS) GmbH, D-63110 Rodgau) and thoroughly mixed.
The level of 3HTdR incorporation was then measured on a ß-scintillation counter (Tricarb 2900 TR, Perkin Eimer (LAS) GmbH, D-63110 Rodgau). Similarly, background 3HTdR levels were also measured in two 1 ml-aliquots of 5% trichloroacetic acid. The ß- scintillation counter expresses 3HTdR incorporation as the number of radioactive disintegrations per minute (DPM).

Positive control substance(s):
hexyl cinnamic aldehyde (CAS No 101-86-0)

Results and discussion

In vivo (LLNA)

Resultsopen allclose all
Remarks on result:
other: see Remark
ln this study Stimulation Indices of 0.60, 0.90, and 0.20 were determined with the test item at concentrations of 25, 50, and 100% in acetone:olive oil (4+1).The EC3 value could not be calculated, since none of the tested concentrations induced an S.l. greater than 3.
other: disintegrations per minute (DPM)
Remarks on result:
other: see Remark
The relatively low S.I. obtained for the group treated with 100 % of the test item is due to a DPM value per Iymph node (200.7) that is at the lower border of the historical range meanwhile the DPM value of the vehicle control (999.3) is in the upper range of the historical controls. The result is, therefore, regarded as valid.

Any other information on results incl. tables

Viability / Monolity: No deaths occurred during the study period.

Clinical Signs: No symptoms of Iocal toxicity at the ears of the animals and no systemic findings were observed during the study period.

Body Weights: The body weight of the animals, recorded prior to the first application and prior to treatment with 3HTdR, was within the range commonly recorded for animals of this strain and age.

Applicant's summary and conclusion

Interpretation of results:
not sensitising
Migrated information Criteria used for interpretation of results: EU
The test item was not a skin sensitiser in this assay.
Executive summary:

In the study the test item dissolved in acetone:olive oil (4 +1) was assessed for its possible contact allergenic potential. For this purpose a local Iymph node assay was performed using test item concentrations of 25, 50, and 100% (w/v). The animals did not show any clinical signs during the course of the study and no cases of mortality were observed. In this study Stimulation Indices (Si.) ) of 0.60, 0.90, 0.20 were determined with the test item at concentrations of 25, 50, and 100 % (w/v) in acetone:olive oil (4 +1), respectively. The test item was not a skin sensitiser in this assay.