Registration Dossier

Administrative data

Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
17 Sept - 01 Dec 2009
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
GLP - Guideline study, tested with the source substance Silicic acid, aluminium salt (CAS 1335-30-4). According to the ECHA guidance document “Practical guide 6: How to report read-across and categories (March 2010)”, the reliability was changed from RL1 to RL2 to reflect the fact that this study was conducted on a read-across substance.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010
Report Date:
2010

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Remarks:
Hess. Ministerium für Umwelt, Energie, Landwirtschaft und Verbraucherschutz, Mainzer Straße 80, D-65189 Wiesbaden
Type of study:
mouse local lymph node assay (LLNA)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Silicic acid, aluminium salt
- CAS No.: 1335-30-4
- Analytical purity: >99%
- Lot/batch No.: 1000168802
- Expiration date of the lot/batch: 01.April 2011
- Stability in solvent: Confirmed by the sponsor
- Storage condition of test material: at room temperature, protected from moisture and light

In vivo test system

Test animals

Species:
mouse
Strain:
other: CBA/CaOlaHsd
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Harlan Laboratories B.V., AD Horst, The Netherlands
- Age at study initiation: 8 - 12 weeks
- Weight at study initiation: 19 - 24.2 g
- Housing:single caging in Makrolon Type II cages with wire mesh top; granulated soft wood bedding
- Diet (e.g. ad libitum): pelleted standard diet, ad libitum
- Water (e.g. ad libitum): community tap water Rossdorf, ad libitum
- Acclimation period: 5 days


ENVIRONMENTAL CONDITIONS
- Temperature: 22 +/- 2°C
- Humidity: 45 - 65%
- Photoperiod: 12 hrs dark / 12 hrs light

Study design: in vivo (LLNA)

Vehicle:
dimethyl sulphoxide
Remarks:
Purity: 99.5%; Batch No.: K385049575-749; supplier: VWR Intern. GmbH, Darmstadt, Germany
Concentration:
0, 5%, 10% and 25% Silicic acid aluminium salt, in dimethylsulfoxide
No. of animals per dose:
4
Details on study design:
RANGE FINDING TESTS:
- 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 25% suspension in dimethylsulfoxide.
- Irritation: A pre-test was performed in two animals. Two mice were treated with concentrations of 10 and 25% each on three consecutive days. At the tested concentrations the animals did not show any signs of irritation or systemic toxicity up to 7 days after application.
- Lymph node proliferation response: level of 3HTdR incorporation / number of radioactive disintegrations per minute per lymph node (measured on a beta-scintillation counter)

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Criteria used to consider a positive response: SI > 3: First, that exposure to at least one concentration of the test item resulted in an incorporation of 3HTdR at least 3-fold or greater than that recorded in control mice, as indicated by the stimulation index. Second, that the data are compatible with a conventional dose response, although allowance must be made for either local toxicity or immunological suppression.

TREATMENT PREPARATION AND ADMINISTRATION:
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 5,10 and 25% (w/v) in dimethylsulfoxide. The application volume, 25 µl, was spread over the entire dorsal surface (diameter ~ 8 mm) of each ear lobe once daily for three consecutive days.
5 days after the first topical application, all mice were administered with 250 µl of 78.3 µCi/ml 3H-Methyl Thymidine (3HTdR) (corresponds to 19.6 µCi 3HTdR per mouse) by intravenous injection via a tail vein. Approximately five hours after treatment with 3HTdR all mice were euthanised by intraperitoneal injection of Pentobarbital-Natrium. The draining lymph nodes were rapidly excised and pooled per group (8 nodes per group). The level of 3HTdR incorporation was then measured on a beta-scintillation counter (background were also measured).
Positive control substance(s):
hexyl cinnamic aldehyde (CAS No 101-86-0)
Statistics:
The mean values and standard deviations were calculated in the body weight tables.

Results and discussion

Positive control results:
The GLP Positive control was performed in June 2009. It was seen a dose dependent effect up to a Stimulation Index of 6.84 in the highest dose group (25% w/v).

In vivo (LLNA)

Resultsopen allclose all
Parameter:
SI
Remarks on result:
other: 5% w/v: 0.62 10% w/v:0.92 25% w/v:0.72
Parameter:
other: disintegrations per minute (DPM)
Remarks on result:
other: Control: 602.0 5% w/v: 372.0 10% w/v:552.9 25% w/v:436.0

Any other information on results incl. tables

After the application of up to 25% w/v silicic acid, aluminium salt in DMSO, the highest technically achievable concentration, all Stimulation indices were below 3. All treated mice survived the scheduled study period and no signs of toxicity were observed.

The test item was not a skin sensitiser under the described conditions.

Applicant's summary and conclusion

Interpretation of results:
not sensitising
Remarks:
Migrated information