Tetrabutyltin

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)

Test guideline 3

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

Reference substance name:

Tetrabutyltin

EC Number:

215-960-8

EC Name:

Tetrabutyltin

Cas Number:

1461-25-2

Molecular formula:

C16H36Sn

IUPAC Name:

tetrabutylstannane

Test material form:

liquid

Details on test material:

- Name of test material (as cited in study report): Tetrabutyltin, TBT
- Substance type: organometallic
- Physical state: colourless liquid
- Analytical purity: 83.8 %
- Expiration date of the lot/batch: 31 October 2011

In vivo test system

Test animals

Species:

mouse

Strain:

CBA:J

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Age at study initiation: 8-12 weeks
- Housing: group housing in cages (maximally 5/cage), from the start of treatment animals were housed individually
- Diet: standard diet ad libitum
- Water: Domestic mains tap water, provided ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 2
- Humidity (%): 45-65
- Air changes (per hr): ca. 10
- Photoperiod (hrs dark / hrs light): 12/12

Study design: in vivo (LLNA)

Vehicle:

acetone/olive oil (4:1 v/v)

Concentration:

0, 0.25, 0.5 and 1 %

No. of animals per dose:

5 females/dose

Details on study design:

RANGE FINDING TESTS:
Based on the presence of systemic toxicity and skin irritation in previous studies, a dose range finding test was conducted to selected suitable dose concentrations for use in the main study. Five animals were treated in the dose range finding test, each with a test substance concentration from the series: undiluted, 50, 25, 10 and 5 %. Each test substance formulation was applied on both ears for three consecutive days. All animals were observed daily for signs of toxicity, including effects on body weights, and their treated ears for signs of irritation. All findings were recorded. The animals were sacrificed on day 3 approximately 24 hours after the last treatment.
Based on the results of the study, dose levels of 0.25, 0.5 and 1 % were selected for the main study.

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: LLNA
- Criteria used to consider a positive response: The present Local Lymph Node Assay was conducted simultaneously with a LLNA reliability study. The results of the vehicle control group that is part of the reliability check were used for evaluation of the data of test groups. The 3H-thymidine incorporation was compared between the different treatment groups. Changes in 3H-thymidine incorporation in the test substance treatment groups were evaluated and expressed as stimulation index (SI) relative to the vehicle control group. The SI was obtained by dividing the individual values of the 3H-thymidine incorporation, expressed as DPM (corrected for background), with the mean proliferation of the vehicle control group. Since also the DPM-data of the vehicle-treated group are divided with its own mean DPM-data, this results in an average SI for vehicle-treated controls of 1. The decision process with regard to a positive response includes a stimulation index ≥3 together with consideration of dose response and statistical analyses based on the test guideline and the recommendations done by ICCVAM.

TREATMENT PREPARATION AND ADMINISTRATION:
The test substance was applied topically once daily for three consecutive days on the dorsum of both ears (by means of a pipette 25 µL on each ear). Immediately after application, the test substance was spread over the dorsum of the ear with the tip of the pipette. Each animal received a total amount of 50 µL per dosing.

Positive control substance(s):

hexyl cinnamic aldehyde (CAS No 101-86-0)

Statistics:

Statistical evaluation of the data (body weights and 3H-thymidine incorporation) was performed by one-way ANOVA, followed by Dunnett’s multiple comparison tests. Probability values of p<0.05 were considered significant.

Results and discussion

In vivo (LLNA)

Results

Results 1

Key result

Parameter:

SI

Value:

1.85

Test group / Remarks:

0.25 %

Results 2

Key result

Parameter:

SI

Value:

1.96

Test group / Remarks:

0.5 %

Results 3

Key result

Parameter:

SI

Value:

10.82

Test group / Remarks:

1 %

Results 4

Key result

Parameter:

SI

Value:

1

Test group / Remarks:

0 %

Cellular proliferation data / Observations:

Disintegrations per minute (DPM) were 1400, 2583, 2739 and 15149 for 0, 0.25, 0.5 and 1 % dose levels, respectively.

Any other information on results incl. tables

No signs of local irritation or other clinical signs were observed in any of the animals during the study period. No aberrant body weights or body weight gains were observed, and no statistical significant difference was found between the vehicle and the positive control group.

Applicant's summary and conclusion

Interpretation of results:

Category 1 (skin sensitising) based on GHS criteria

Conclusions:

Since the SI was > 3 after 1 % tetrabutyltin treatment, the limiting value required for classification as a skin sensitiser, it was concluded that tetrabutyltin should be regarded as a skin sensitiser when applied at concentrations of 1 % (v/v) and higher.

Executive summary:

The sensitisation of Tetrabutyltin was examined in a Local Lymph Node Assay (LLNA) in accordance with OECD 429 and EU Method B.42 under GLP conditions. The test substance was applied topically once daily for three consecutive days on the dorsum of both ears (by means of a pipette 25 µL on each ear). Immediately after application, the test substance was spread over the dorsum of the ear with the tip of the pipette. Each animal received a total amount of 50 µL per dosing.

Since the SI was > 3 after 1 % tetrabutyltin treatment, the limiting value required for classification as a skin sensitiser, it was concluded that tetrabutyltin should be regarded as a skin sensitiser when applied at concentrations of 1 % (v/v) and higher.