Dodecanal

Skin sensitisation

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:

2001-08-28 to 2001-09-21

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

A valid study is available for the analogue substance, Undec-10-enal. It is a GLP compliant study conducted in compliance with agreed protocols, with no or minor deviations for the standard test. The read-across is considered to be suitable based on the structural and “mechanistic action” similarities between the target substance (Dodecanal) and source substance (Undec-10-enal) and their similar physico-chemical properties.

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

2001

Report date:

2001

Reference 2

Reference Type:

publication

Title:

QSARs for the skin sensitisation potential of aldehydes and related compounds

Author:

Patlewicz G, Roberts DW, Walker JD

Year:

2003

Bibliographic source:

QSAR & Combinatorial Science Vol. 22 (2) pp 196-203

Report date:

2002

Materials and methods

Test guideline

Qualifier:

according to guideline

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

Test material information

Constituent 1

Reference substance name:

Undec-10-enal

EC Number:

203-973-1

EC Name:

Undec-10-enal

Cas Number:

112-45-8

IUPAC Name:

undec-10-enal

Constituent 2

Reference substance name:

Undecylenic aldehyde

IUPAC Name:

Undecylenic aldehyde

Details on test material:

- Name of test material (as cited in study report): Undecylenic aldehyde.
- Molecular formula: C₁₁H₂₀O
- Molecular weight: 168.275894
- Smiles notation: C=CCCCCCCCCC=O
- InChl: InChI=1S/C11H20O/c1-2-3-4-5-6-7-8-9-10-11-12/h2,11H,1,3-10H2
- Structural formula attached as image file.
- Substance type: Very deep yellow and clear liquid
- Physical state: Liquid
- Analytical purity: 95 %
- Impurities (identity and concentrations): No data
- Composition of test material, percentage of components:No data
- Isomers composition:No data
- Purity test date: No data
- Batch No: 12319CO
- Expiration date of the lot/batch: 2002-05-15
- Stability under test conditions: Stable under test conditions
- Storage condition of test material: In original container in refrigerator (3-5 °C) away from direct sunlight.

In vivo test system

Test animals

Species:

mouse

Strain:

other: CBA/Jlbm (SPF)

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: RCC Ltd, Biotechnology and Animal Breeding Division, Wölferstrasse 4, Füllinsdorf, Switzerland.
- Age at study initiation: 7-12 wks
- Weight at study initiation: 17.7 g to 24.8 g
- Parity: Nulliparous and non-pregnant
- Housing: In groups of 4 in Makrolon type-3 cages with standard softwood bedding.
- Diet: Pelletted standard Kilba 3433, batch No. 73/01.
- Water: Tap water, ad libitum.
- Acclimation period: Yes, under test conditions (time not specified), after health examination.

ENVIRONMENTAL CONDITIONS
- Temperature 22 °C ± 3 °C, occasional deviations did not affect integrity of study.
- Humidity: 30 % - 70 %, occasional deviations did not affect integrity of study.
- Air changes: 10-15 per hr
- Photoperiod: 12 hrs dark / 12 hrs light

Study design: in vivo (LLNA)

Vehicle:

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

Concentration:

0 % (control), 5 %, 10 %, 25 %, 50 %, 75 % (v/v)

No. of animals per dose:

4 female

Details on study design:

TEST ITEM PREPRARATION
- The test item was placed into a glass beaker on a tared Mettler balance and the vehicle (acetone:olive oil, 4:1 (v/v) was added. A weight by weight dilution was prepared using a magnetic stirrer as a homogeniser. Homogeneity of the test item in the vehicle was maintained during treatment with the magnetic stirrer.
- The preparation was made shortly before each dosing.
- The test item in the main study was assay at 5 consecutive concentrations chosen by the sponsor.

TOPICAL APPLICATION
- Each test group of mice was treated with topical (epidermal) application to the dorsal surface of each earlobe, with different test item concentrations or vehicle control.
- The application volume, 25 µL was spread over the entire dorsal surface of each earlobe once daily for 3 consecutive days.
- A hairdryer was used to dry the surface of the ear as quickly as possible to avoid loss of applied test item.

ADMINISTRATION OF ³H-METHYL THYMIDINE
- ³H-methyl thymidine (³HTdR) was purchased from Amersham International (product code TRA 310, specific activity 2 Ci/mmol, concentration 1 mCi/mL)
- 5 days after the 1st topical application, all mice were administered with 250 µL of 83.32 µCi/mL ³HTdR (equivalent to 20.83 µCi ³HTdR) by intravenous injection via a tail vein.

DETERMINATION OF INCORPORATED ³HTdR
- Approx. 5 hrs after treatment with ³HTdR all mice were euthanised by intraperioneal injection of Narcoren at a dose of ≥ 2 mL/kg bw (equivalent to 320 Mg sodium pentobarbitone/kg bw).
- The draining lymph nodes were rapidly excised and pooled for each experimental group (8 nodes/group). Single cell suspensions (phosphate buffered saline) of pooled lymph node cells were prepared by mental disaggregation through stainless steel gauze (200 µm mesh size). After washing 3 × with phosphate buffered saline (approx. 10 mL) the lymph node cells were resuspended in 5 % trichloroacetic acid (approx. 3 mL) and incubated at approx. 4 °C overnight for precipitation of macromolecules. The precipitates were then resuspended in 5 % trichloroacetic acid (1 mL) and transferred to glass scintillation vials with 10 mL of "Ultima Gold" scintillation liquid and thoroughly mixed.
- The level of ³HTdR incorporation was then measured on a β-scintillation counter. Similarly, background ³HTdR were also measured in 2 × 1 mL aliquots of 5 % trichloroacetic acid. The β-scintillation counter expresses ³HTdR incorporation as the number of radioactive disintegrations per minute (DPM).

INTERPRETATION OF RAW DATA
- The proliferative response of lymph node cells was expressed as the number of radioactive disintegrations per minute per lymph node (DPM/node) and as the ratio of ³HTdR into lymph node cells of test lymph nodes relative to that recorded for control lymph nodes (stimulation index, SI). Before DPM/node values were determined, mean scintillation-background DPM was subtracted from test and control raw data.
- A test item would have been regarded as a sensitiser in the LLNA if the following criteria were fulfilled:
-- First, that exposure to ≥ concentration of the test item resulted in an incorporation of ³HTdR ≥ 3 × recorded in control mice, as indicated by the stimulation index.
-- That the data are consistent with a conventional dose-response, allowing (especially at high concentrations) for either local toxicity or immunological suppression.
-- The decision to select a stimulation index of 3 an as arbitrary indication of sensitising activity was made on the basis of investigations performed with a wide range of chemicals.

OBSERVATIONS
- In addition to the sensitising reactions, the following observations were recorded during the test and observation period:
-- Mortality/viability
-- Body weights (at acclimitisation and at necropsy)
-- Clinical signs, local and systemic (daily from acclimitisation to termination, treatment sites paid particular attention).

Positive control substance(s):

mercaptobenzothiazole (CAS No 149-30-4)

Statistics:

- The mean values and standard deviations were calculated in the body weight tables
- The EC3 value was calculated according to the equation: EC3 = (a-c)((3-d)/(b-d))+c, where (a, b) and (c, d) are the co-ordinates of the two pair of data lying immediately above and below the S.I. value of 3 on the dose-response plot.

Results and discussion

Positive control results:

1 %: 3725 DPM, SI of 1.0 (negative)
5 %: 11251 DPM, SI of 2.9 (negative)
10 %: 16792 DPM, SI of 4.4 (positive)
25 %: 24360 DPM, SI of 6.4 (positive)

Overall result positive. EC3 = 5.33 %

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Remarks on result:

other: 0 % (negative control): 0 5 %: 1.7 10 %: 5.3 25 %: 7.5 50 %: 8.7 75 %: 8.8 EC3 = 6.8 %

Results 2

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: 0 % (negative control): 4146 5 %: 7028 10 %: 21816 25 %: 31132 50 %: 36016 75 %: 36335

Applicant's summary and conclusion

Interpretation of results:

sensitising

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

The test substance was assessed for skin sensitisation according to OECD guideline 429. The test material was found to be sensitising with an EC3 value of 6.8 % concentration w/v.

A valid study is available for the analogue substance, Undec-10-enal. It is a GLP compliant study conducted in compliance with agreed protocols, with no or minor deviations for the standard test. The read-across is considered to be suitable based on the structural and “mechanistic action” similarities between the target substance (Dodecanal) and source substance (Undec-10-enal) and their similar physico-chemical properties.