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Toxicological information

Skin sensitisation

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Administrative data

Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
12th March 2012 - 21st June 2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2012
Report Date:
2012

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Deviations:
no
GLP compliance:
yes
Type of study:
mouse local lymph node assay (LLNA)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Type:
Constituent
Type:
Constituent
Test material form:
other: liquid.
Details on test material:
- Name of test material (as cited in study report): Capa 2043
- Physical state: Colourless liquid.
- Analytical purity: 97%
- Lot/batch No.: WAC000392
- Expiration date of the lot/batch: 17th February 2014
- Storage condition of test material: Stored in the dark at room temperature.
Specific details on test material used for the study:
CAPA 2043 (2-oxepanone, polymer with 1,4-butanediol)

In vivo test system

Test animals

Species:
mouse
Strain:
CBA/Ca
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River UK Limited, Manston Road, Margate, Kent, UK.
- Age at study initiation: 8 and 10 weeks old on the first day of dosing.
- Weight at study initiation: 16.2 and 21.3 g on the first day of dosing.
- Housing: All mice were housed in pairs in solid-bottomed polypropylene cages (dimensions 48 x 15 x 13 cm) with a stainless steel grid top and an integrated food hopper. Wood shavings were used as bedding and nesting material was provided.
- Diet: PMI Nutrition International Certified Rodent Diet No. 5CR4 (14% protein) was available ad libitum throughout the study.
- Water: Water taken from the public supply (Scottish Water, Edinburgh, Midlothian, UK) was available from water bottles ad libitum throughout the study. Bottles were changed as necessary throughout the course of the study.
- Acclimation period: At least 8 days before the start of dosing.

ENVIRONMENTAL CONDITIONS
- Temperature: 21 - 22°C
- Humidity: 45 - 55%
- Air changes: Minimum of 10 air changes per hour.
- Photoperiod: 12 hours light/12 hours dark (light hours between 07:00 and 19:00)

Study design: in vivo (LLNA)

Vehicle:
acetone/olive oil (4:1 v/v)
Concentration:
0, 25, 50 and 100%
No. of animals per dose:
4 animals per dose.
Details on study design:
RANGE FINDING TESTS:
A preliminary study was conducted on 2 female mice. The animals received an open application of 25 μL of undiluted test item onto the dorsum of each ear once daily on 3 consecutive days. Animals were checked for mortality twice a day and were examined for reaction to the treatment each day of dosing (predose, immediately post dose and approximately 1 and 2 h after dosing) and once daily thereafter.

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
No formal randomisation procedure was applied when assigning test animals. Four female mice were assigned to each dose group and were treated on 3 consecutive days (days 1 - 3). On each day of treatment, each mouse received an open application of 25 μL of the formulation onto the dorsum of each ear. On day 6, each animal received an intravenous injection (250 μL) of phosphate buffered saline (PBS) containing 22.3 μCi of [methyl-3H] thymidine into the lateral tail vein. Five hours after intravenous administration, all animals were euthanised and the major blood vessels severed to exsanguinate. Each pair of draining auricular lymph nodes was collected from each animal and the animal was then discarded.

A single cell suspension of lymph node cells from each paired sample was prepared by gentle disaggregation through a 200 μm mesh stainless steel gauze into conical centrifuge tubes. The lymph node cells were washed in an excess of PBS (approximately 1 mL) and the mesh was discarded. The lymph node cells were then centrifuged at approximately 1300 g for 10 min at 4°C. The supernatant was drawn off and the cells were washed a second time with approximately 1 mL PBS and then centrifuged. Following centrifugation, the supernatant was discarded and the DNA was precipitated with approximately 1 mL 5% trichloroacetic acid at 2 to 8°C for approximately 17½ h. The resulting pellet was again centrifuged at approximately 1300 g for 10 min at 4°C and the supernatant discarded. The pellet was then re-suspended in 200 μL ‘Solvable’, an aqueous-based solubiliser, and the suspension transferred to a vial containing 10 mL scintillation fluid. Incorporation of tritiated thymidine was measured by β- scintillation counting and was expressed as disintegrations per minute (DPM).

TREATMENT PREPARATION AND ADMINISTRATION:
Formulations were prepared on the day of dosing. The required amount of CAPA 2043 was weighed and formulations were made up to the final volume by addition of the requisite amount of vehicle. Formulations were stirred using a magnetic stirrer until visibly homogeneous. The density of the test item, 1.05 g/cm3, was taken into account in preparing formulations at the 25% and 50% concentrations.
Positive control substance(s):
hexyl cinnamic aldehyde (CAS No 101-86-0)
Statistics:
Group means and standard deviations were calculated for disintegrations per minute. Group means and standard deviations were calculated for body weights, along with body weight gains. The percentage change in ear thickness of preliminary test mice was calculated. Dixon’s Q-test for the detection of a single outlier was performed on disintegrations per minute values.

Results and discussion

Positive control results:
The stimulation indices in a recent positive control study were 1.9, 1.6 and 10.1 for formulations of hexylcinnamicaldehyde prepared at concentrations of 5%, 10% and 25%, respectively.

In vivo (LLNA)

Resultsopen allclose all
Key result
Parameter:
SI
Value:
1.57
Test group / Remarks:
25%
Key result
Parameter:
SI
Value:
2.79
Test group / Remarks:
50%
Key result
Parameter:
SI
Value:
2.97
Test group / Remarks:
100%

Any other information on results incl. tables

No systemic signs and no signs of local irritation were seen in any animal during the observation period. Clinical signs were restricted to wetness to the head, which was observed between 1 hours post dosing on Day 1 through to Day 5. This was considered to be merely an accumulation of formulation residues. Two of the mice treated with the 25% concentration and one mouse treated with the 100% concentration lost approximately 2% in body weight, when the weight recorded at the start of treatment was compared with the weight at the end of the study. These slight losses were within the range of background values recorded at these laboratories and were considered to be acceptable for mice of this age and strain.

Applicant's summary and conclusion

Interpretation of results:
not sensitising
Conclusions:
Under the conditions of this study, treatment with CAPA 2043 at concentrations of up to 100% did not show skin sensitisation potential.
Executive summary:

The potential of CAPA 2043 (2 -oxepanone, polymer with 1,4 -butanediol) to cause skin sensitisation was determined in a LLNA in groups of female CBA/Ca mice, in accordance with OECD Test Guideline 429. Following completion of a preliminary study, 4 groups of 4 female mice were tested at 0 (control), 25, 50 and 100% concentrations of test substance. The mice received open applications of 25 μL of test formulation onto the dorsum of each ear, with the control receiving vehicle only (acetone:olive oil). The test animals received this treatment for three consecutive days (Days 1 - 3). On Day 8, mice were euthanized following intravenous injection of [methyl-3H] thymidine into the lateral tail vein and the draining lymph nodes were collected approximately 5 hours after intravenous injection. Mice were checked twice daily for viability, with body weights recorded on Day 1 (prior to testing) and on Day 6; all mice were examined for their reactions to treatment. There were no signs of systemic toxicity and body weight gains were considered to be acceptable for mice of this age and strain. The stimulation indices (SI) for 25%, 50% or 100% CAPA 2043, when compared with the vehicle control were 1.57, 2.79 and 2.97, respectively. Under the conditions of this study, treatment with CAPA 2043 at concentrations of up to 100% did not show skin sensitisation potential.