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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:
27 January to 12 February 2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

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:
yes
Remarks:
Minor protocol deviations occurred but these did not affect the overall outcome of the study (purity data not available, an analytical certificate for nesting material was not retained, brief excursions outside of the humidity range in the animal room)
GLP compliance:
yes
Type of study:
mouse local lymph node assay (LLNA)

Test material

Reference
Name:
Unnamed
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 3050
- Substance type: Oligomer
- Physical state: Liquid
- Analytical purity: 100%
- Lot/batch No.: WCB000999
- Expiration date of the lot/batch: 23th August 2015
- Stability under test conditions: Stable for the duration of the study
- Storage condition of test material: Ambient

In vivo test system

Test animals

Species:
mouse
Strain:
CBA
Sex:
female
Details on test animals and environmental conditions:
The animals were female (nulliparous and non-pregnant) mice of the CBA/Ca strain. They were supplied by Charles River UK Ltd., Kent, UK and arrived at Charles River on 19 January 2010 (allowing an 8 day acclimatisation period prior to study initiation). They were 7 to 8 weeks old and weighed 15.2 to 19.1 g on despatch.No formal randomisation procedure was applied: the mice were removed from their tranport boxes in random order and allocated to groups by placing them into labelled cages. Each mouse received a subcutaneous implant for identification purposes.The mice were housed in groups of 2 or 3 in cages with a stainless steel grid top and an integrated food hopper. Wood shavings were used as bedding and nesting material ('Nestlets') was provided. A wooden chewstick was provided as environmental enrichment. Analysis of bedding and chewsticks did not provide evidence of contamination. Each cage was supplied with a water bottle. From animal arrival to the end of the observation period, average daily environmental temperature in the animal room was approximately 21°C and the range for average daily relative humidity was approximately 41 to 58%. A 12 hour light/dark cycle was in operation with a minimum of 15 air changes per hour.Rat and Mouse No. 1 Maintenance Diet (Special Diet Services, UK) and tap water (Scottish Water, UK) were available ad libitum. The results of diet and water analyses did not provide evidence of contamination and so the outcome of the study was not prejudiced. Certificates relevant to this study were retained in the data.

Study design: in vivo (LLNA)

Vehicle:
dimethylformamide
Concentration:
0, 25, 50 and 100%
No. of animals per dose:
Preliminary study: 2 mice
Main study: 5 mice per dose
Details on study design:
A preliminary test was conducted with two females, with a formulation concentration of 100%. For 3 consecutive days, animals received an open application of 25 µL of undiluted test item onto the dorsum of each ear. All animals were observed for reaction to treatment. Observations were conducted frequently on each day of dosing (predose, immediately post dose and approximately 1 and 2 h after dosing) and once daily thereafter until the kill (exposure to CO2 followed by cervical dislocation) on Day 6. Individual body weights were recorded on Day 1 (before the first dose) and Day 6. There were no signs of systemic toxicity or local irritation and no effect on body weight was noted. Therefore, dose concentrations of 25%, 50% and 100% were selected as suitable non-toxic doses for the main study.After the preliminary test, concentrations were selected for the main study and 5 females per group were treated with the vehicle alone (0%), 25%, 50% or 100% CAPA 3050. For 3 consecutive days (Days 1 to 3), animals received an open application of 25 µL of the appropriate formulation onto the dorsum of each ear, there was no treatment on Days 4 and 5. On day 6 each animal received an intravenous injection (250 µL) of PBS containing approximately 19 µCi of [methyl-³H] thymidine into the lateral tail vein. All animals were examined for reaction to treatment. On each day of dosing the observations were conducted predose, immediately post dose and approximately 1 and 2 h post dose. Thereafter mice were observed once daily until kill on Day 6. Individual body weights were recorded on Day 1 (before the first dose) and Day 6.Approximately 6 h after intravenous administration all animals were killed by exposure to a rising concentration of carbon dioxide and exsanguinated. Each pair of draining auricular lymph nodes was collected from each mouse. 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. The lymph nodes cells were washed in excess of PBS and centrifuged. The supernatant was drawn off, and the pellet was washed a second time with PBS and then centrifuged. Following centrifugation, the supernatant was discarded and the pellet was precipitated with ~1 mL 5% trichloroacetic acid at 2 to 8°C for ~21 h. The pellet was centrifuged again and the supernatant discarded. The pellet was then re-suspended in 200 µL 'Solvable' and the suspension transferred to a vial containing 10 mL scintillation fluid ('Aquasafe 500 plus liquid', Zinsser Analytic, UK). Incorporation of tritiated thymidine was measured by ß-scintillation counting.All animals were checked for viability early in the morning and again as late as possible on each day. Results were corrected for background radiation and expressed as the Stimulation Index (SI). This was obtained by dividing the mean disintegrations per minute (DPM) obtained from each group by the mean DPM for the control group. The SI for the control group, therefore, is one. A positive response is indicated by an SI≥3, together with consideration of dose-response.
Positive control substance(s):
hexyl cinnamic aldehyde (CAS No 101-86-0)
Statistics:
No formal statistical analysis was carried out.

Results and discussion

Positive control results:
The stimulation indices in the recent positive control study were 1.2, 1.5 and 5.0 for 5%, 10% and 25% hexylcinnaminicaldehyde, respectively.

In vivo (LLNA)

Resultsopen allclose all
Key result
Parameter:
SI
Value:
1.9
Test group / Remarks:
25%
Key result
Parameter:
SI
Value:
2
Test group / Remarks:
50%
Key result
Parameter:
SI
Value:
2.7
Test group / Remarks:
100%
Parameter:
EC3
Remarks on result:
not determinable

Any other information on results incl. tables

No systemic signs and no signs of local irritation were noted in any animal during the observation period. Body weight gains were considered to be acceptable for mice of this age and strain.

Applicant's summary and conclusion

Interpretation of results:
not sensitising
Remarks:
Migrated information
Conclusions:
Under the conditions of the study, since treatment with CAPA 3050 at concentrations of up to 100% (ie undiluted CAPA 3050) did not achieve a stimulation index of ≥3, it was considered that the test item does not have the potential to cause sensitisation.
Executive summary:

The delayed contact hypersensitivity potential of the test item, CAPA 3050, was investigated in CBA/Ca mice. A preliminary test was conducted using 2 females. Each mouse received an open application of 25 μL of undiluted CAPA 3050 onto the dorsum of each ear on 3 consecutive days. There was no evidence of systemic toxicity and no signs of local irritation and, as a result of these findings, formulation concentrations were selected for the main study. Three groups, each consisting of 5 females, were treated in the same manner as the preliminary test mice with concentrations prepared at 25%, 50% and 100% (ie undiluted CAPA 3050), respectively, also for 3 consecutive days. The vehicle was dimethylformamide and one group of 5 females received only this and acted as controls. Three days after the final application each animal received an intravenous injection of [methyl-³H] thymidine into the lateral tail vein and approximately 6 h later the draining lymph nodes were collected in order that incorporation of tritiated thymidine could be assessed by scintillation counting. There were no systemic signs noted in any animal during the observation period and body weight changes were considered to be acceptable for mice of this age and strain.

The stimulation index (SI) values for the mice treated with CAPA 3050 at concentrations of 25%, 50% or 100%, when compared with the control group, were 1.9, 2.0 and 2.7, respectively. Under the conditions of the study, since treatment with CAPA 3050 at concentrations of up to 100% (ie undiluted CAPA 3050) did not achieve a stimulation index of ≥3, it was considered that the test item does not have the potential to cause sensitisation.

CAPA 3050 is not classified as a skin sensitiser according to CLP.