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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:
2 October 2006 - 13 December 2006
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Study conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results. The study report was conclusive, done to a valid guideline and the study was conducted under GLP conditions.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2006
Report date:
2006

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EPA OPPTS 870.2600 (Skin Sensitisation)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of study:
mouse local lymph node assay (LLNA)

Test material

Constituent 1
Test material form:
solid: particulate/powder
Remarks:
migrated information: powder
Details on test material:
- Physical state: solid
- Appearance: grey powder with lumps
- Storage condition of test material: room temperature in the dark

In vivo test system

Test animals

Species:
mouse
Strain:
CBA
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River France, L 'Arbresle Cedex, France
- Age at study initiation: ca. 11 weeks
- Housing: animals were housed individually in labelled Macrolon cages furnished with sterilised sawdust as bedding material.
- Diet: pelleted rodent diet (SM R/M-Z from SNIFF® Spezialdiäten GmbH, Soets, Germany) ad libitum
- Water: ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20.1 - 22.7 °C
- Humidity (%): 43 - 89 %
- Air changes (per hr): ca. 15 air changes per hour
- Photoperiod (hrs dark / hrs light): 12 hours light / 12 hours dark

Study design: in vivo (LLNA)

Vehicle:
dimethylformamide
Concentration:
10, 25 and 50%
No. of animals per dose:
5
Details on study design:
In the main study, three groups of five experimental animals were treated with 25 µL test material concentrations of 10%, 25% or 50% on three consecutive days, by open application on the ears. Five vehicle control animals were similarly treated, but with vehicle alone (dimethyl formamide). Three days after the last exposure, all animals were injected with 0.25 mL 3H-methyl thymidine and after five hours the draining (auricular) lymph nodes were excised. After precipitating the DNA of the lymph node cells, radioactivity measurements were performed. The activity was expressed as the number of Disintegrations Per Minute (DPM) and a stimulation index was subsequently calculated for each group.
Positive control substance(s):
hexyl cinnamic aldehyde (CAS No 101-86-0)

Results and discussion

Positive control results:
The SI values calculated for the substance concentrations 5, 10 and 25% were 1.4, 2.2 and 6.2 respectively. An EC3 value of 13.1% was calculated using linear interpolation.

The calculated EC3 value was found to be in the acceptable range of 2 and 20%. The results of the 6 monthly HCA reliability checks of the recent years were 8.8, 5.5, 7.3 and 10.3%.

Based on the results, it was concluded that the Local Lymph Node Assay as performed at NOTOX is an appropriate model for testing for contact hypersensitivity.

In vivo (LLNA)

Resultsopen allclose all
Parameter:
SI
Remarks:
10%
Value:
1.4
Parameter:
SI
Remarks:
25%
Value:
2.2
Parameter:
SI
Remarks:
50%
Value:
6.2
Parameter:
EC3
Value:
13.1
Test group / Remarks:
Extrapolated
Parameter:
other: disintegrations per minute (DPM)
Remarks on result:
other: Mean DPM/animal values for the experimental groups treated with test substance concentrations 10, 25 and 50% were 408, 727 and 582 respectively. The mean DPM/animal value for the vehicle control group was 290.

Any other information on results incl. tables

Skin reaction/ irritation
No skin reactions were observed in any of the animals examined.

Macroscopy of the auricular lymph nodes and surrounding area

All nodes of the experimental and control groups were considered normal in size. No macroscopic abnormalities of the surrounding area were noted.

Body weights

Body weights and body weight gain of experimental animals remained in the same range as controls over the study period.

Toxicity and mortality

No mortality occurred and no symptoms of systemic toxicity were observed in the animals of the main study.


Positive control

The six monthly reliability check with Hexylcinnamic aldehyde indicates that the Local Lymph Node Assay as performed at NOTOX is an appropriate model for testing for contact hypersensitivity.

Applicant's summary and conclusion

Interpretation of results:
not sensitising
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
Under the conditions of the study the test material was found not to be a skin sensitiser.
Executive summary:

The potential of the test material to cause skin sensitisation was investigated in a study which was conducted under GLP conditions and in accordance with the standardised guidelines OECD 429, EU Method B.42 and EPA OPPTS 870.2600.

Test material concentrations selected for the main study were based on the results of a preliminary study.

In the main study, three groups of five experimental animals were treated with test material concentrations of 10%, 25% or 50% on three consecutive days, by open application on the ears. Five vehicle control animals were similarly treated, but with vehicle alone (dimethyl formamide). Three days after the last exposure, all animals were injected with 0.25 mL 3H-methyl thymidine and after five hours the draining (auricular) lymph nodes were excised. After precipitating the DNA of the lymph node cells, radioactivity measurements were performed. The activity was expressed as the number of Disintegrations Per Minute (DPM) and a stimulation index was subsequently calculated for each group.

No skin reactions were observed in any of the animals examined.

All nodes of the experimental and control groups were considered normal in size. No macroscopic abnormalities of the surrounding area were noted.

Mean DPM/animal values for the experimental groups treated with test substance concentrations 10, 25 and 50% were 408, 727 and 582 respectively.

The mean DPM/animal value for the vehicle control group was 290.

The SI values calculated for the substance concentrations 10%, 25% and 50% were 1.4, 2.5 and 2.0 respectively.

Since there was no indication that the test material could elicit an SI ≥ 3 when tested up to 50%, it was established that the EC3 value (if any) exceeds 50%.

The six monthly reliability check with Hexylcinnamic aldehyde indicates that the Local Lymph Node Assay as performed at the test laboratory is an appropriate model for testing for contact hypersensitivity.

Based on these results, the test material was not considered to be a skin sensitiser.