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Diss Factsheets

Toxicological information

Skin sensitisation

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Administrative data

skin sensitisation: in vivo (LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
07 August 2013 to 26 August 2013 (in life phases)
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
according to 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 form:
other: Clear amber slightly viscous liquid
Details on test material:
Identification: Alkylated naphthalene, EC Number 700-826-8
Structure: UVCB
Molecular formula: UVCB
Molecular weight: UVCB
Description: Clear amber slightly viscous liquid (determined at WIL Research Europe B.V.)
Batch: 18515
Purity/Composition: UVCB
Test substance storage: At room temperature in the dark
Stability under storage conditions: Stable
Expiry date: 31 August 2013

In vivo test system

Test animals

Details on test animals and environmental conditions:
20 young females, approximately 9 weeks old, were group housed in Makrolon cages. Temperature was controlled (18-24 °C) and approxmately 70% humidity. Animals had free access to food and water.

Study design: in vivo (LLNA)

methyl ethyl ketone
0, 25, 50 and 100%
No. of animals per dose:
Details on study design:
Induction was carried out on days 1, 2 and 3 with application of 25 ul of material .
On Day 6, each animal was injected in the tail vein with 0.25 ml of sterile phosphate buffered saline containing 20 uCi of 3H-methyl thymidine.
After 5 hours exposure the mice were killed and the lymph node of each ear was excised.
Radioactivity measurements were performed using a Packard scintillation counter (2800TR).
Counting time was to a statistical precision of +/- 0.2% or a maximum of 5 minutes whichever came first.

Results and discussion

In vivo (LLNA)

Resultsopen allclose all
>= 0.9 - <= 1.3
0.2 - 0.4
Test group / Remarks:
Group 1 (0%): 1.0 +/- 0.2 Group 2 (25%): 0.9 +/- 0.2 Group 3 (50%): 1.3 +/- 0.3 Group 4 (100%): 1.3 +/- 0.4
other: disintegrations per minute (DPM)
>= 215 - <= 315
Test group / Remarks:
Group 1 (0%): 236 +/- 36 Group 2 (25%): 215 +/- 19 Group 3 (50%): 308 +/- 38 Group 4 (100%): 315 +/- 70

Any other information on results incl. tables

A slight irritation was shown by the mice in the 100% dose group. It was judged of no toxicological significance which had no effect on the activity of the nodes.

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
The substance is not a skin sensitiser.
Executive summary:

An assessment of contact hypersensitivity to Alkylated Naphthalene was made with the Mouse Local Lymph Node Assay. The study was carried out based on the guidelines described in:

OECD, Section 4, Health Effects, No.429 (2010),

EC, No 440/2008; B42: "Skin Sensitization: Local Lymph Node Assay"

EPA, OPPTS 870.2600 (2003) “Skin Sensitization”.


Test substance concentrations selected for the main study were based on the results of a pre-screen test.


In the main study, three experimental groups of five female CBA/J mice were treated with test substance concentrations of 25, 50 or 100% w/w on three consecutive days, by open application on the ears. Five vehicle control animals were similarly treated, but with vehicle alone (Methyl ethyl ketone).


Three days after the last exposure, all animals were injected with 3H-methyl thymidine and after five hours the draining (auricular) lymph nodes were excised and pooled for each animal. 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 (SI) was subsequently calculated for each group.


The slight irritation of the ears as shown by all animals treated at 100% was considered not to have a toxicologically significant effect on the activity of the nodes.


The majority of auricular lymph nodes were considered normal in size, except for the nodes of most animals treated at 50 and 100%.

No macroscopic abnormalities of the surrounding area were noted in any of the animals.


Mean DPM/animal values for the experimental groups treated with test substance concentrations 25, 50 and 100% were 215, 308 and 315 DPM respectively. The mean DPM/animal value for the vehicle control group was 236 DPM.


The SI values calculated for the substance concentrations 25, 50 and 100% were 0.9, 1.3 and 1.3 respectively.


Since there was no indication that the test substance elicited an SI3 when tested up to 100%, Alkylated Napthalene was considered to be a non skin sensitizer


The six-month reliability check with Alpha-hexylcinnamicaldehyde indicates that the Local Lymph Node Assay as performed at WIL Research Europe is an appropriate model for testing for contact hypersensitivity.


Based on these results, Alkylated Naphthalene would not be regarded as a skin sensitizer according to the recommendations made in the test guidelines. The test substance does not have to be classified and has no obligatory labelling requirement for sensitization by skin contact according to the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) of the United Nations (2011) and theRegulation (EC) No 1272/2008 on classification, labelling and packaging of substances and mixtures.