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Description of key information

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records
Reference
Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
23-08-2012 to 04-09-2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: study according to the guidelines under GLP
Qualifier:
according to
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Qualifier:
according to
Guideline:
EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)
GLP compliance:
yes (incl. certificate)
Type of study:
mouse local lymph node assay (LLNA)
Species:
mouse
Strain:
CBA
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Strain: CBA/CaOlaHsd
- Source: Harlan Laboratories UK Ltd., Oxon, UK
- Age at study initiation: 8-12 weeks
- Weight at study initiation: 15 - 23 g,
- Housing: individually in solid-floor polypropylene cages
- Diet: 2014C Teklad Global Rodent diet ad libitum
- Water: ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19 - 25°C
- Humidity (%): 30-70
- Air changes (per hr): ca 15
- Photoperiod (hrs dark / hrs light): 12/12

Vehicle:
acetone/olive oil (4:1 v/v)
Concentration:
0, 10, 25 and 50%
No. of animals per dose:
4/dose
Details on study design:
RANGE FINDING TESTS:
- dose: 50%
- Irritation: very slight erythema on day 4 and 5
- Lymph node proliferation response: no increase of ear thickness > 25%
- Toxicity: none

MAIN STUDY
TREATMENT PREPARATION AND ADMINISTRATION:
Exposure during 3 consecutive days at the dorsal site of the ears (50 μl (25 μl per ear)) with test substance or vehicle. On day 6 3H-methyl thymidine(20 μCi/mouse) was injected in the tail vein. Five hours thereafter mice were killed and draining auricular lymph nodes were pooled per dose group and assessed for 3HTdR after 18 hours incubation at 4°C using a Beckman LS6500 scintillation system. The EC3 value is calculated based on the results at the different tested concentrations.

EXAMINATIONS
Clinical signs: twice daily on day 1-3, daily on day 3-6
Body weights: propor to administration on day 1, and prior to termination at day 6

ANIMAL ASSIGNMENT AND TREATMENT
- Criteria used to consider a positive response: a threefold or greater increase in 3HTdR incorporation compared to control values (expressed as DPM/min).
Statistics:
NA
Parameter:
SI
Remarks on result:
other: at 50% 4.75
Parameter:
other: disintegrations per minute (DPM)
Remarks on result:
other: at 50 % > three fold increase compared to vehicle controls

Concentration (% w/w) in acetone/

olive oil 4:1

dpm (pooled)

dpm/Node

Stimulation Index

Result

Vehicle

14866.96

1858.37

 na

na

10

15180.10

1897.51

1.02

Negative

25

39147.58

4893.45

2.63

Negative

50

70616.64

8827.08

4.75

Positive

No effects on bodyweight or clinical signs, except for slight redness of the ears at the highest concentration.

Interpretation of results:
sensitising
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
The test substance is considered sensitizing to the skin
Executive summary:

Exposure of 4 mice/ treatment during 3 consecutive days at the dorsal site of the ears with test substance (10, 25 or 50%) or vehicle. On day 6, 3H-methyl thymidine(20 μCi/mouse) was injected in the tail vein. Five hours thereafter mice were killed and draining auricular lymph nodes were pooled per dose group and assessed for 3HTdR after 18 hours incubation at 4°C using a Beckman LS6500 scintillation system.

At the highest dose tested the stimulation index was 4.75. The calculated EC3 is 27%. The test substance is considered sensitizing to the skin.

Endpoint conclusion
Endpoint conclusion:
adverse effect observed (sensitising)
Additional information:

In an LLNA test 4 mice/treatment were exposed to the test substance (10, 25 or 50%) or vehicle at the dorsal site of the ears

during 3 consecutive days. On day 6, 3H-methyl thymidine(20 μCi/mouse) was injected in the tail vein. At the highest dose tested the stimulation index was 4.75. The calculated EC3 is 27%. The test substance is considered sensitizing to the skin (Harlan 2012k). A maximisation test with an analogue (BSL 2010b) showed sensitization. The result of this test would have led to a classification as category 1B, H317 (which is similar to the classification of the test substance based on the outcome of the LLNA test).

The outcomes of the tests with the test substance and the analogue show similar results, as is expected for structural similar compounds. The rationale for the read-across is included in chapter 13.


Migrated from Short description of key information:
The test substance was sensitizing in the local lymphnode assay at a concentration of 50%. The EC3 was calculated to be 27%.

Justification for selection of skin sensitisation endpoint:
Study according to the guideline under GLP

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available
Additional information:

In view of the low vapour pressure (1.9E-03 Pa at 25 °C) and the extreme viscosity of the test substance, exposure via the inhalation route is expected to negligible.

Justification for classification or non-classification

The test substance needs to be classified as a skin sensitizer: category 1B H317