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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:
The study was performed between 22 June 2010 and 06 July 2010
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:
2010
Report Date:
2010

Materials and methods

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

Test material

Reference
Name:
Unnamed
Type:
Constituent

In vivo test system

Test animals

Species:
mouse
Strain:
other: CBA/Ca (CBA/CaOlaHsd)
Sex:
female
Details on test animals and environmental conditions:
Animals and Animal Husbandry
Female CBA/Ca (CBA/CaOlaHsd) strain mice were supplied by Harlan Laboratories U.K. Ltd., Oxon, UK. On receipt the animals were randomly allocated to cages. The animals were nulliparous and non pregnant. After an acclimatisation period of at least five days the animals were selected at random and given a number unique within the study by indelible ink marking on the tail and a number written on a cage card. At the start of the study the animals were in the weight range of 15 to 23 g, and were eight to twelve weeks old.
The animals were individually housed in suspended solid floor polypropylene cages furnished with softwood woodflakes. Free access to mains tap water and food (2014 Teklad Global Rodent diet supplied by Harlan Laboratories U.K. Ltd., Oxon, UK) was allowed throughout the study.

The temperature and relative humidity were controlled to remain within target ranges of 19 to 25°C and 30 to 70%, respectively. Any occasional deviations from these targets were considered not to have affected the purpose or integrity of the study. The rate of air exchange was approximately fifteen changes per hour and the lighting was controlled by a time switch to give twelve hours continuous light (06.00 to 18.00) and twelve hours darkness.
The animals were provided with environmental enrichment items which were considered not to contain any contaminant of a level that might have affected the purpose or integrity of the study.

Study design: in vivo (LLNA)

Vehicle:
acetone/olive oil (4:1 v/v)
Remarks:
Please see below for Vehicle Determination Record
Concentration:
Each group was exposed to concentrations of 100% (undiluted), 50% or 25% v/v (in acetone/olive oil 4:1)
No. of animals per dose:
Groups of four mice were treated
Details on study design:
RANGE FINDING TESTS:
Using available information regarding the systemic toxicity/irritancy potential of the test material, a preliminary screening test was performed using one mouse. The mouse was treated by daily application of 25 µl of the undiluted test material to the dorsal surface of each ear for three consecutive days (Days 1, 2, 3). The mouse was observed twice daily on Days 1, 2 and 3 and once daily on Days 4, 5 and 6. Any signs of toxicity or excessive local irritation noted during this period were recorded. The bodyweight was recorded on Day 1 (prior to dosing) and on Day 6.

- Lymph node proliferation response:
Clinical observations, bodyweight and mortality data are give in the results section (table 1).

No signs of systemic toxicity were noted.

Based on this information the dose levels selected for the main test were 25% and 50% v/v in acetone/olive oil 4:1 and 100%.

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT

- Name of test method:
Local Lymph Node Assay in the Mouse. The assay has undergone extensive inter-laboratory validation and has been shown to reliably detect test materials that are moderate to strong sensitisers.

- Criteria used to consider a positive response:
The proliferation response of lymph node cells was expressed as the number of radioactive disintegrations per minute per lymph node(dpm/node) and as the ratio of 3HTdR incorporation in lymph node cells of test nodes relative to that recorded for the control nodes (stimulation Index).

The test material will be regarded as a sensitiser if at least one concentration of the test material results in a threefold or greater increase in 3HTdR incorporation compared to control values. Any test material failing to produce a threefold or greater increase in 3HTdR incorporation will be classified as a "non-sensitier".

TREATMENT PREPARATION AND ADMINISTRATION:
For the purpose of the study, the test material was used undiluted and also freshly prepared in acetone/olive oil 4:1. This vehicle was chosen as it produced the most suitable formulation at the required concentration. The concentrations used are given above.

Determination, by analysis, of the concentration, homogeneity and stability of the test material preparations was not appropriate because it was not specified in the Study Plan and is not a requirement of the Test Guidelines.

The preliminary screening test suggested that the test material would not produce systemic toxicity or excessive local irritation at the highest suitable concentration. The mice were treated by daily application of 25 µl of the appropriate concentration of the test material to the dorsal surface of each ear for three consecutive days (Days 1, 2 and 3). The test material formulation was administered using an automatic micropipette and spread over the dorsal surface of the ear using the tip of the pipette.

3H-Methyl Thymidine Administration:
Five days following the first topical application of the test material (Day 6) all mice were injected via the tail vein with 250 µl of phosphate buffered saline (PBS) containing 3H-methyl thymidine (3HTdR: 80 µCi/ml, specific activity 2.0 Ci/mmol, GE Healthcare UK Ltd) giving a total of 20 µCi to each mouse.
Positive control substance(s):
hexyl cinnamic aldehyde (CAS No 101-86-0)
Statistics:
None provided.

Results and discussion

Positive control results:
One group of five animals was treated with 50 µl (25 µl per ear) of alpha-Hexylcinnamaldehyde, Tech, 85% as a solution in acetone/olive oil 4:1 at a concentration of 15% v/v. A further group of five animals was treated with acetone/olive oil 4:1 alone.

The Stimulation Index expressed as the mean radioactive incorporation for the treatment group divided by the mean radioactive incorporation of the vehicle control group are as follows:

Concentration % v/v in acetone/olive oil 4:1 Stimulation Index (SI) Result
15 3.12 Positive

Alpha-Hexylcinnamaldehyde, Tech 85% was considered to be a sensitiser under the conditions of the test.

In vivo (LLNA)

Resultsopen allclose all
Parameter:
SI
Remarks on result:
other: A stimulation index of less than 3 was recorded for the undiluted test material and the test material at concentrations of 50% and 25% v/v in acetone/olive oil 4:1. The stimulation index (SI) results are given in Table 2.
Parameter:
other: disintegrations per minute (DPM)
Remarks on result:
other: The radioactive disintegrations per minute (dpm) per lymph node are given in Table 2.

Any other information on results incl. tables

Table 1               Clinical Observations, Bodyweight and Mortality Data – Preliminary Screening Test

Concentration

Animal Number

Bodyweight (g)

Day

1

2

3

4

5

6

Day 1

Day 6

Pre-Dose

Post Dose

Pre-Dose

Post Dose

Pre-Dose

Post Dose

100%

S-1

19

19

0

0

0

0

0

0

0

0

0


0= No signs of systemic toxicity

Table 2              Disintegrations per Minute, Disintegrations per Minute/Node and Stimulation Index

Concentration
(%v/v) in
acetone/olive oil 4:1

dpm

dpm/Nodea

Stimulation Indexb

Result

Vehicle

16262.12

2032.77

na

na

25

10130.36

1266.30

0.62

Negative

50

13459.21

1682.40

0.83

Negative

100

42838.50

5354.81

2.63

Negative


dpm = Disintegrations per minute

a =       Disintegrations per minute/node obtained by dividing the disintegrations per minute value by 8 (total number of lymph nodes)

b =       Stimulation Index of 3.0 or greater indicates a positive result

na  =    Not applicable


Table 3               Individual Clinical Observations and Mortality Data

Concentration
(% v/v) in
acetone/olive oil 4:1

Animal Number

Day 1

Day 2

Day 3

Day 4

Day 5

Day 6

Pre-Dose

Post Dose

Pre-Dose

Post Dose

Pre-Dose

Post Dose

Vehicle

1-1

0

0

0

0

0

0

0

0

0

1-2

0

0

0

0

0

0

0

0

0

1-3

0

0

0

0

0

0

0

0

0

1-4

0

0

0

0

0

0

0

0

0

25

2-1

0

0

0

0

0

0

0

0

0

2-2

0

0

0

0

0

0

0

0

0

2-3

0

0

0

0

0

0

0

0

0

2-4

0

0

0

0

0

0

0

0

0

50

3-1

0

0

0

0

0

0

0

0

0

3-2

0

0

0

0

0

0

0

0

0

3-3

0

0

0

0

0

0

0

0

0

3-4

0

0

0

0

0

0

0

0

0

100

4-1

0

0

0

0

0

0

0

0

0

4-2

0

0

0

0

0

0

0

0

0

4-3

0

0

0

0

0

0

0

0

0

4-4

0

0

0

0

0

0

0

0

0


0= No signs of systemic toxicity

Table 4              Individual Bodyweights and Bodyweight Changes

Concentration
(% v/v) in
acetone/olive oil 4:1

Animal Number

Bodyweight (g)

Bodyweight Change (g)

Day 1

Day 6

Vehicle

1-1

18

18

0

1-2

21

20

-1

1-3

22

20

-2

1-4

20

19

-1

25

2-1

20

19

-1

2-2

20

19

-1

2-3

17

17

0

2-4

18

18

0

50

3-1

19

19

0

3-2

17

17

0

3-3

18

17

-1

3-4

21

20

-1

100

4-1

20

20

0

4-2

20

19

-1

4-3

20

20

0

4-4

21

20

-1


Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
The test material was considered to be a non-sensitiser under the conditions of the test.
Executive summary:

Introduction. 

A study was performed to assess the skin sensitisation potential of the test material in the CBA/Ca strain mouse following topical application to the dorsal surface of the ear. The method was designed to meet the requirements of the following:

 OECD Guideline for the Testing of Chemicals No. 429 "Skin Sensitisation: Local Lymph Node Assay" (adopted 24 April 2002)

 Method B42 Skin Sensitisation (Local Lymph Node Assay) of Commission Regulation (EC) No. 440/2008

Methods. 

Following a preliminary screening test in which no clinical signs of toxicity or skin irritation were noted at a concentration of 100%, this concentration was selected as the highest dose investigated in the main test of the Local Lymph Node Assay. Three groups, each of four animals, were treated with 50 µl (25 µl per ear) of the undiluted test material or the test material as a solution in acetone/olive oil 4:1 at concentrations of 50% or 25% v/v. A further group of four animals was treated with acetone/olive oil 4:1 alone.

Results. 

The Stimulation Index expressed as the mean radioactive incorporation for each treatment group divided by the mean radioactive incorporation of the vehicle control group are as follows:

Concentration (%v/v) in
acetone/olive oil 4:1

Stimulation Index

Result

25

0.62

Negative

50

0.83

Negative

100

2.63

Negative

Conclusion. 

The test material was considered to be a non-sensitiser under the conditions of the test.