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Skin sensitisation

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Administrative data

Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Study period:
13 Sep - 02 Oct 2006
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
GLP - Guideline study. According to the ECHA guidance document "Practical guide 6: How to report read-across and categories (March 2010)", the reliability was changed from RL1 to RL2 to reflect the fact that this study was conducted on a read-across substance.

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)
Version / remarks:
adopted in 2002
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)
Version / remarks:
adopted in 2004
Deviations:
no
Qualifier:
according to guideline
Guideline:
EPA OPPTS 870.2600 (Skin Sensitisation)
Version / remarks:
adopted in 2003
Deviations:
no
GLP compliance:
yes
Type of study:
mouse local lymph node assay (LLNA)

Test material

Constituent 1
Reference substance name:
Fatty acids, coco, 2,2-dimethyl-1,3-propanediyl esters
EC Number:
292-990-8
EC Name:
Fatty acids, coco, 2,2-dimethyl-1,3-propanediyl esters
Cas Number:
91031-85-5
IUPAC Name:
91031-85-5
Details on test material:
- Name of test material (as cited in study report): only trade name given
- Physical state: yellow liquid
- Analytical purity: 98%
- Lot/batch No.: OE40323
- Stability under storage conditions: stable
- Storage condition of test material: at room temperature in the dark
- Expiration date of the lot/batch: 01 Jan 2008

In vivo test system

Test animals

Species:
mouse
Strain:
other: CBA strain, inbred, SPF-Quality
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River France, L´Arbresle Cedex, France
- Age at study initiation: approx. 11 weeks old
- Weight at study initiation: 20-25 g (females)
- Housing: individual housing in labelled Macrolon cages (MI type) containing sterilized sawdust as bedding material
- Diet: pelleted rodent diet, ad libitum
- Water: tap water, ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21 ± 3
- Humidity (%): 30 - 70 (relative humidity); 40 – 70 (actual range)
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12 / 12

IN-LIFE DATES: From: 13 Sept 2006 To: 02 October 2006

Study design: in vivo (LLNA)

Vehicle:
acetone/olive oil (4:1 v/v)
Concentration:
25, 50 and 100%
No. of animals per dose:
5
Details on study design:
RANGE FINDING TESTS:
- Irritation: a preliminary irritation study (range-finding study) was run in order to select the highest test substance concentration to be used in the main study.
A series of two test substances concentrations was tested, selected from the series: 100% (undiluted), 50%, 25%, 10%, 5%, 2.5%, and 1% and if needed further lower concentrations using the same steps. The test system, procedures and techniques were identical to those used during days 1 to 3 of the main study unless otherwise specified.
2 young adult animals were selected (5-14 weeks old). Each animal was treated with one concentration on 3 consecutive days.
Approximately 4 hours after the last exposure, the ear was cleaned of residual test substance with tap water and the irritation was assessed. Body weight were recorded on day 3.

At 50% dose concentration a grade 2 erythema (well defined erythema) was observed in 1 animal on the left and right dorsal surface ear. At 100% dose concentration a grade 1 erythema (slight erythema) was observed in the other animal on the left and right dorsal surface area. Based on the results, the highest test substance concentration selected for the main study was 100% concentration.

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: ³H-methyl thymidine incorporation determined by ß-scintillation
- Criteria used to consider a positive response: DPM (disintegration per minutes) values were presented for each animal and for each dose group. A stimulation index (SI, ratio of the DPM/ treated group compared to DPM/vehicle control group) was calculated for each group. If the results indicate a SI ≥ 3, the test substance was regarded as a skin sensitizer.

TREATMENT PREPARATION AND ADMINISTRATION: 25 µL of test substance was applied to the dorsal surface of each ear of each mouse. The application was repeated on Days 2 and 3. On Day 6 an injection of 250 µL phosphate buffered saline (PBS) containing 20 µCi of ³H-methyl thymidine (³H-TdR) was made into the tail vein of each experimental mouse. Five hours later, the draining auricular lymph node of each ear was excised in PBS. A single cell suspension of lymph node cells (LNC) was prepared in PBS by gentle separation through stainless steel gauze (diameter 125 µm). LNC were washed twice with an excess of PBS by centrifugation at 200 g for 10 minutes at 4 °C. To precipitate the DNA, the LNC were exposed to 5% trichloroacetic acid (TCA) at 4 °C during the night.
Positive control substance(s):
hexyl cinnamic aldehyde (CAS No 101-86-0)
Statistics:
Linear interpolation was used to calculate EC3 value for positive control concentrations

Results and discussion

Positive control results:
Mean DPM/animal values for the experimental groups treated with positive control concentrations 5, 10 and 25% were 324, 621, and 1145 respectively.The SI values calculated for the alpha-hexylcinnamic aldehyde concentrations 5, 10 and 25% were 1.6, 3.0 and 5.5 respectively. An EC3 value of 10.0% was calculated using linear interpolation.

In vivo (LLNA)

Resultsopen allclose all
Parameter:
SI
Remarks on result:
other: see Remark
Remarks:
The SI values calculated for the substance concentrations 25, 50 and 100% were 1.1, 0.9 and 2.3 respectively. The SI value calculated for the control group (vehicle) was 1.0. These results indicate that the test substance could not elicit an SI of 3.
Parameter:
other: disintegrations per minute (DPM)
Remarks on result:
other: see Remark
Remarks:
No significant increase in isotope incorporation was detected after repeated application in treated animals compared with controls. Mean DPM/animal values for the experimental groups treated with test substance concentrations of 25, 50 and 100% were 256, 213, and 553 respectively. The mean DPM/animal value for the control group (vehicle group) was 241.

Any other information on results incl. tables

Slight irritation was noted among the animals of the control group and in all animals treated at 25%. Slight or well-defined irritation was noted among the animals of the higher dose groups.

 

Table 1: Skin reactions, body weights and relative size auricular lymph nodes

Group

%Test substance

Animal

Day 3

Day 6

 

 

 

Skin reactions dorsal surface ear

Size nodes

 

 

 

left

right

 

 

 

 

erythema

oedema

erythema

oedema

left

right

1

0% (vehicle)

1

0

0

0

0

n

n

 

 

2

0

0

1

0

n

n

 

 

3

0

0

1

0

n

n

 

 

4

0

0

0

0

n

n

 

 

5

0

0

1

0

n

n

 

25%

6

1

0

1

0

n

n

 

 

7

0

0

1

0

n

n

 

 

8

0

0

1

0

n

n

 

 

9

0

0

1

0

n

n

 

 

10

1

0

1

0

n

n

 

50%

11

1

0

2

0

n

n

 

 

12

1

0

1

0

n

n

 

 

13

1

0

2

0

n

-

 

 

14

1

0

1

0

n

n

 

 

15

1

0

1

0

-

n

 

100%

16

0

0

1

0

n

-

 

 

17

1

0

2

0

n

n

 

 

18

1

0

1

0

n

n

 

 

19

1

0

1

0

n

n

 

 

20

1

0

2

0

n

n

n= considered to be normal

Applicant's summary and conclusion

Interpretation of results:
not sensitising
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
CLP: not classified
DSD: not classified