2-[2-(3,4-dihydro-6-methoxy-1(2H)-naphthylidene)ethyl]-2-ethylcyclopentane-1,3-dione

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Well documented study according to international accepted guidelines and GLP compliant.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2014

Report date:

2014

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

2-[2-(3,4-dihydro-6-methoxy-1(2H)-naphthylidene)ethyl]-2-ethylcyclopentane-1,3-dione

EC Number:

212-705-2

EC Name:

2-[2-(3,4-dihydro-6-methoxy-1(2H)-naphthylidene)ethyl]-2-ethylcyclopentane-1,3-dione

Cas Number:

850-92-0

Molecular formula:

C20H24O3

IUPAC Name:

2-ethyl-2-[2-(6-methoxy-3,4-dihydronaphthalen-1(2H)-ylidene)ethyl]cyclopentane-1,3-dione

Test material form:

solid: crystalline

Details on test material:

Test Item: Ethyl-secodion
CAS No.: 850-92-0
Batch No.: L39082N
Physical state: solid, crystalline substance
Colour: beige
Odour: characteristic
Active ingredient content (UV): 101.0%
Storage: at room temperature, dry place

In vivo test system

Test animals

Species:

mouse

Strain:

CBA

Sex:

female

Details on test animals and environmental conditions:

Species and strain: CBA/Ca Ola Hsd mice
Source: TOXI-COOP ZRT.
Hygienic level at arrival: SPF
Hygienic level during the study: Good conventional
Number of animals: 24 animals/main test (4 animals/treatment group)
Sex: Female, nulliparous, non-pregnant
Age of animals: Young adult mice; 10-12 weeks old (at start of the main test)
Body weight range at starting: 19.3-24.7 g
Acclimatization time: 7 days
Animal health: Only healthy animals were used

Housing during acclimatization period: Grouped caging in small groups
Housing during the test: Grouped caging (4 animals/cage)
Light: 12 hours daily, from 6.00 a.m. to 6.00 p.m.
Temperature: 22 ± 3 °C
Relative humidity: 30 – 70 %

Study design: in vivo (LLNA)

Vehicle:

dimethylformamide

Remarks:

AOO (acetone:olive oil, 4:1) for positive control groups

Concentration:

The test item was administered at three different concentrations (50; 25; 10 w/v%) according to the results of the dose range finding test.

No. of animals per dose:

4 animal/dose

Details on study design:

Selection of test item concentrations was based on the results of a formulation evaluation and also results of preliminary irritation/toxicity tests to find an appropriate solvent and the maximum applicable concentration according to the relevant guidelines. Based on the preliminary test results the test item was examined in the main test at 50 %, 25 % and 10 % (w/v) concentrations as formulations in the selected vehicle of N,N-Dimethylformamide (DMF). Appropriate positive control (α-Hexylcinnamaldehyde [HCA] in 25 % (w/v) concentration), furthermore two negative control groups dosed with the vehicles of the test and positive control groups, respectively, were employed.
The positive control item (25 % (w/v) HCA in Acetone: Olive oil 4:1 (v/v) mixture, AOO) induced the appropriate stimulation over the control, thus confirming the validity of the assay.

Positive control substance(s):

hexyl cinnamic aldehyde (CAS No 101-86-0)

Results and discussion

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Remarks on result:

other: see Remark

Remarks:

The stimulation index (SI = the DPN of a treated (positive control or test item) group divided by the DPN of the respective negative control group) for each treatment group was also calculated. A stimulation index of 3 or greater is an indication of a positive result. When monotonic dose-response is seen, attempt is made to calculate EC3 (dose calculated to induce a stimulation index of 3) with the help of linear regression on dose-response relationship. All calculations were made by Microsoft Excel Software. (See Table1 for the values.)

Results 2

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: see Remark

Remarks:

DPM (disintegration per minute) was measured for each treatment group. The measured DPM values were corrected with the background DPM value. The average of the two measured DPM values of 5 % (w/v) TCA solutions was used as the background DPM value. The results were expressed as DPN (DPM divided by the number of pooled lymph nodes). (See Table1 for the values.)

Any other information on results incl. tables

Test Group Name	Measured DPM/group	Group* DPM	DPN (DPM/Node)	Stimulation Index Values
Vehicle control for the positive control: AOO	4171	4148.0	518.5	1.0
Positive control: 25 % HCA in AOO	90117	90094.0	11261.8	21.7
Ethyl-secodione 50 % in DMF	21311	21288.0	2661.0	5.0
Ethyl-secodione 25 % in DMF	6911	6888.0	861.0	1.6
Ethyl-secodione 10 % in DMF	5360	5337.0	667.1	1.2
Vehicle control for the test item: DMF	4313	4290.0	536.3	1.0

 *Group DPM = measured DPMgroup- average DPMbackground

Applicant's summary and conclusion

Interpretation of results:

Category 1 (skin sensitising) based on GHS criteria

Remarks:

Migrated information

Conclusions:

In conclusion, under the conditions of the present Local Lymph Node Assay, Ethyl-secodion (CAS No. 850-92-0) tested at the maximum attainable concentration of 50 % (based on solubility) and at concentrations of 25 % and 10 % (w/v) as formulations in an appropriate vehicle (DMF) was shown to have skin sensitization potential. In this LLNA the resulting EC3 values were 35 % or 32 % (w/v) based on the dose response and the regression curves, respectively. Based on the EC3 values the test item was considered a weak sensitizer according to published data.
According to GHS classification criteria (EC3 > 2%) the substance is classified as skin senzitization 1B sub-category.