1-(2,2,4-trimethyl-1-quinolyl)ethanone

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

18 Jul - 1 Aug 2012

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Remarks:

GLP compliance unknown, deviations from guideline (3 instead of 4 animals / group, no information on positive control, no clinical observations performed)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2012

Report date:

2012

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

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

Version / remarks:

adopted 22 Jul 2010

Deviations:

yes

Remarks:

- 3 instead of 4 animals / group - no information on positive control - no statistical analysis performed - no clinical observations performed

GLP compliance:

not specified

Remarks:

in-house safety study

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

1-(2,2,4-trimethyl-1,2-dihydroquinolin-1-yl)ethan-1-one

EC Number:

665-911-3

Cas Number:

5855-23-2

Molecular formula:

C14 H17 N O

IUPAC Name:

1-(2,2,4-trimethyl-1,2-dihydroquinolin-1-yl)ethan-1-one

In vivo test system

Test animals

Species:

mouse

Strain:

other: CBA/JCrlj

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Age at study initiation: 8 weeks (preliminary study); 9 weeks (main study)
- Weight at study initiation: preliminary study: 19.72 - 20.77 g; main study: 19.57 - 23.94 g
- Housing: 3 animals per cage in suspended cages with aluminum/stainless steel walls and stainless steel netting floor and front opening (W176 × D302 × H130 mm, Yamato Scientific Co., Ltd.); cages were exchanged for clean sterile cages once a week
- Diet: solid mouse chow (CRF-1, Oriental Yeast Co., Ltd.); ad libitum
- Water: tap water; ad libitum
- Acclimation period: not specified

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21 - 25
- Humidity (%): 40 - 70
- Air changes (per hr): ≥ 10
- Photoperiod: 12 / 12

IN-LIFE DATES:
Preliminary study: 18 - 23 Jul 2012
Main study: 25 Jul - 1 Aug 2012

Study design: in vivo (LLNA)

Vehicle:

acetone/olive oil (4:1 v/v)

Concentration:

preliminary study: 5%, 25%, 100%
main study: 0.2%, 1%, 5%, 25%

No. of animals per dose:

preliminary study: 3 animals (one per dose group)
main study: 15 animals (3 per dose group and negative control)

Details on study design:

PRE-SCREEN TESTS
- Compound solubility: The test substance dissolved at 50% (v/v) in acetone/olive oil (4:1 v/v). Therefore, acetone/olive oil (4:1 v/v) was selected as the vehicle.
- Irritation: No irritation was observed after applying the test substance at 5% or 25%. However, with application at 100%, very slight erythema was noted on days 2 and 3 of the study.
- Lymph node weights: 0.0078 g, 0.0090 g, and 0.0112 g in the 5%, 25% and 100% application groups, respectively.

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: 3H-methyl thymidine incorporation
- Criteria used to consider a positive response: The ratios [radioactivity in the groups with the test substance applied (dpm) / radioactivity in the control group (dpm)] were calculated, and a ratio of ≥ 3 was assessed as positive.

TREATMENT PREPARATION AND ADMINISTRATION
For the preliminary study, acetone/olive oil (4:1 v/v) solutions with the test substance at 5% and 25%, and the undiluted substance (100%) were applied open to both ears of the mice at 0.025 mL/site for 3 consecutive days (1 mouse / concentration). The day that application was started was calculated as day 1 of the study, and the presence or absence of irritation (erythema) was confirmed on day 2, 3 and 6 of the study. In addition, on day 6 of the study the auricular lymph nodes were collected, and the weight was measured.
For the main study, concentrations of the test substance were set to on the basis of the results of the preliminary study (0.2%, 1%, 5% and 25% acetone/olive oil (4:1, v/v) solutions) and were applied open to both ears of the mice at 0.025 mL/site for 3 consecutive days (3 mice / concentration). In addition, there was a group to which acetone/olive oil (4:1 v/v) only was applied, as a control group. The day that application was started was calculated as day 1 of the study, and the presence or absence of irritation (erythema) was confirmed on days 2 and 3 of the study. On day 6 of the study, [methyl-3H]thymidine prepared to a concentration of 2.96 MBq (80 µCi)/mL by using PBS was administered intravenously at 0.25 mL/animal, and 5 hours after administration cells were recovered from auricular lymph nodes, and radiation (dpm) was measured by liquid scintillation counting.

Positive control substance(s):

not specified

Statistics:

not performed

Results and discussion

Positive control results:

no data

In vivo (LLNA)

Results

Results 1

Key result

Parameter:

EC3

Value:

ca. 5

Results 2

Key result

Parameter:

SI

Value:

30.2

Test group / Remarks:

25%

Results 3

Key result

Parameter:

SI

Value:

2.7

Test group / Remarks:

5%

Results 4

Key result

Parameter:

SI

Value:

1.3

Test group / Remarks:

1%

Results 5

Key result

Parameter:

SI

Value:

2.5

Test group / Remarks:

0.2%

Cellular proliferation data / Observations:

DETAILS ON STIMULATION INDEX CALCULATION:
The SI of the 0.2%, 1%, 5% and 25% treatment group was 2.5, 1.3, 2.7 and 30.2, respectively.

EC3 CALCULATION:
The EC3 value was estimated to be ca. 5%.

CLINICAL OBSERVATIONS
Not performed.

BODY WEIGHTS:
Body weight gain after application of the test substance averaged 0.81 g, 1.78 g, 1.43 g, 0.91 g and 0.90 g in the control group and the 0.2%, 1%, 5% and 25% application groups, respectively.

SIGNS OF TOXICITY:
In the preliminary study, very slight erythema was noted on days 2 and 3 in the treatment group receiving the undiluted (100%) test substance.
In the main study, no irritation was noted at any concentration.

LYMPH NODE WEIGHTS:
Lymph node weight in the control group and the 0.2%, 1%, 5% and 25% application groups, averaged 0.0045 g, 0.0053 g, 0.0049 g, 0.0054 g and 0.0122 g, respectively.

Any other information on results incl. tables

Table 1: Results of the skin sensitisation study

Dose (%)*	Body weight (g)				Irritation		Lymph node weight			Radioactivity
	Study day 1	Study day 6	Weight gain	Average weight gain	Study day 2	Study day 3	Individual	Group total	Group average	dpm	ratio
0	21.50	22.62	1.12	0.81	No irritation		0.0040	0.0134	0.0045	1146	-
	20.39	20.63	0.24		No irritation		0.0045
	22.54	23.60	1.06		No irritation		0.0049
0.2	20.82	22.52	1.70	1.78	No irritation		0.0067	0.0160	0.0053	2812	2.5
	20.14	22.32	2.18		No irritation		0.0045
	20.91	22.38	1.47		No irritation		0.0048
1	21.13	22.80	1.67	1.43	No irritation		0.0044	0.0147	0.0049	1447	1.3
	19.57	21.81	2.24		No irritation		0.0059
	21.57	21.96	0.39		No irritation		0.0044
5	23.94	25.01	1.07	0.91	No irritation		0.0051	0.0161	0.0054	3088	2.7
	20.93	21.72	0.79		No irritation		0.0050
	21.94	22.80	0.86		No irritation		0.0060
25	20.95	22.36	1.41	0.90	No irritation		0.0118	0.0367	0.0122	34578	30.2
	22.76	23.62	0.86		No irritation		0.0137
	21.37	21.79	0.42		No irritation		0.0112

*in acetone/olive oil (4/1 v/v); vehicle

Applicant's summary and conclusion

Interpretation of results:

other: Skin Sens.1B (H317) according to Regulation (EC) No 1272/2008

Conclusions:

Under the present test conditions, the test substance 1-(2,2,4-trimethylquinolin-l (2H)-yl)ethanone was assessed to be positive of exhibiting skin sensitising potential and meets the classification criteria Skin sens 1B (H317) according to Regulation (EC) No 1272/2008.