2-[(2-methyl-1-oxoallyl)oxy]ethyl acetoacetate

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

15 December - 11 January 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP compliant study conduct in accordance with international guidelines.

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2012

Report date:

2012

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)

Principles of method if other than guideline:

Not applicable.

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Test material form:

other: Colourless to yellowish clear liquid

Details on test material:

- Name of test material (as cited in study report): LZ649
- Physical state: Colourless to yellowish clear liquid
- Expiration date of the lot/batch: 23 November 2014
- Storage condition of test material: Room temperature in the dark, desiccated

In vivo test system

Test animals

Species:

mouse

Strain:

CBA

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: a reputable supplier
- Age at study initiation:10-11 weeks
- Weight at study initiation: 17.4 to 21.2 g
- Housing: animals were housed two animals per cage, in solid bottomed polycarbonate cages with a stainless steel mesh lid. Each cage contained a quantity of autoclaved wood flake bedding, additionally Nestlets and a plastic shelter were included for environmental enrichment.
- Diet (e.g. ad libitum): The animals were allowed free access to a standard rodent diet (Rat and Mouse No. 1 Maintenance Diet). This diet contained no added antibiotic or other chemotherapeutic or prophylactic agent.
- Water (e.g. ad libitum): Potable water taken from the public supply was freely available via polycarbonate bottles fitted with sipper tubes.
- Acclimation period: 7 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19 to 23°C
- Humidity (%): 40 to 70%
- Air changes (per hr): not reported
- Photoperiod (hrs dark / hrs light): Artificial lighting was controlled to give a cycle of 12 hours continuous light and 12 hours continuous dark per 24 hours.

IN-LIFE DATES: From: 1st December 2011 To: 3rd January 2012

Study design: in vivo (LLNA)

Vehicle:

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

Concentration:

25, 50% v/v and As supplied main test

No. of animals per dose:

No preliminary test required
4 main test

Details on study design:

RANGE FINDING TESTS:
The maximum practical concentration for dermal administration (using a micropipette) of the test substance prepared in acetone:olive oil (4:1) was assupplied. Available toxicity and irritancy information indicated this would be a suitable high concentration for the study therefore no preliminary
investigations were performed. The low and intermediate concentrations were selected from the concentration series given in regulatory guidelines
and the concentrations administered were:
25, 50% v/v or As supplied in acetone:olive oil (4:1)

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: The animals were allocated without conscious bias to cages within the treatment groups.
- Criteria used to consider a positive response: Results for each treatment group were expressed as the Stimulation Index (SI), derived by dividing the mean dpm/mouse for each treated group and the positive control group by the mean dpm/mouse in the vehicle control group. If the SI is 3 or more, the test substance is regarded as a skin sensitizer.

TREATMENT PREPARATION AND ADMINISTRATION:
The test substance, LZ649, was prepared for administration as a series of graded concentrations in the vehicle, by direct dilution.
The test substance was used as supplied and all formulations were prepared on the day of dosing at the required concentration(s).
The absorption of the test substance was not determined.

In the main phase of the study, five days following the first topical application of test substance (Day 6) all mice were injected via the tail vein with 250 µL of phosphate buffered saline containing 3H-methyl Thymidinea (3HTdR: 80 µCi/mL) giving a nominal 20 µ0Ci to each mouse. The injection into
the tail vein was carried out using a plastic syringe and needle after the mouse had been heated in a warming chamber.

Positive control substance(s):

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

Statistics:

Not applicable

Results and discussion

Positive control results:

The SI for the positive control substance hexyl cinnamic aldehyde (HCA), was 8.4 which demonstrates the validity of this study.

In vivo (LLNA)

Results

Results 1

Key result

Parameter:

SI

Value:

1.3

Test group / Remarks:

concentration as supplied

Results 2

Parameter:

SI

Value:

1.6

Test group / Remarks:

concentration 25% v/v

Results 3

Parameter:

SI

Value:

1.7

Test group / Remarks:

concentration 50% v/v

Any other information on results incl. tables

PRELIMINMARY TEST

The maximum practical concentration for dermal administration (using a micropipette) of the test substance prepared in acetone:olive oil (4:1) was as supplied. Available toxicity and irritancy information indicated this would be a suitable high concentration for the study therefore no preliminary investigations were performed.

MAIN TEST

There were no deaths and no signs of ill health or toxicity were observed during this study.

No signs of dermal irritation were seen on the ears during the study. There was no indication of an effect of treatment on bodyweight gain.

Concentration	dpm	No. lymph nodes per group	Dpm/node	Stimulation index*	Result + = positive - = negative
AOO	6153.80	8.0	769.23	n/a	n/a
25% v/v	9737.50	8.0	1217.19	1.6	-
50% v/v	10584.30	8.0	1323.04	1.7	-
As supplied	7964.90	8.0	995.61	1.3	-
HCA 25% v/v	51437.70	8.0	6429.71	8.4	+

*           Stimulation Index of 3 or more indicates a positive result
n/a        not applicable

dpm     disintegrations per minute
AOO    acetone:olive oil (4:1 v/v) vehicle control

HCA    hexyl cinnamic aldehyde (positive control)

Applicant's summary and conclusion

Interpretation of results:

not sensitising

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

LZ649 is not regarded as a potential skin sensitizer.

Executive summary:

The LLNA study was performed between December 2011 and January 2012 according to OECD Guideline 429 and GLP.

There were no deaths and no signs of ill health or toxicity were observed during this study. No signs of dermal irritation were seen on the ears during the study. There was no indication of an effect of treatment on bodyweight gain.

The SI (test/control ratios) obtained for 25, 50% v/v or as supplied LZ649 were 1.6, 1.7 or 1.3 respectively. As a SI of 3 or more was not recorded for any of the concentrations tested, LZ649 is not considered to have the potential to cause skin sensitization.

The SI for the positive control substance hexyl cinnamic aldehyde (HCA) was 8.4 which demonstrates the validity of this study.