Phenyl methacrylate

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2012-03-07 to 2012-03-27

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study. GLP.

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)

Version / remarks:

adopted 22 July 2010

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

30 May 2008

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:

Phenyl methacrylate

EC Number:

218-542-3

EC Name:

Phenyl methacrylate

Cas Number:

2177-70-0

Molecular formula:

C10H10O2

IUPAC Name:

phenyl 2-methylprop-2-enoate

Test material form:

other: liquid

Details on test material:

- Name of test material (as cited in study report): Phenyl methacrylate (PHMA)

In vivo test system

Test animals

Species:

mouse

Strain:

other: CBA/CaOlaHsd

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Age at study initiation: 8-12 weeks (pretests), 8-9 weeks (main study)
- Housing: all animals of the same group were kept in one cage
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: min. 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22±2
- Humidity (%): 45-65
- Photoperiod (hrs dark / hrs light): 12/12

Study design: in vivo (LLNA)

Vehicle:

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

Concentration:

5, 10, 25%

No. of animals per dose:

4

Details on study design:

RANGE FINDING TESTS:
Treatment of 2 mice with 50 and 100% test item lead to erythema scores of 2-3 and enlarged lymph nodes. In a second pretest, animals treated with 12.5 and 25% test item showed erythema scores of 1.

MAIN STUDY
TREATMENT PREPARATION AND ADMINISTRATION:
The preparations were made freshly for each treatment.
Each test group was treated by topical application to the dorsal surface of each ear with 25 µL/ear/day test item at concentrations of 0, 5, 10 and 25% (w/v) in acetone:olive oil (4+1 v/v) once daily for 3 consecutive days.
5 days after the first topical application (day 6) 250 µL of phosphate-buffered saline containing 19.8 µCi 3-HTdR were injected into each test and control mouse via the tail vein. App. 5 h after injection mice were euthanised. The draining lymph nodes were excised and pooled per group (8 nodes/group). Single cell suspensions were prepared by mechanical disaggregation. Finally, the levels of 3-HTdR incorporation were measured in a beta-scintillation counter.

- Criteria used to consider a positive response:
At least one concentration results in a 3-fold greater 3-HTdR incorporation than in control mice.
The data are compatible with a conventional dose response.

Positive control substance(s):

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

Statistics:

EC3 values were calculated as follows:
EC3 = (a-c) [(3-d)/(b-d)] + c
where EC3 is the estimated concentration of the test item required to produce a 3-fold increase in draining lymph node cell proliferative activity; with (a,b) and (c,d) being the pairs of coordinates lying immediately above and below the S.I. value of 3 on the dose response plot.

Results and discussion

Positive control results:

experimental result from December 2011:
EC3 = 14.4%; S.I. for 25% = 5.9
The result was in the historical range

In vivo (LLNA)

Results

Results 1

Key result

Parameter:

SI

Value:

10.51

Test group / Remarks:

Experiment 3: 25% (w/v) test substance in acetone: olive oil (4+1 , v/v)

Results 2

Key result

Parameter:

SI

Value:

4.63

Test group / Remarks:

Experiment 2: 10% (w/v) test substance in acetone: olive oil (4+1 , v/v)

Results 3

Key result

Parameter:

SI

Value:

1.69

Test group / Remarks:

Experiment 1: 5% (w/v) test substance in acetone: olive oil (4+1 , v/v)

Results 4

Key result

Parameter:

SI

Remarks on result:

other: 0%: 1.00 5%: 1.69 10%: 4.63 25%: 10.51 EC3 = 7.2%

Results 5

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: background I: 27 dpm background II: 22 dpm 0%: 1929 5%: 3245 10%: 8842 25%: 20036

Any other information on results incl. tables

- No deaths occurred during the study.

- No systemic toxicity was observed during the study period. From day 2 to 6, the animals showed erythema of the ear skin (see table below). The animals had the expected gains in body weight during the study period.

Dose group [%], all animals	Erythema score, day 2/3/4/5/6 (max. score: 4)
5	0/1/1/0/0
10	0/1/1/1/0
25	1/1/2/1/1

Applicant's summary and conclusion

Interpretation of results:

sensitising

Remarks:

Migrated information Criteria used for interpretation of results: other: CLP, EU GHS (Regulation (EC) No 1272/2008)

Conclusions:

In this Local Lymph Node Assay PHMA is a dermal sensitiser.

Executive summary:

In a dermal sensitisation study according to OECD Guideline 429 (adopted 22 July 2010) with PHMA in acetone:olive oil (4+1, v/v), groups of 4 female CBA/CaOlaHsd mice were tested using the LLNA method.

In preliminary tests, the highest concentration not leading to systemic toxicity and excessive local irritation was determined.

Stimulation indices (S.I.) of 1.69, 4.63 and 10.51 were determined with the test substance at concentrations of 5, 10, 25% (w/v) in acetone:olive oil (4+1, v/v), respectively.

The positive control substance was α-Hexylcinnamaldehyde, which resulted in an EC3 of 14.4% (w/v).

A result is regarded as positive when the S.I. is ≥ 3.

Based on these criteria, the test substance was found to be a sensitiser. The EC3 was 7.2%.

In this Local Lymph Node Assay, PHMA is a moderate dermal sensitiser.