Isobutyl methacrylate

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

24 July 2013 - 14 August 2013

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study OECD 429, GLP.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2013

Report date:

2013

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

individual approach (adopted 22 July 2010)

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

dated May 30, 2008

GLP compliance:

yes

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

Isobutyl methacrylate

EC Number:

202-613-0

EC Name:

Isobutyl methacrylate

Cas Number:

97-86-9

Molecular formula:

C8H14O2

IUPAC Name:

isobutyl methacrylate

Specific details on test material used for the study:

Identification: Isobutyl methacrylate
Origin: Evonik Industries AG, Darmstadt
Batch: 730514T40
Purity: 99.83% stabilised with 99 ppm HQME
Expiry Date: 20 December 2013
Storage Conditions:
(provided by the Sponsor) Room temperature

In vivo test system

Test animals

Species:

mouse

Strain:

other: Mice, CBA/CaOlaHsd

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- CBA/CaOlaHsd mice, nulliparous, non-pregnant
- Age at study initiation: 9 - 10 weeks (beginning of treatment)
- Weight at study initiation: 21.7 g ± 1.5 g
- Housing: single; Makrolon Type I, with wire mesh top
- Diet (e.g. ad libitum):2018C Teklad Global 18% protein rodent diet (certified), ad libitum
- Water (e.g. ad libitum): tap water, ad libitum
- Acclimation period: no data
ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22°C ± 2°C
- Humidity (%): 45-94 %
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light): 12 / 12

Study design: in vivo (LLNA)

Vehicle:

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

Concentration:

1 (Control ) 0
2 (Low Dose) 25% (w/v)
3 (Mid Dose) 50% (w/v)
4 (High Dose) 100% (w/v)

No. of animals per dose:

Main study: 5 females (nulliparous and non-pregnant)
Pre-test: 2 females

Details on study design:

RANGE FINDING TESTS:
Concentrations were tested on two mice on one ear each.
From day 2 up to day 6, the animal treated with 50% test item concentration showed an erythema of the ear skin (Score 1). From day 2 up to day 4 and on day 6 the animal treated with 100% test item concentration showed an erythema of the ear skin (Score 1). On day 5, the animal treated with 100% test item concentration showed an erythema of the ear skin (Score 2). In addition, the erythema of the animal treated with 100% test item concentration was scabby on day 5 and 6.
Thus, the test item in the main study was assayed at 25, 50 and 100%. The highest concentration tested was the highest level that could be achieved whilst avoiding systemic toxicity and excessive local skin irritation as confirmed in the pre-experiment.

Positive control substance(s):

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

Statistics:

The mean values and standard deviations were calculated in the body weight tables and for the DPM values (group mean DPM ± standard deviation).
The Dean-Dixon-Test was used for identification of possible outliers (performed with Microsoft Excel 2007).
However, both biological and statistical significance were considered together.

Results and discussion

Positive control results:

A positive control performed with alpha-Hexylcinnamaldehyd in April 2013 resulted in an S.I. of 1.6 at 5% (w/v)
alpha-Hexylcinnamaldehyd in acetone/olive oil (4+1, v/v), 2.4 at 10 % and 5.9 at 25 %. An EC3 of 12.6% was calculated.

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Value:

1.78

Test group / Remarks:

25 %

Remarks on result:

other: DPM/lymph node: 229.5

Results 2

Key result

Parameter:

SI

Value:

3.64

Test group / Remarks:

50 %

Remarks on result:

other: DPM/lymph node: 469.1

Results 3

Key result

Parameter:

SI

Value:

5.13

Test group / Remarks:

100 %

Remarks on result:

other: DPM/lymph node: 661.9

Results 4

Parameter:

EC3

Value:

41.4

Any other information on results incl. tables

Calculation and Results of Individual Data

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

Test item concentration			DPM values measured	DPM-BG per animal (2 lymph nodes)^a)	S.I.^b)
%	Group no.	Animal no.
---	---	BG I	22	---	---
---	---	BG II	25	---	---
0	1	1	108	84.5	---
0	1	2	176	152.5	---
0	1	3	99	75.5	---
0	1	4	129	105.5	---
0	1	5	250	226.5	---
25	2	6	214	190.5	1.5
25	2	7	261	237.5	1.8
25	2	8	255	231.5	1.8
25	2	9	134	110.5	0.9
25	2	10	401	377.5	2.9
50	3	11	430	406.5	3.2
50	3	12	563	539.5	4.2
50	3	13	644	620.5	4.8
50	3	14	443	419.5	3.3
50	3	15	383	359.5	2.8
100	4	16	731	707.5	5.5
100	4	17	775	751.5	5.8
100	4	18	659	635.5	4.9
100	4	19	689	665.5	5.2
100	4	20	573	549.5	4.3

1    =  Control Group

2-4=  Test Group

^a)   =  values corrected for mean background value (BGI and BGII)

^b)    =  Stimulation Indices relative to the mean of the control group (Group 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 Isobutyl methacrylate is a dermal sensitiser.
CLP EU GHS (Regulation (EC) No 1272/2008) classification: sensitizing category 1B (EC3 value > 2%)

Executive summary:

In a dermal sensitisation study according to OECD Guideline 429 (adopted July 2010) Isobutyl methacrylate in acetone:olive oil (4+1, v/v), groups of 5 female CBA/CaOlaHsd mice were tested using the LLNA method with the individual approach.

In this Local Lymph Node Assay Isobutyl methacrylate is a dermal sensitiser.

 

No clinical signs and no systemic findings were observed after the first and second application (25% and 50%). Only the highest dose (100%) induced slight erythema on the ear skin of all four animals of the group.

The body weight of the animals, recorded prior to the first application and prior to treatment with 3HTdR, was within the range commonly recorded for animals of this strain and age. No cases of mortality were observed.

STIMULATION INDICES (S.I.) of 1.78, 3.64, and 5.13 were determined with the test substance at concentrations of 25%, 50% and 100% (w/v) in acetone:olive oil (4+1, v/v), respectively. The positive control substance wasα-Hexylcinnamaldehyde, which gave an EC3 at 5.9 % (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 calculated to be 41.4 %.

In this study, Isobutyl methacrylate is a dermal sensitiser.

CLP EU GHS (Regulation (EC) No 1272/2008) classification: sensitizing category 1B (EC3 value > 2%)

 

 

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