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Description of key information

In a Local Lymphnode Assay LLNA acc. OECD 429 methacrylamide was not sensitising to skin at test concentrations of 5, 10 and 25 % (w/v).

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records
Reference
Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2007-03-08 until 2007-06-27
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Version / remarks:
(adopted 24 April 2002)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Remarks:
OECD Principles of GLP, as revised in 1997 [C(97)186/Final]
Type of study:
mouse local lymph node assay (LLNA)
Specific details on test material used for the study:
- Name of test material (as cited in study report): Methacrylamide
- Substance type: organic
- Physical state at roomtemperature: solid
- Analytical purity: 99.5 %
- Isomers composition: not applicable
- Purity test date: no data
- Lot/batch No.: 11170123
- Expiration date of the lot/batch: August 08, 2007
- Stability under test conditions: Stability in water: Several days at room temperature and refrigerated
- Storage condition of test material: At room temperature
Species:
mouse
Strain:
other: CBA/CaOlaHsd
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Harlan Netherlands, B.V. Postbus 6174, NL - 5960 AD Horst / The Netherlands
- Age at study initiation: 7-8 weeks (beginning acclimatisation)
- Weight at study initiation: no data
- Housing: single
- Diet (e.g. ad libitum): pelleted standard diet, ad libitum (Harlan Winkelmann GmbH, D-33178 Borchen
- Water (e.g. ad libitum): tap water, ad libitum, (Gemeindewerke, D-64380 Rossdorf)
- Acclimation period: At least 5 days. Under test conditions after health examination. Only animals without any visible signs of
illness were used for the study.


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ±3 °C
- Humidity (%): relative humidity: 30-70 %
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light): artifical light: 6.00 a.m. - 6.00 p.m
Vehicle:
dimethylformamide
Remarks:
Purity: 99%; Supplier: VWR International GmbH (64295 Darmstadt, Germany)
Concentration:
Test concentrations (main study): 0 (vehicle group), 5, 10, 25 %
Test concentrations (non-GLP) pre-tests: 3.13, 6.25, 12.5, and 25 %
No. of animals per dose:
Main study: 4 females (nulliparous and non-pregnant)
Pre-tests (non-GLP): 2 females
Details on study design:
RANGE FINDING TESTS:
- Compound solubility: in water: 202 g/L at 20°C
- Irritation: no irritation effects were observed at test concentrations after single or triple application.
- Lymph node proliferation response:

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: Local Lymph Node assay
- Criteria used to consider a positive response:
The proliferative response of lymph node cells is expressed as the number of radioactive disintegrations per minute per lymph node (DPM/node)
and as the ratio of ³HTdR incorporated into lymph node cells of test lymph nodes relative to that recorded for control lymph nodes (stimulation
index). Before DPM/node values were determined, mean scintillation-background DPM was subtracted from test and control raw data.

A test item is regarded as a sensitiser in the LLNA if the following criteria are fulfilled:
- First, that exposure to at least one concentration of the test item resulted in an incorporation of ³HTdR at least 3-fold or greater than that recorded in control mice, as indicated by the stimulation index.
- Second, that the data are compatible with a conventional dose response, although allowance must be made (especially at high topical
concentrations) for either local toxicity or immunological suppression.

TREATMENT PREPARATION AND ADMINISTRATION:

Topical Application
Each test group of mice was treated by topical (epidermal) application to the dorsal surface of each ear lobe (left and right) with different test item
concentrations of 5, 10, and 25% (w/v) in dimethyl formamide. The application volume, 25 µl, was spread over the entire dorsal surface (diameter
ca. 8 mm) of each ear lobe once daily for three consecutive days. A further group of mice was treated with an equivalent volume of the relevant
vehicle alone (control animals).

Administration of 3H-Methyl Thymidine
³H-methyl thymidine (³HTdR) was purchased from GE Healthcare (GE Healthcare product code no. TRA 310; specific activity, 2 Ci/mmol;
concentration, 1 mCi/ml). Five days after the first topical application, all mice were administered with 250 µl of 78.5 µCi/ml ³HTdR (corresponds to
19.6 µCi ³HTdR per mouse) by intravenous injection via a tail vein.

Determination of Incorporated ³HTdR
Approximately five hours after treatment with ³HTdR all mice were euthanised by intraperitoneal injection of Na-thiopental (Trapanal, Altana,
78467 Konstanz, Germany).
The draining lymph nodes were rapidly excised and pooled per group (8 nodes per group). Single cell suspensions (in phosphate buffered saline) of pooled lymph node cells were prepared by gentle mechanical disaggregation through stainless steel gauze (200 µm mesh size). After washing two
times with phosphate buffered saline (approx. 10 ml) the lymph node cells were resuspended in 5 % trichloroacetic acid (approx. 3 ml) and incubated at approximately +4 °C for at least 18 hours for precipitation of macromolecules. The precipitates were then resuspended in 5 % trichloroacetic acid
(1 ml) and transferred to plastic scintillation vials with 10 ml of ‘Ultima Gold’ scintillation liquid and thoroughly mixed.
The level of ³HTdR incorporation was then measured on a beta-scintillation counter. Similarly, background ³HTdR levels were also measured in two
1ml-aliquots of 5 % trichloroacetic acid. The beta-scintillation counter expresses ³HTdR incorporation as the number of radioactive disintegrations
per minute (DPM).

Observations
In addition to the sensitising reactions the following observations and data were recorded during the test and observation period:
Mortality / Viability: once daily (week day) from experimental start to necropsy.
Body weights: prior to the first application and prior to treatment with ³HTdR.
Clinical signs (local / systemic): once daily (week day). Especially the treatment sites were observed carefully.

Positive control substance(s):
hexyl cinnamic aldehyde (CAS No 101-86-0)
Positive control results:
Results of the GLP Positive Control

Experiment performed in May 2007.
Positive control substance: alpha-Hexylcinnamaldehyde
Vehicle: acetone:olive oil (4+1)

table see: Remarks on results including tables and figures (results of the GLP positive control)
Parameter:
SI
Value:
0.94
Test group / Remarks:
Test Group 1: 5 % (w/v)
Parameter:
SI
Value:
1.03
Test group / Remarks:
Test Group 2: 10 % (w/v)
Parameter:
SI
Value:
1.6
Test group / Remarks:
Test Group 3: 25 % (w/v)

Calculation and Results of Individual Data

Vehicle: dimethyl formamide

Test item concentration % (w/v)

Group

Measurement DPM

Calculation

Result

DPM-BGa)

number of lymph nodes

DPM per lymph nodeb)

S.I.

---

BG I

26.06

---

---

---

---

---

BG II

23.48

---

---

---

---

---

1

5889.14

5864.4

8

733.0

 

5

2

5559.39

5534.6

8

691.8

0.94

10

3

6069.93

6045.2

8

755.6

1.03

25

4

9427.20

9402.4

8

1175.3

1.60

BG  =   Background (1 ml 5% trichloroacetic acid) in duplicate

1     =   Control Group

2-4 =   Test Group

S.I.  =   Stimulation Index

a)     =   The mean value was taken from the figures BG I and BG II

b)     =   Since the lymph nodes of the animals of a dose group were pooled, DPM/node was determined by dividing the measured value by the number of lymph nodes pooled

The EC3 value could not be calculated, since all SI´s are below 3.

Viability / Mortality

No deaths occurred during the study period.

Clinical Signs

No symptoms of local toxicity at the ears of the animals and no systemic findings were observed during the study.

Body Weights

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.

The individual body weight values are included in the following table:

Tables of Body Weights

Animal No.

Dose Group

Initial Weight (g)

weight prior to treatment with 3HTdR (g)

1

1

21.0

21.9

2

1

20.7

21.2

3

1

19.8

20.7

4

1

19.9

20.3

5

2

20.7

21.0

6

2

18.2

19.1

7

2

21.9

22.8

8

2

19.4

20.9

9

3

19.5

20.2

10

3

20.8

23.1

11

3

21.2

21.2

12

3

20.2

20.5

13

4

21.5

22.2

14

4

18.6

20.1

15

4

18.8

20.4

16

4

19.5

20.9

Mean

20.1

21.0

Standard Deviation

1.1

1.0

Results of the GLP Positive Control

Experiment performed in May 2007.

Positive control substance: alpha-Hexylcinnamaldehyde

Vehicle: acetone:olive oil (4+1)

Test item concentration % (w/v)

Group

Measurement DPM

Calculation

Result

DPM-BG a)

number of lymph nodes

DPM per lymph node b)

S.I.

---

BG I

21.62

---

---

---

---

---

BG II

33.29

---

---

---

---

---

1

3115.01

3087.6

8

385.9

 

5

2

7516.37

7488.9

8

936.1

2.43

10

3

12579.80

12552.3

8

1569.0

4.07

25

4

11326.90

11299.4

6

1883.2

4.88

BG  =   Background (1 ml 5% trichloroacetic acid) in duplicate

1     =   Control Group

2-4 =   Test Group

S.I.  =   Stimulation Index

a)     =   The mean value was taken from the figures BG I and BG II

b)     =   Since the lymph nodes of the animals of a dose group were pooled, DPM/node was determined by dividing the measured value by the number of lymph nodes pooled

Test item concentration % (w/v)

S.I.

Group 2

5 (a)

2.43(b)

Group 3

10 (c)

4.07(d)

EC3 = (a-c) [(3-d)/(b-d)] + c = 6.7% (w/v)

Interpretation of results:
not sensitising
Conclusions:
The test item Methacrylamide was found to be not a skin sensitiser under the described conditions.
Executive summary:

In a dermal sensitization study with Methacrylamide (99.5%) dissolved in dimethyl formamide as a vehicle, 16 (4per dode group) 7 -8 week old female CBA/CaOlaHsd mice were tested using the method of OECD 429 (Local Lmyphnode Assay). The validation-/positive control experiment was performed with alpha-Hexyl cinnamic aldehyde.

The animals did not show any clinical signs during the course of the study and no cases of mortality were observed. In this study Stimulation Indices (S.I.) of 0.94, 1.03, and 1.60 were determined with the test item at concentrations of 5, 10, and 25% in dimethyl formamide, respectively. The EC3 value could not be calculated, since all SI´s were below 3.

In this study, Methacrylamide was not a dermal sensitizer.

                                             

 

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

In a Local Lymphnode Assay LLNA acc. OECD 429 methacrylamide was not sensitising to skin at test concentrations of 5, 10 and 25 % (w/v). According to reliable test data methacrylamide is not classified for skin sensitisation.