3-trimethoxysilylpropyl methacrylate

Endpoint summary

Description of key information

In the key mouse local lymph node assay, conducted according to OECD Test Guideline 429 and in compliance with GLP, 3-trimethoxysilylpropyl methacrylate (CAS 2530-85-0, EC No. 219-85-0) was reported not to elicit a SI = 3 when tested up to 10% and it was established that the EC3 value exceeds 10%. The test material was concluded not to be sensitising to skin (Charles River, 2018, Reliability Score 1).

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

2010

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2600 (Skin Sensitisation)

Version / remarks:

2003

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Specific details on test material used for the study:

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: At room temperature container flushed with nitrogen
- Stability under test conditions: There was no information available about the stability and solubility of the test item in vehicle.
- Solubility and stability of the test substance in the solvent/vehicle: There was no information available about the stability and solubility of the test item in vehicle.
- Reactivity of the test substance with the solvent/vehicle of the cell culture medium: not applicable

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: Test item dosing formulations (w/w) were homogenized to visually acceptable levels at appropriate concentrations to meet dose level requirements. The dosing formulations were prepared daily and dosed within 4 hours after adding the vehicle to the test item. The dosing formulations were kept at room temperature until dosing. The dosing formulations were stirred until and during dosing.
- Preliminary purification step: none
- Final dilution of a dissolved solid, stock liquid or gel: not applicable
- Final preparation of a solid: not applicable

Species:

mouse

Strain:

CBA:J

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Janvier, Le Genest-Saint-Isle, France
- Females nulliparous and non-pregnant: yes
- Microbiological status of animals, when known: not specified
- Age at study initiation: Young adult animals (approximately 10 weeks old)
- Weight at study initiation: 20.4 to 24.1 grams
- Housing: Animals were group housed in polycarbonate cages.
- Diet: Pelleted rodent diet ad libitum
- Water: Municipal tap-water ad libitum
- Acclimation period: at least 5 days
- Indication of any skin lesions: none reported

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21 to 22°C
- Humidity (%): 42 to 46 %
- Air changes (per hr): Ten or greater air changes per hour with 100% fresh air
- Photoperiod (hrs dark / hrs light): 12 hours light/12 hours dark cycle

Vehicle:

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

Concentration:

2, 5 or 10% w/w
The vehicle was chosen from the vehicles specified in the test guideline (in order of preference): Acetone/Olive oil (4:1 v/v), N,N-dimethylformamide, methylethylketone, propylene glycol, dimethylsulfoxide and 1% Pluronic© L92 in Elix water (in case an aqueous vehicle is suitable). The vehicle was selected on the basis of maximizing the solubility based on trial preparations performed at Charles River Den Bosch and on information provided by the Sponsor.

No. of animals per dose:

5 females

Details on study design:

PRE-SCREEN TESTS: A pre-screen test was conducted in order to select the highest test item concentration to be used in the main study. In principle, this highest concentration should cause no systemic toxicity, may give well-defined irritation as the most pronounced response (maximum grade 2 and/or an increase in ear thickness < 25%) and/or is the highest possible concentration that can technically be applied.
- Compound solubility: yes
- Irritation: yes
- Systemic toxicity: yes
- Ear thickness measurements: Ear thickness measurements were conducted using a digital thickness gauge prior to dosing on Days 1 and 3, and on Day 6.
- Erythema scores: not specified.

MAIN STUDY: Three groups of five animals were treated with one test item concentration per group. The highest test item concentration was selected from the pre-screen test. One group of five animals was treated with the vehicle. Throughout the study, animals were observed for general health/mortality and moribundity twice daily, in the morning and at the end of the working day. Postdose observations were performed once daily on Days 1-6. Animals were weighed individually on Day 1 (predose) and 6 (prior to necropsy). Erythema and eschar formation observations were performed once daily on Days 1-6 (on Days 1-3 within 1 hour after dosing).

ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: local lymph node assay
- Criteria used to consider a positive response: A Stimulation Index (SI) is calculated for each group using the individual SI values. The individual SI is the ratio of the DPM/animal compared to the DPM/vehicle control group mean. If the results indicate a SI = 3, the test item may be regarded as a skin sensitizer.


TREATMENT PREPARATION AND ADMINISTRATION:
Test item dosing formulations (w/w) were homogenized to visually acceptable levels at appropriate concentrations to meet dose level requirements. The dosing formulations were prepared daily and dosed within 4 hours after adding the vehicle to the test item. The dosing formulations were kept at room temperature until dosing. The dosing formulations were stirred until and during dosing. During induction, the dorsal surface of both ears was topically treated (25 µL/ear) with the test item, at approximately the same time on each day. The concentrations were stirred with a magnetic stirrer immediately prior to dosing. The control animals were treated in the same way as the experimental animals, except that the vehicle was administered instead of the test item. Each animal was injected via the tail vein with 0.25 mL of sterile phosphate buffered saline (PBS) containing 20 µCi of 3H-methyl thymidine. After five hours, all animals were killed by intraperitoneal injection (0.2 mL/animal) of Euthasol® 20%. The draining (auricular) lymph node of each ear was excised. The relative size of the nodes (as compared to normal) was estimated by visual examination and abnormalities of the nodes and surrounding area were recorded.

Positive control substance(s):

other: not included for animal welfare reasons

Statistics:

not used

Positive control results:

No positive control was used in the study.

Key result

Parameter:

SI

Value:

0.9

Test group / Remarks:

2% concentration

Key result

Parameter:

SI

Value:

1.2

Test group / Remarks:

5% concentration

Key result

Parameter:

SI

Value:

0.9

Test group / Remarks:

10% concentration

Key result

Parameter:

EC3

Value:

> 10

Cellular proliferation data / Observations:

PRE-SCREEN TEST: At a 100%, 50% and 25% test item concentration, variation in ear thickness during the observation period were more than 25% from Day 1 pre-dose values and/or clinical signs of systemic toxicity were noted. Therefore, these concentrations did not meet the selection criteria. At a 10% test item concentration no signs of toxicity or excessive irritation were noted and therefore, 10% was selected as the highest concentration to be used in the main study.

CELLULAR PROLIFERATION DATA: The majority of the auricular lymph nodes were considered normal in size, except for one node of one animal treated at a 2% test item concentration, which was considered to be enlarged. No macroscopic abnormalities of the surrounding area were noted for any of the animals.

DETAILS ON STIMULATION INDEX CALCULATION: Mean DPM/animal values for the experimental groups treated with test item concentrations 2, 5 and 10% were 517, 656 and 488 DPM, respectively. The mean DPM/animal value for the vehicle control group was 550. The SI values calculated for the test item concentrations 2, 5 and 10% were 0.9, 1.2 and 0.9, respectively.

EC3 CALCULATION: Since there was no indication that the test item elicits a SI = 3 when tested up to 10%, 3-(Trimethoxysilyl)propyl methacrylate (CAS 2530-85-0) was not considered to be a skin sensitizer. It was established that the EC3 value exceeds 10%.

CLINICAL OBSERVATIONS: No irritation was observed in any of the animals. No mortality occurred and no clinical signs of systemic toxicity were observed in the animals of the main study.

BODY WEIGHTS: Body weights and body weight gain of experimental animals remained in the same range as controls over the study period.

Interpretation of results:

GHS criteria not met

Conclusions:

In the mouse local lymph node assay, conducted according to OECD Test Guideline 429 and in compliance with GLP, 3-(trimethoxysilyl)propyl methacrylate (CAS 2530-85-0) was reported not to elicits a SI = 3 when tested up to 10% and the EC3 value exceeded 10%. The test material was concluded to be not sensitising to skin.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

The sensitising potential of 3-trimethoxysilylpropyl methacrylate (CAS 2530-85-0; EC No. 219-785-0) was assessed in a mouse local lymph node assay. Three experimental groups of five female mice were treated with test item concentrations of 2, 5 or 10% w/w on three consecutive days, by open application on the ears. Five vehicle control animals were similarly treated, but with the vehicle alone (Acetone/Olive oil (4:1 v/v)). The vehicle was chosen from the vehicles specified in the test guideline (in order of preference): acetone/olive oil (4:1 v/v), N,N-dimethylformamide, methylethylketone, propylene glycol, dimethylsulfoxide and 1% Pluronic© L92 in Elix water (in case an aqueous vehicle is suitable). The vehicle was selected on the basis of maximizing the solubility based on trial preparations performed at Charles River Den Bosch and on information provided by the Sponsor. Three days after the last exposure, all animals were injected with 3H-methyl thymidine and after five hours the draining (auricular) lymph nodes were excised and pooled for each animal. After precipitating the DNA of the lymph node cells, radioactivity measurements were performed.

No irritation was observed in any of the animals. The mean body weight gain shown by the animals over the study period was considered to be normal. The majority of the auricular lymph nodes were considered normal in size, except for one node of one animal treated at a 2% test item concentration. No macroscopic abnormalities of the surrounding area were noted for any of the animals.

3 -Trimethoxysilylpropyl methacrylate (CAS 2530-85-0) was reported not to elicit a SI = 3 when tested up to 10% and it was established that the EC3 value exceeds 10%. The test material was concluded to be not sensitising to skin (Charles River, 2018).

In a guinea pig maximisation test, a strict interpretation of the results would conclude the test substance was not sensitising in the guinea pig since there were no reactions in the treated group that exceeded the highest reaction in the negative control group at challenge. However, both the treated group and the negative control group exhibited a high incidence of grade 1 sites, suggesting that the vehicle (cottonseed oil) may itself have irritant properties. There was a significantly increased number of moderate (grade 2) reactions to 50% test substance in the test group (14/20 and 5/20 at 24 and 48 hours, respectively, as compared to only 1/10 and 0/10 at 24 and 48 hours, respectively, in the negative control group). This increased incidence of moderate reactions suggests a sensitization response to 50% test substance. Although increased severity of the delayed response was not seen for 3-trimethoxysilylpropyl methacrylate, the irritant properties of the cottonseed oil vehicle were a potential confounding factor. Given the overall increased incidence and duration of responsiveness observed in the treated group, the report author concluded that data suggested that 3-trimethoxysilylpropyl methacrylate had the potential for weak dermal sensitisation (WIL, 1994). Subsequently, the LLNA was conducted to clarify the sensitising potential of the registered substance at the request of ECHA.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Based on the available sensitisation data, 3-trimethoxysilylpropyl methacrylate does not require classification for sensitisation according to Regulation (EC) No 1272/2008.