N-butyl-N-[(triethoxysilyl)methyl]butan-1-amine

Short-term toxicity to aquatic invertebrates

Administrative data

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to the appropriate OECD test guideline, and in compliance with GLP.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2015

Report date:

2015

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

N-butyl-N-[(triethoxysilyl)methyl]butan-1-amine

EC Number:

810-490-5

Cas Number:

35501-23-6

Molecular formula:

C15H35NO3Si

IUPAC Name:

N-butyl-N-[(triethoxysilyl)methyl]butan-1-amine

Constituent 2

Reference substance name:

N,N-Dibutylaminomethyl-triethoxysilan

IUPAC Name:

N,N-Dibutylaminomethyl-triethoxysilan

Test material form:

other: liquid

Details on test material:

- Identification: N,N-Dibutylaminomethyl-triethoxysilane
- CAS Number: 35501-23-6
- Batch: 310113
- Purity: 96.6%
- Molecular Formula: C15H35NO3Si
- Molecular Weight: 305.53 g/mol
- Expiry Date: 06 February 2016
- Storage Conditions: At room temperature, at 20 ± 5 °C, under N2
- Water solubility: Rapid hydrolysis at contact with water
- Hydrolysis: Wacker Chemie AG Report (*1): “At all examined pH values only signals of N,N-dibutylaminomethylsilanetriol and ethanol could be observed after the first 1H-NMR measurements. There was no signal of ethoxysilane detectable. Therefore it was concluded that hydrolysis was already completed when the first
spectrum of these pH series (pH 4.0, pH 7.0, pH 9.0 respectively) was measured. Because hydrolysis was finished after the first 1H-NMR measurements (about
2 minutes after mixing the test sample) no exact halflife time or reaction rate could be calculated.” It can be concluded that the hydrolysis half-life of the test item at pH 7 is below two minutes. The water solubility of the hydrolysis product N,N-dibutylaminomethylsilanetriol is > 300 mg/L (*2) at 25 °C. However, the silanetriol tends to form condensation products, which are much less soluble in water. The concentration limit for condensation must be determined prior to testing to achieve stable solutions.

(*1) Final Report Determination of Physico-chemical Properties of SILAN DBA-TEO (CAS No. 35501-23-6) Wacker Chemie AG Study number: N-0002109725-P, see IUCLID chapter 5.1.2 Hydrolysis
(*2) QSAR calculation using WSKOWWIN V 1.42 (US EPA)

Sampling and analysis

Analytical monitoring:

no

Test solutions

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method:

In consultation with the Sponsor, the test concentrations and the test media preparation steps were chosen based on the results of GLP pre-experiments to determine the solubility of the test item in the test water. It was the aim of the procedure to achieve the maximum technically feasible concentration of the test item or its hydrolysis products in the test solution.

- Controls: Test water without addition of test item or solvent, Solvent control was prepared by adding 100 μL THF to 1.0 L test water
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): (THF, HPLC grade, 99.99%)
- Concentration of vehicle in test medium (stock solution and final test solution): 100 μL THF to 1.0 L
- Evidence of undissolved material (e.g. precipitate, surface film, etc): The test media were observed to be clear and colorless with no visible undissolved test substance following preparation with the exception of the test medium with a nominal concentration of 4.0 mg/L, which was observed to contain scattered small particles on the water surface.

FOR DETAILS OF PREPARATION OF TEST SOLUTION SEE ALSO: Any other information on materials and methods

Test organisms

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna
- Strain: Daphnia magna Straus
- Source: University of Sheffield / UK in 1992
- Age at study initiation: 6-24 hours
- Method of breeding: Since 1992, the clone has been bred at Harlan Laboratories in reconstituted water of the quality identical to the water quality used in the tests (with respect to pH, main ions, and total hardness) and under temperature and light conditions identical to those of the test. During breeding, daphnids are generally fed three times a week with an algal suspension of the green algae Desmodesmus subspicatus CHODAT, Strain No. 86.81 SAG, supplied by the Collection of Algal Cultures (SAG, Institute for Plant Physiology, University of Göttingen, 37073 Göttingen / Germany) and cultivated at Harlan Laboratories under standardized conditions or a mixture of this algal suspension and a commercial fish diet (Tetra Min® Hauptfutter, supplied by TETRA-Werke, 49304 Melle / Germany).
- Feeding during test: The daphnids were not fed during the test.

Study design

Test type:

static

Water media type:

freshwater

Total exposure duration:

48 h

Test conditions

Hardness:

Water Hardness: 2.5 mmol/L; 250 mg/L as CaCO3

Test temperature:

The water temperature was maintained at 21 °C.

pH:

The pH value of the test media and the control was constantly at 7.9.

Dissolved oxygen:

The test water was aerated prior to the start of the study until oxygen saturation was reached. During the test period, the test water was not aerated.

At the beginning and end of the test period, the dissolved oxygen concentration in the test media and the control was at least 8.4 mg/L.

Nominal and measured concentrations:

No analytical work was performed, with respect to the hydrolytic instability of the test item. A measurement of total organic carbon (TOC) was not reasonable due to the low test item concentrations and the use of the solvent tetrahydrofuran (THF). For this reason, the reported biological results were based on the nominal concentrations of the test item N,N-Dibutylaminomethyltriethoxysilane.

The following nominal concentrations of N,N-Dibutylaminomethyl-triethoxysilane were tested:
0.25, 0.50, 1.0, 2.0 and 4.0 mg/L.

Details on test conditions:

TEST SYSTEM
- Test vessel: 100-mL glass beakers filled with 50 mL of test medium
- Type: covered with glass plates
- Renewal rate of test solution (frequency/flow rate): A static test without test medium renewal was performed.
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water:

Test Water:
Reconstituted test water according to ISO 6341 [ISO, 1996] was used in the study. It consisted of analytical grade salts dissolved in purified water at the following nominal concentrations:
Ingredients/Properties Concentration
[mmol/L] [mg/L]
CaCl2 × 2H2O 2.0 294
MgSO4 × 7H2O 0.5 123
NaHCO3 0.75 65
KCl 0.075 5.8
Water Hardness 2.5 250 as CaCO3
Alkalinity 0.8 ---

- Ca/mg ratio: The ratio of Ca:Mg and Na:K was 4:1 and 10:1, respectively, based on molarities.

OTHER TEST CONDITIONS
- Photoperiod: 16-hour light to 8-hour dark cycle with a 30-minute transition period
- Light intensity: Light intensity during the light period was approximately between 800 and 1060 Lux
- The water temperature was maintained at 21 °C.

TEST CONCENTRATIONS
- Spacing factor for test concentrations:
- Justification for using less concentrations than requested by guideline: In consultation with the Sponsor, the test concentrations and the test media preparation steps were chosen based on the results of pre-experiments.
- Range finding study: GLP Pre-experiments to determine the solubility of the test item in the test water
- Test concentrations: The following nominal concentrations of N,N-Dibutylaminomethyl-triethoxysilane were tested:
0.25, 0.50, 1.0, 2.0 and 4.0 mg/L.

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

> 4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Effect concentrations 2

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Behavioural abnormalities: After 24 and 48 hours of exposure, no immobilized test organisms were determined in the control, solvent control and in the test item treatments. Thus, the 24- and 48-hour EC50 values were greater 4.0 mg/L.

- Mortality of control: In the control no daphnids showed immobilization or other signs of disease or stress (e.g., discoloration or unusual behavior such as trapping at the surface water).

- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: No remarkable observations were made concerning the appearance of the test media up to the nominal concentration of 2.0 mg/L; the test media were clear throughout the whole test duration.

- Effect concentrations exceeding solubility of substance in test medium: At the highest nominal concentration of 4.0 mg/L, the test medium was clear throughout the test period, but there were small particles observed on the water surface on Day 0; at the observation times after 24 and 48 hours, no particles were noted.

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- EC50/LC50: 1.0 mg/L
- Other: The result of the latest positive control test in August 2014 (48-hour EC50: 1.0 mg/L, Harlan Laboratories Study D94990) showed that the sensitivity of the test organisms was within the internal historical range (48-hour EC50 from 2000 to 2014: 0.36-1.1 mg/L).

Any other information on results incl. tables

Since in agreement with the Sponsor no analytical work was performed, the reported biological results were based on the nominal concentrations of the test item N,N-Dibutylaminomethyltriethoxysilane.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The test item N,N-Dibutylaminomethyl-triethoxysilane had no acute toxic effects on Daphnia magna up to the maximum technically feasible concentration of the test item or its hydrolysis products in test water under the test conditions, which was determined to be below 4.0 mg/L based on visual inspection (LC50 > 4.0 mg/L).

Executive summary:

SUMMARY

The acute toxicity of the test item N,N-Dibutylaminomethyl-triethoxysilane to Daphnia magna was determined in a 48-hour static test according to the Commission Regulation (EC) No. 440/2008, Part C.2 and the OECD Guideline for Testing of Chemicals, No. 202 (2004).

The nominal test item concentrations tested were 0.25, 0.50, 1.0, 2.0 and 4.0 mg/L test water. Additionally, a control and a solvent control group were tested in parallel. Due to the low solubility (refer also to section DETAILS ON TEST MATERIAL) of the test item in water, the organic solvent tetrahydrofuran (THF) was used to dose the test item. The solvent was chosen based on information provided by the Sponsor.

The preparation of the test media was based on the OECD Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures, 2000. It was the aim of the procedure to achieve the maximum technically feasible concentration of the test item or its hydrolysis products in the test solution.

In the controls and up to and including the nominal test item concentration of 4.0 mg/L, no immobilized test organisms were observed during the test period of 48 hours. All required validity criteria were fulfilled in this test.

Since in agreement with the Sponsor no analytical work was performed, the reported biological results were based on the nominal concentrations of the test item N,N-Dibutylaminomethyltriethoxysilane:

Parameter (0-48 h) Immobility	Nominal Concentration [mg/L]
24-hour EC50	>4.0
24-hour EC0	4.0
24-hour EC100	>4.0
48-hour EC50	>4.0
48-hour EC0 and 48-hour NOEC	4.0
48-hour EC100	>4.0

In conclusion, the test item N,N-Dibutylaminomethyl-triethoxysilane had no acute toxic effects on Daphnia magna up to the maximum technically feasible concentration of the test item or its hydrolysis products in test water under the test conditions, which was determined to be below 4.0 mg/L based on visual inspection.