1,1-dimethyl-N,N'-bis(1-methylpropyl)silanediamine

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

28 April 2016 to 13 October 2016

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

No analysis of test material concentrations

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

yes

Remarks:

No analysis was carried out of the test substance concentrations

GLP compliance:

yes

Remarks:

Statement of compliance dated 08 March 2017

Specific details on test material used for the study:

See test material information

Analytical monitoring:

no

Vehicle:

yes

Remarks:

Tetrahydrofuran (THF)

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method:
Pre-testing
The study started with the determination of the test item solubility in tetrahydrofuran. Thereafter, the solubility of test item stock solutions in test medium was determined. Based on the results of this test, the test concentrations for the full acute toxicity test in Daphnia magna were determined. The test item undergoes rapid hydrolysis in contact with water. The onset of condensation of the hydrolysis products limited the highest soluble test concentration (“technical feasible maximum test concentration”) and was therefore experimentally determined. In this pre-test, tetrahydrofuran THF was used as a solubilizing agent to avoid concentration peaks during sample preparation and allow observing the onset of condensation of the hydrolysis product by visual inspection of the test medium. The determined solubility limit in test medium was applied to justify the selected dose range in the full test.

Determination of solubility in tetrahydrofuran
A concentration of 1000 mg test item per 1 mL THF (99.7%, VWR, Belgium) was prepared. No special treatment other than vigorous shaking was required to fully dissolve the test item at this concentration in THF. The resulting solution was clear and colourless

Determination of solubility in test medium
A concentration of 1000 mg test item per 1 mL THF was prepared.
No special treatment other than vigorous shaking was required to fully dissolve the test item at this concentration in THF. The resulting solution was clear and colourless.
To determine the solubility of a test item stock solution in test medium, two tests were performed. Preparation of stock solutions started with a concentration of 100 mg/mL. No special treatment other than vigorous shaking was required to fully dissolve the test item in THF.
Lower concentrations (i.e. 1.56, 3.13, 6.3, 12.5, 25 and 50 mg/mL) were obtained by subsequent dilutions of the highest concentration in THF with a factor of 2. All stock solutions were clear and colourless.
After preparation, volumes of 100 μL were spiked into 1 L of test medium to achieve the concentrations. Spiking was done slowly by adding the respective stock solution in steps of 20 μL below the test medium surface over a period of six minutes.
Throughout, the test medium was magnetically stirred without turbulence at approximately 200 rpm.
The pH values of these solutions were in a range of 7.6 to 8.3 and correspondingly adjusted to 7.0 ± 0.2 using 1 M HCl. Thereafter, a 24-hour period of magnetic stirring at 200 rpm was applied. Solutions spiked with stocks of 6.3 mg/mL and lower were clear and colourless at the end of the preparation period.
Solutions spiked with stocks of 12.5 mg/mL and higher were colourless but contained undissolved material.
The dissolution of the test item was determined visually using a laser pointer.

Preparation of stock and test solutions for the full test
The highest concentration of the selected range was intended to slightly exceed the determined solubility limit to avoid a potential gap between the highest test concentration and the possible maximum test concentration.
Based on the results of the pre-test, a stock solution of 15 mg test item per mL THF was prepared. No special treatment other than vigorous shaking was required to fully dissolve the test item in THF. Lower concentrations (i.e. 0.94, 1.9, 3.8, and 7.5 mg/mL) were obtained by subsequent dilutions of the highest stock in THF. All resulting stock solutions were clear and colourless.
Thereafter, test solutions were prepared individually by spiking volumes of 100 μL stock solution into 1 L of test medium. Spiking was done slowly by adding the respective stock solution in steps of 20 μL below the test medium surface over a period of six minutes. Throughout, the test medium was magnetically stirred without turbulence at 200 rpm.
The pH of the resulting test solutions as well as the solvent control was 8.0 and subsequently adjusted to 7.0 ± 0.2 using 1 M HCl. Afterwards, the obtained solutions were magnetically stirred for 24 hours at 200 rpm. At the end of the stirring period, pH values were measured again. The pH values of the resulting test solutions as well as the solvent control were in a range of 7.2 to 7.6 and correspondingly adjusted to 7.1 to 7.2 using 1 M HCl. The pH of the blank control was adjusted from 7.7 to 7.2 using 1 M HCl. All final test solutions were clear and colourless.

Preparation of stock and test solutions for the limit test
In contrast to the pre-test, the onset of condensation was not observed in the highest test concentration in the full test. An additional limit test was performed to assure that no effects would occur up to the solubility limit of the test item. For this test, three higher test concentrations were prepared. The limit test was conducted with the lowest concentration out of these three concentrations at which undissolved test item/condensation products were observed.
A stock solution of 50 mg test item per mL THF was prepared. No special treatment other than vigorous shaking was required to fully dissolve the test item in THF. Lower concentrations (i.e. 37.5 and 25 mg/mL) were obtained by subsequent dilutions of the highest stock in THF. All stock solutions were clear and colourless.
Thereafter, test solutions were prepared individually by spiking volumes of 100 μL stock solution into 1 L of test medium in steps of 20 μL below the test medium surface over a period of six minutes. Throughout, the test media were magnetically stirred without turbulence at approximately 200 rpm. The pH values of the resulting solutions as well as the solvent control were in a range of 7.6 to 8.7 and correspondingly adjusted to 7.0 ± 0.2 using 1 M HCl . Afterwards, the obtained solutions were magnetically stirred for 24 hours at 200 rpm. At the end of the stirring period, pH values were measured again. The pH values of the resulting test solutions were in a range of 6.5 to 7.3. The solutions exceeding a pH of 7.2 were adjusted to 7.2 using 1 M HCl. The solutions with a pH below 6.8 were adjusted to 6.8 using 1 M NaOH. The blank control was not stirred for 24 hours prior to the limit test.
The lowest test concentration as well as the solvent- and the blank-control were clear and colourless, while the two highest test concentrations contained undissolved test item. The lower of these concentrations, i.e. 3.75 mg/L, was selected for the limit test. To remove the undissolved fraction, the test solution was siphoned off. The resulting solution was clear and colourless.

- Controls: Test medium without test item or other additives (blank-control) and one control containing the additive used in the treatment of the stock solutions (solvent-control).
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): Tetrahydrofuran (THF).
- Concentration of vehicle in test medium (stock solution and final test solution(s) or suspension(s) including control(s)): Stock: 1000 mg test material/ml THF.
- Evidence of undissolved material (e.g. precipitate, surface film, etc.): Yes

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna
- Strain/clone: Straus, 1820
- Justification for species other than prescribed by test guideline: n/a
- Source: In-house laboratory culture with a known history.
- Age of parental stock (mean and range, SD): For the test selection of young daphnids with an age of < 24 hours, from parental daphnids of more than two weeks old.
- Feeding during test: None

ACCLIMATION
- Acclimation period: Not reported.
- Acclimation conditions (same as test or not): Not reported.
- Type and amount of food: During Breeding: suspension of fresh water algae
- Feeding frequency: Daily
- Health during acclimation (any mortality observed): Not reported.


METHOD FOR PREPARATION AND COLLECTION OF EARLY INSTARS OR OTHER LIFE STAGES: Not reported.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

180 mg/L expressed as CaCO3 of Medum M7

Test temperature:

20-22°C

pH:

7.1-7.8

Dissolved oxygen:

8.3-9.1

Salinity:

n/a

Conductivity:

Not reported

Nominal and measured concentrations:

Full test: blank control, solvent control, 0.094, 0.19, 0.38, 0.75 and 1.5 mg/L (nominal).
Limit test: blank control, solvent control, 3.75 mg/L (nominal).

Details on test conditions:

TEST SYSTEM
- Test vessel: all glass vessel.
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: Glass, 100 ml, 20 ml, 80 ml.
- Aeration: No
- Type of flow-through (e.g. peristaltic or proportional diluter): n/a
- Renewal rate of test solution (frequency/flow rate): n/a
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- No. of vessels per vehicle control (replicates): 4
- Biomass loading rate: not reported.

TEST MEDIUM / WATER PARAMETERS
Composition of medium M7:
Adjusted ISO medium: the following chemicals (analytical grade) are dissolved in tap water purified by Reverse Osmosis (RO-water, GEON Waterbehandeling, Berkel-Enschot, The Netherlands):
Macro salts: CaCl2.2H2O 211.5 mg/L
MgSO4.7H2O 88.8 mg/L
NaHCO3 46.7 mg/L
KCl 4.2 mg/L

Medium M7: trace elements, macronutrients and vitamins are added to freshly prepared ISO medium to reach the following concentrations:
Trace elements: B 0.125 mg/L
Fe 0.05 mg/L
Mn 0.025 mg/L
Li, Rb and Sr 0.0125 mg/L
Mo 0.0063 mg/L
Br 0.0025 mg/L
Cu 0.0016 mg/L
Zn 0.0063 mg/L
Co and I 0.0025 mg/L
Se 0.0010 mg/L
V 0.0003 mg/L
Na2EDTA.2H2O 2.5 mg/L
Macro nutrients: Na2SiO3.9H2O 10.0 mg/L
NaNO3 0.27 mg/L
KH2PO4 0.14 mg/L
K2HPO4 0.18 mg/L
Vitamins: Thiamine 75.0 μg/L
B12 1.0 μg/L
Biotin 0.75 μg/L
The hardness: 180 mg/L expressed as CaCO3 and the pH: 7.7 ± 0.3.

- Culture medium different from test medium: No
- Intervals of water quality measurement: Dissolved oxygen and pH: At the beginning and at the end of the test in all test groups.
Temperature of medium: Continuously in a temperature control vessel, beginning at the start of the test.

OTHER TEST CONDITIONS
- Adjustment of pH: Yes
- Photoperiod: 16 hours photoperiod daily
- Light intensity: Not reported

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): Immobility (including mortality) At 24 hours and at 48 hours.

VEHICLE CONTROL PERFORMED: yes

RANGE-FINDING STUDY
A pre-test to determine the solubility of the test substance in THF was performed. Based on the solubility results the test concentrations for the full acute toxicity test in Daphnia magna were determined.
- Test concentrations: Full test: 0.094, 0.19, 0.38, 0.75, 1.5 mg/l
- Results used to determine the conditions for the definitive study: No immobilisation occurred in the full test. An additional limit test was performed with the lowest concentration at which undissolved material was observed during preparation of the test solutions in order to assure that no effects would occur up to the solubility limit of the test item.

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 3.75 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

but exposure will be to the hydrolysis products

Basis for effect:

mobility

Remarks on result:

other: no effects at highest concentration tested, which was limit of solubility of the test substance

Details on results:

- Behavioural abnormalities: None reported
- Observations on body length and weight: Not reported
- Other biological observations: None reported
- Mortality of control: None
- Other adverse effects control: None
- Abnormal responses: Not reported
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: n/a
- Effect concentrations exceeding solubility of substance in test medium: yes

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- Relevant effect levels: 0.39 mg/l
- Dose-response test: Yes
- ECx:
- Other:

Table: Number of introduced daphnids and incidence of immobility in the full test

		1-Methyl-N,N’,N’’-tris(1-methylpropyl)silantriamine Nominal concentration (mg/L)
Time	Replicate	Blank control	Solvent control	0.094	0.19	0.38	0.75	1.5
0	A	5	5	5	5	5	5	5
0	B	5	5	5	5	5	5	5
0	C	5	5	5	5	5	5	5
0	D	5	5	5	5	5	5	5
	Total Introduced	20	20	20	20	20	20	20
24	A	0	0	0	0	0	0	0
24	B	0	0	0	0	0	0	0
24	C	0	0	0	0	0	0	0
24	D	0	0	0	0	0	0	0
	Total Immobilised	0	0	0	0	0	0	0
	Effect %	0	0	0	0	0	0	0
48	A	0	0	0	0	0	0	0
48	B	0	0	0	0	0	0	0
48	C	0	0	0	0	0	0	0
48	D	0	0	0	0	0	0	0
	Total Immobilised	0	0	0	0	0	0	0
	Effect %	0	0	0	0	0	0	0

Table: Number of introduced daphnids and incidence of immobility in the limit test

		1-Methyl-N,N’,N’’-tris(1-methylpropyl)silantriamine Nominal concentration (mg/L)
Time	Replicate	Blank control	Solvent control	3.75
0	A	5	5	5
0	B	5	5	5
0	C	5	5	5
0	D	5	5	5
	Total Introduced	20	20	20
24	A	0	0	0
24	B	0	0	0
24	C	0	0	0
24	D	0	0	0 (3)
	Total Immobilised	0	0	0
	Effect %	0	0	0
48	A	0	0	0
48	B	0	0	0
48	C	0	0	1
48	D	0	0	0 (1)
	Total Immobilised	0	0	1
	Effect %	0	0	5

( ) between brackets: number of daphnia observed trapped at the surface of the test solutions. These organisms were reimmersed into the respective solutions before recording of mobility.

Validity criteria fulfilled:

yes

Conclusions:

A 48 hour EC50 value of >3.75 mg/l (nominal) (highest concentration tested) has been determined for effects of the test substance on mobility of Daphnia magna. No effects were observed in the test. In view of the rapid hydrolysis rate of the test substance and the test preparation methods, it is likely that the Daphnia would have been exposed to the hydrolysis products of the test substance.

Description of key information

48-hour EC₅₀: >3.75 mg/l (nominal) (highest concentration tested) has been determined for effects of 1-methyl-N,N',N''-tris(1-methylpropyl)silanetriamine (CAS 37697-65-7) on mobility of Daphnia magna, in compliance with OECD guideline 202.

Additional information

A 48-hour EC₅₀ value of >3.75 mg/l (nominal) (highest concentration tested) has been determined for effects of the read-across substance 1-methyl-N,N',N''-tris(1-methylpropyl)silanetriamine (CAS 37697-65-7) on mobility of Daphnia magna. No effects were observed in the test. In view of the rapid hydrolysis rate of the test substance and the test preparation methods, it is likely that the Daphnia would have been exposed to the hydrolysis products of the test substance.

It should be noted that the nominal concentration of 3.75 mg/l tested was considered higher than the maximum soluble concentration in test medium, therefore there is no gap between maximum soluble concentration and the highest test concentration.

See the ecotoxicological discussion for further details on the test substance and justification of read-across.