N-{3-[dimethoxy(methyl)silyl]propyl}butan-1-amine

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

05 - 08 Jun 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

Version / remarks:

2011

GLP compliance:

yes (incl. QA statement)

Remarks:

Staatliches Gewerbeaufsichtsamt Hildesheim, Germany

Analytical monitoring:

yes

Remarks:

LC-MS/MS

Details on sampling:

- Concentrations: 0 (control), 1.00, 3.16, 10.0, 31.6, 100 mg/L
- Sampling method: All concentration levels and the control were analytically verified via LC-MS/MS at the start (0 hours), after 24, 48 hours and at the end of the exposure (72 hours) with algae. Due to the rapid abiotic degradation of the test item, the hydrolysis product of the test item was determined. After preparation of the test item solutions, samples were taken after preparation of each concentration and 4-6 hours later (-24, -20 and -18 hours) and analysed. At the start of the exposure (0 hours), samples from the freshly prepared media were taken after preparation of each concentration and the control. After 24, 48 hours and at the end of the exposure (72 hours), samples of the old media were taken from the test vessels for analysis. Due to the rapid degradation of the test item, the hydrolysis product of the substance was analytically determined.
- Sample storage conditions before analysis: All original samples were stored at room temperature before preparation. Prepared samples were stored in an autosampler at room temperature until analysis.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Five concentration levels were prepared. Each loading level was prepared individually. For each loading level an appropriate amount of the test item was transferred with an appropriate amount of dilution water into a glass flask. The solutions were stirred for 24 h at room temperature at 1100 rpm with a magnetic stirrer. The solutions were removed from the bottom of the flask and were checked via laser beam (Tyndall effect) for undissolved test item. No undissolved test item was confirmed by Tyndall effect.
- Differential loading: yes
- Controls: dilution water without test item

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

TEST ORGANISM
- Common name: green algae
- Source: Originally from Culture Collection of Algae and Protozoa (CCAP) SAMS Research Services Ltd Scotland, UK. Fresh stocks are prepared every month on Z-Agar (according to LÜTTGE et al. (1994)) in the laboratory. Light intensity was 2567 – 5130 lux for 24 h per day.
- Age of inoculum (at test initiation): A four days old preculture, prepared in dilution water, was used as inoculum.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

0.24 mmol Ca+Mg/L.

Test temperature:

21 - 23°C

pH:

7.75 - 8.23 (0 hours)
8.25 - 9.07 (72 h)
8.07 - 9.25 (Control)

Nominal and measured concentrations:

Nominal: 0 (control), 1.00, 3.16, 10.0, 31.6, 100 mg/L
Measured: 91 to 116% of the nominal concentrations throughout the test

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 mL Erlenmeyer flasks
- Type: flasks were covered with cotton wool plugs
- Fill volume: 100 mg/L
- Initial cells density: 6442 cells/mL
- Control end cells density: 2122238 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes, according to the guideline

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: according to guideline
- Intervals of water quality measurement: The pH-values at the start of exposure were measured in one additional replicate of each test item concentration and the control. At the end of exposure, the pH-values were measured from pooled samples of each test item concentration and the control. The room temperature was measured continuously. Light intensity was measured prior to the start of exposure.

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 24 h/day light
- Light intensity and quality: 4440 - 8880 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable)
- Determination of cell concentrations: The cell density was measured daily via Chlorophyll a-fluorescence, excitation at 436 nm, emission at 685 nm. Dilution water was used as a background signal. No self-fluorescence was found.
- Other: Microscopic evaluation of the cells at the start and the end of the incubation period was carried out. The cells were checked for unusual cell shapes, colour differences, differences in chloroplast morphology, flocculation, adherence of algae to test containers and agglutination of algae cells.

TEST CONCENTRATIONS
- Range finding study: yes
- Test concentrations: 1, 10, 100 mg/L
- Results used to determine the conditions for the definitive study: yes, 11% growth rate inhibition was fount at the concentration of 10 mg/L and 54% inhibition at 100 mg/L.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

29.2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% CI: 10.8 - 86.2 mg/L

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

31.6 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

35.1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% CI: 12-91 mg/L

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

30.6 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yield

Remarks on result:

other: 95% CI: 12.3-72.8 mg/L

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

17.5 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yield

Remarks on result:

other: 95% CI: 1-31.5 mg/L

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

23.7 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yield

Remarks on result:

other: 95% CI: 10.3 - 31.5 mg/L

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yield

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

3.16 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yield

Details on results:

- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): no
- Unusual cell shape: no

Results with reference substance (positive control):

- Results with reference substance valid: yes
- ErC50 (72 h) :1.09 mg/L (95% CI: 0.842 – 1.31 mg/L)

BIOLOGICAL RESULTS:

Table 1: Inhibitions of Growth rate and Yield after 72 h incubation.

Nominal test item concentration [mg/L]	Growth rate (mean) [d-1]	Inhibition of growth rate [%]	Yield (mean) [cells/mL]	Inhibition of yield [%]
100	(+) 1.30	33	(+) 338184	84
31.6	(+) 1.66	14	(+) 960718	55
10	(+)* 1.90	2	(+) 1936994	9
3.16	(+)* 1.89	2	(+) 1851612	13
1	(+)* 1.92	1	(-) 2020985	5
Control	1.93	-	2122238	-

Statistically significant differences of growth rates and yield compared to control values are marked (+), not significant differences are marked (-).

* = The NOEC suggested by the program is lower than 1 mg/L. However inhibition values of growth rate for concentrations < 31.6 mg/L are below 3% and are therefore considered not biologically significant by expert judgment.

Further effect values:

- EyC10 = 17.5 mg/L (nominal, 95% CI: 1-31.5 mg/L)

- EyC50 = 30.6 mg/L (nominal, 95% CI: 12.3-72.8 mg/L)

-NOEyC = 1 mg/L (nominal)

ANALYTICAL RESULTS:

The measured concentrations of the test item during the test were in the range of 91 to 116% of the nominal concentrations of the test item.

Table 2: Measured Concentrations of the Hydrolysis product of the Test item during the definitive test.

Sampling timepoint	0 hours		24 hous		48 hours		72 hours
Nominal Test item Concentration [mg/L]	Hydrolysis product of N-(n-Butyl)-3-aminopropylmethyldimethoxysilane
	Meas. conc. [mg/L]	[%]	Meas. conc. [mg/L]	[%]	Meas. conc. [mg/L]	[%]	Meas. conc. [mg/L]	[%]
100	96.7	97	96.1	96	99.5	100	99.4	99
31.6	29.7	94	28.8	91	29.1	92	29.8	94
10	11.1	111	10.9	109	11.1	111	10.8	108
3.16	3.67	116	3.55	112	3.59	114	3.45	109
1	1.14	114	1.11	111	1.16	116	1.08	108
Control	< LOQ	-	< LOQ	-	< LOQ	-	< LOQ	-

VALIDITY CRITERIA:

Table 3: Validity Criteria

Validity Criterion	Required	This study
Increase of the cell growth in the control cultures	Exponentially, ≥ 16-fold corresponding to a specific growth rate of 0.92/day	330-fold (specific growth rate 1.93 day-1)
Mean coefficients of variation for section-by-section specific growth rates (days 0-1, 1-2 and 2-3) in the control cultures	≤ 35%	16.70%
Coefficient of variation of average specific growth rates during the whole test period in replicate control cultures	≤ 7%	0.78%

Validity criteria fulfilled:

yes

Remarks:

For further details please refer to “Any other information on results incl. tables”.

Conclusions:

In a test according to OECD 201 an ErC50 (72 h) > 100 mg/L and an ErC10 (72 h) = 29.2 mg/L were determined after 72 h of exposure.

Description of key information

ErC50 (72 h) > 100 mg/L and ErC10 (72 h) = 29.2 mg/L (nominal, OECD 201, Pseudokirchneriella subcapitata)

Additional information

One study is available testing the toxicity of N-{3-[dimethoxy(methyl)silyl]propyl}butan-1-amine (CAS 120939-52 -8) towards algae. The study has been performed according to the OECD guideline 201 and GLP standards. Pseudokirchneriella subcapitata was exposed for 72 h to the nominal test item loading rates of 0 (control), 1.00, 3.16, 10.0, 31.6 and 100 mg/L. The loading levels were prepared individually. The solutions were stirred for 24 h at room temperature and 1100 rpm. The solutions were then taken from the bottom of the flask and were checked via laser beam (Tyndall effect) for undissolved test item. Due to the rapid degradation of the test item, the silanol hydrolysis product of the substance was analytically determined. The analytical monitoring was performed via LC-MS/MS. 91 to 116% of the nominal loading rates were analytically recovered during the test. The study resulted into an EC50 (72 h) > 100 mg/L and an EC10 (72 h) of 29.2 mg/L.