N-[3-(trimethoxysilyl)propyl]butylamine

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

June 22 to July 12 2001

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: Nominal: 4.6, 10, 22, 46 and 100 mg/L

- Sampling method: Small volumes of the test media and the control (1.0 to 2.0 ml) were taken out of all the test flasks after 24, 48 and 72 hours and not replaced. The algal cell densities in the samples was determined by counting with an electronic particle counter (Coulter Counter, Model ZM) with at least 2 measurements per sample. In addition, after 72 hours, a sample was taken from the control and a test item which showed reduced algal growth (nominal 100 mg/L). The shape of the algal cells was microscopically examined.

- Sample storage conditions before analysis: Not stated

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The test medium of nominal 100 mg/L was prepared by dissolving 80 mg of test item completely in 800 ml test water by intense stirring for 5 minutes at room temperature. pH was adjusted from pH 9.4 to pH 8.0 with a hydrochloric acid solution (0.1 M). This test medium was then diluted with test water to prepare the rest of the test concentrations. The test media were prepared just before the addition of the algae.

- Controls: Yes - test water without test item

- Evidence of undissolved material (e.g. precipitate, surface film, etc): none stated

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: Scenedesmus suspicatus CHODAT

- Strain: No. 86.81 SAG

- Source (laboratory, culture collection): Sammlung von Algenkulturen, Albrecht-von-Haller-Institut fur Pflanzenwissenschaften, Universistat Gottingen, D-37073 Gottingen, Germany

- Age of inoculum (at test initiation): Not stated

- Method of cultivation: Not stated

ACCLIMATION
- Acclimation period: Exponentially growing pre-culture for 3 days prior to the test in conditions same as the test

- Culturing media and conditions (same as test or not): yes

- Any deformed or abnormal cells observed: Not stated

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

0.24 mmol/L test water

Test temperature:

Incubated in a temperature controlled water bath at 22°C

pH:

Range pH 7.9 - 8.8

Nominal and measured concentrations:

Nominal: 4.6, 10, 22, 46 and 100 mg/L
Measured from nominal 22 mg/L: 0 hours: 21.6 mg/L, 72 hours: 22.2 mg/L
Measured from nominal 46 mg/L: 0 hours: 48.2 mg/L, 72 hours: 47.6 mg/L
Measured from nominal 100 mg/L: 0 hours: 100 mg/L, 72 hours: 100 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer flask

- Type: covered with glass dishes

- Material, size, headspace, fill volume: 50 ml flask, 15 ml algal suspension

- Aeration: Not stated

- Initial cells density: 10000 algal cells per ml test medium

- No. of vessels per concentration (replicates): 3

- No. of vessels per control (replicates): 6

- Other: Continuous stirring by magnetic stirrers

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Synthetic test water prepared according to the test guidelines

- Intervals of water quality measurement: pH: start and end of test
Temperature: daily
Appearance: daily

OTHER TEST CONDITIONS
- Sterile test conditions: yes/no Not stated

- Adjustment of pH: Yes

- Photoperiod: Continuous

- Light intensity and quality: range 8310 - 9260 lux by fluorescent tubes installed above test flasks


EFFECT PARAMETERS MEASURED (with observation intervals if applicable)
- Determination of cell concentrations: electronic particle counter

- Chlorophyll measurement: Not stated

- Other: Shape of algal growth microscopically examined

TEST CONCENTRATIONS

- Range finding study: Yes

- Test concentrations: Not stated

Reference substance (positive control):

no

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.:

87 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95 % CL 60-181

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

22 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

46 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

47 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

22 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

46 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Details on results:

- Observation of abnormalities (for algal test): No abnormalities onserved

- Unusual cell shape: No - not affected

- Colour differences: Not stated

- Effect concentrations exceeding solubility of substance in test medium:No

Table 1: Mean algal cell densities during the test period of 72 hours

Nominal test item concentration (mg/L)	Mean density of algal cells (cell number x 10000/ml) after:
	24 h	48 h	72 h
Control	5.56	13.37	61.47
4.6	5.67	13.33	59.38
10	5.48	12.82	59.88
22	5.57	13.38	60,92
46	5.53	11.25	55.27
100	4.77	8.72	36.33

Table 2: Growth rates (µ) and percentage inhibition of µ (Iµ) during the test period

Nominal test item concentration (mg/L)	Growth rate µ and % inhibition of µ
	0 - 24 hours		0 - 48 hours		0 - 72 hours
	µ (1/day)	Iµ (%)	µ (1/day)	Iµ (%)	µ (1/day)	Iµ (%)
Control	1.71	0.0	1.30	0.0	1.37	0.0
4.6	1.73	­1.1	1.29	0.1	1.36	0.8
10	1.70	0.7	1.28	1.6	1.36	0.6
22	1.72	­0.1	1.30	­0.1	1.37	0.2
46	1.71	0.4	1.21	6.7	1.34	2.6
100	1.56	9.0	1.08	16.4	1.20	12.7

Validity criteria fulfilled:

yes

Remarks:

Biomass growth in control cultures exceeded the necessary minimum

Conclusions:

a 72-h ErC50 >100 mg/l and NOEC of 22 mg/l were determined in a guideline test conducted according to GLP. The result is taken to be reliable.

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

Please refer to the analogue approach justification provided in section 13.

Reason / purpose for cross-reference:

read-across source

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.:

87 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95 % CL 60-181

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

22 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

46 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

47 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

22 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

46 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Conclusions:

a 72-h ErC50 >100 mg/l and NOEC of 22 mg/l were determined in a guideline test conducted according to GLP. The result is taken to be reliable.

Reference 3

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

10 Oct 2012 - 14 Jan 2013

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes

Analytical monitoring:

yes

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A stock solution was prepared by solving the test substance in THF. The test concentrations were prepared separately by dilution with THF and AAP medium. The test solutions were stirred overnight to allow hydrolysis.
- Chemical name of vehicle: tetrahydrofuran (THF)
- Concentration of vehicle in test medium (stock solution and final test solution(s) including control(s)): 0.10 mL/L
- Evidence of undissolved material (e.g. precipitate, surface film, etc): not observed

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Strain: 1648
- Source: obtained from University of Texas, Austin, Texasand maintained at the testing facility.
- Method of cultivation: in culture medium Algal Assay Procedure at 23 ± 2 ºC under constant shaking (100 ± 10 rpm) and continuous illumination (3900 to 4700 lux)

ACCLIMATION
- Culturing media and conditions (same as test or not): same

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

23 ± 2 ºC

pH:

7.4 - 7.8

Nominal and measured concentrations:

Nominal loading rates:
0.063, 0.13, 0.25, 0.50, and 1.0 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer flasks (250 mL)
- Type: closed with stainless steel caps
- Material: glass, fill volume 100 mL
- Initial cells density: 1.0 x E4 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3
- No. of vessels per vehicle control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Algal Assay Procedure (AAP) medium prepared with sterile, deionized water
- Conductivity: 110 - 120 μS/cm
- Culture medium different from test medium: no
- Intervals of water quality measurement: pH and conductivity were measured at test start and termination

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: continuous illumination
- Light intensity and quality: 4400 - 5900 lux


EFFECT PARAMETERS MEASURED:
- Determination of cell concentrations: cell counts after 24, 48 and 72 hours with a hemacytometer (Neubauer Improved)


TEST CONCENTRATIONS
- Range finding study: yes
- Test concentrations: 0.010, 0.10, 1.0 and 10 mg/L,
- Results used to determine the conditions for the definitive study: 91.38 x E4 cells/mL at 10 mg/L and 84.75 E4 cells/mL in control

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

loading rate, parent material

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

loading rate, parent material

Basis for effect:

growth rate

Details on results:

- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): no
- Any stimulation of growth found in any treatment: no
The average measured TOC concentrations in solvent control and treatment solutions ranged from 30 to 32 mg C/L. A concentration gradient was not observed. The comparable TOC content in all treatments and the solvent control indicates that the measured organic carbon originated from the solubiliser THF. The concentration of the hydrolysis products of the test substance could not be determined.

Reported statistics and error estimates:

The data were checked for normality using Shapiro-Wilks' Test (U.S. EPA, 2002) and for homogeneity of variance using Bartlett's Test (U.S. EPA, 2002). If the data sets passed the tests for homogeneity and normality, then Bonferroni’s Adjusted t-Test (U.S. EPA, 2002) was used to determine the NOEC. If the data did not pass the tests for homogeneity and normality, then Jonckheere-Terpstra Step-Down Test (U.S. EPA, 2002) was used to determine the NOEC.

Algal growth rate after 72 hours.

Nominal loading rate	Growth rate	Percent inhibition
Control	1.44	NA
Solvent control	1.42	NA
0.063	1.50	2
0.13	1.58	-2
0.25	1.35	6
0.50	1.29	11
1.0	1.53	0

Inhibition relative to the solvent control

Description of key information

EC50 (72 h) > 100 mg/L (OECD 201, S. subspicatus, read across from CAS No. 227085-51-0), equivalent to > 81 mg/L when expressed in terms of the silanol hydrolysis product of the source substance, N-ethyl-3-trihydroxysilyl-2-methylpropanamine

NOEC (72 h) = 22 mg/L (OECD 201, S. subspicatus, read across from CAS No. 227085-51-0), equivalent to 18 mg/L when expressed in terms of the silanol hydrolysis product of the source substance, N-ethyl-3-trihydroxysilyl-2-methylpropanamine

Key value for chemical safety assessment

EC50 for freshwater algae:

81 mg/L

EC10 or NOEC for freshwater algae:

18 mg/L

Additional information

A 72-hour ErC50 value of > 1 mg/L and NOEC of ≥ 1 mg/L have been determined for the effects of the test substance on mobility of Pseudokirchneriella subcapitata. The results are expressed relative to nominal concentrations of the test substance. The corresponding mean measured concentration of the substance in the treated test medium over the course of the test could not be determinate. No effects could be detected up to the highest tested concentration but the maximum concentration used (1 mg/L) was well below the predicted solubility of the substance (13000 mg/L) and so does not provide an accurate representation of the likely toxicity of the substance.

Therefore it was considered appropriate to read across from the structurally analogous substance N-ethyl-3-trimethoxysilyl-2-methylpropanamine (CAS No. 227085-51-0).

A test was conducted at test concentrations of 4.6, 10, 22, 46 and 100 mg/L (OECD 201). A 72-h ErC50 > 100 mg/L and NOEC of 22 mg/L were determined. As the substance is subject to rapid hydrolysis, it is therefore likely that the test organisms were also exposed to hydrolysis products retained in the test media.

The results may be expressed in terms of concentration of the silanol hydrolysis product, N-ethyl-3-trihydroxysilyl-2-methylpropanamine, by applying a molecular weight correction: (MW of silanol (source) = 179.29 / MW of parent (source) = 221.37) * 100 = 81 mg/l, and MW of silanol (source) = 179.29 / MW of parent (source) = 221.37) * 22 = 18 mg/L, respectively).

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