N-methyl-3-(trimethoxysilyl)propylamine

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:

25 - 29 Apr 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

2011

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

GLP compliance:

yes (incl. QA statement)

Remarks:

Staatlisches Gewerbeaufsichtsamt Hildesheim, Germany

Analytical monitoring:

yes

Details on sampling:

- Concentrations and method: analytical determination of the test item and the control were carried out from freshly prepared media after 0 h (with algae) and old test media after 72 h (with algae). The hydrolysis product of the test item was analytically verified, since the substance hydrolyses fast in aqueous media.
- Sample storage conditions before analysis: all original samples were stored at room temperature

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: stock solution of 100 mg/L was prepared in dilution water and was stirred for 24 ± 1 h (1100 rpm, room temperature)

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: green algae
- Strain: HINDAK, SAG 61.81
- Source (laboratory, culture collection): fresh stocks are prepared every month on Z-Agar (algae originaly from Sammlung von Algenkulturen (SAG) Pflanzenphysiologisches Institut der Universitat Goettingen)
- Age of inoculum (at test initiation): a three to four day old preculture, prepared in ditulion water, will be used as inoculum

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

22.5 - 23.5 °C

pH:

in vessels without pH adjustment: 8.05 - 9.67
in vessels with pH adjustment: 8.31 - 9.02
in control vessel: 8.05 - 9.46

Nominal and measured concentrations:

6.25, 12.5, 25, 50, 100, 100 (with pH adjustment) mg/L (nominal)

Details on test conditions:

TEST SYSTEM
- Test vessel: sterile Erlenmeyer flasks (vol. 250 mL) with cotton wool plugs
- Fill volume: 100 mL
- Initial cells density: 5 x 10^3 - 10^4 cells/mL
- Control end cells density: 2088469 cells(mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: according to guideline
- Intervals of water quality measurement: pH was measured in one additional replicate of each test item concentration and the control at the start of the exposure. After 24 and 48 h an aliquot of each test item concentration and the control was taken out of the test replicates for pH measurement. The pH measurement at the end of the exposure were conducted in a pooled sample of each test item concentration and the control

OTHER TEST CONDITIONS
- Sterile test conditions: no
- Adjustment of pH: three replicates of the highest test concentrations, adjusted with 1 M NaOH and HCL to pH 8.1 +/- 0.2
- Photoperiod: 24 h light
- Light intensity and quality: 60 - 120 µE m^-2 s^-1 (fluorescent tubes, OSRAM L 36 W/865, cool daylight)
- Other: oscillation at 70 rpm

EFFECT PARAMETERS MEASURED
- Determination of cell concentrations: algae cells were evaluated microscopically at the start and at the end of the incubation period. Ccells were checked for unusual cell shapes, colour differences, differences in chloroplast morphology, flocculation, adherence of algae to test containers and agglutination of algae cells.
- Chlorophyll measurement: cell density was measured daily via Chlorophyll-a-fluorescence (excitation at 436 nm, emission at 685 nm)


TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2
- Range finding study: yes
- Test concentrations: 10 mg/L and 100 (with pH adjustment and without) mg/L
- Results used to determine the conditions for the definitive study: growth rate inhibition was 6-13% in the 100 mg/L concentrated solution

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

50 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

- Exponential growth in the control (for algal test): yes
-Observation of abnormalities (for algal test): icroscopic evaluation of the cells at start and end of the incubation period revealed no morphological abnormalities

Results with reference substance (positive control):

- ErC50: 0.460 mg/L (95% CI: 0.443 - 0.481 mg/L)

Further biological results reported:

EyC50 > 100 mg/L (nominal)

NOEyC = 50 mg/L (nominal)

Table 1: Cell densities.

Nominal Test Item Concentration [mg/L]	Mean values of cell densities [cells/mL]
	0 hours	24 hours	48 hours	72 hours
100 (pH-adjusted)	6305	21188	231419	1247674
100	6305	12151	144951	1452935
50	6305	23258	295991	2064620
25	6305	33666	388919	2212299
12.5	6305	37933	404444	2447685
6.25	6305	37335	422602	2535487
Control	6305	34458	394313	2088469

Table 2: Mean growth rate and % inhibition of growth rate.

Nominal Test Item Concentration [mg/L]	Mean growth rate [d^-1]	Inhibition of growth rate [%]
100 (pH-adjusted)	(+) 1.76	9
100	(+) 1.81	6
50	(-) 1.93	0
25	(-) 1.95	-1
12.5	(+)* 1.99	-3
6.25	(+)* 2	-3
Control	1.93	-

(+) Statistically significant differences of growth rates and yield compared to control values

(-) Not significant differences

* Statistically significance caused by growth stimulation

Table 3: Section-by-section and average specific growth rates of the control group (0 - 72 hours).

	Replicate No.	Specific growth rate [d^-1] section-by-section			Mean {0-72 hours)	SD ±	CV [%]	Mean CV [%]
		0 - 24 hours	24-48 hours	48 - 72 hours
Control	1	1.43	2.5	1.81	1.91	0.542	28.4
	2	1.87	2.35	1.66	1.96	0.358	18.3
	3	1.85	2.39	1.63	1.96	0.391	20	23.5
	4	1.67	2.35	1.73	1.92	0.377	19.6
	5	1.74	2.43	1.71	1.96	0.41	20.9
	6	1.56	2.63	1.48	1.89	0.642	34
				Mean	1.93
				SD ±	0.03

The measured concentrations of the hydrolysis product of the test item in the fresh media (0 h) were in the range of 113 to 118 % of the nominal values at all tested concentration levels. The measured concentrations in the old media (72 h) were in the range of 109 to 120 % of the nominal values of ail concentrations. Therefore, the nominal concentrations of the test item were used for the calculations.

Validity criteria fulfilled:

yes

Conclusions:

The study with Pseudokirchneriella subcapitata as the test organism, resulted in a 72 h ErC50 of > 100 mg/L and 72 h NOErC of 50 mg/L. The results are expressed in nominal concentrations, since 100% of the test substance was analytical verified at test end.

Description of key information

ErC50 (72 h) > 100 mg/L, NOErC (72 h) = 50 mg/L (nominal, OECD 201, P. subcapitata)

Additional information

The toxicity of N-methyl-3-(trimethoxysilyl)propylamine (CAS 3069-25-8) to algae was tested according to OECD 201 and GLP standards (Noack Laboratories, 2016). In the 72 h study, the test organism Pseudokirchneriella subcapitata was exposed to nominal test item concentrations of 0 (control), 6.25, 12.5, 25, 50 and 100 mg/L. The highest test item concentration of 100 mg/L was additionally tested with a pH adjustment to a pH of 8.1 ± 0.2. Since the tested substance hydrolyses rapidly in aqueous media, its hydrolysis product was analytically monitored by LC-MS. 109 – 120% of the hydrolysis product was recovered at test end. The test resulted in an NOEC (72 h) of 50 mg/L and an EC50 (72 h) > 100 mg/L.