4-Methyl-N-[3-(triethoxysilyl)propyl]-2-pentanimine

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:

07 February 2018 to 03 May 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

After 0h; 24h and 48h exposure, 2 samples of 5 ml per treatment group and per control; one sample per replicate
After 72h exposure, 4 samples of 5 ml per treatment group and per control, one sample per replicate
Of each sampled treatment, one of the analytical samples from 0h, 24h, 48h and 72h was sent to the analytical laboratory at the test site for chemical analysis. The remaining samples were stored as retain samples in the freezer (<=18°C) until finalization of the study.

Vehicle:

no

Details on test solutions:

The stock solution was prepared as Water Soluble Fraction (WSF) by adding 88.7 mg test item (including a factor of 1.11 to take into account the dilution caused by addition of the algal inoculum) to 1000 ml test medium and shaking for 24 h using an overhead shaker at 20.2 - 21.3 °C. The stock solution was allowed to settle for 1.5 h before decanting the upper part of the liquid column for use in the test. The negative control (test medium) was treated in the same way as the test item solution.

Test organisms (species):

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

Details on test organisms:

The test organism (Train No. 61.81 SAG) originated from the Culture Collection of Algae at the University of Goettingen and was cultivated in suspension culture. The strain used for this study has been cultured at the test lab since July 2017. Twice a week, the stock suspension is inoculated into fresh Holm-Hansen medium under axenic conditions to keep it in exponential growth.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Remarks on exposure duration:

according to OECD 201

Post exposure observation period:

no

Hardness:

the test was performed with OECD TG 201 medium according to OECD 201 (2006)

Test temperature:

22.5 - 22.9°C

pH:

control: 7.5 - 8.0
treatment group: 7.6 - 7.9

Nominal and measured concentrations:

nominal: 5; 10; 20; 40; 80 mg/l
geometric mean test item concentration: 4.56; 9.4; 18.4; 34.4; 62.10mg/l

Details on test conditions:

TEST SYSTEM
- Test vessel: 100 ml Erlenmeyer glass flasks
- Type (delete if not applicable): closed with cellulose stoppers
- fill volume: 50 ml
- Initial cells density: 0.07x10E5 cells/ml
- Control end cells density: 5.73x10E5
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes
OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: no
- Photoperiod: conti
- Light intensity and quality:
- Salinity (for marine algae):

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: [counting chamber; electronic particle counter; fluorimeter; spectrophotometer; colorimeter]
- Chlorophyll measurement:
- Other:

TEST CONCENTRATIONS
- Range finding study: yes
- Test concentrations: nominal: 50; 100; 200 mg/l
- Results used to determine the conditions for the definitive study: inhibition of growth rate after 72H = 61.8%

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

19.2 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

4.56 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

4.56 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

sample stability during storage: It was observed, that the sample stability during storage at -20+-10°C, in the period from sampling in the inhibition test until analytical measurement of the test item concentrations, could not be demonstrated for all applied test item concentrations (treatment group). During the storage stability test, recovery after 3 d was 69.5 - 106.5% (the maximum storage time for analytical samples from 0h was 3d. As a consequence for the study, a loss of test item in the analytical samples, in the period from sampling in the algae growth inhibition test until analytical measuerement of the test item concentration (i.e. <= 3 d), is likely. Accordingly, the analytically determined test item concentrations in the analytical samples were probably lower than the test item concentrations in the test vessels at the time of sampling. As the data evaluation is based on analytically measured concentrations (geometric mean concentrations), the results (EC50, NOEC/LOEC) are, thus probably lower than they would have been, if the analytical measurement had been conducted directly after sampling without interim storage of the analytical samples.
Therefore, the results of this R.subcapitata Algal Growth Inhibition test rather overestimate the toxic effects of the test item on the organism.
- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): in the control no obvious abnormalities
- Unusual cell shape: in test item loading rates, thikened cells were sporadically observed

Results with reference substance (positive control):

ErC50 = 1.11 mg/l (CL95%: 0.65-1.86 mg/l

Reported statistics and error estimates:

Statistical evaluation with ToxRat Professional 3.2.1

Inhibition of growth rate after 24 h, 48 h and 72 h exposure

Nominal test item loading rate (mg/l)	Inhibition of growth rate (%)
	24 h	48 h	72 h
control	-	-	-
5	20.5	21.2	26.3
10	18.6	24.0	25.7
20	38.0	37.0	37.7
40	79.1	106.3	111.3
80	225.1	138.2	116.1

Validity criteria fulfilled:

yes

Conclusions:

The EC50 based on the analytically measured test item concentrations, ErC50 = 19.2 mg/l
Because of the instability of the test item from sampling time to analytical measurement time, the results of this R.subcapitata Algal Growth Inhibition test rather overestimate the toxic effects of the test item on the organism.

Executive summary:

In a valid growth inhibition test (Raphidocelis subcapitata) according to OECD 201 under GLP conditions, the calculated ErC50 = 19.2 mg/l based on analytically measured test item concentration (geometric mean concentration).

Description of key information

In a valid growth inhibition test (Raphidocelis subcapitata) according to OECD 201 under GLP conditions, the calculated ErC50 = 19.2 mg/l based on analytically measured test item concentration (geometric mean concentration).

Because of the instability of the test item from sampling time to analytical measurement time, the results of this R.subcapitata Algal Growth Inhibition test rather overestimate the toxic effects of the test item on the organism.

Because the substance was readily biodegradable in an OECD 310, the substance meets not the criteria for a classification to the aquatic environment.

Key value for chemical safety assessment

EC50 for freshwater algae:

19.2 mg/L

EC10 or NOEC for freshwater algae:

4.56 mg/L