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Toxicity to aquatic algae and cyanobacteria

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Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
3 (not reliable)
Rationale for reliability incl. deficiencies:
other: Test method was not according to any guideline. No GLP.
Principles of method if other than guideline:
Filled culture tubes were maintained at 27 ºC and relative humidity of 50%. The concentration of the algal suspension is measured turbidmetrically (while diffused light is screened off) and expressed by the extinction of the primary light of the monochromatic radiation at 578 nm for a layer of 10 mm thickness. The test temperature was 25 ºC.
GLP compliance:
no
Analytical monitoring:
not specified
Vehicle:
yes
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Dillutions of test substance were prepared with sterile double-distilled water.
Test organisms (species):
Scenedesmus quadricauda
Details on test organisms:
Filled culture tubes were maintained at 27 °C and relative humidity of 50%.
Test type:
not specified
Water media type:
freshwater
Total exposure duration:
8 d
Test temperature:
25 ºC
Nominal and measured concentrations:
No data on test substance concentrations.
Details on test conditions:
TEST SYSTEM
- Test vessel:
- Material, size, headspace, fill volume: Kapsenberg culture tubes 08 x 180 mm.

GROWTH MEDIUM
Nutrient solution 1 (for stock and preliminary cultures): Dissolve in double-distilled water:
496 mg sodium nitrate (NaNO3, A.R); 39 mg dipotassium hydrogen phosphate (K2HPO, anhydrous, high purity); 75 mg magnesium sulphate, MgSO4.7H20,A.R); 36 mg calcium chloride (CaCl2 . 2 H2O, A.R); 40 mg sodium metasilicate (Na2SiO3); 58 mg sodium carbonate (Na2CO3, anhydrous, A.R).;
3 mg citric acid, C6H5O7 . H20, A.R); 3 mg iron (III) citrate C6H5FeO7 . 5 H2O; 10mg disodium salt of ethylene diamine tetracetic acid (C10H14N2Na2O8 . 2 H20.
Add 10 mL of the trace elements operating solution, complete to 1 L with double-distilled water and adjust pH to 7.0 using the minimum of Na2CO3 solution.

TEST MEDIUM / WATER PARAMETERS
Stock solution 1 (for test cultures): Dissolve in double-distilled water:
248 mg sodium nitrate (NaNO3, A.R); 19.5 mg disodium hydrogen phosphate (K2HPO4, anhydrous, high purity); 750 mg magnesium sulphate, MgSO4 . 7H2O, A.R.; 360 mg calcium chloride (CaCI2 . 2 H20, A.R); 30 mg iron (III) citrate (C6H5sFeO7 . 5 H20).
Add 10 mL of the trace elements operating solution, complete to 1 L with double-distilled water and adjust pH to 7.0 using the minimum of Na2CO3 solution.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): Growth inhibition.
The concentration of the algal suspension is measured turbidimetrically (while diffused light is screened off) and expressed by the extinction of the primary light of the monochromatic radiation at 578 nm for a layer of 10 mm thickness.
Toxicity threshold is defined as the pollutant concentration resulting in a mean extinction value that is ≥ 3% below the mean of the extinction value for the nontoxic dilutions of the test culture.
Reference substance (positive control):
not specified
Duration:
8 d
Dose descriptor:
other: TT (toxicity threshold)
Effect conc.:
4 000 mg/L
Nominal / measured:
not specified
Conc. based on:
test mat.
Basis for effect:
other: growth inhibition
Remarks on result:
other: (Toxicity threshold is defined as the pollutant concentration resulting in a mean extinction value that is ≥ 3% below the mean of the extinction value for the nontoxic dilutions of the test culture)

The toxicity threshold of Acetic acid for Scenedesmus quadricauda was 4000 mg/L.

Validity criteria fulfilled:
not applicable
Conclusions:
The toxicity threshold of Acetic acid for Scenedesmus quadricauda was 4000 mg/L.
Executive summary:

Using analogous methods of the cell multiplication inhibition test, the toxicity threshold (TT) of Acetic acid was determined for green algae of the species Scenedesmus quadricauda. Filled culture tubes were maintained at 27 ºC and relative humidity of 50%. The concentration of the algal suspension is measured turbidmetrically (while diffused light is screened off) and expressed by the extinction of the primary light of the monochromatic radiation at 578 nm for a layer of 10 mm thickness. The test temperature was 25 ºC.

Toxicity threshold is defined as the pollutant concentration resulting in a mean extinction value that is ≥ 3% below the mean of the extinction value for the nontoxic dilutions of the test culture).

The toxicity threshold of Acetic acid for Scenedesmus quadricauda was 4000 mg/L.

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with national standard methods with acceptable restrictions
Remarks:
This method has a central position in water-toxicological studies of the Federal Institute of Hydrology. No data on GLP.
Principles of method if other than guideline:
The assimilation-depletion test (A-D test) developed in the Federal Institute of Hydrology as a method for assessing the harmful effects of waste waters or chemicals on the self-purification capacity of a recipient stream is described. The photosynthetic oxygen production of plankton algae (assimilation test) serves as measurement criteria. The importance of the A-D test in water-resources development and management lies in the possibility of quantifying the harmful effects on the oxygen balance of surface waters. The effective concentration of acetic acid is presented.
One of the two basic reactions of biological self·purification in natural waters is the incorporation of the resulting mineralization products by algae and other plants by producing organic substances through photosynthesis ("assimilation"). The bioproduction of plants through photosynthesis releases molecular oxygen. The measured parameter is the photosynthetic oxygen production of planktonic algae. It is measured in dilution series depending on the concentration of the wastewater or test substance. The EC 50 value after a test period of 24 hours is determined. The concentrations were computed from the weighed samples (nominal concentration).
GLP compliance:
not specified
Analytical monitoring:
not specified
Vehicle:
not specified
Test organisms (species):
other: Chlorococcales
Details on test organisms:
Green Algae Order
Test type:
static
Water media type:
freshwater
Total exposure duration:
24 h
Nominal and measured concentrations:
No data.
Details on test conditions:
The measured parameter is the photosynthetic oxygen production of planktonic algae. It is measured in dilution series depending on the concentration of the wastewater or test substance.
The pH of the original solution has not been standardized.
Reference substance (positive control):
not specified
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
156 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate

The (24 h) EC50 for acetic acid is 156 mg/L.

Validity criteria fulfilled:
not applicable
Conclusions:
The (24 h) EC50 for acetic acid is 156 mg/L.
Executive summary:

The assimilation-depletion test (A-D test) developed in the Federal Institute of Hydrology as a method for assessing the harmful effects of waste waters or chemicals on the self-purification capacity of a recipient stream is described. The photosynthetic oxygen production of plankton algae (assimilation test) serves as measurement criteria. The importance of the A-D test in water-resources development and management lies in the possibility of quantifying the harmful effects on the oxygen balance of surface waters. The effective concentration of acetic acid is presented.

One of the two basic reactions of biological self·purification in natural waters is the incorporation of the resulting mineralization products by algae and other plants by producing organic substances through photosynthesis ("assimilation"). The bioproduction of plants through photosynthesis releases molecular oxygen. The measured parameter is the photosynthetic oxygen production of planktonic algae. It is measured in dilution series depending on the concentration of the wastewater or test substance. The EC 50 value after a test period of 24 hours is determined. The concentrations were computed from the weighed samples (nominal concentration). The pH of the original solution has not been standardized.

The (24 h) EC50 for acetic acid is 156 mg/L.

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
3 (not reliable)
Rationale for reliability incl. deficiencies:
other: Test method was not according to any guideline. No GLP.
Principles of method if other than guideline:
Using analogous methods of the cell multiplication inhibition test, the toxicity threshold (TT) of Acetic acid was determined for blue-green algae of the specie Microcystis aeruginosa. Filled culture tubes were maintained at 27 ºC and relative humidity of 50%. The concentration of the algal suspension is measured turbidmetrically (while diffused light is screened off) and expressed by the extinction of the primary light of the monochromatic radiation at 578 nm for a layer of 10 mm thickness.
Toxicity threshold is defined as the pollutant concentration resulting in a mean extinction value that is ≥ 3% below the mean of the extinction value for the nontoxic dilutions of the test culture).
GLP compliance:
no
Analytical monitoring:
not specified
Vehicle:
yes
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Dilutions of test substance were prepared with sterile double-distilled water.
Test organisms (species):
Microcystis aeruginosa
Details on test organisms:
Filled culture tubes were maintained at 27 °C and relative humidity of 50%.
Test type:
static
Water media type:
freshwater
Total exposure duration:
8 d
Test temperature:
27 ºC
Nominal and measured concentrations:
No data on test substance concentrations.
Details on test conditions:
TEST SYSTEM
- Material, size, headspace, fill volume: Kapsenberg culture tubes 08 x 180 mm.

GROWTH MEDIUM
Nutrient solution 1 (for stock and preliminary cultures): Dissolve in double-distilled water:
496 mg sodium nitrate (NaNO3, A.R); 39 mg dipotassium hydrogen phosphate (K2HPO, anhydrous, high purity); 75 mg magnesium sulphate, MgSO4.7H2O, A.R); 36 mg calcium chloride (CaCl2 . 2 H2O, A.R); 40 mg sodium metasilicate (Na2SiO3); 58 mg sodium carbonate (Na2CO3, anhydrous, A.R).;
3 mg citric acid, C6H5O7. H2O, A.R); 3 mg iron (III) citrate C6H5FeO7 . 5 H2O; 10mg disodium salt of ethylene diamine tetracetic acid (C10H14N2Na2O8 . 2 H2O).
Add 10 mL of the trace elements operating solution, complete to 1 L with double-distilled water and adjust pH to 7.0 using the minimum of Na2CO3 solution.

TEST MEDIUM / WATER PARAMETERS
Stock solution 1 (for test cultures): Dissolve in double-distilled water:
248 mg sodium nitrate (NaNO3, A.R); 19.5 mg disodium hydrogen phosphate (K2HPO4, anhydrous, high purity); 750 mg magnesium sulphate, MgSO4 . 7H2O, A.R.; 360 mg calcium chloride (CaCI2 . 2 H2O, A.R); 30 mg iron (III) citrate (C6H5sFeO7 . 5 H2O).
Add 10 mL of the trace elements operating solution, complete to 1 L with double-distilled water and adjust pH to 7.0 using the minimum of Na2CO3 solution.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): Cell multiplication.
The concentration of the algal suspension is measured turbidimetrically (while diffused light is screened off) and expressed by the extinction of the primary light of the monochromatic radiation at 578 nm for a layer of 10 mm thickness.
Toxicity threshold is defined as the pollutant concentration resulting in a mean extinction value that is ≥ 3% below the mean of the extinction value for the nontoxic dilutions of the test culture.
Reference substance (positive control):
not specified
Duration:
8 d
Dose descriptor:
other: TT (toxicity threshold)
Effect conc.:
90 mg/L
Nominal / measured:
not specified
Conc. based on:
test mat.
Basis for effect:
other: cell multiplication
Remarks on result:
other: (Toxicity threshold is defined as the pollutant concentration resulting in a mean extinction value that is ≥ 3% below the mean of the extinction value for the nontoxic dilutions of the test culture)

The toxicity threshold of Acetic acid for Microcystis aeruginosa was 90 mg/L.

Validity criteria fulfilled:
not applicable
Conclusions:
The 8d toxicity threshold of Acetic acid for Microcystis aeruginosa was 90 mg/L.
Executive summary:

Using analogous methods of the cell multiplication inhibition test, the toxicity threshold (TT) of Acetic acid was determined for blue-green algae of the specie Microcystis aeruginosa. Filled culture tubes were maintained at 27 ºC and relative humidity of 50%. The concentration of the algal suspension is measured turbidmetrically (while diffused light is screened off) and expressed by the extinction of the primary light of the monochromatic radiation at 578 nm for a layer of 10 mm thickness.

Toxicity threshold is defined as the pollutant concentration resulting in a mean extinction value that is ≥ 3% below the mean of the extinction value for the nontoxic dilutions of the test culture).

The 8d toxicity threshold of Acetic acid for Microcystis aeruginosa was 90 mg/L.

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
3 (not reliable)
Rationale for reliability incl. deficiencies:
other: A scientific study, no GLP.
Principles of method if other than guideline:
A static test was conducted at a temperature of 30 ºC, a pH of 7.6-7.8, and a light intensity of 1000 ft. candles. Growth rate was determined by measuring optical density of the cultures.
GLP compliance:
no
Analytical monitoring:
not specified
Vehicle:
not specified
Test organisms (species):
other: Anacystis nidulans (blue-green algae)
Test type:
static
Water media type:
freshwater
Total exposure duration:
60 h
Test temperature:
30 ºC
pH:
7.6-7.8
Nominal and measured concentrations:
Nominal concentrations: 1 to 10 mmol/L.
Details on test conditions:
- Light intensity and quality: 1000 ft. candles

Growth rate was determined by measuring optical density of the cultures.
Duration:
60 h
Dose descriptor:
EC50
Effect conc.:
1 640 mg/L
Nominal / measured:
not specified
Conc. based on:
test mat.
Basis for effect:
other: growth inhibition
Details on results:
Growth inhibition in photoautotrophic algae at 2460 mg/L (0.03 mol/L) after 60 hours.
Retardation of growth (i.e., slowed but did not otherwise restrict growth) occurred at 1640 mg/L (0.01 and 0.02 mol/L).
Inhibition of growth (i.e., prevented growth) occurred at 2460 and 3290 mg/L (0.03 and 0.04 mol/L). However, even at the highest concentrations, the cultures remained viable after being transferred to clean culture water.

Retardation of growth (i.e., slowed but did not otherwise restrict growth) occurred at 1640 mg/L (0.02 mol/L). Inhibition of growth (i.e., prevented growth) occurred at 2460 and 3290 mg/L (0.03 and 0.04 mol/L)

Validity criteria fulfilled:
not applicable
Conclusions:
Retardation of growth occurred at 1640 mg/L (0.02 mol/L). Inhibition of growth (i.e., prevented growth) occurred at 2460 and 3290 mg/L (0.03 and 0.04 mol/L)
Executive summary:

A static test was conducted at a temperature of 30 ºC, a pH of 7.6-7.8, and a light intensity of 1000 ft. candles. Growth rate was determined by measuring optical density of the cultures.

Retardation of growth in blue-green algae occurred at 1640 mg/L (0.01 and 0.02 mol/L). Inhibition of growth (i.e., prevented growth) occurred at 2460 and 3290 mg/L (0.03 and 0.04 mol/L). However, even at the highest concentrations, the cultures remained viable after being transferred to clean culture water.

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
February 2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
According to OECD Guideline 201. GLP 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:
Propyltriacetoxysilane undergoes rapid hydrolysis in aqueous to acetic acid and the corresponding trisilanols and these trisilanols undergo continuous condensation reactions to produce higher molecular weight siloxanes. Due to very rapid hydrolysis of the test substance (half-life < 37.5 seconds), there was no possibility to determine the parent compound and therefore the content of hydrolysis product acetic acid was chemically analyzed.
- Concentrations:
Series without pH adjustment: 0 (control), 10, 18, 32, 56, 100 mg/L
Series with pH adjustment: 0 (control) 40, 100, 250, 625, 1562.5 mg/L
- Sampling method: The content of acetic acid was determined by validated high performance liquid chromatography method with UV-VIS detection. Each sample of 10.0 mL volume (i.e. control sample, test sample, sample fortified with standard) was added to vial and 100 µL was applied to chromatographic column. If necessary, samples were diluted with deionized water
- Validity of analytical method: Linearity of response for the analysis method, its specificity, precision, recovery of acetic acid, limit of quantification and detection were assessed in process of analytical method validation
Vehicle:
no
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Common name: Pseudokirchneriella subcapitata (syn. Selenastrum capricornotum)
- Source (laboratory, culture collection): Algae Collection University of Göttingen, Germany.
- Method of cultivation: Algae were transferred from agar bevels to the fresh medium (AAP medium) in 250 mL Erlenmeyer flask and incubated in 21 – 24 ºC in constant illumination (pre-culture). The algae culture was renewed (inoculated to a new medium) twice a week in sterile conditions.
A pre-culture with cell density of 1 x 10E+04 per mL was renewed three days before the definitive test. The pre-culture was used for inoculation of the test concentrations and the control.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Test temperature:
Series without pH adjustment: 21.1-21.7 ºC
Series with pH adjustment: 21.4-22.5 ºC
pH:
Series without pH adjustment: 4.14-7.98
Series with pH adjustment: 7.52-8.35
Nominal and measured concentrations:
Nominal concentration:
Series without pH adjustment: 0 (control), 10, 18, 32, 56, 100 mg/L
Series with pH adjustment: 0 (control), 40, 100, 250, 625, 1562.5 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: Erlenmeyer glass flasks
- Type (delete if not applicable): closed with air permeable stoppers
- Material, size, headspace, fill volume: glass, 250 ml.
- Aeration: mechanically shaken at 100 rounds per minute in order to maintain stable conditions during the test.
- Initial cells density: 1*10E+04 cell/mL
- Control end cells density: without pH adjustment: 1.321*10E+06 cells/ml, with pH adjustment: 232.5*10E+06 cells/ml
- No. of organisms per vessel: 1*10E+04 cell/mL
- No. of vessels per concentration (replicates): 3 replicates
- No. of vessels per control (replicates): 6 replicates

GROWTH MEDIUM
- Standard medium used: yes (AAP medium)

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: The AAP medium was prepared on the basis of deionised water by addiing stock solutions of reagent-grade chemicals. The stock solutions were renewed in algae culturing and sterilised by autoclaving (with exception of sodium hydrogen carbonate-the buffering ingredient) and stored in the refrigerator.
- Culture medium different from test medium: No

OTHER TEST CONDITIONS
- Sterile test conditions: no
- Adjustment of pH: series without pH adjustment and series with pH adjustment (4% NaOH, pH 7.5) were performed.
- Photoperiod: Constant illumination
- Light intensity and quality: Fluorescent light source of six 24 W light bulbs.
Series without pH adjustment: 5620-7025 lx. light intensity
Series with pH adjustment: 7123-7843 lx. light intesity

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: the algal biomass was determined from results of microscopic counting of algae cells in Bürker chamber (Microscope CX-40 RF200, Olympus Optical Co. Ltd.) in order to avoid counting error due high molecular weight polymers. The microscopic observations were performed at 24, 48 and 72 hours of exposure.
- Other: At the end of the test the microscopic observations of cells morphology were performed.
Temperature: constantly recorded with a sensor submerged in an additional test vessel with 100 mL test medium.
Light intensity: measured at 24 h intervals.
pH: at the beginning and at the end of the test pH values were measured.

TEST CONCENTRATIONS
- Range finding study: 3 preliminary tests were performed:
1) Range finding without pH adjustment: test concentrations: 0.1, 1.0, 10 and 100 mg/L (3 replicates). Algae biomass was measured at 24, 48 and 72 h exposition by spectrometry (absorbance at 670 mm)
2) Study to find the impact of pH effect: test concentrations: 0 (pH 7.56), 10 (pH 6.93) and 100 (pH 4.40) mg/L (3 replicates). Algae biomass was measured at 24, 48 and 72 h exposition by spectrometry (absorbance at 670 mm).
3) Range finding with pH adjustment with 4% NaoH to pH 7.5: test concentrations: 100, 240, 576, 1382.4 and 3317.8 mg/L (3 replicates). Algae biomass was measured at 24, 48 and 72 h exposition by microscopic counting in a Bürker chamber in order to avoid counting errors due to high molecular weight polymers.
- Test concentrations:
Series without pH adjustment: 0 (control), 10, 18, 32, 56, 100 mg/L
Series with pH adjustment: 0 (control), 40, 100, 250, 625, 1562.5 mg/L
- Results used to determine the conditions for the definitive study:
1) Range finding without pH adjustment: At test termination the inhibition (calculated from average algae cell number) compared with the control was 99.62% in 100 mg/L test concentration, -4.54% in 10.0 mg/L, 3.85% in 1.0 mg/L and 1.96% in 0.1 mg/L.
2) Study to find the impact of pH effect: test concentrations: At test termination the inhibition (calculated from average algae cell number) compared with the control (pH value 7.56) was 97.35% in 100 mg/L test concentration, -19.10% in 10.0 mg/L 98.58% in control of pH value 4.40 and 5.13% in control of pH value 6.93. It cannot be excluded that the low pH value caused growth inhibition of algae.
3) At test termination the inhibition compared with the control was 100% in 3317.8 mg/L test concentration, 92% in 1382.4 mg/L, 90% in 576 mg/L, 79% in 240 mg/L and 16% in 100 mg/L.
Reference substance (positive control):
no
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
24.41 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: (95% CL: 22.52 – 26.42) (without pH adjustment)
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
32 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: (without pH adjustment)
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
18 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: (without pH adjustment)
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 1 562.5 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: (with pH adjustment)
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: (with pH adjustment)
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
40 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: (with pH adjustment)
Details on results:
- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): Based on microscopic observations performed at test termination in all test concentrations no differences in size and shape of algal cells were reported as compared to the algae cells in the control.
Reported statistics and error estimates:
Probit method calculations and analysis: Shapiro-Wilk’s Test on Normal Distribution, Levene’s Test on Variance Homogeneity (with Residuals), Multiple Sequentialy-rejective U-test After Bonferroni-Holm, Welch-t test for Inhomogeneous Variances with Bonferroni-Holm Adjustment, Williams Multiple Sequential t-test Procedure, Fisher’s exact test

Inhibition of growth rate and yield of algae [%] - definitive test (series without pH adjustment)

Nominal concentration of test item [mg/L]

Inhibition at 72 h (growth rate)

Inhibition at 72 h (yield)

Control

0.0

0.0

10

-3.2

-16.8

18

16.2

55.0

32

81.2

98.0

56

219.5

100.1

100

219.5

100.1

Inhibition of growth rate and yield of algae [%] - definitive test (series with pH adjustment)

Nominal concentration of test item [mg/L]

Inhibition at 72 h (growth rate)

Inhibition at 72 h (yield)

Control

0.0

0.0

40

-1.0

-5.4

100

2.2

11.2

250

22.5

70.9

625

21.6

69.5

1562.5

38.1

87.8

Endpoint values of growth rate and yield based on nominal concentrations of test item [mg/L] - definitive test (series with and without pH adjustment, exposure period 72 h)

Endpoint value

without pH adjustment

with pH adjustment

ErC50with 95% CL

24.41 (22.52 – 26.42)

> 1562.5

ErC20with 95% CL

18.78 (16.43 – 20.57)

436.55 (298.94 – 577.64)

ErC10with 95% CL

16.38 (13.75 – 18.30)

155.86 (74.72 – 239.18)

LOEC (growth rate)

32*

100

NOEC (growth rate)

18*

40

EyC50with 95% CL

17.52 (17.31 – 17.67)

237.75 (168.30 – 335.69)

EyC20with 95% CL

14.60 (13.53 – 15.26)

91.58 (43.09 – 135.16)

EyC10with 95% CL

13.27 (11.89 – 14.15)

55.62 (< 40 – 91.43)

LOEC (yield)

18

100

NOEC (yield)

10

40

* based on Fisher’s exact test

Concentration of acetic acid in series without pH adjustment:

Nominal concentration of test item [mg/L]

Mean concentration (n=3) of acetic acid

measured in samples collected [mg/L]

at test initiation

at test termination

% of initial concentration of acetic acid

Control

<LoD

<LoD

--

10

5.4

<LoQ

--

18

10.1

<LoQ

--

32

18.7

21.6

115.51

56

38.3

44.8

116.97

100

66.5

69.2

104.06

Concentration of acetic acid in series with pH adjustment:

Nominal concentration of test item [mg/L]

Mean concentration (n=3) of acetic acid

measured in samples collected [mg/L]

at test initiation

at test termination

% of initial concentration of acetic acid

Control

<LoD

<LoD

--

40

30.2

0.8

2.65

100

65.5

1.6

2.44

250

148.1

7.4

5.00

625

386.3

256.0

66.27

1562.5

950.1

780.3

82.13

Validity criteria fulfilled:
yes
Remarks:
(increase of biomass in control during 72h > 16 fold; coefficient of variation of the mean specific growth rate among replicates in control (t0-t72) < 7%; the mean of the replicate coefficients of variation in section-by-section growth rate < 35%)
Conclusions:
In the Pseudokirchneriella subpicata green algae toxicity test the EC50 (72 h) based on nominal concentration of propyltriacetoxysilane was determined to be 24.41 mg/L without pH adjustment and > 1562.5 mg/L with pH adjustment (basis for effect: growth rate).
Executive summary:

An Algae Growth Inhibition Test was performed according to OECD Guideline 201 on test item Propyltriacetoxysilane in a 72 hour static toxicity study with an initial density of 1*10E+04 Pseudokirchenriella subpicata green algae. The test item propyltriacetoxysilane polymerizes triggered by hydrolysis (half-life < 37.5 seconds) in contact with water and the degradation product acetic acid decreases the pH of the test solution. Moreover, the second preliminary test pointed out that the low pH caused growht inhibition of algae. Therefore, the test was conducted in series without pH adjustment and with pH adjustment to 7.5 (with 4% NaOH). According to preliminary range finding tests, the green algae were exposed to 0 (control), 10, 18, 32, 56 and 100 mg/L in the series without pH and to 0 (control), 40, 100, 250, 625 and 1562.5 mg/L (3 replicates per each test concentration and 6 per each control). Due to very rapid hydrolysis of the test substance, there was no possibility to determine the parent compound and therefore the content of acetic acid was chemically analyzed by a validated high performance liquid chromatography with UV-VIS detection. The algal biomass was determined from results of microscopic counting of algae cells in Bürker chamber in order to avoid counting error due high molecular weight polymers, and growth rate inhibition and yield inhibition were calculated. The microscopic observations were performed at 24, 48 and 72 hours of exposure. Moreover, at the end of the test the microscopic observations of cells morphology were performed.

In series without pH adjustment, the determined ErC50 (72h) was 24.41 mg/L and EyC50 (72h) was 17.52 mg/L based on nominal concentrations of propyltriacetoxysilane. The LOEC (72h) and NOEC (72h) for growth rate were 32 and 18 mg/L respectively. The LOEC (72h) and NOEC (72h) for yield were 18 and 10 mg/L respectively

In series with pH adjustment, the determined ErC50 (72h) was higher than 1562.5 mg/L and EyC50 (72h) was 237.75 mg/L based on nominal concentrations of propyltriacetoxysilane. The LOEC (72h) and NOEC (72h) for growth rate and yield were 100 and 40 mg/L respectively.

Based on microscopic observations performed at test termination in all test concentrations no differences in size and shape of algal cells were reported as compared to the algae cells in the control.

The validity criteria according to OECD Guideline 201 were met in both series with and without pH adjustment of the definitive tests.

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:
REPORTING FORMAT FOR THE ANALOGUE APPROACH
The analogue Propyltriacetoxysilane which shares the same functional group with Triacetoxyvinylsilane, also has comparable values for the relevant molecular properties for toxicity to algae.
See attached the reporting format.
Reason / purpose for cross-reference:
read-across source
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
22.83 mg/L
Conc. based on:
other: (read-across approach from analogue propyltriacetoxysilane)
Basis for effect:
other: (read-across from analogue propyltriacetoxysilane effect concentration. Basis for effect: growth rate)
Remarks on result:
other: (without pH concentration)
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
29.93 mg/L
Conc. based on:
other: (read-across approach from analogue propyltriacetoxysilane)
Basis for effect:
other: (read-across from analogue propyltriacetoxysilane effect concentration. Basis for effect: growth rate)
Remarks on result:
other: (without pH adjustment)
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
16.84 mg/L
Conc. based on:
other: (read-across approach from analogue propyltriacetoxysilane)
Basis for effect:
other: (read-across from analogue propyltriacetoxysilane effect concentration. Basis for effect: growth rate
Remarks on result:
other: (without pH adjustment)
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 1 461.57 mg/L
Conc. based on:
other: (read-across approach from analogue propyltriacetoxysilane)
Basis for effect:
other: (read-across from analogue propyltriacetoxysilane effect concentration. Basis for effect: growth rate)
Remarks on result:
other: (with pH adjustment)
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
93.54 mg/L
Conc. based on:
other: (read-across approach from analogue propyltriacetoxysilane)
Basis for effect:
other: (read-across from analogue propyltriacetoxysilane effect concentration. Basis for effect: growth rate)
Remarks on result:
other: (with pH adjustment)
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
37.42 mg/L
Conc. based on:
other: (read-across approach from analogue propyltriacetoxysilane)
Basis for effect:
other: (read-across from analogue propyltriacetoxysilane effect concentration. Basis for effect: growth rate)
Remarks on result:
other: (with pH adjustment)
Details on results:
Based on the experimental results obtained with the analogue substance propyltriacetoxysilane for Pseudokirchenriella subpicata green algae (in series with pH adjustment EC50, LOEC and NOEC at 72 h were determined to be 24.41, 32 and 18 mg/L respectively based on growth rate; and in series with pH adjustment EC50, LOEC and NOEC at 72 h were determined to be > 1562, 100 and 40 mg/L respectively based on growth rate), the read-across approach was applied and the EC50, LOEC and NOEC for triacetoxyvinylsilane were calculated to be as follows:
- In series without pH adjustment: EC50 (72h) = 22.83 mg/L; LOEC (72h) = 29.93 mg/L; NOEC (72h) = 16.84 mg/L.
- In series with pH adjustment: EC50 (72h) > 1461.57 mg/L; LOEC (72h) = 93.54 mg/L; NOEC (72h) = 37.42 mg/L.
Validity criteria fulfilled:
not applicable
Conclusions:
Based on experimental results with analogue propyltriacetoxysilane for Pseudokirchenriella subpicata green algae, the read-across approach was applied and the EC50 (72h, based on growth rate) for trieacetoxyvinylsilane was determined to be 22.83 mg/L without pH adjustment and > 1461.57 mg/L with pH adjustment and the NOEC (72h, based on growth rate) was determined to be 16.84 without pH adjustment and 37.42 mg/L with pH adjustment.
Executive summary:

Based on the Algae Growth Inhibition Test was performed according to OECD Guideline 201 on analogue substance Propyltriacetoxysilane in a 72 hour static toxicity study for Pseudokirchenriella subpicata green algae (72 h-EC50 based on growth rate were 24.41 without pH adjustment and > 1562.5 mg/L with pH adjustment and 72h-NOEC based on growth rate were 18 mg/L without pH adjustment and 40 mg/L with pH adjustment), read-across approach was applied and the EC50 (72h, based on growth rate) for triacetoxyethylsilane was determined to be 22.83 mg/L without pH adjustment and > 1461.57 mg/L with pH adjustment and the NOEC (72h, based on growth rate) was determined to be 16.84 without pH adjustment and 37.42 mg/L with pH adjustment.

Based on microscopic observations performed at test termination in all test concentrations with analogue substance propyltriacetoxysilane no differences in size and shape of algal cells were reported as compared to the algae cells in the control.

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH
Triacetoxyvinylsilane undergoes rapid hydrolysis in aqueous to acetic acid and the corresponding trisilanols. Trisilanols undergo continuous condensation reactions to produce higher molecular weight siloxanes which are considered biologically unavailable. Therefore, the observed toxicity is likely due to the acetic acid and their values are comparable.
See attached the reporting format.
Reason / purpose for cross-reference:
read-across source
Duration:
8 d
Dose descriptor:
other: TT (Toxicity threshold)
Effect conc.:
5 157.26 mg/L
Conc. based on:
other: (Read-across approach from acetic acid effect concentration was based on test material)
Basis for effect:
other: (Read-across approach from acetic acid effect concentration, basis for effect: growth inhibition)
Remarks on result:
other: (Toxicity threshold is defined as the pollutant concentration resulting in a mean extinction value that is ≥ 3% below the mean of the extinction value for the nontoxic dilutions of the test culture)
Details on results:
Based on the experimental results obtained with the supporting substance acetic acid for Scenedermus quadricauda (8d toxicity threshold = 4000 mg/L, basis for effect: growth inhibition), the read-across approach is applied and the 8d toxicity threshold for triacetoxyvinylsilane is calculated to be 5157.26 mg/L.
Validity criteria fulfilled:
not applicable
Conclusions:
Based on the experimental results obtained with the supporting substance acetic acid for Scenedermus quadricauda (8d toxicity threshold = 4000 mg/L, basis for effect: growth inhibition), the read-across approach is applied and the 8d toxicity threshold for triacetoxyvinylsilane is calculated to be 5157.26 mg/L.
Executive summary:

Based on the experimental results obtained with the supporting substance acetic acid for Scenedermus quadricauda (8d toxicity threshold = 4000 mg/L, basis for effect: growth inhibition), the read-across approach is applied and the 8d toxicity threshold for triacetoxyvinylsilane is calculated to be 5157.26 mg/L.

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH
Triacetoxyvinylsilane undergoes rapid hydrolysis in aqueous to acetic acid and the corresponding trisilanols. Trisilanols undergo continuous condensation reactions to produce higher molecular weight siloxanes which are considered biologically unavailable. Therefore, the observed toxicity is likely due to the acetic acid and their values are comparable.
See attached the reporting format.
Reason / purpose for cross-reference:
read-across source
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
201.13 mg/L
Remarks on result:
other: (Read-across approach from acetic acid effect concentration based on the nominal concentration of test material, basis for effect: growth rate)
Details on results:
Based on the experimental results obtained with the supporting substance acetic acid for green algae (24h EC50 = 156 mg/L, basis for effect: growth inhibition), the read-across approach is applied and the 24h EC50 for triacetoxyvinylsilane is calculated to be 201.13 mg/L.
Validity criteria fulfilled:
not applicable
Conclusions:
Based on the experimental results obtained with the supporting substance acetic acid for green algae (24h EC50 = 156 mg/L, basis for effect: growth inhibition), the read-across approach is applied and the 24h EC50 for triacetoxyvinylsilane is calculated to be 201.13 mg/L.
Executive summary:

Based on the experimental results obtained with the supporting substance acetic acid for green algae (24h EC50 = 156 mg/L, basis for effect: growth inhibition), the read-across approach is applied and the 24h EC50 for triacetoxyvinylsilane is calculated to be 201.13 mg/L.

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH
Triacetoxyvinylsilane undergoes rapid hydrolysis in aqueous to acetic acid and the corresponding trisilanols. Trisilanols undergo continuous condensation reactions to produce higher molecular weight siloxanes which are considered biologically unavailable. Therefore, the observed toxicity is likely due to the acetic acid and their values are comparable.
See attached the reporting format.
Reason / purpose for cross-reference:
read-across source
Duration:
8 d
Dose descriptor:
other: TT (toxicity threshold)
Effect conc.:
116.04 mg/L
Conc. based on:
other: (Read-across approach from acetic acid effect concentration based on test material)
Basis for effect:
other: (Read-across approach from acetic acid effect concentration basis for effect: cell multiplication)
Remarks on result:
other: (Toxicity threshold is defined as the pollutant concentration resulting in a mean extinction value that is ≥ 3% below the mean of the extinction value for the nontoxic dilutions of the test culture)
Details on results:
Based on the experimental results obtained with the supporting substance acetic acid for Microcystis aeruginosa (8d Toxicity threshold = 90 mg/L, basis for effect: cell multiplication), the read-across approach is applied and the 8d Toxicity threshold for triacetoxyvinylsilane is calculated to be 116.04 mg/L.
Validity criteria fulfilled:
not applicable
Conclusions:
Based on the experimental results obtained with the supporting substance acetic acid for Microcystis aeruginosa (8d Toxicity threshold = 90 mg/L, basis for effect: cell multiplication), the read-across approach is applied and the 8d Toxicity threshold for triacetoxyvinylsilane is calculated to be 116.04 mg/L.
Executive summary:

Based on the experimental results obtained with the supporting substance acetic acid for Microcystis aeruginosa (8d Toxicity threshold = 90 mg/L, basis for effect: cell multiplication), the read-across approach is applied and the 8d Toxicity threshold for triacetoxyvinylsilane is calculated to be 116.04 mg/L.

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH
Triacetoxyvinylsilane undergoes rapid hydrolysis in aqueous to acetic acid and the corresponding trisilanols. Trisilanols undergo continuous condensation reactions to produce higher molecular weight siloxanes which are considered biologically unavailable. Therefore, the observed toxicity is likely due to the acetic acid and their values are comparable. Acetic acid and its salts are grouped together because of their close structural relationship (US EPA officially recognises acetic acid and acetates as a subcategory). Therefore, sodium acetate has comparable values with acetic acid and the target substance triacetoxyvinylsilane.
See attached the reporting format.
Reason / purpose for cross-reference:
read-across source
Duration:
60 h
Dose descriptor:
EC50
Effect conc.:
1 547.83 mg/L
Remarks on result:
other: (Read-across approach from sodium acetate effect concentration based on test material, basis for effect: growth inhibition)
Details on results:
Based on the experimental results obtained with the supporting substance sodium acetate for Anacystis nidularis (blue-green algae) (60h EC50 = 1640 mg/L, basis for effect: growth inhibition), the read-across approach is applied and the 60h EC50 for triacetoxyvinylsilane is calculated to be 1547.83 mg/L.
Validity criteria fulfilled:
not applicable
Conclusions:
Based on the experimental results obtained with the supporting substance sodium acetate for Anacystis nidularis (blue-green algae) (60h EC50 = 1640 mg/L, basis for effect: growth inhibition), the read-across approach is applied and the 60h EC50 for triacetoxyvinylsilane is calculated to be 1547.83 mg/L.
Executive summary:

Based on the experimental results obtained with the supporting substance sodium acetate for Anacystis nidularis (blue-green algae) (60h EC50 = 1640 mg/L, basis for effect: growth inhibition), the read-across approach is applied and the 60h EC50 for triacetoxyvinylsilane is calculated to be 1547.83 mg/L.

Description of key information

Key study:  Based on the read-across approach from experimental data on analogue propyltriacetoxysilane, the read-across approach was applied and the EC50 (72h, based on growthrate) for triacetoxyvinylsilane was determined to be 22.83 mg/L without pH adjustment and > 1461.57 mg/L with pH adjustment. NOEC (72h, based on growth rate) was determined to be 16.84 without pH adjustment and 37.42 mg/L with pH adjustment.

Key value for chemical safety assessment

EC50 for freshwater algae:
22.83 mg/L
EC10 or NOEC for freshwater algae:
16.84 mg/L

Additional information

Key study: Read-across from experimental results on analogue Propyltriacetoxysilane:

An Algae Growht Inhibition Test was performed according to OECD Guideline 201 (GLP study) on test item Propyltriacetoxysilane. The EC50 value (based on growht) rate for Pseudokirchenriella subpicata at 72 hour exposure period was 24.42 mg/L without pH adjustment and > 1562.50 mg/L with pH adjustment. The NOEC (72h and based on growth rate) was determined to be 18 mg/L without pH adjustment and 40 mg/L with pH adjustment. Based on microscopic observations performed at test termination in all test concentrations no differences in size and shape of algal cells were reported as compared to the algae cells in the control. Based on these results, the read-across approach was applied and the EC50 (72h) for triacetoxyvinylsilane was calculated to be 22.83 mg/L without pH adjustment and > 1461.57 mg/L with pH adjustment, and NOEC (72) was 16.84 mg/L without pH adjustment and 37.42 mg/L with pH adjustment.

Supporting studies: Read-across from experimental data on supporting substance acetic acid:

In the study by Bringmann and Kühn 1980 (klimisch 3) performed with acetic acid, the 8 days Toxicity Threshold for Scenedermus quadricauda was determined to be 4000 mg/L based on growth rate. Based on this result, the read-across approach was applied and the 8 days Toxicity Threshold for triacetoxyvinylsilane was calculated to be 5157.26 mg/L.

In the study by Krebs, 1991 (klimisch 2) conducted on acetic acid, the EC50 at 24 hours of green algae exposure was 156 mg/L based on growth inhibition. The read-across was applied and EC50 (24h) for triacetoxyvinylsilane was calculated to be 201.13 mg/L.

Based on the experimental results obtained by Bringmann and Kühn 1978 (klimisch 3) with acetic acid for Microcystis aeruginosa (8d Toxicity threshold = 90 mg/L, basis for effect: cell multiplication), the read-across approach was applied and the 8 days Toxicity Threshold for triacetoxyvinylsilane was calculated to be 116.04 mg/L.

In the publication by Hoare et al., 1967 (klimisch 3) the EC50 at 60 hours of Anacystis nidularis (blue-green algae exposure) was determined to be 1640 mg/L based on growth inhibition. Taking into account this result, the read-across approach was applied and EC50 (60h, basis for effect: growth inhibition) for triacetoxyvinylsilane was calculated to be 1547.83 mg/L.

Discussion:

Taking into account the growth inhibition test performed on analogue propyltriacetoxysilane and the supporting studies on acetic acid and sodium acetate, should be pointed out that the toxicity of triacetoxyvinylsilane seems to be caused by the pH effect of acetic acid since the effect concentration obtained in the read-across approaches from the studies conducted on analogue propyltriacetoxysilane without pH adjustment and supporting acetic acid (EC50 (72h): 22.83 mg/L, EC50 (24h): 201.13 mg/L; TT (8d): 116.04 mg/L) are much lower than those obtained in the read-across approaches from studies conducted on analogue propyltriacetoxysilane with pH adjustment and supporting sodium acetate (EC50 (72h) > 1461.57 mg/, EC50 (60h): 1547.83 mg/L). In fact, as mentioned before, triacetoxyvinylsilane polymerizes triggered by hydrolysis (half-life < 37.5 seconds) in contact with water into polymers with molecular weight high enough to be considered biologically unavailable and the toxicity of the substance is due to the degradation product acetic acid which decreases the pH of test solution.