Reaction mass of tetrahydroxysilane and choline chloride and calcium chloride and water

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

19/01/2018 - 26/03/2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Reaction mass of tetrahydroxysilane and choline chloride and calcium chloride and water

IUPAC Name:

Reaction mass of tetrahydroxysilane and choline chloride and calcium chloride and water

Test material form:

liquid

Specific details on test material used for the study:

Batch 17I13, clear pale yellow liquid

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

Samples were taken at 0 and 72 hours and provided to the Sponsor for analysis of Si by GFAAS.

Test solutions

Vehicle:

no

Test organisms

Test organisms (species):

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

Details on test organisms:

The test was carried out using Pseudokirchneriella subcapitata strain CCAP 278/4.
Liquid cultures of Pseudokirchneriella subcapitata were obtained from the Culture Collection of Algae and Protozoa (CCAP), SAMS Research Services Ltd, Scottish Marine Institute, Oban, Argyll, Scotland. Master cultures were maintained in the laboratory by the periodic replenishment of culture medium. The master cultures were maintained under constant agitation by orbital shaker (100 to 150 rpm) and constant illumination at 24 ±1 °C.
Prior to the start of the test sufficient master culture was added to approximately 100 mL volumes of culture media contained in conical flasks to give an initial cell density of approximately 10^3 cells/mL. The flasks were plugged with polyurethane foam stoppers and kept under constant agitation by orbital shaker (100 to 150 rpm) and constant illumination at 24 ±1 °C until the algal cell density was approximately 10^4 to 10^5 cells/mL.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Test conditions

Test temperature:

24 ± 1°C

pH:

7.8-8.1

Nominal and measured concentrations:

nominal: 6.25, 12.5,25, 50 and 100 mg/L
recovery at 0h (start of exposure): not analyzed, 119, 123, 99 and 98 %
recovery at 48h (end of exposure): not analyzed, 40, 51, 59 and 55 %
At the start of the test all control and test cultures were observed to be clear colorless solutions. After the 72-Hour test period all control, 12.5, 25, 50 and 100 mg/L test cultures were observed to be green dispersions, whilst the 6.25 mg/L test cultures were observed to be pale green dispersions.

Details on test conditions:

In the definitive test 250 mL plastic bottles were used in order to minimize contamination of the test medium with silicon from glassware. Six bottles each containing 100 mL of test preparation were used for the control and three bottles each containing 100 mL were used for each treatment group.
The control group was maintained under identical conditions but not exposed to the test item.
Pre-culture conditions gave an algal suspension in log phase growth characterized by a cell density of 8.45 x 10^5 cells per mL. Inoculation of 450 mL of test medium with 2.7 mL of this algal suspension gave an initial nominal cell density of 5.00 x 10^3 cells per mL and had no significant dilution effect on the final test concentration.
The flasks were plugged with polyurethane foam bungs and incubated (INFORS Multitron Version 2 incubator) at 24 ±1 °C under continuous illumination (intensity approximately 7000 lux) provided by warm white lighting (380 to 730 nm) and constantly shaken at approximately 150 rpm for 72 hours.

Samples were taken at 17, 39 and 72 hours and the cell densities determined using a Coulter Multisizer Particle Counter. These time points are equivalent to approximately 24, 48 and 72 hours, the exact timings have been taken into account during the calculations of results as such this had no impact in the validity of the results. Three determinations were made for each sample. The nominally inoculated cell concentration (5.00 x 10^3 cells/mL) was taken as the starting cell density.
To determine the potential effect of the test item on the appearance of algal cells, a sample was removed from each test and control culture (replicates pooled) at the end of the test. The shape and size of the algal cells was inspected microscopically and any abnormalities recorded.

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 3

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 4

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Effect concentrations 5

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Effect concentrations 6

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Details on results:

The following data show that the cell concentration of the control cultures increased by a factor of 235 after 72 hours. This increase was in line with the OECD Guideline that states the enhancement must be at least by a factor of 16 after 72 hours.
Nominal cell density of controlat 0 hours: 5.00x10^3 cells per mL
Mean cell density of control at 72 hours: 1.17x10^6 cells per mL

The mean coefficient of variation for section by section specific growth rate for the control cultures was 17% and hence satisfied the validation criterion given in the OECD Guideline which states the mean must not exceed 35%.

The coefficient of variation for average specific growth rate for the control cultures over the test period (0 to 72 hour) was 1% and hence satisfied the validation criterion given in the OECD Guideline which states that this must not exceed 7%.

Results with reference substance (positive control):

Exposure of Pseudokirchneriella subcapitata (CCAP 278/4) to the reference item gave the following results:
ErC50 (0 to 72 hour): 1.6 mg/L; 95% confidence limits 1.4 to 1.8 mg/L
EyC50 (0 to 72 hour) : 0.77 mg/L; 95% confidence limits 0.68 to 0.87 mg/L
No Observed Effect Concentration based on growth rate: 0.25 mg/L
No Observed Effect Concentration based on yield: 0.25 mg/L
Lowest Observed Effect Concentration based on growth rate: 0.50 mg/L
Lowest Observed Effect Concentration based on yield: 0.50 mg/L

The results from the positive control with potassium dichromate were within the normal ranges for this reference item (average result of 1.3 mg/L for ErC50 over past 4 years).

Reported statistics and error estimates:

One way analysis of variance incorporating Bartlett's test for homogeneity of variance (Sokal and Rohlf, 1981) and Dunnett's multiple comparison procedure for comparing several treatments with a control (Dunnett, 1955) was carried out on the growth rate and yield data after 72 hours for the control and all test concentrations to determine any statistically significant differences between the test and control groups. All statistical analyses were performed using the SAS computer software package (SAS, 1999 - 2001).

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The effect of the test item on the growth of Pseudokirchneriella subcapitata has been investigated and based on the nominal test concentrations gave EC50 values of greater than 100 mg/L. The No Observed Effect Concentration was equal to or greater than 100 mg/L.