Tetraethylammonium tetrafluoroborate

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:

1 November 2018 - 4 March 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2019

Report date:

2019

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

Adopted March 23, 2006; Annex 5 corrected 28 July 2011

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

tetraethylammonium tetrafluoroborate

Cas Number:

429-06-1

Molecular formula:

C8H20BF4N

IUPAC Name:

tetraethylammonium tetrafluoroborate

Test material form:

solid: crystalline

Test solutions

Vehicle:

yes

Details on test solutions:

Preparation of test solutions started with the highest concentration of 100 mg/L applying 15 minutes of magnetic stirring to ensure complete dissolution of test item in test medium. Lower test concentrations were prepared by subsequent dilutions of the highest concentration in test medium. All test solutions were clear and colorless at the end of the preparation procedure.
After preparation, volumes of 50 mL were added to each replicate of the respective test concentration. Subsequently, 1 mL of an algal suspension was added to each replicate providing a cell density of 104 cells/mL.

Test organisms

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Raphidocelis subcapitata (formerly known as Pseudokirchneriella subcapitata)
- Strain: NIVA CHL 1
- Source (laboratory, culture collection): In-house laboratory culture.
- Reason for selection: This system is a unicellular algal species sensitive to toxic items in the aquatic ecosystem and has been selected as an internationally accepted species.

ACCLIMATION
- Acclimation period:
- Culturing media and conditions (same as test or not):
- Any deformed or abnormal cells observed:

Study design

Test type:

static

Total exposure duration:

72 h

Test conditions

Hardness:

0.24 mmol/L (24 mg CaCO3/L)

Test temperature:

22 - 24°C

pH:

8.1 ± 0.2

Nominal and measured concentrations:

nominal concentrations: 0.10, 1.0, 10, and 100 mg/L
measured concentration: 133 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 100 mL, all-glass with aluminium caps, perforated for ventilation, containing 50 mL of test solution
- Test Medium: M2
- Initial cell density: 1 x 104 cells/mL.
- Illumination: Continuously using TLD-lamps with a light intensity within the range of 81 to 83 µE.m-2.s-1.
- Incubation: Vessels were distributed at random in the incubator and daily repositioned. During incubation the algal cells were kept in suspension by continuous shaking.
- Replicates: 6 replicates of the control and limit concentration,
3 replicates each for the lower test concentrations,
1 extra replicate of each test group for sampling purposes after 24 h of exposure,
1 or 2 replicates of each test concentration without algae.

OTHER TEST CONDITIONS
- Light intensity and quality: 60 to 120 µE/m2/s when measured in the photosynthetically effective wavelength range of 400 to 700 nm.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable):
- Cell Densities:
At the beginning of the test, cells were counted using a microscope and a counting chamber. Thereafter, cell densities were determined by spectrophotometric measurement of samples at 680 nm using a spectrophotometer (path length = 10 mm). Test medium was used as blank and the extra replicates, without algae, as background for the treated solutions.
Cell densities were recorded at 24-hour intervals in the control and the limit concentration. Lower concentrations were measured only at the end of the exposure period.

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Effect concentrations 2

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

133 mg/L

Basis for effect:

growth rate

Details on results:

No significant inhibition of growth rate and yield was recorded at the limit concentration.
Microscopic observations at the end of the test revealed a normal and healthy appearance of the algal cells exposed to the limit concentration when compared to the control.

Any other information on results incl. tables

Samples taken from the limit concentration were analysed. The measured concentration was 133 mg/L at the start of the test, which remained stable throughout the test, i.e. was at the level of 99% of the initially measured at the end of the test.

It should be noted that the mean recovery of test item was 115 and 119% in the Quality Control (QC) samples prepared at target concentrations of 0.1 and 100 mg/L, respectively. Consequently, the measured concentrations could be slightly over-estimated. Nevertheless, testing was performed at the regulatory limit concentration of nominally 100 mg/L. Additionally, a small test item response was detected in the control sample taken at the end of the test, which was, however, negligible.

The concentrations measured in the solution incubated with algae were comparable to the concentrations measured in its counterpart incubated without algae. Hence, it can be stated that the presence of the algae had no effect on the concentration of the test item in test medium.

Based on the obtained results, the initially measured concentration of 133 mg/L was used to express effect parameters. 

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

In conclusion, under the conditions of the present study with Raphidocelis subcapitata (formerly known as Pseudokirchneriella subcapitata), no significant inhibition of growth rate and yield was recorded at the maximum concentration of Tetraethylammonium tetrafluoroborate tested.
The 72h-EC50 for growth rate inhibition (ERC50) was beyond the maximum concentration tested, i.e. exceeded the regulatory limit concentration of nominally 100 mg/L.
The 72h-EC50 for yield inhibition (EYC50) was beyond the maximum concentration tested, i.e. exceeded the regulatory limit concentration of nominally 100 mg/L.
The 72h-NOEC for growth rate inhibition was 133 mg/L.
The 72h-NOEC for yield inhibition was 133 mg/L.

Executive summary:

The objective of the study was to evaluate Tetraethylammonium tetrafluoroborate for its ability to generate toxic effects in Raphidocelis subcapitata (formerly known as Pseudokirchneriella subcapitata) during an exposure period of 72 hours and, if possible, to determine the NOEC, EC₁₀, EC₂₀ and EC₅₀ for both inhibition of growth rate and inhibition of yield.

A combined limit/range-finding test was performed. Six replicates of exponentially growing algal cultures per group were exposed to an untreated control and to nominally 100 mg/L, in a limit test. In addition, three replicates per group were exposed to nominal concentrations of 0.10, 1.0, and 10 mg/L in the combined range-finding test. The initial algal cell density was 10⁴ cells/mL. The total exposure period was 72 hours and samples for analytical confirmation of exposure concentrations were taken at the start, after 24 and 72 hours of exposure.

No significant inhibition of growth rate and yield was recorded at the limit concentration.

Samples taken from the limit concentration were analysed. The measured concentration was 133 mg/L at the start of the test, which remained stable throughout the test, i.e. was at the level of 99% of the initially measured at the end of the test. Based on these results, the initially measured concentration of 133 mg/L was used to express effect parameters.

The study met the acceptability criteria prescribed by the study plan and was considered valid.

The effect parameters obtained in this study are summarized below:

The 72h-EC50 for growth rate inhibition (ERC50) was beyond the maximum concentration tested, i.e. exceeded the regulatory limit concentration of nominally 100 mg/L.

The 72h-EC50 for yield inhibition (EYC50) was beyond the maximum concentration tested, i.e. exceeded the regulatory limit concentration of nominally 100 mg/L.

The 72h-NOEC for growth rate inhibition was 133 mg/L.

The 72h-NOEC for yield inhibition was 133 mg/L.