4'-Ethyl-2,3-difluorbiphenyl-4-boronic acid

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:

Aug 06 - Nov 29, 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

The samples were taken from the biological phase of the study. Collecting, storage and handing over of the samples were the Study Director’s responsibility. The information concerning the samples was provided by the Study Director.
One sample from the freshly prepared stock solution filtrate and duplicate samples from the freshly prepared test media (containing algae) of all test concentrations and from the control were taken at the start of the test.
For the determination of the stability of the test item under the test conditions and of the maintenance of the test item concentrations during the test period, duplicate samples from the test media of all test concentrations and the control (containing algae) were taken at the end of the test (after the 72 hours test period) by pouring together the contents of the test beakers of each treatment.
The samples were diluted by a factor of two with acetonitrile.
Additional samples of the control and of the dilution solvent were taken at each sampling without any sample treatment.

Vehicle:

no

Details on test solutions:

Due to the low limit of water solubility of the test item, a filtrate of nominal 100 mg/L was prepared. As highest test concentration, the 1:10 dilution of this filtrate was tested. Further dilutions of 1:3, 1:9, 1:27 and 1:81 of the highest test concentration (1:10 dilution of filtrate) were tested. Additionally, a control was tested in parallel.
This filtrate and its dilutions correspond to the following geometric mean measured concentrations:
0.917, 0.299, 0.0555, 0.0375 and 0.00100 mg test item/L.

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Selenastrum capricornutum
- Strain: 61.81 SAG
- Source (laboratory, culture collection): "Sammlung von Algenkulturen, Albrecht-von-Haller-Institut für Pflanzenwissenschaften, Universität Göttingen", 37073 Göttingen, Germany.
- Method of cultivation: The algae were cultivated in the laboratories of ibacon under standardised conditions according to the test guidelines.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

24 mg/L

Test temperature:

22.4 to 22.6 °C (

pH:

7.9 to 8.0 at test start
8.1 to 9.5 at test end

The pH was adjusted with 1 M NaOH to pH 8.1

Nominal and measured concentrations:

This filtrate and its dilutions correspond to the following geometric mean measured concentrations:
0.917, 0.299, 0.0555, 0.0375 and 0.00100 mg test item/L.

Reference substance (positive control):

yes

Remarks:

Potassium Dichromate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.64 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.134 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

cell number

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.114 mg/L

Nominal / measured:

meas. (geom. mean)

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): none
- Unusual cell shape: no
- Colour differences: no
- Flocculation: no
- Adherence to test vessels: no
- Aggregation of algal cells: no
- Other: -
- Any stimulation of growth found in any treatment:
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values:
- Effect concentrations exceeding solubility of substance in test medium:

Results with reference substance (positive control):

Parameter (0-72 h)
EC50 (yield) = 0.442 mg/L
EC50 (growth rate) = 1.11 mg/L
EC50 (biomass) = 0.487 mg/L

Validity criteria fulfilled:

yes

Conclusions:

The influence of the test material on the growth of the freshwater green algae Pseudokirchneriella subcapitata was assessed in a static concentration-response test. The 72-hour ErC10 was calculated to be 0.114 mg test item/L, and the 72-hour ErC50 value was calculated to be 0.640 mg test item/L based on mean measured concentrations.
The initial concentrations and the maintenance of the exposure concentrations during the test were verified in the analytical part. All reported results refer to geometric mean measured values since the concentrations of the test item were not within ± 20 % of the nominal concentrations due to filtration of the stock solution.

Description of key information

OECD 201:

EC50 (growth rate, 72h) = 0.640 mg/L (geometric mean measured values)

EC10 (growth rate, 72h) = 0.114 mg/L (geometric mean measured values)

Key value for chemical safety assessment

EC50 for freshwater algae:

0.64 mg/L

EC10 or NOEC for freshwater algae:

0.114 mg/L