3-(benzothiazol-2-yl)-7-(diethylamino)-2-oxo-2H-1-benzopyran-4-carbonitrile

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:

September 2017 - March 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:

Samples (at least 2 x 20 mL) were taken from all five test solutions and controls at the beginning of the test prior to addition of the algae (2 x 6 samples). At the end of the growth test, samples were taken directly from representative replicates per test concentration and control (2 x 6 samples). Additionally, samples after 24 and 48 h were taken but not analyzed, since the results obtained at test start and test end were sufficient for the evaluation of the study.
A volume of 7.5 mL of sample was used and all samples were stabilized with 7.5 mL of acetonitrile immediately after the sampling. Samples were stored at -20°C in a refrigerator until shipment to Currenta for analysis. For security reasons, a reserve set of stabilized samples was stored deep frozen at Fraunhofer.

Vehicle:

no

Test organisms (species):

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

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

21.5°C - 22.0 °C

pH:

The pH of the controls increased during the test from 7.37 at test start to a mean value (n = 8) of 7.89 at test end.
In the test cultures the initial pH values in the treatments ranged from 7.32 to 7.46 and were between 7.81 and 8.09 at the end of the test.

Nominal and measured concentrations:

Range-finder: 1.0, 10 and 100.0 mg test item / L (nominal concentrations)
Definite test: control, 6.25, 12., 25.0, 50.0 and 100.0 mg test item / L (nominal concentrations)

Details on test conditions:

The sterilised synthetic growth medium (OECD medium) according to OECD 201 was used as growth medium.
All stock solutions and the medium were prepared with purified water processed using an ELGA „PURELAB Ultra“. The pH of the medium was obtained at equilibrium between the carbonate system of the medium and the partial pressure of CO2 in atmospheric air.

Reference substance (positive control):

yes

Remarks:

The sensitivity of the test organism is routinely checked using 3,5-dichlorophenol as primary standard following internal SOPs in a non-GLP test twice a year.

Duration:

72 h

Dose descriptor:

EL10

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOELR

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EL10

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yield

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yield

Duration:

72 h

Dose descriptor:

NOELR

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yield

Details on results:

No concentration-dependent inhibiting effect on the growth of the freshwater green algae was observed over the range of the tested concentrations. The respective 72 hour ErL50 and EyL50 were above the highest nominal loading of 100 mg test item/L. For growth rate and yield, a NOEL of above or equal to 100 mg test item/L was determined. At test start and at test termination in all treatments the measured concentrations were below the LOQ. Therefore, the evaluation of the test was based on the nominal loading of the test item.

Results with reference substance (positive control):

The sensitivity of the test organism is routinely checked using 3,5-dichlorophenol as primary standard following internal SOPs in a non-GLP test twice a year. The latest (December 2017) ErC50 value of 2.90 mg/L (nominal; 95% confidence limits: 2.66 – 3.16 mg/L) for inhibition of growth rate is in good agreement with the results of an international ring test with an ErC50 of 3.38 ± 1.30 mg/L.

Validity criteria fulfilled:

yes

Conclusions:

The Growth inhibition of Macrolex Fluoreszenzrot G was investigated according to Guideline OECD 201 on Raphidocelis subcapitata. After 72 hours no effects were observed up to the highest nominal concentration of 100.0 mg test item/L based on growth rate and yield.

Executive summary:

The growth inhibition on freshwater algae of Marcolex Fluoreszenzrot G was investigated according to Guideline OECD 201 on Raphidocelis subcapitata at five nominal concentrations (6.25, 12., 25.0, 50.0 and 100.0 mg test item / L) under static conditions.

The concentrations of the test item in the media were confirmed by measurements of the test item concentrations before and after the test by HPLC-MS/MS (LOQ = 0.003 mg/L). At test start and at test termination in all treatments the measured concentrations were below the LOQ. Therefore, the evaluation of the test was based on the nominal loading of the test item.

After an exposure duration of 72 hours no concentration-dependent inhibiting effect on the growth of the freshwater green algae was observed over the range of the tested concentrations. The respective 72 hour ErL50 and EyL50 were above the highest nominal loading of 100 mg test item/L. For growth rate and yield, a NOEL of above or equal to 100 mg test item/L was determined (Fraunhofer 2018).

Description of key information

The Growth inhibition of Marcolex Fluoreszenzrot G was inverstigated according to Guideline OECD 201 on Raphidocelis subcapitata. After 72 hours no effects were observed up to the highest nominal concentration of 100.0 mg test item/L based on growth rate and yield.