1-Naphthalenesulfonic acid, 3-diazo-3,4-dihydro-4-oxo-, ester with phenyl(2,3,4-trihydroxyphenyl)methanone 6-diazo-5,6-dihydro-5-oxo-1-naphthalenesulfonate

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:

April 12, 2020 to July 10, 2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Version / remarks:

2015

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

2011

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 0 and 100 mg/L
- Sampling method: samples were taken directly after preparation of the test solutions and after 24 h. Since no test item was detected after 24 h, no further measurements were conducted after 48 and 72 hours.
- Sample storage conditions before analysis: one replicate was directly anaylsed, the other replicate was deep-frozen as backup

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: green algae
- Source: Pflanzenphysiologisches Institut der Universität Göttingen, Germany
- Age of inoculum (at test initiation): 2-4 days

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Test temperature:

21.4-23.4 °C

pH:

pH was not adjusted and ranged from 7.8 to 8.89
(measurements of freshly prepared test solution and after 24 h)

Nominal and measured concentrations:

nominal: 0, 10, 17.8, 31.6, 56.3 and 100 mg/L
measured: recovery rate 4.5 % for the test substances concentrations at 0 hours. At 24 h, the measured concentration was

Details on test conditions:

TEST SYSTEM
- Test vessel: flasks containing 100 mL
- Type: open
- Initial cells density: 10000 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: continuous light
- Light intensity and quality: 7112 Lux +/- 4 %

EFFECT PARAMETERS MEASURED
- Determination of cell concentrations: particle counter
- Other: microscopical analysis of the cell morphology

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 0.05 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

A small significant effect on growth rate and yield of the algae was observed at a nominal concentration of 100 mg/L, i.e. up to the maximum water solubility, but the EC10, EC20 and EC50 values were >0.05 mg/L (nominal 100 mg/L).

Validity criteria fulfilled:

yes

Conclusions:

The EC10, EC20 and EC50 values were >0.05 mg/L (=LOQ), correspondingto a nominal concentration of >100 mg/L.

Executive summary:

The toxicity of the test item to the unicellular freshwater green alga Pseudokirchneriella subcapitata was determined according to the principles of OECD 201 and Council Regulation (EC) No. 266/2016/Method C.3. The aim of the study was the determination of the effects on growth rate and yield over a period of 72 hours. The study was conducted under static conditions with an initial cell density of 10000 cells/mL. The following nominal test concentrations were prepared: 0, 10, 17.8, 31.6, 56.3 and 100 mg/L. HPLC analysis resulted in a recovery rate of 4.5 % for the test substances concentrations at 0 hours. At 24 h, the measured concentration was <LOQ for all concentrations. No further measurements were performed. A small significant effect on growth rate and yield of the algae was observed at a nominal concentration of 100 mg/L, i.e. up to the maximum water solubility, but the EC10, EC20 and EC50 values were >0.05 mg/L (nominal 100 mg/L). The NOEC was determined to be 56.3 mg/L (nominal).

Description of key information

The EC10, EC20 and EC50 values were >0.05 mg/L (=LOQ), corresponding to a nominal concentration of >100 mg/L.

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:

56.3 mg/L