Calcium 4-[(5-chloro-4-methyl-2-sulphonatophenyl)azo]-3-hydroxy-2-naphthoate

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes

Specific details on test material used for the study:

- Storage condition of test material: at room teperature at about 20 °C, away from direct sunlight

Analytical monitoring:

yes

Details on sampling:

The analytical measurements were based on the main component of the test item. Samples taken at the following timepoints:
- Just before the start of the test (duplicate samples from each test medium (without algae); duplicate samples from the control (without algae))
- After 72 hours (duplicate samples from each test medium (with algae) (stability samples); duplicate samples from the control (with algae)). For the 72-hour stability samples, additional flasks with algae were incubated for each test concentration separately under identical conditions as in the actual test.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Five WAFs (Water Accommodated Fractions) with loading rates of 3.2, 10, 32, 100 mg/L were prepared according to the OECD Guidance Document 23. The dispersions were prepared by mixing 8.0, 25.0, 80.0 and 250.2 mg of the test item into 2500 ml of test water, respectively, using ultrasonic treatment for 15 minutes. The dispersions were stirred at room temperature in the dark for 3 hours. After the stirring period of 3 hours, the saturated dispersions were filtered through a membrane filter. The filtrates of the dispersions with dissolved test item were tested on algae as WAFs. Due to technical reasons, the WAF with the lowest loading rate of 1.0 mg/L was prepared as a dilution of the WAF with the loading rate of 3.2 mg/L.

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: green algae
- Strain: 61.81 SAG
- Source: Supplied by the Collection of Algal Cultures (SAG, Institute for Plant Physiology, University of Göttingen, Göttingen / Germany). The algae are cultivated in RCC's laboratories under standardized conditions according to the test guidelines.
- Age of inoculum (at test initiation): 10000 algal cells/mL

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

24 mg/L as CaCO3

Test temperature:

23 °C

pH:

8.3 - 8.8

Nominal and measured concentrations:

- Nominal test concentrations: control, 1.0, 3.2, 10, 32, 100 mg/L as loading rates of the WAFs
- Mean measured concentrations: -, 0.026, 0.073, 0.053, 0.059, 0.064 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Material, nominal volume, fill volume: Erlenmeyer flasks covered with glass dishes, 50 mL, 15 mL
- Initial cells density: 10000 algal cells /mL
- No. of vessels per concentration: 3
- No. of vessels per control: 6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: synthetic test water
- Culture medium different from test medium: no
- Intervals of water quality measurement: pH at the test start and the test end, temperature daily

OTHER TEST CONDITIONS
- Photoperiod: continuously light
- Light intensity and quality: 6800 - 7900 lux

EFFECT PARAMETERS MEASURED: cell density, shape and size of the algal cells microscopically
- Determination of cell concentrations: electronic particle counter

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3.2 (enlarged spacing factor was choosen since according to the results of the range-finding test a large concentration range had to be tested in the definitive test)
- Range finding study: yes

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

102 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: no effects observed up to the limit of water solubility

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

Duration:

72 h

Dose descriptor:

EC90

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

3.2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.76 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yield

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yield

Duration:

72 h

Dose descriptor:

EC90

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yield

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yield

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

3.2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yield

Details on results:

- Appearance of the test media: no remarkable observations, clear test medium
- Unusual cell shape: none
- Unusual cell size: none

Validity criteria fulfilled:

yes

Conclusions:

With high probability acutely not toxic to aquatic algae.

Description of key information

With high probability acutely not toxic to aquatic algae.

Additional information

The effect of the substance on the growth of Pseudokirchnerella subcapitata was investigated in a study following GLP and OECD guideline 201 (RCC Ltd, 2007). Due to the low solubility of the test substance a water accommodated fraction has been tested. The algae were exposed for 72 hours to the test substance. At test termination no effects were observed up to the limit of water solubility (at a nominal loading rate of 100 mg/L).