P 16513

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:

2008

Reliability:

1 (reliable without restriction)

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2008

Report date:

2008

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

yes

Remarks:

ETAD method, to differ between light shading and toxic effects

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Strontium 4-chloro-2-[2-hydroxy-6-sulfonatonaphthalen-1-yl)diazenyl]benzoate

Cas Number:

474814-88-5

Molecular formula:

C17H9ClN2O6SSr

IUPAC Name:

Strontium 4-chloro-2-[2-hydroxy-6-sulfonatonaphthalen-1-yl)diazenyl]benzoate

Test material form:

solid: nanoform, no surface treatment

Sampling and analysis

Details on sampling:

- Concentrations: 0.388, 1.20, 4.00, 12.4, 38.9 mg/l

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: a saturated solution was prepared. A dispersion of 100 mg/l prepared in dilution water was shaken with 110 rpm for 24 h at room temperature. After 24 h particles were removed by centrigugation at 3000 rpm for 20 min. 5 dilution levels of the saturated solution were tested.

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

Strain: CHODAT SAG 86.81

Study design

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Post exposure observation period:

6 d

Test conditions

Hardness:

0.24 mmol Ca+Mg/l

Test temperature:

21-24 +/- 2°C

pH:

8.0 +/-0.2

Dissolved oxygen:

n.a.

Salinity:

*

Nominal and measured concentrations:

A saturated solution of 100 mg/l was prepared by shaking with 110 rpm for 24 h at room temp. and centrifugation at 3000 rpm for 20 min. . 5 dilution levels were tested, corresponding to 0.288, 1.20, 4,00, 12.4 and 38.9 mg/l

Details on test conditions:

- Initial cells density: 2-5E3 cells/ml
- Control end cells density: 177333 cells/ml

- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes


- Light intensity and quality: 35-70 µE x mE-2 x sE-1 for 24 h per day


- Determination of cell concentrations: counted with an inverse microscope

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 38.9 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

cell number

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 38.9 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 3

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 38.9 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Results with reference substance (positive control):

- Results with reference substance valid? y
- EC50: rate-related inhibition: 0.74

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The difference of the rate-related inhibition and Yield inhibition measured for group A (test item dissolved in the test medium) and group B (test item solution above the algae cultures) is below 10%. Therefore the observed inhibition is caused by lack of light and not by direct intoxitation.
The test substance has no effect to the Yield inhibition and the Specific Growth Rate Inhibition of green algea until the limit of the solubility of 38.9 mg/l of the substance