[Name confidential or not available]

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study and GLP

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2009

Report date:

2009

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Deviations:

yes

Remarks:

, see "prinicples of method if other than guideline"

Principles of method if other than guideline:

ln OECD Guideline 201 and EU Method C.3, different compositions of stock solution ll are
stated. The study was conducted in accordance with OECD Guideline 201, therefore, the
composition of stock solution ll must be stated as deviation from EU Method C.3.

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Sampling and analysis

Analytical monitoring:

yes

Test solutions

Vehicle:

yes

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Study design

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

3.8 µg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: limit of water solubility

Effect concentrations 2

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

> 3.8 µg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: limit of water solubility

Effect concentrations 3

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 3.8 µg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: limit of water solubility

Any other information on results incl. tables

Two experiments were performed.

In the first experiment, the measured values were lower than expected and in the chromatograms,

a contamination with another test item was observed. Therefore, the experiment

was repeated. In the second experiment, a higher concentrated stock solution was used to

prepare a test solution in the range of water solubility. The results of the first experiment

aren't reported.

The main study was performed as a limit test using one concentration in the range of water

solubility. The water solubility was determined as approximately 8 µg/L. At the start and at

the end of the test, the content of the test item in the test solutions was determined using

GC. ln both experiments the measured values at the start of the test were in the same

range (about half of the water solubility). That means the solubility of the test item in algae

medium enriched with nutrient medium and algae was lower than the solubility in water. As

the test item wasn't stable in under test condilions, the measured concentrations test item

after72 hours were lower than LOQ.

The treatment was used to incubate the unicellular freshwater green algae Desmodesmus

subspicatus for a period of 72 hours. The cell concentration of each replicate was determined

by measuring the absorption of the cuvettes at 440 nm every 24 hours with a spectral

photometer. With these measured values, the number of cells was calculated (linear

correlation between cell concentration and absorption given). Then the growth rate, the

area under the growth curve (AUC) and the Yield were determined.

The determination of the results was based on the measured start concentration.

The EC50s of potassium dichromate was tested in a current reference test. The values

were within the normal range of the laboratory.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

Allvalidity criteria were met.
The EC50s of potassium dichromate were determined in a current reference test. For the
estimation of the EC50s of the positive control, the fits showed sufficient statistical correspondence
of the data with the dose-response-equation. The values were within the normal
range of the laboratory as well as in correspondence with the values from the international
ring testwhich are stated in EU Method C.3.
The study was performed as a limit test in the range of water solubility. The water solubility
was determined as approximately 8 µg/L. To produce a test solution in the range of water
solubility, a stock solution containing 100 mg/L test item in methanol was used for the
preparation of the test solution (0.1 ml/L) in the first experiment. The measured concentration
at the beginning was lower than expected (about half of water solubility). Therefore the
experiment was repeated using a stock solution containing 200 mg/L.
The measured concentration in the second experiment was in the same range. The lower
measured values might be caused by lower solubility of test item in algae medium enriched
with nutrient medium and alga.
In the both experiments, no inhibition could be observed.
The result of the test can be considered valid.