[No public or meaningful name is 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

Study period:

From 2 November 2006 to 16 March 2007

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study, GLP compliant; no restrictions, fully adequate for assessment

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2007

Report date:

2007

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:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

Two samples of the solvent control and each replicate test vessel were taken at 0 hours. One sample was analysed untreated and one sample after centrifugation (40000 g for approximately 30 minutes). Further samples (in duplicate) were taken at 0 hours and stored at approximately -20ºC for further analysis if necessary. In order to ensure sufficient sample volume for analysis at 72 hours two additional test replicates were prepared at 0 hours and incubated alongside the test. At 72 hours two samples of the solvent control and the test group were taken for analysis. One sample was analysed untreated and one sample after centrifugation (40000 g for approximately 30 minutes).

Test solutions

Vehicle:

yes

Details on test solutions:

During the definitive test samples of the test preparations were analysed untreated and following centrifugation at 40000 g for 30 minutes. The
untreated samples indicated the total amount of test material present in the test preparations whilst the centrifuged samples indicated the amount of soluble and hence bioavailable test material present.

Analysis of the untreated test preparations at 0 hours showed measured test concentrations to range from 100% to 119% of nominal thereby indicating that the test system was correctly dosed. Analysis of the centrifuged test preparations showed measured test concentrations to range from 63% to 74% of nominal.

Analysis of both the untreated and centrifuged test preparations at 72 hours showed a decline in measured test concentrations in the range of 67% to 76% of nominal for the untreated test samples and 37% to 39% of nominal for the centrifuged test samples.

Given that the preliminary stability analyses conducted indicated that the test material was stable in culture medium over the test period this decline in measured concentrations was considered to be due to possible adsorption of the test material to the algal cells present. Whilst the preliminary recovery analyses conducted in the presence of algal cells indicated that no immediate adsorption occurred this does not preclude long-term adsorption over the test period. Adsorption was not a factor in the preliminary stability analyses since no algal cells were present.

Given this decline in measured test concentrations it was considered justifiable to base the results on the geometric mean measured test concentrations of the centrifuged test media in order to give a "worst case" analysis of the data.

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

Liquid cultures of Desmodesmus subspicatus were obtained from the Culture Collection of Algae and Protozoa (CCAP), Dunstaffnage Marine Laboratory, Oban, Argyll, Scotland. Master cultures were maintained in the laboratory by the periodic replenishment of culture medium. The master cultures were maintained in the laboratory under constant aeration and constant illumination at 21 ± 1°C.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Post exposure observation period:

None

Test conditions

Hardness:

Not determined

Test temperature:

24 ± 1ºC, recorded daily

pH:

Determined at start and at 72h: 7.6-7.8

Dissolved oxygen:

Not determined

Nominal and measured concentrations:

Nominal: 0.0015 mg/l
Mean measured: 0.00076 mg/l
See also 'Details on test solutions'

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Type: covered
- Material, size, headspace, fill volume: 250 ml glass conical flask plugged with polyurethane foam bungs

- Type of flow-through (e.g. peristaltic or proportional diluter):
- Renewal rate of test solution (frequency/flow rate):
- Initial cells density: 3370 cells/ml
- No. of vessels per concentration (replicates): 6
- No. of vessels per control (replicates): 6
- No. of vessels per vehicle control (replicates): 6


GROWTH MEDIUM
- ASTM


OTHER TEST CONDITIONS
Maintained under constant illumination at approximately 7000 lux, 24 ± 1°C, constant aeration, constant shaken

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 0.001 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.002 mg/L

Nominal / measured:

nominal

Effect concentrations 3

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 0.001 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 4

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.001 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Effect concentrations 5

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.001 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Results with reference substance (positive control):

Sensitivity to control substance
ErC50 (0-72 h) : 0.58 mg/l
EbC50 (0-72 h) : 0.20 mg/l
EyC50 (0-72 h): 0.16 mg/l