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Diss Factsheets

Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Administrative data

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)
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Vehicle:
yes
Test organisms (species):
Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Test temperature:
24 degrees Celcius
pH:
7.6-8.6
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
15 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
5.3 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
cell number
Validity criteria fulfilled:
yes
Conclusions:
The effect of the test item on the growth of Pseudokirchneriella subcapitata has been investigated over a 72-Hour period and based on the geometric mean measured test concentrations gave the following results:
Response Variable EC50 (mg/L) 95% Confidence Limits (mg/L) No Observed Effect Concentration (NOEC) (mg/L) Lowest Observed Effect Concentration (LOEC) (mg/L)
Growth Rate 15 13-17 2.6 8.3
Yield 5.3 4.4-6.5 0.92 2.6
Executive summary:

Introduction

A study was performed to assess the effect of the test item on the growth of the green alga Pseudokirchneriella subcapitata.  The method followed was designed to be compatible with

the OECD Guidelines for Testing of Chemicals (2006) No 201, "Freshwater Alga and Cyanobacteria, Growth Inhibition Test" referenced as Method C.3 of Commission Regulation

(EC) No 761/2009.

Methods

Following a preliminary range-finding test, Pseudokirchneriella subcapitata was exposed to an aqueous solution of the test item at concentrations of 1.0, 3.2, 10, 32 and 100 mg/L (three replicate flasks per concentration) for 72 hours, under constant illumination and shaking at a temperature of 24 ± 1 °C.

Samples of the algal populations were removed daily and cell concentrations determined for each control and treatment group, using a Coulter® Multisizer Particle Counter.

Results

Chemical analysis of the test preparations at 0, 24 and 48 hours showed measured test concentrations to be near nominal.  A slight decline in measured test concentration was observed at 72 hours in the range of 67% to 75% of nominal.

Given this decline in measured test concentrations it was considered justifiable to base the results on the geometric mean measured test concentrations in order to give a "worst case" analysis of the data.   These were determined to be 0.92, 2.6, 8.3, 26 and 84 mg/L.

Exposure of Pseudokirchneriella subcapitata to the test item gave the following results based on the geometric mean measured test concentrations:

Response Variable        EC50 (mg/L)    95% Confidence Limits (mg/L)  No Observed Effect Concentration (NOEC) (mg/L) Lowest Observed Effect Concentration (LOEC) (mg/L) 
 Growth Rate  15 14 - 17  2.6    8.3
 Yield  5.3 4.4 - 6.5  0.92  2.6

Description of key information

The effect of the test item on the growth of Pseudokirchneriella subcapitata has been investigated over a 72-Hour period and based on the geometric mean measured test concentrations gave the following results:

Response Variable        EC50 (mg/L)    95% Confidence Limits (mg/L)  No Observed Effect Concentration (NOEC) (mg/L) Lowest Observed Effect Concentration (LOEC) (mg/L) 
 Growth Rate  15 14 - 17  2.6    8.3
 Yield  5.3 4.4 - 6.5  0.92  2.6 

Key value for chemical safety assessment

EC50 for freshwater algae:
5.3 mg/L

Additional information