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Toxicity to aquatic algae and cyanobacteria

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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):
Pseudokirchneriella subcapitata (previous names: Raphidocelis 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:
EL50
Effect conc.:
0.98 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
0.27 mg/L
Nominal / measured:
nominal
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 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 0.98 0.82-1.2 0.10 0.32
Yield 0.27 0.22-0.34 0.10 0.32
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 that described in 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

Due to the low aqueous solubility and complex nature of the test item for the purposes of the test the test item was prepared as a Water Accommodated Fraction (WAF).

Following preliminary range-finding tests, Pseudokirchneriella subcapitata was exposed to Water Accommodated Fractions (WAFs) of the test item over a range of nominal loading rates of 0.032, 0.10, 0.32, 1.0 and 3.2 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

Analysis of the test preparations at 0 hours showed measured test concentrations to range from 0.017 to 1.6 mg/L whilst measured concentrations in the range of 0.013 to 1.6 mg/L were obtained at 72 hours.

Given that the toxicity cannot be attributed to a single component or a mixture of components but to the test item as a whole, the results were based on nominal loading rates only.

Exposure of Pseudokirchneriella subcapitata to the test item 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  0.98 0.82 - 1.2  0.10    0.32
 Yield  0.27

0.22 - 0.34

 0.10

 0.32 

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 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              0.98       0.82-1.2                     0.10                            0.32

Yield              0.27       0.22-0.34                     0.10                            0.32

Key value for chemical safety assessment

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