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Ecotoxicological information

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
Study period:
The study was conducted between 19 July 2013 and 3 August 2013
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:

Description: Clear colourless liquid
Batch: 20130510
Purity: Not applicable - complex mixture
Expiry date: 10 May 2018
Storage conditions: Room temperature in the dark
Analytical monitoring:
yes
Details on sampling:
The concentration and stability of the test item in the test preparations were verified by chemical analysis at 0 and 72 hours.
Vehicle:
no
Details on test solutions:
Range-finding test:
The loading rate to be used in the definitive test was determined by a preliminary range-finding test. The range finding test was conducted by exposing Pseudokirchneriella subcapitata cells to nominal loading rates of 10 and 100 mg/L for a period of 72 hours.

The results showed no effect on growth at 10 and 100 mg/L loading rate WAF. Based on this information a single loading rate of six replicates of 100 mg/L was selected for the definitive test.

Definitive test:
An amount of test item (250 mg) was addd to the surface of 2.5 litres of culture medium to give the 100 mg/L loading rate. After the addition of the test item, the culture medium was stirred by magnetic stirrer using a stirring rate such that a vortex was formed to give a dimple at the water surface. the stirring was stopped after 71 hours and the mixture allowed to stand for 1 hour. The aqueous phase or WAF was removed by mid-depth siphoning to give the 100 mg/L loading rate WAF. Microscopic inspection of the AF showed no micro-dispersions or undissolved test item to be present.

An aliquot of the WAF was innoculated with algal suspension (6.4 mL) to give the required test concentration of 100 mg/L loading rate WAF.
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
The test was carried out using Pseudokirchneriella subcapitata strain CCAP 278/4.
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Post exposure observation period:
None
Hardness:
Not measured
Test temperature:
24 ± 1 ºC
pH:
7.5 to 8.0
Dissolved oxygen:
Not measured
Salinity:
Not measured
Conductivity:
Not measured
Nominal and measured concentrations:
Nominal: 100 mg/L loading rate WAF
Measured: 0.048 mg/L at the start of the test and 0.0054 mg/L at 72 hours.

Results based on nominal loading rates only.
Reference substance (positive control):
no
Key result
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
NOELR
Effect conc.:
100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EL10
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EL20
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EL10
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: Yield
Duration:
72 h
Dose descriptor:
EL20
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: Yield
Key result
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: Yield
Key result
Duration:
72 h
Dose descriptor:
NOELR
Effect conc.:
100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: Yield
Details on results:
From the results it is clear that the growth rate and yield of Pseudokirchneriella subcapitata (CCAP 278/4) were not affected by the presence of the test item over the 72-hour period.

It was considered unnecessary and unrealistic to test at loading rates in excess of 100 mg/L.
Reported statistics and error estimates:
There were no statistical significance differences (P ≥ 0.05) between the control and 100 mg/L loading rate WAF test group.
Validity criteria fulfilled:
yes
Conclusions:
The effect of the test item on the growth of Pseudokirchneriella subcapitata has been investigated and gave EL50 values of greater than 100 mg/L loading rate WAF. The No Observed Effect Loading Rate was 100 mg/L loading rate WAF.
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) 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 a preliminary range-finding test, Pseudokirchneriella subcapitata was exposed to a WAF of the test iteam, at a single nominal loading rate of 100 mg/L (six replicate flasks) for 72 hours, under constant illumination and shaking at a temperature of 24 ± 1 ºC.

Samples of the algal populations were removed daily and cell concentrations determined for each control and treatment group.

Results

Exposure of Pseudokirchneriella subcapitata to the test item gave EL50 values of greater than 100 mg/L loading rate WAF. The No Observed Effect Loading Rate was 100 mg/L loading rate WAF.

Analysis of the 100 mg/L loading rate WAF test preparation at 0 hours showed a measured test concentration of 0.048 mg/L was obtained. A decline in measured test concentration was observed at 72 hours to 0.0054 mg/L.

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

Description of key information

The effect of the test item on the growth of Pseudokirchneriella subcapitata has been investigated and gave EL50 values of greater than 100 mg/L loading rate WAF. The No Observed Effect Loading Rate was 100 mg/L loading rate WAF.

Key value for chemical safety assessment

EC50 for freshwater algae:
100 mg/L
EC10 or NOEC for freshwater algae:
100 mg/L

Additional information