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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
Study period:
2009-05-26 till 2009-07-03
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study
Reason / purpose for cross-reference:
reference to same study
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
yes
Details on sampling:
- direct injection
- The samples were analysed immediately.
Vehicle:
no
Details on test solutions:
- direct weighing
- 124.7 mg of the test item in 1 litre of dilution water
- The pH was measured to be pH 4.8 and was adjusted to pH 7.8.
- 80 mL of the prepared solution were taken and diluted with 10 mL nutrient medium and 10 mL algal inoculum with a cell density of 5000 cells/mL resulting in a final nominal concentration of 100 mg/L.
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
- Name : Desmodesmus subspicatus (formerly Scenedesmus subspicatus) Strain No. 86.81 SAG
- Source : Strain of the test species obtained from 'The Collection of Algal Cultures' of the Institute of Plant Physiology at the University of Göttingen (Germany).
- Maintenance and Acclimatisation : Exponentially-growing stock cultures were maintained in the test facility under constant temperature conditions (23 +/- 2°C) at a light intensity in the range 60 – 120 μE. x m-2 x s-1 (measured in the range 400 to 700 nm using a spherical quantum flux meter). The nutrient medium (according to BRINGMANN & KÜHN (1977) was renewed once a week. Cell density measurements were made using a microcell- counter, Sysmex F300, Digitana.
- Preparation of pre-cultures : Pre-cultures were set up three days before the start of a test. They were grown under identical exposure conditions as the stock cultures, except from the use of a different nutrient medium .
- Test cultures : The algal inocula for a test were taken from an exponentially-growing pre-culture and were mixed with the nutrient medium to make up to a final cell density of about 5000 cells per millilitre in the test medium.
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Hardness:
1.3°dH (22.5 mg/L CaCO3)
Test temperature:
21 - 25°C +/- 2°C
pH:
8.3 - 9.0
Nominal and measured concentrations:
- nominal: control and 100 mg/L
- measured: <3.2269 mg/L and 100.2 - 100.9 mg/L
Details on test conditions:
- A range-finding (non-GLP) test preceded the main test and provided information about the range of concentrations which were used in the main test. The following nominal concentrations of the test item were tested in the range-finding test: 1 , 10 and 100 mg/L.
- Test vessels : 300 mL Erlenmeyer flasks with cotton stoppers
- Culturing apparatus : Light chamber in which a temperature in the range 21°C to 25°C was maintained at +/- 2°C, and continuous uniform illumination was provided in the spectral range 400 to 700 nm. Temperature was measured and recorded daily in a water filled flask which was incubated under the same conditions as the test flasks.
- Light intensity : At the average of the test solutions, a light intensity in the range 60 to 120 μE. x m-2 x s-1, or an equivalent range of 4000 to 8000 lx, was used. Light intensity was checked before start of the study.
- Cell density measurements : Cell densities were measured in a microcell counter (Sysmex F300, Digitana) by taking small aliquots from each test flask for measurements, which were not replaced .
- Experimental design : 1 test concentration plus 1 control
6 replicates per concentration, 6 replicates per control
Initial cell density in the test cultures approximately 5000 cells per millilitre
- Test item concentration/s : 100 mg/L
- Method of administration : direct weighing
- Duration of exposure : 72 hours
Criteria of effects : The criteria of adverse effects used in this study were the item-induced inhibition of yield [y] and growth rate [r], respectively, of the algal population.
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: Test concentration was analytically confirmed.
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
>= 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
The results are expressed in terms of nominal concentrations. Recovery rates ranged from 100.5 % of nominal values at 0 hours, and from 100.9 % of nominal values at 72 hours, respectively.
Validity criteria fulfilled:
yes
Executive summary:

The acute toxicity of Ethane-1,2 -diol, propoxylated, to Alga (Desmodesmus subspicatus former name: Scenedesmus subspicatus) was tested according to EU method C.3 'Alga, Inhibition Test' (2009). During 72 hours exposure an EC50 of >100 mg/L was measured and a NOEC of >=100 mg/L was calculated (Currenta, 2009).

Description of key information

The acute toxicity of Ethane-1,2 -diol, propoxylated, to Alga (Desmodesmus subspicatus former name: Scenedesmus subspicatus) was tested according to EU method C.3 'Alga, Inhibition Test' (2009). During 72 hours exposure an EC50 of >100 mg/L was measured and a NOEC of >=100 mg/L was calculated (Currenta, 2009).

Key value for chemical safety assessment

Additional information

The acute toxicity of Ethane-1,2 -diol, propoxylated, to Alga (Desmodesmus subspicatus former name: Scenedesmus subspicatus) was tested according to EU method C.3 'Alga, Inhibition Test' (2009). During 72 hours exposure an EC50 of >100 mg/L was measured and a NOEC of >=100 mg/L was calculated (Currenta, 2009).