Registration Dossier

Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Currently viewing:

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:
OECD Guideline 201 (Alga, Growth Inhibition Test)
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
The concentrations of the test item in the test medium were measured by DOC analysis at the beginning and after 24 and 48h of exposure
Vehicle:
no
Details on test solutions:
following test flasks were set up:•Test solution (Tn); containing test medium, test item and algae (three replicate samples per test concentration)•Blank control (Bn); containing test medium and algae (six replicate samples)Since the test item is soluble, the test solutions were prepared by respective dilutions of a stock solution (test item dissolved in Algal medium) with algal medium. The pH of the test solutions was adjusted (pH 8.0 ± 0.2) after what the test solutions was sterile filtered (0.45 µm aPES membrane Rapid-Flow, Thermo Scientific) into sterile test flasks. Finally, each flask (containing the resulting sterile test medium) was inoculated with an exponentially growing preculture of algae.Pure Algal medium, also sterile filtered into sterile test flasks and inoculated with the exponentially growing preculture of algae mentioned above, served as blank controls.For the incubation, the test flasks was then placed on an orbital shaker at a nominal shaking speed of about 130 revolutions per min.
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
Test organism: Axenic slope culture of Desmodesmus subspicatus 86.81 SAG (Collection of Algal Cultures, Institute of Freshwater Ecology, University of Göttingen, D-37073 Göttingen, GermanyCulture: 250 ml flask containing 100 ml of sterile OECD medium (Table 2) inoculated with cell material from an axenic slope cultureIllumination: Continuous (2000–3000 lux) from Osram Fluora L18W77 and Osram Daywhite L18W840 (Osram AG, Winterthur, Switzerland)Temperature: 21 to 24°C, maintained at ± 2°C in a thermo-controlled roomControl of sensitivity: Not conducted – the culture is re-purchased annually.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Test temperature:
21-24°C maintained at +/-2°C in the thermo-controlled room
pH:
Initially adjusted to 8 ± 0.2; the pH of the control medium should not increase by more than 1.5 units during the test
Nominal and measured concentrations:
nominal concentrations: 1.02, 2.56, 6.40, 16.0 and 40.0 mg/lmeasured geometric means (0-72h): 0.70, 1.76, 6.12, 10.9 and 20.3 mg/l
Details on test conditions:
Test vessels: 250 ml flasks, all-glass, with 100 ml of test medium, shaken (about 130 rpm)Test medium: Recommended OECD medium Preculture: Exponentially growing liquid culture of Desmodesmus subspicatusCell densityCell concentrations are determined every 24 h using a spectrophotometer at 680 nm wavelength (Shimadzu UV 1800, Shimadzu Schweiz GmbH, Römerstr. 3, CH-4153 Reinach). Aliquots of 5 ml were removed from each test flask under sterile conditions. Cell concentrations at time 0 h were only determined in the blank controls. pHDetermined in the medium batch which was used for the preparation of the test solutions, in each test solution before filtration into each test vessel, and in the blank control and the highest concentration at the end of the test.TemperatureDetermined with a data logger in an additional vessel in the incubation chamber several times per day.LightMeasured at the start and the end of the test at several points over the whole incubation area.IlluminationSource: continuous from Osram Fluora L 18W77 and Osram Daywhite L 18W840 (Osram AG, Winterthur, Switzerland)Light intensity : the light intensity amounts to about 3000 lux which corresponds to about 40 μE•m-2•s-2 Homogeneity: the light intensity is maintained within ±15% from the average light intensity over the incubation area. The test vessels are repositioned every day within the incubation area to minimize variation.Starting cell density0.5–0.85 µg/ml with respect to dry weight corresponding to about 2–5•103 cells/ml (i.e. OD680 of about 0.005 units)
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
ca. 6.29 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
ca. 2.76 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
ca. 1.41 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
ca. 1.17 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Basis for effect:
biomass
Validity criteria fulfilled:
yes
Conclusions:
The substance was tested for toxicity to aquatic algae following OECD 201. Under the experimental conditions the 72h, ErC50 is equal to 6.26 mg/l.
Executive summary:

The effective concentrations (ErCxand EyCx) as well as the no observed effect concentrations (NOErC and NOEyC) of test item to the green alga Desmodesmus subspicatus based on the average specific growth rate and the yield (algal biomass production) were investigated over a period of 72 h according to the test guideline OECD 201.

Since the test item is well soluble, the test media were prepared by respective dilutions of a stock solution

The investigated nominal concentrationswere 40.0, 16.0, 6.40, 2.56 and 1.02 mg/l. Pure Algal medium served as blank controls.

Three parallel test vessels were used for each test concentration of the test item and six vessels forthe blank controls.

The concentrations of the substance in the test media were measured by DOC analysis at the beginning and after 24, 48 and 72 h of exposure. The analyses revealed that the concentrations did not remain within the 80-120% of the nominal concentration over the 72 h test period. Consequently, the effective concentrations (ECx) were assessed based on the geometric mean of the measured concentrations.

The 72 h ErC50of test item toDaphnia magnais 6.29 mg/l (95% confidence interval: 4.97–7.69 mg/l). This result is based on measured concentrations.

All validity criteria were fulfilled.

Description of key information

OECD 201, EC50r, 72h, Desmodesmus subspicatus = 6.29 mg/l

Key value for chemical safety assessment

Additional information

The substance was tested for toxicity to aquatic algae following OECD 201 (Ricci, 2016). Under the experimental conditions the EC50r, 72h is equal to 6.29 mg/l