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
Study period:
16 Oct 2017 - 22 May 2018
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)
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
Concentrations of the test material were determined by treating aqueous samples with formic acid, then extracting with hexane. The extracts were diluted with hexane as required to bring the response within the calibration range. Samples were analysed by injection onto a gas chromatography / mass spectrometry (GC/MS) system.
At the start of the test (0 hours), ca 20 mL samples of freshly prepared test media were taken from control, 1.0, 3.2, 10, 32 and 100% saturated solution test media preparation flasks for chemical analysis.
At 72 hours, replicate test vessels at each treatment level were pooled and sampled. Samples (ca 20 mL) of each were taken for chemical analysis. At each sampling occasion, duplicate samples were taken. One sample for the initial analysis and one stored as “back-up”.
Vehicle:
no
Details on test solutions:
The dilution media used was EC medium as described in the OECD 201 Test Guideline.
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Common name: Pseudokirchneriella subcapitata
- Strain: 278/4
- Source (laboratory, culture collection): Culture Collection of Algae and Protozoa (CCAP)
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Hardness:
18 mg caCl 2H2O
Test temperature:
23-23.5 °C
pH:
7.6 - 8.9
Nominal and measured concentrations:
Nominal Measured values in mg/L
% 0 h 72 h geom. mean
saturated
solution
--------------------------------------------------------------
Control - - -
1.0 0.000308 0.000125** 0.000196
3.2 0.000599 0.00117 0.000837
10 0.00593* 0.000640 0.00195
32 0.00119 0.00032 0.000617
100 0.00350 0.00116 0.00202
--------------------------------------------------------------

- None found above limit of quantification (LOQ) of 0.000025 mg/L
* Mean of two results (0.00729 and 0.00456 mg/L)
** ½ LOQ value used as 72 hour result was found to be below the LOQ
Details on test conditions:
Preparation of Test Medium
The dilution media used was EC medium as described in the OECD 201 Test Guideline.
At the start of the definitive test, the 100% saturated solution test concentration was prepared by weighing 100.03 mg of test substance into a glass vial, the test substance was then added to 1000 mL of EC medium. This was then stirred for ca 24 hours, after stirring the media was filtered through 0.45 μm filters, discarding the first 100 mL filtered, the remaining concentrations were prepared using a serial dilution from the top concentration. A control treatment was prepared by adding EC medium only to the control vessels.

Test Vessel Preparation
The test vessels were sterile autoclaved glass 250 mL Erlenmeyer (conical) flasks, into which 100 mL of the appropriate control or test media was added. Sterile foam bungs were used to cover the top of the vessels.
Each test and control vessel was inoculated with sufficient Pseudokirchneriella subcapitata cells to achieve a starting algae cell concentration of 1 × 10^4 cells/mL. An additional inoculated vessel was prepared for the control and each test concentration for initial water quality analysis.

Test Vessel Sampling
At approximately 24-hour intervals after the start of the incubation period, pre-determined volumes of test media (1.0 mL at 24 hours and 0.5 mL at 48 and 72 hours) were removed from each incubated test vessel, and transferred to individually identified cell counting vials. The contents of each vial were diluted to a 10 mL final volume with an electrolyte solution. The cell density of the vial contents was then determined using a particle counter (Z2 Coulter Counter®).
Reference substance (positive control):
yes
Remarks:
Potassium dichromate,
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 0.002 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: nominal > 100 mg/L
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 0.002 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
other: yield
Remarks on result:
other: nominal > 100 mg/L
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
>= 0.002 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: limit of solubility
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
>= 0.002 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
other: Yield
Remarks on result:
other: = limit of solubility
Results with reference substance (positive control):
The 72-hour EC50 values for Yield, Area Under the Growth Curve and Growth Rate were determined to be 0.599, 0.604 and 0.875 mg/L, respectively. The 72-hour NOEC value for Yield, Area Under the Growth Curve and Growth Rate were determined to be 0.32, <0.1 and 0.32 mg/L, respectively.
Validity criteria fulfilled:
yes
Conclusions:
The results indicated that there was no toxicity at the limit of solubility of the test substance in the test media. Based on geometric mean measured concentrations, the 72-hour ErC50 and the 72-hour NOEC values were determined to be > 0.00202 mg/L and >= 0.00202 mg/L (nominal 100 mg/L), respectively.

Description of key information

Based on geometric mean measured concentrations, the 72-hour ErC50 and the 72-hour NOEC values were determined to be > 0.00202 mg/L and >= 0.00202 mg/L (nominal 100 mg/L), respectively.

Key value for chemical safety assessment

Additional information