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EC number: 306-238-4 | CAS number: 96690-44-7
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
Toxicity to aquatic algae and cyanobacteria
Administrative data
Link to relevant study record(s)
- Endpoint:
- toxicity to aquatic algae and cyanobacteria
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- From March 12, 2018 to March 19, 2018
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)
- Deviations:
- yes
- Remarks:
- Deviations are minimal and which doesn’t have any impact on the outcome of the study.
- Qualifier:
- according to guideline
- Guideline:
- EU Method C.3 (Algal Inhibition test)
- Deviations:
- yes
- Remarks:
- Deviations are minimal and which doesn’t have any impact on the outcome of the study.
- GLP compliance:
- yes (incl. QA statement)
- Analytical monitoring:
- yes
- Details on sampling:
- At the start and at the end of the test, the content of the test substance in the test solutions was determined.
- Vehicle:
- yes
- Remarks:
- emineralised water enriched with minerals but without algae
- Details on test solutions:
- A stock solution containing 100.0 mg/L in algal medium (demineralised water enriched with minerals but without algae) was prepared. The lower treatments were prepared by dilution of this stock solution with algal medium.
- Test organisms (species):
- Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
- Details on test organisms:
- Specification:
Unicellular freshwater green alga.
Genus: Desmodesmus
Species: subspicatus
SAG Strain Number: 86.81
Taxonomic position: Chlorophyta - Chlorophyceae
Source and Culture
Source: The culture of Desmodesmus subspicatus was obtained in January 2016 by MBM Sci-encebridge GmbH (Institut für Pflanzenphysiologie of Universität Göttingen).
Culture: The algae are kept as stock culture on solid agar at 2 - 8 °C. From the stock culture, a permanent cul-ture was prepared. From an aliquot of the permanent culture, the pre-culture was pre-pared. - Test type:
- not specified
- Water media type:
- freshwater
- Total exposure duration:
- 72 h
- Test temperature:
- 19.2 – 22.4°C
- pH:
- 7.6 - 8.1
- Salinity:
- Fresh wter
- Nominal and measured concentrations:
- Nominal concentration: 0.32, 1, 3.2, 10 and 32 µg/L
Measured concentrations: < LOQ, < LOQ, < LOQ, 1.89, 4.98 and 19.30 µg/L respectively to nominal concentrations - Details on test conditions:
- Treatments tested: 0.32 / 1 / 3.2 / 10 / 32 µg/L nominal concentration. The concentrations to be tested based on non GLP pre-tests
Number of replicates:
6 replicates for the blank control
3 replicates for each treatment
Vessels: glass flasks total volume 65 mL
Duration: 72 h
Lighting:: 5000 lux
Temperature: 19.2 – 22.4 °C
Replicates (Blank control): 45 ±1 mL algal medium and alga
Replicates (Treatments): 45 ±1 mlL test solution and alga - Reference substance (positive control):
- yes
- Remarks:
- Potassium dichromate K2Cr2O7 (CAS No. 7778-50-9)
- Key result
- Duration:
- 72 h
- Dose descriptor:
- NOEC
- Effect conc.:
- 1.89 µg/L
- Nominal / measured:
- meas. (initial)
- Conc. based on:
- test mat.
- Basis for effect:
- other: Growth rate and yeild
- Key result
- Duration:
- 72 h
- Dose descriptor:
- EC50
- Effect conc.:
- 10.3 µg/L
- Nominal / measured:
- meas. (initial)
- Conc. based on:
- test mat.
- Basis for effect:
- growth rate
- Key result
- Duration:
- 72 h
- Dose descriptor:
- EC50
- Effect conc.:
- 4.08 µg/L
- Nominal / measured:
- meas. (initial)
- Conc. based on:
- test mat.
- Basis for effect:
- other: Yield
- Key result
- Duration:
- 72 h
- Dose descriptor:
- EC10
- Effect conc.:
- 2.68 µg/L
- Nominal / measured:
- meas. (initial)
- Conc. based on:
- test mat.
- Basis for effect:
- growth rate
- Key result
- Duration:
- 72 h
- Dose descriptor:
- EC10
- Effect conc.:
- 2.73 µg/L
- Nominal / measured:
- meas. (initial)
- Conc. based on:
- test mat.
- Basis for effect:
- other: Yield
- Results with reference substance (positive control):
- The results of the last study with the positive control K2Cr2O7 are presented below.
Biological Results of K2Cr2O7
Parameter Value 95% confidence interval
72h ErC50 0.90 mg/L 0.77 – 1.06 mg/L
72h EyC50 0.42 mg/L 0.35 - 0.51 mg/L - Validity criteria fulfilled:
- yes
- Conclusions:
- Under the study conditions, the 72 h EC10 were determined to be at 2.68 µg/L (growth rate) and 2.73 µg/L (yield) respectively. The 72 h EC50 were determined to be 10.30 (growth rate) and 4.08 µg/L (yield) respectively
- Executive summary:
A study was conducted to determine the short term toxicity of the test substance to the algae Desmodesmus subspicatus according to OECD Guideline 201 and EU Method C.3, in compliance with GLP. Algae were exposed to the test substance at nominal concentrations of 0, 0.32, 1, 3.2, 10 and 32 µg/L. Algal cell concentrations were determined spectrophotometrically. All the validity criteria were fulfilled. Analytical assessment was performed for the test substance in aqueous samples, at the beginning, mid and at the end of the test. Procedures and instrumentation were based on High Performance Liquid Chromatography combined with mass spectrometry (HPLC-MS/MS).The test substance was only detectable at the beginning of the test and in the top three concentrations. The measured concentrations lay between 50% and 60% of the nominal concentrations at the beginning of the test. During validation the test substance was stable under test conditions. In this study it might be possible that the measurable amount of test substance was biased by the test organism (ingestion or adsorption of test substance onto the algae cells). Nevertheless a clear dose-response relationship could be observed. Therefore, the biological results were based on the measured concentration at the beginning of the test. This is in agreement with the OECD Guideline. Significant inhibition of algal growth was observed at the top two concentrations. Inhibition of algal growth was also observed at the lowest tested concentration. This was caused probably due to contaminated test vessels because no inhibition occurred at the next higher concentration. This concentration was therefore not used for evaluation. Because significant inhibition of algal growth was observed only at the top two concentration, therefore, only the top three concentrations were used for statistical evaluation. Under the study conditions, the 72 h EC10 were determined to be at 2.68 µg/L (growth rate) and 2.73 µg/L (yield) respectively. The 72 h EC50 were determined to be 10.30 (growth rate) and 4.08 µg/L (yield) respectively (Muckle, 2018).
Reference
Results:
Cell uumbers: The cell numbers were determined with an electronic substance counter. The measns and standard deviations of the cell numbers of the blank control and the treatments are presented in the following table:
Cell Number/mL
Nominal Concentration in µg/L |
Parameter |
Cell Number/mL |
|||
0 h |
24 h |
48 h |
72 h |
||
Blank control |
Mean |
2000 |
7383 |
45433 |
304340 |
Blank control |
SD |
0 |
759 |
2225 |
12011 |
0.32* |
Mean |
2000 |
7147 |
34640 |
229193 |
0.32* |
SD |
0 |
843 |
2344 |
35138 |
1 |
Mean |
2000 |
8393 |
50933 |
299167 |
1 |
SD |
0 |
947 |
1781 |
11725 |
3.2 |
Mean |
2000 |
8360 |
49093 |
302160 |
3.2 |
SD |
0 |
625 |
2833 |
3120 |
10 |
Mean |
2000 |
7360 |
24500 |
81793 |
10 |
SD |
0 |
1129 |
3296 |
5307 |
32 |
Mean |
2000 |
5600 |
4187 |
8480 |
32 |
SD |
0 |
212 |
1157 |
503 |
SD = Standard Deviation
*Contamination is suspected. Excluded from evaluation Treatments 0.32 µg/L and 1 µg/L not used for statistical evaluation.
Light intensity: In the following table,the light intensity during the test is stated:
Light Intensity
|
0 h |
24 h |
48 h |
72 h |
Light intensity [Lux] |
5000 |
5000 |
5000 |
5000 |
pH values:
In the following table,the pH values measured at the start and the end of the test are stated:
pH values
Nominal Concentrationin µg/L |
0 h |
72 h |
Blank control |
7.6 |
8.1 |
0.32* |
7.6 |
8.1 |
1 |
7.6 |
8.2 |
3.2 |
7.6 |
8.3 |
10 |
7.6 |
7.8 |
32 |
7.6 |
7.6 |
*Contamination is suspected. Excluded from evaluation Treatments 0.32 µg/L and 1 µg/L not used for statistical evaluation
Microscopical observation:
In the following table, the appearance of the algae at the end of the test is stated:
Microscopical Observations
Nominal Concentrationin µg/L |
Normal and Healthy Appearance of the Algae |
Blank control |
Yes |
0.32* |
Yes |
1 |
Yes |
3.2 |
Yes |
10 |
Yes |
32 |
No cells visible |
*Contamination is suspected. Excluded from evaluation Treatments 0.32 µg/L and 1 µg/L not used for statistical evaluation
Analytical determination:
The test substance was only detectable at the beginning of the test and in the 3 highest concentrations. The measured concentrations lay between 50 % and 60 % of the nominal concentrations at the beginning of the test.
During validation the test substance was stable under test conditions. In this study it might be possible that the measurable amount of test substance was biased by the test organism (inges-tion or adsorption of test substance onto the algae cells). Nevertheless a clear dose-response relationship could be observed. Therefore, the biological results were based on the meas-ured concentration at the beginning of the test in the 3 highest concentrated treatments. This procedure is in agreement with the OECD guideline see point 40 on page 6.
The details are given in the following tables:
Measured Concentrations and % of Nominal
Nominal |
Measured concentrations |
Measured concentrations |
% of Nominal |
% of Nominal |
µg/L |
µg/L |
µg/L |
|
|
Blank control |
< LOQ |
< LOQ |
-- |
-- |
0.32 |
< LOQ |
< LOQ |
-- |
-- |
1 |
< LOQ |
< LOQ |
-- |
-- |
3.2 |
1.89 |
< LOQ |
58.93 |
-- |
10 |
4.98 |
< LOQ |
49.82 |
-- |
32 |
19.30 |
< LOQ |
60.32 |
-- |
LOQ (Limit of quantification) = 1 µg/L
Growth Rate, Yield
From the cell numbers, the Growth Rate µ and the Yield were calculated. The means and standard deviations at the end of the test are given in the following table:
Growth Rate µ, Yield
Nominal Concentration in µg/L |
Parameter |
Growth Rate (0-72h) [day-1] |
Yield (0-72h) |
Blank control |
Mean |
1.67 |
302340 |
SD |
0.01 |
12011 |
|
0.32* |
Mean |
1.58 |
227193 |
SD |
0.05 |
35138 |
|
1 |
Mean |
1.67 |
297167 |
SD |
0.01 |
11725 |
|
3.2 |
Mean |
1.67 |
300160 |
SD |
0.00 |
3120 |
|
10 |
Mean |
1.24 |
79793 |
SD |
0.02 |
5307 |
|
32 |
Mean |
0.48 |
6480 |
SD |
0.02 |
503 |
SD = Standard Deviation
*Contamination is suspected. Excluded from evaluation Treatments 0.32 µg/L and 1 µg/L not used for statistical evaluation
Inhibition:
The following mean inhibition values were calculated for the Growth Rate µ and the Yield.
Inhibition Values
Nominal concentration in µg/L |
% Inhibition |
|
Growth Rate (0-72h) |
Yield (0-72h) |
|
Blank control |
0 |
0 |
0.32* |
5.79 |
24.86 |
1 |
0.34 |
1.71 |
3.2 |
0.13 |
0.72 |
10 |
26.17 |
73.61 |
32 |
71.27 |
97.86 |
*Contamination is suspected. Excluded from evaluation Treatments 0.32 µg/L and 1 µg/L not used for statistical evaluation
Biological Results
The following values were determined:
Biological Results of the Test Substance
Parameter |
Value |
95% confidence interval |
NOEC (Growth Rate) 72 h |
1.89 µg/L |
-- |
NOEC (Yield) 72 h |
1.89 µg/L |
-- |
LOEC (Growth Rate) 72 h |
4.89 µg/L |
-- |
LOEC (Yield) 72 h |
4.98 µg/L |
-- |
72h ErC10 |
2.68 µg/L |
2.52 – 2.85 µg/L |
72h EyC10 |
2.73 µg/L |
1.76 – 4.22 µg/L |
72h ErC50 |
10.30 µg/L |
9.58 – 11.04 µg/L |
72h EyC50 |
4.08 µg/L |
2.60 – 6.53 µg/L |
Cell Numbers measured
Nominal Concentration in µg/L |
Cell Number/mL |
|||
0 h |
24 h |
48 h |
72 h |
|
Blank control |
100 |
367 |
2423 |
15490 |
100 |
425 |
2255 |
15177 |
|
100 |
401 |
2349 |
16089 |
|
100 |
360 |
2291 |
15083 |
|
100 |
337 |
2209 |
15220 |
|
100 |
325 |
2103 |
14243 |
|
0.32* |
100 |
406 |
1856 |
13035 |
100 |
332 |
1717 |
11779 |
|
100 |
334 |
1623 |
9565 |
|
1 |
100 |
398 |
2477 |
14362 |
100 |
387 |
2516 |
14979 |
|
100 |
474 |
2647 |
15534 |
|
3.2 |
100 |
438 |
2514 |
14935 |
100 |
434 |
2557 |
15151 |
|
100 |
382 |
2293 |
15238 |
|
10 |
100 |
385 |
1055 |
3864 |
100 |
414 |
1236 |
4023 |
|
100 |
305 |
1384 |
4382 |
|
32 |
100 |
276 |
195 |
395 |
100 |
292 |
273 |
437 |
|
100 |
272 |
160 |
440 |
*Contamination is suspected. Excluded from evaluation Treatments 0.32 µg/L and 1 µg/L not used for statistical evaluation
Cell Numbers calculated
Nominal Conc. in µg/L |
Replicate |
Cell Number/mL |
|||
0 h |
24 h |
48 h |
72 h |
||
Blank control |
1 |
2000 |
7340 |
48460 |
309800 |
2 |
2000 |
8500 |
45100 |
303540 |
|
3 |
2000 |
8020 |
46980 |
321780 |
|
4 |
2000 |
7200 |
45820 |
301660 |
|
5 |
2000 |
6740 |
44180 |
304400 |
|
6 |
2000 |
6500 |
42060 |
284860 |
|
Mean |
2000 |
7383 |
45433 |
304340 |
|
SD |
0 |
759 |
2225 |
12011 |
|
0.32* |
1 |
2000 |
8120 |
37120 |
260700 |
2 |
2000 |
6640 |
34340 |
235580 |
|
3 |
2000 |
6680 |
32460 |
191300 |
|
Mean |
2000 |
7147 |
34640 |
229193 |
|
SD |
0 |
843 |
2344 |
35138 |
|
1 |
1 |
2000 |
7960 |
49540 |
287240 |
2 |
2000 |
7740 |
50320 |
299580 |
|
3 |
2000 |
9480 |
52940 |
310680 |
|
Mean |
2000 |
8393 |
50933 |
299167 |
|
SD |
0 |
947 |
1781 |
11725 |
|
3.2 |
1 |
2000 |
8760 |
50280 |
298700 |
2 |
2000 |
8680 |
51140 |
303020 |
|
3 |
2000 |
7640 |
45860 |
304760 |
|
Mean |
2000 |
8360 |
49093 |
302160 |
|
SD |
0 |
625 |
2833 |
3120 |
|
10 |
1 |
2000 |
7700 |
21100 |
77280 |
2 |
2000 |
8280 |
24720 |
80460 |
|
3 |
2000 |
6100 |
27680 |
87640 |
|
Mean |
2000 |
7360 |
24500 |
81793 |
|
SD |
0 |
1129 |
3296 |
5307 |
|
32 |
1 |
2000 |
5520 |
3900 |
7900 |
2 |
2000 |
5840 |
5460 |
8740 |
|
3 |
2000 |
5440 |
3200 |
8800 |
|
Mean |
2000 |
5600 |
4187 |
8480 |
|
SD |
0 |
212 |
1157 |
503 |
SD = Standard Deviation
*Contamination is suspected. Excluded from evaluation Treatments 0.32 µg/L and 1 µg/L not used for statistical evaluation
Growth Rate µ
Nominal Conc. in µg/L |
Replicate |
Growth Rate µ [day-1] |
||
24 h |
48 h |
72 h |
||
Blank control |
1 |
1.30 |
1.59 |
1.68 |
2 |
1.45 |
1.56 |
1.67 |
|
3 |
1.39 |
1.58 |
1.69 |
|
4 |
1.28 |
1.57 |
1.67 |
|
5 |
1.21 |
1.55 |
1.68 |
|
6 |
1.18 |
1.52 |
1.65 |
|
Mean |
1.30 |
1.56 |
1.67 |
|
SD |
0.10 |
0.02 |
0.01 |
|
0.32* |
1 |
1.40 |
1.46 |
1.62 |
2 |
1.20 |
1.42 |
1.59 |
|
3 |
1.21 |
1.39 |
1.52 |
|
Mean |
1.27 |
1.43 |
1.58 |
|
SD |
0.11 |
0.03 |
0.05 |
|
1 |
1 |
1.38 |
1.60 |
1.66 |
2 |
1.35 |
1.61 |
1.67 |
|
3 |
1.56 |
1.64 |
1.68 |
|
Mean |
1.43 |
1.62 |
1.67 |
|
SD |
0.11 |
0.02 |
0.01 |
|
3.2 |
1 |
1.48 |
1.61 |
1.67 |
2 |
1.47 |
1.62 |
1.67 |
|
3 |
1.34 |
1.57 |
1.68 |
|
Mean |
1.43 |
1.60 |
1.67 |
|
SD |
0.08 |
0.03 |
0.00 |
|
10 |
1 |
1.35 |
1.18 |
1.22 |
2 |
1.42 |
1.26 |
1.23 |
|
3 |
1.12 |
1.31 |
1.26 |
|
Mean |
1.29 |
1.25 |
1.24 |
|
SD |
0.16 |
0.07 |
0.02 |
|
32 |
1 |
1.02 |
0.33 |
0.46 |
2 |
1.07 |
0.50 |
0.49 |
|
3 |
1.00 |
0.24 |
0.49 |
|
Mean |
1.03 |
0.36 |
0.48 |
|
SD |
0.04 |
0.14 |
0.02 |
SD = Standard Deviation
*Contamination is suspected. Excluded from evaluation Treatments 0.32 µg/L and 1 µg/L not used for statistical evaluation
Yield
Nominal Conc. in µg/L |
Replicate |
Yield [Cell Concentration/mL] |
72 h |
||
Blank control |
1 |
307800 |
2 |
301540 |
|
3 |
319780 |
|
4 |
299660 |
|
5 |
302400 |
|
6 |
282860 |
|
Mean |
302340 |
|
SD |
12011 |
|
0.32* |
1 |
258700 |
2 |
233580 |
|
3 |
189300 |
|
Mean |
227193 |
|
SD |
35138 |
|
1 |
1 |
285240 |
2 |
297580 |
|
3 |
308680 |
|
Mean |
297167 |
|
SD |
11725 |
|
3.2 |
1 |
296700 |
2 |
301020 |
|
3 |
302760 |
|
Mean |
300160 |
|
SD |
3120 |
|
10 |
1 |
75280 |
2 |
78460 |
|
3 |
85640 |
|
Mean |
79793 |
|
SD |
5307 |
|
32 |
1 |
5900 |
2 |
6740 |
|
3 |
6800 |
|
Mean |
6480 |
|
SD |
503 |
SD = Standard Deviation
*Contamination is suspected. Excluded from evaluation Treatments 0.32 µg/L and 1 µg/L not used for statistical evaluation
Inhibition Values at the end of the test (72 hours)
Nominal Conc. in µg/L |
Replicate |
Inhibition Growth Rate µ 72 hours |
Inhibition Yield 72 hours |
Blank control |
1 |
-0.37 |
-1.81 |
2 |
0.04 |
0.26 |
|
3 |
-1.12 |
-5.77 |
|
4 |
0.16 |
0.89 |
|
5 |
-0.02 |
-0.02 |
|
6 |
1.30 |
6.44 |
|
Mean |
0! |
0! |
|
SD |
0.79 |
3.97 |
|
0.32* |
1 |
3.07 |
14.43 |
2 |
5.08 |
22.74 |
|
3 |
9.23 |
37.39 |
|
Mean |
5.79 |
24.86 |
|
SD |
3.14 |
11.62 |
|
1 |
1 |
1.14 |
5.66 |
2 |
0.30 |
1.57 |
|
3 |
-0.42 |
-2.10 |
|
Mean |
0.34 |
1.71 |
|
SD |
0.78 |
3.88 |
|
3.2 |
1 |
0.36 |
1.87 |
2 |
0.07 |
0.44 |
|
3 |
-0.04 |
-0.14 |
|
Mean |
0.13 |
0.72 |
|
SD |
0.21 |
1.03 |
|
10 |
1 |
27.27 |
75.10 |
2 |
26.47 |
74.05 |
|
3 |
24.76 |
71.67 |
|
Mean |
26.17 |
73.61 |
|
SD |
1.28 |
1.76 |
|
32 |
1 |
72.66 |
98.05 |
2 |
70.65 |
97.77 |
|
3 |
70.51 |
97.75 |
|
Mean |
71.27 |
97.86 |
|
SD |
1.20 |
0.17 |
SD = Standard Deviation
*Contamination is suspected. Excluded from evaluation Treatments 0.32 µg/L and 1 µg/L not used for al evaluation
Description of key information
Key value for chemical safety assessment
- EC50 for freshwater algae:
- 0.01 mg/L
- EC10 or NOEC for freshwater algae:
- 0.003 mg/L
Additional information
A study was conducted to determine the short term toxicity of the test substance to the algae Desmodesmus subspicatus according to OECD Guideline 201 and EU Method C.3, in compliance with GLP. Algae were exposed to the test substance at nominal concentrations of 0, 0.32, 1, 3.2, 10 and 32 µg/L. Algal cell concentrations were determined spectrophotometrically. All the validity criteria were fulfilled. Analytical assessment was performed for the test substance in aqueous samples, at the beginning, mid and at the end of the test. Procedures and instrumentation were based on High Performance Liquid Chromatography combined with mass spectrometry (HPLC-MS/MS).The test substance was only detectable at the beginning of the test and in the top three concentrations. The measured concentrations lay between 50% and 60% of the nominal concentrations at the beginning of the test. During validation the test substance was stable under test conditions. In this study it might be possible that the measurable amount of test substance was biased by the test organism (ingestion or adsorption of test substance onto the algae cells). Nevertheless a clear dose-response relationship could be observed. Therefore, the biological results were based on the measured concentration at the beginning of the test. This is in agreement with the OECD Guideline. Significant inhibition of algal growth was observed at the top two concentrations. Inhibition of algal growth was also observed at the lowest tested concentration. This was caused probably due to contaminated test vessels because no inhibition occurred at the next higher concentration. This concentration was therefore not used for evaluation. Because significant inhibition of algal growth was observed only at the top two concentration, therefore, only the top three concentrations were used for statistical evaluation. Under the study conditions, the 72 h EC10 were determined to be at 2.68 µg/L (growth rate) and 2.73 µg/L (yield) respectively. The 72 h EC50 were determined to be 10.30 (growth rate) and 4.08 µg/L (yield) respectively (Muckle, 2018).
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