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Toxicity to aquatic algae and cyanobacteria

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Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
February 2013
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Remarks:
Freie und Hansestadt Hamburg, Behörde für Soziales, Familie, Gesundheit und Verbraucherschutz
Analytical monitoring:
yes
Details on sampling:
- Concentrations: all concentrations were analysed
- Sampling method: samples of approx. 10 mL were taken at start and end of the test
- Sample storage conditions before analysis: samples were retained at -20 °C or colder until shipment for analysis
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION:
The test substance was dissolved in exposure medium by vigorously shaking the flask. The test started with a limit test at 100, 10, and 1.0 mg product/L (equal to 38.8, 3.9 and 0.39 mg a.i./L). For the main test, six concentrations arranged in a geometric series were selected (0.39, 1.2, 3.9, 12.2, 38.8 and 122.6 mg a.i./L).
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Common name: green algae
- Strain: Pseudokirchnerella subcapitata/61.81 SAG
- Source (laboratory, culture collection): Pflanzenphysiologisches Institut der Universität Göttingen, Sammlung von Algenkulturen, Göttingen, Germany
Maintanance of the culture: 23.0 – 23.4°C maintained in the air-conditioned chamber

ACCLIMATION
- Culturing media and conditions (same as test or not): yes
- Any deformed or abnormal cells observed: no
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Post exposure observation period:
none
Test temperature:
23.0 – 23.4°C
pH:
Control: 7.74 - 7.86 (main study)
Test bottles: 8.47 - 9.67
Nominal and measured concentrations:
Range finding test: 0, 0.39, 3.9, 38.8 mg a.i./L (nominal)
Main test: 0, 0.39, 1.2, 3.9, 12.2, 38.8 and 122.6 mg a.i./L (nominal)
The determination of the test item concentrations revealed actual concentrations of the test substance 82.6% to 132.1% of the nominal concentration. However, the concentration range of 0.39 to 1.2 mg/L was below the detection limit.
Details on test conditions:
TEST SYSTEM
- Test vessel: 250 mL conical flasks containing 100 mL of medium, continuously shaken on an orbital bottle shaker
- Aeration: no
- Initial cells density: 1 x 10^4 cells/mL
- Control end cells density: 1.3 x 10^8
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- prepared according to OECD guideline 201 in 5 L distilled and demineralised water

OTHER TEST CONDITIONS
- Sterile test conditions: all procedures were carried out taking the necessary sterility precautions
- Adjustment of pH: no
- Photoperiod: 24-hour white-type fluorescent lamp
- Light intensity and quality: 7200 lux (0.63 x 1020 photons/m2*s)

EFFECT PARAMETERS MEASURED:
- Determination of cell concentrations: counting chamber

TEST CONCENTRATIONS
- Range finding study: range finding test: 0, 0.39, 3.9, 38.8 mg a.i./L (nominal)
- Test concentrations: 0, 0.39, 1.2, 3.9, 12.2, 38.8 and 122.6 mg a.i./L (nominal)
Reference substance (positive control):
yes
Remarks:
Potassium dichromate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
8.64 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Remarks on result:
other: 95% confidence limits: 1.76 - 42.5 mg/L
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
0.95 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Details on results:
- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): no
- Unusual cell shape: no
- Colour differences: no
- Any stimulation of growth found in any treatment: no
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: no
- Effect concentrations exceeding solubility of substance in test medium: no
Results with reference substance (positive control):
The positive control substance potassium dichromate caused the expected effect on algal growth inhibition and demonstrated the sensitivity of the test system. An EC50 of 0.23 mg/L was calculated.

Inhibition of cell growth (main test):

Concentration

[mg a.i./L]

Inhibition of cell growth caused by C10AS

[%]

0

 

1

5.4

3.16

25.1

10

26.7

31.6

32.9

100

42.1

316

99.7

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
09 Jan - 12 Jan 1995
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
GLP compliance:
yes
Analytical monitoring:
yes
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Stock solution of 2.27 g test substance/L in VE-Water
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Strain: 86.81 SAG
- Source: originally obtained from Insitut für Wasser-, Boden- und Lufthygiene, Berlin, Germany, since then in-house culture
- Age of inoculum (at test initiation): 3 days
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Post exposure observation period:
not relevant
Hardness:
not reported
Test temperature:
22.6 - 22.9 °C
pH:
8.5 - 8.8 (measured at test start)
8.2 - 9.6 (measured at test end)
Dissolved oxygen:
not reported
Salinity:
not reported
Nominal and measured concentrations:
nominal: 0, 60, 100, 170, 300, 500 and 900 mg/L
measured geometric mean: 0, 34, 61, 103, 188, 297 and 511 mg/L
Concentration are given for anionic active substance.
Details on test conditions:
TEST SYSTEM
- Test vessel: Erlenmeyer flask
- Initial cells density: 2 * 10E4 cells/mL
- Control end cells density: 88 * 10E4 cells/mL
- No. of vessels per concentration (replicates): 5
- No. of vessels per control (replicates): 8

GROWTH MEDIUM
- Standard medium used: yes, according to EU C.3

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: VE water

OTHER TEST CONDITIONS
- Light intensity and quality: 8000 Lux (white)

EFFECT PARAMETERS MEASURED: number of cells after 0, 24, 48 and 72 h, cells per mL is calculated
- Determination of cell concentrations: absorption at 685 nm with photometer

Reference substance (positive control):
no
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 511 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Remarks:
anionic active substance
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
199 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Remarks:
anionic active substance
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
103 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Remarks:
anionic active substance
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
133 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Remarks:
anionic active substance
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
511 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Remarks:
anionic active substance
Basis for effect:
biomass
Details on results:
- Exponential growth in the control (for algal test): yes
Results with reference substance (positive control):
not reported
Reported statistics and error estimates:
- The NOEC was determined via t-test.
- EC50 calculation was conducted according to Probit analysis adapted from Cavalli-Sforza (1972)
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Remarks:
Summary of available data used for the endpoint assessment of the target substance
Adequacy of study:
key study
Justification for type of information:
Refer to the Category Approach Justification document provided in IUCLID6 Section 13.
Reason / purpose:
read-across source
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
8.64 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Remarks on result:
other: Source, key, 142-87-0, 2013
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
0.95 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Remarks on result:
other: Source, key, 142-87-0, 2013

Description of key information

72h EC50 (Pseudokirchneriella subcapitata, growth rate) = 8.64 mg/L (measured concentration, OECD 201)
72h EC10 (Pseudokirchneriella subcapitata, growth rate) = 0.95 mg/L (measured concentration, OECD 201)

Key value for chemical safety assessment

EC50 for freshwater algae:
8.64 mg/L
EC10 or NOEC for freshwater algae:
0.95 mg/L

Additional information

Since no reliable toxicity test with aquatic algae is available for Sulfuric acids, C9-11-iso-C10 rich, alkyl esters, sodium salt, in accordance to Regulation (EC) No. 1907/2006 Annex XI, 1.5 a read-across to other structurally related substances was conducted. As the toxicity of alkyl sulfates is dependent on the carbon chain length, it is expected that the toxic effects are comparable for the similar homologues.

One key study investigating the effects of C10AS Na (CAS 142-87-0) to the freshwater algae Pseudokirchneriella subcapitata is available (Innospec, 2013). The test was performed according to OECD guideline 201 and is GLP compliant. Growth inhibition caused by the test substance was determined after 24, 48 and 72 h of exposure to seven test concentrations up to 122 mg a.i./L (nominal concentrations were shown to be in accordance with the measured ones with recoveries of 82.6% to 132.1%). The results showed that the 72-hour EC50 value for growth rate was 8.64 mg/L and the EC10 value for growth rate was 0.95 mg/L.

Moreover, a supporting study investigating toxic effects of C8-isoAS Na (CAS 126-92-1) to freshwater algae Desmodesmus subspicatus is available (Elementis, 1995). The test was performed according to EU Method C.3 and is GLP compliant. Growth inhibition caused by the test substance was determined after 24, 48 and 72 h of exposure to five test concentrations up to 511 mg a.i./L (measured concentration equal to 900 mg a.i./L of nominal concentration). The results show that the 72-hour EC50 value for growth rate was above the highest test concentration of 511 mg a.i./L (measured concentration). The 72-hour EC10 value for growth rate was determined to be 199 mg a.i./L (measured concentration).

Due to structural and property similarities with the tested substance, it can be concluded that the above results apply also to Sulfuric acids, C9-11-iso-C10 rich, alkyl esters, sodium salt. The 72-hour EC50 value for growth rate is assumed to be 8.64 mg/L and the EC10 is 0.95 mg/L. Since the chronic EC10 value for algae is the lowest of all available results from three tropic levels (invertebrates, fish and algae), this value is further used for the PNEC freshwater calculation.