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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Administrative data

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Study test phase 2013-08-13 to 2013-08-17.
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Meets the criteria for classification as reliable without restriction according to Klimisch et al (1997).

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2013

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
GLP compliance:
yes

Test material

Constituent 1
Chemical structure
Reference substance name:
lithium 3-((3,4-dicyanophenyl)thio)propane-1-sulfonate
EC Number:
700-787-7
Cas Number:
769953-18-6
Molecular formula:
C11H9N2O3S2Li
IUPAC Name:
lithium 3-((3,4-dicyanophenyl)thio)propane-1-sulfonate
Test material form:
solid: particulate/powder

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
- Sampling method: Samples for analysis were taken at 0h from the excess test solutions and at 72h from a single test replicate solution of each concentration (containing alga). Samples containing algae were analysed post centrifugation.

Test solutions

Vehicle:
yes
Details on test solutions:
A nominal 120 mg/L primary stock solution of test material was prepared by dissolving 0.240 g in 2000 mL of culture medium. This stock solution was stirred for 10 minutes using magnetic follower. The stock solution was observed to be clear and colourless.

One litre of each test solution was prepared by the addition of aliquots of primary stock solution to sterile culture medium to final volumes of 1000 mL. The resultant solutions were clear and colourless. The control consisted of culture medium only. The appropriate test solution (100 mL volume) was dispensed to each test and blank vessel.

Test organisms

Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
The test species was the unicellular green alga P. subcapitata blue green alga strain CCAP 278/4 from laboratory cultures maintained under axenic conditions. A 4 day old culture of the alga in the exponential growth phase was used as inoculum for the test. The culture was grown in the medium, and under the environmental conditions, described for the test.

Study design

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h

Test conditions

Test temperature:
22 +/-2 C
pH:
At the start of the test the pH ranged from 7.5 to 7.7 and at the end of the test the range was from 7.3 to 7.4. The maximum pH shift for the control replicates was 0.2.
Nominal and measured concentrations:
The limit of quantification in this study was 0.010 mg/l. The overall mean measured concentration ranged from 99 to 107% of the nominal values confirming that the test material was in solution. The nominal concentrations of test material were used in the calculating and reporting of the results.
Details on test conditions:
TEST SYSTEM
The test vessels were glass conical flasks of 250 mL nominal capacity closed with foam bungs. Each flask contained 100 mL of test solution. The cultures were incubated at 22 +/- 2°C (the nominal test temperature), under continuous "cool-white" illumination of approximately 6000 lux, with nominal orbital shaking at 160 rpm.

- Initial cells density: 5370 x104 cells/ml
- Control end cells density: 638000
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates):6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Culture medium different from test medium: no
- Intervals of water quality measurement: The pH of the control and test solutions was measured at the start of the test with a calibrated pH meter, using the excess remaining after filling the test vessels. At the end of the test the pH of one replicate vessel (containing algae) from each test concentration was determined. The temperature of the incubator was continuously monitored using an electronic recording system with hourly recording of values. The light intensity was measured once during the study, in each of four representative positions, using a photometer reading in lux (cosine).


OTHER TEST CONDITIONS
- Sterile test conditions: no
- Adjustment of pH: no
- Photoperiod: continuous
- Light intensity and quality: 'cool white' illumination of approx. 6000 lux.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: The algal cell densities of the inoculum and test cultures were determined by electronic particle counting, using a Coulter counter and counting at a lower threshold equivalent spherical diameter of approximately 2.3 µm. After 24, 48 and 72 hours, samples were removed from each test and blank vessel. The appropriate blank particle count was subtracted from that of the test culture to obtain the cell density.

TEST CONCENTRATIONS
- Test concentrations: 3.75, 7.5, 15, 30, 60 and 120 mg/l of test material
Reference substance (positive control):
no

Results and discussion

Effect concentrationsopen allclose all
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 120 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC20
Effect conc.:
66 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: 95% CL 53-75 mg/L
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
45 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: 95% CL 5.8-58 mg/L
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
30 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
60 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 120 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC20
Effect conc.:
> 120 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
97 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% CL 87-106 mg/L
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
30 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
60 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
- Exponential growth in the control : yes
- Observation of abnormalities: The microscopic observations made at test end showed that for the control and all test concentrations, the cells appeared normal.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The 72h EC50 was determined to be >120 mg/L, using biomass as a basis for effect. The 72h EC50, using growth rate as a basis for effect, was determined to be >120 mg/L.
Executive summary:

Introduction

This study was undertaken to assess the toxicity of the test material to the green alga P.subcapitata. The test method was designed to be compatible with the following guidelines:

- OECD Guidelines for Testing of Chemicals. Test Guideline 201, Freshwater Alga and Cyanobacteria, Growth Inhibition Test. Adopted 23 March 2006.

- Official Journal of the European Communities, L383 A, Part C.3, Algal Inhibition test. 29 December 1992.

Results & Conclusions

The 72h EC50 was determined to be >120 mg/L, using biomass as a basis for effect. The 72h EC50, using growth rate as a basis for effect, was determined to be >120 mg/L.