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Toxicity to aquatic algae and cyanobacteria

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Reference
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
6 - 27 Mar 2012
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP guideline study with acceptable restrictions
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
- Concentrations: Samples were taken from all test concentrations at the beginning of exposure and 1, 5, 24, 48 and 72 hours after exposure.
- Sampling method: Collected in the middle layer of the vessel
Vehicle:
yes
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Stock solution I was prepared by dissolving 195 mg test substance in tetrahydrofuran to a concentration of 3900 mg/L. Stock solution II was obtained by taking 400 µL of stock solution I and adding tetrahydrofuran to a final volume of 20 mL, resulting in a concentration of 78 mg/L. Stock solution III was obtained by taking 200 µL of stock solution II and adding medium to a final volume of 2200 mL, resulting in a concentration of 0.0078 mg/L
- Controls: The solvent control was prepared by adding 200 µL tetrahydrofuran in medium to a final volume of 2000 mL. Additionally, a control without solvent or test material was prepared.
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): tetrahydrofuran
- Concentration of vehicle in test medium (stock solution and final test solution): 100 µL/L
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Common name: unicellular green algae
- Strain: ATCC22662
- Source (laboratory, culture collection): American Type Culture Collection; received 20 June 1996
- Method of cultivation: Algae have been maintained by period subculture using Gorham medium. Algae are kept under sterile conditions. Sterile test has been performed periodically, every six months, to confirm that the algae are not contaminated.

PRECULTURE
- Preculture period: 2 - 6 March 2012
- Culturing media and conditions (same as test or not): same as test
- Any deformed or abnormal cells observed: Neither modified nor unusual cells were obseved.
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Test temperature:
22 ± 2 °C
pH:
7.8 - 10.3
Nominal and measured concentrations:
Nominal: 0.0078 mg/L
Mean measured (TWA 0-48 h): 0.000202 mg/L
Mean measured (TWA 0-72 h): 0.000170 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel:
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: 500 mL Erlenmeyer flask, fill volume 0.1 L
- Initial cells density: 5000 cells/mL
- Control end cells density: 533000 cells/mL
- No. of vessels per concentration (replicates): 6
- No. of vessels per control (replicates): 6
- No. of vessels per vehicle 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: pH at the beginning an after 72 hours; temperature at least once a day

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: no
- Photoperiod: continuous illumination
- Light intensity and quality: 60 to 65 µE/m2/s white fluorescent lamp

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: electronic particle counter, at 24, 48 and 72 hours
- Other: The color of the test cultures was observed by comparison with the extra vessel of each test group at 0, 24, 48 and 72 hours. At 72 hours appearance of algae was observed through the microscope.

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: 0.0078 mg/L
- Results used to determine the conditions for the definitive study: It was confirmed that the concentrations of the test substance were decreased. It was estimated that the main reason for decrease was volatilisation. It was confirmed that the concentration of the test substance adjusted to ten times as many as the solubility in dilution water could be kept up to 2% at 72 hours and growth inhibition of algae could not be observed.
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 0 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: no effect up to the limit of water solubility
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: no effect up to the limit of water solubility
Details on results:
- No significant difference in growth rate was observed between the control ant the treatment group
- By microscopic observation at the end of exposure, neither unusual shape of algae nor agglutination was observed.
Results with reference substance (positive control):
ErC50 (72 h) = 0.878 mg/L (95% confidence limit: 0.828-0.931 mg/L)
exposure period: 16 - 19 Dec 2011
Reported statistics and error estimates:
The NOEC value was determined by Student's t-test (alpha=0.05), subsequent to F test for homogeneity of variances (alpha=0.05).
Executive summary:

One study is available on the toxicity of3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl 2-chloropropenoic acid ester (CAS 96383-55-0)to algae. The study was conducted as a limit test according to the OECD guideline 201 and GLP (Niino, 2012). As the test substance is poorly soluble in water, the test was performed at the highest concentration that could be attained under test conditions. Tetrahydrofuran was used as a solvent for the preparation of the test solutions. The test organismPseudokirchneriella subcapitatawas exposed to the test concentration of 0.0078 mg/L (nominal) for 72 hours. At the end of the exposure period, no significant difference in growth rate was observed between the control and the treatment group. The EC50 (72h) was therefore determined to be above the test concentration, corresponding to a measured value of > 0.00017 mg/L. 

Description of key information

Up to the highest attainable concentration no EC50 could be reached.

72h-EC50 > 0.00017 mg/L based on growth rate (OECD 201, Pseudokirchneriella subcapitata)

72h-NOEC = 0.00017 mg/L (OECD 201, Pseudokirchneriella subcapitata)

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:
0 mg/L

Additional information

One study is available on the toxicity of 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl 2-chloropropenoic acid ester (CAS 96383-55-0) to algae. The study was conducted as a limit test according to the OECD guideline 201 and GLP (Niino, 2012). As the test substance is poorly soluble in water, the test was performed at the highest concentration that could be attained under test conditions. Tetrahydrofuran was used as a solvent for the preparation of the test solutions. The test organism Pseudokirchneriella subcapitata was exposed to the test concentration of 0.0078 mg/L (nominal) for 72 hours. At the end of the exposure period, no significant difference in growth rate was observed between the control and the treatment group. The EC50 (72h) was therefore determined to be above the test concentration, corresponding to a measured value of > 0.00017 mg/L. 

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