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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:
10.10.2008-14.11.2008
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
GLP compliant guideline study. The test was conducted in closed system to reduce evaporation with the addition of sodium bicarbonate to counteract the increase in pH due to algal growth in an enclosed system. Due to the volatile nature of the test material, the results was calculated using the geometric mean measured test concentrations.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2009

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Principles of method if other than guideline:
The test was conducted in 250 ml glass conical flasks each completely filled with test preparation and sealed with a ground glass stopper to reduce evaporation and minimise losses due to the volatile nature of the test material. Sodium bicarbonate (500 mg/l) was added to counteract the increase in pH due to algal growth in an enclosed system.
GLP compliance:
yes (incl. certificate)
Remarks:
UK, Department of Health, 15 October 2007

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): TAEE (tert-amyl ethyl ether, CAS No 919-94-8)
- Description: clear colourless liquid
- Analytical purity: 99,4 %
- Date received: 26.9.2008
- Batch number: 00931302
- Storage conditions: room temperature

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
Samples were taken from the control and each test group at 0 and 72 hours for quantitative analysis by gas chromatography. Duplicate samples were taken at 0 and 72 hours and stored at approximately -20 C for further analysis if necessary.

Test solutions

Details on test solutions:
The stock solutions and each of the prepared concentrations were inverted several times to ensure adequate mixing and homogeneity. The control group was maintained under identical conditions but not expsed to the test material. The test was conducted in completely filled, stoppered test vessels in order to minimise possible losses due volatilisation.

Test organisms

Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Common name: Green alga
- Strain: CCAP 278/4
- Source (laboratory, culture collection): Culture collection of Algae and Protozoa (CCAP), Dunnstaffnage Marine Laboratory, Oban, Argyll, Scotland
- Method of cultivation: The master cultures were maintained in the laboratory at 21 +/- 1 C under constant aeradation

Study design

Test type:
static
Water media type:
freshwater
Total exposure duration:
72 h

Test conditions

Test temperature:
24 +/- 1 C
pH:
7.5 +/- 0.1
Nominal and measured concentrations:
Nominal: 62.5, 125, 250, 500, 1000 mg/l
Measured: 36, 67, 154, 358, 853 mg/l (geometric mean measured concentration)
Details on test conditions:
TEST SYSTEM
- Test vessel:
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: 250 ml conical flasks, completely filled and stopped
- Aeration: No
- Sodium bicarbonate (500 mg/l) was added to system
- Initial cells density: 4000 cells/ml
- Control end cells density: 625000 cells/ml
- No. of organisms per concentration (replicates): 3
- No. of vessels per control (replicates): 6


GROWTH MEDIUM
- Standard medium used: yes


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: The culture medium was prepared using reverse osmosis purified deionized water.
- Culture medium different from test medium: No
- Intervals of water quality measurement: pH was recorded in the beginning and in the end of the test, temperature was monitored daily

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: yes
- Photoperiod: continous illumination
- Light intensity and quality: 7000 lux


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: Coulter Multisizer Particle Counter

TEST CONCENTRATIONS
- Spacing factor for test concentrations: The preliminary range-finding test was performed to determinate the test concentrations
- Range finding study
- Test concentrations: 1, 10, 100 and 1000 mg/l
- Results used to determine the conditions for the definitive study: Based on the results of the range finding test the following nominal concentrations were assigned to the definitive test: 62.5, 125, 250, 500, 1000 mg/l

Results and discussion

Effect concentrationsopen allclose all
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
160 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: 95%CL: 130-200 mg/L. EbC50 refers to effects on biomass production
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
67 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
36 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
340 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% CL: 280-410 mg/L. ErC50 refers to effects on growth rate
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
67 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
36 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
170 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
other: yield
Remarks on result:
other: 95% CL: 140-200 mg/L. EyC50 refers to effects on cell yield.
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
36 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
other: yield
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
36 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
other: yield
Details on results:
- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): None detected
Results with reference substance (positive control):
- Results with reference substance valid? Yes. Potassium dichromate was used as the reference material (positive control). Pseudokirchneriella subcabitata was exposed to an aqueous solution of the reference material at concentrations of 0.25, 0.50, 1.0, 2.0, and 4 mg/l (three replicates)
- EC50: 1.2 mg/l
- The results from the positive control with potassium dichromate were within the normal range for this reference material

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The results from an acute toxicity to algae gave a EbC50 of 160 mg/l (after 72 hours period). The Lowest Observed Effect Concentration based on biomass production was 67 mg/l, and the No Observed Effect Concentration was 36 mg/l.
Executive summary:

Short-term toxicity of the test material toward an aquatic green algae Pseudokirchneriella subcabitata was determined in GLP compliant laboratory according to OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test). The test (static) was conducted with three replicates and an initial cell density of 4000 cells per ml over 72 hour at 20 C and constant illumination. The test vessels were completely filled and sealed with ground glass stopper to minimise evaporative losses from the system. Additional test replicate was prepared at 0 hours and incubated alongside the test to provide samples for unopened vessel analysis at 72 hours. The decline in measured test concentrations was observed and it was considered justifiable to base the results on the geometric mean measured test concentrations (36, 67, 154, 358 and 853 mg/l) in order to give a "worst case" analysis of data. The test material gave on an EbC50 value of 160 mg/l (after 72 hours period). The Lowest Observed Effect Concentration based on biomass production was 67 mg/l, and the No Observed Effect Concentration was 36 mg/l. Based on these data, TAEE is not acutely toxic to algae (EC50 >100 mg/l).