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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2002-12-16 to 2003-01-30
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
OECD guideline study, GLP. Deviations to the updated OECD Guideline (adopted 2006): The coefficient of analysis of the daily growth rate in the control replicates and the coefficient of analysis of the average specific growth rates in the control replicates were not reported.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2002
Report Date:
2003

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Version / remarks:
adopted 1984
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
Version / remarks:
1992
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
For each test concentrations, samples were drawn from a pool of each corresponding replicate. They were taken at the beginning and the end of the exposure period. Samples were analysed for salicylaldehyde and for DOC (dissolved organic carbon).

Test solutions

Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method:
200 mg test item were weighed, dissolved in 2000 mL test medium. The stock solution was homogenised by ultrasonic treatement for about 10 minutes and then stirred for about 5 minutes. Due to the poor solubility of the test item, the not dissolved parts of the test item were separated by filtration (0.45 µm). The filtration was carried out under pressure with a flow rate not greater than 100 mL/min. The filter was preconditioned with 1000 mL of the stock solution. Aftenwards, the rest of the stock solution was filtrated and the filtrate taken to prepare the test concentrations. Additonally, due to the light sensitivity of the test item, the glass vessel was covered with aluminium foil.

- Control: 10 mL algae suspension were added in 490 mL test water. The solution was divided into 6 groups of 50 mL. 100 mL were placed into flasks for analytical determinations.
- Substance control: the test item was tested in the highest concentration without algae (particle background)

Test organisms

Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Strain: No. 61.81 SAG
- Source: SAG, Institute for Plant Physiology, University of Gottingen, D-37073 Gottingen, Germany
- Age of inoculum (at test initiation):The test was started (0 hours) by inoculation of 10,000 algal cells per mL of test medium. The algal cells were taken from an exponentially growing pre-culture which was set up about 72 hours prior to the test under the same conditions as in the test.
- Method of cultivation: cultivated and tested in synthetic test water, prepared according to the test guidelines.

ACCLIMATION
- Acclimation period: no data
- Culturing media and conditions (same as test or not): same
- Any deformed or abnormal cells observed: no

Study design

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

Test conditions

Test temperature:
between 23 °C and 24.5 °C
pH:
between 7.7 and 8.6
Nominal and measured concentrations:
Nominal: 4.3, 9.4, 21, 45, and 100 mg/L
Measured: < 0.12, 0.4, 5.6 and 15.6 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: 100 mL Erlenmeyer flasks, each with 50 mL algal suspension, sealed with a plug and continuously shaken with a lab shaker
- Aeration: no data
- Initial cells density: 10,000 algal cells per mL test medium.
- No. of vessels 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 algae were cultivated and tested in synthetic test water.
- Culture medium different from test medium: no
- Intervals of water quality measurement: The pH was measured in each test concentration and the control at the start and end of the test. The water temperature was measured daily in an Erlenmeyer flask filled with water and incubated under the same conditions as the test flasks.

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Light: continuous light, 116 (µE/m2s in the spectral range of 400-700 nm, measured at the end of the test with Quantum LI-189 light meter


EFFECT PARAMETERS MEASURED:
- Determination of cell densities: after 24, 48 and 72 hours. Samples of 1 mL test solution were taken out of the test flasks and the number of cells was counted with an electronic particle counter. Additionally, at the end of the test the shape of the algal cells was examined in the highest concentration still showing algal grovirth and in the control.
- Chlorophyll measurement: no


TEST CONCENTRATIONS
The test concentrations were based on the results of a range-finding test
Reference substance (positive control):
yes
Remarks:
potassium dichromate

Results and discussion

Effect concentrationsopen allclose all
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
39 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
9.4 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
21 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
25 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
4.3 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
9.4 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Details on results:
At the end of the exposure, the inhibition values corresponding to the endpoints biomass and growth rates were about 98% and 106%. Both biomass and growth rate gradients may have been caused by a metabolite activation.
Results with reference substance (positive control):
The quality of the algae is checked once within 3 months with the reference item potassium dichromate.
Reference control at 12.11.02 -15.11.02: EbC50 = 0.49 mg/L; ErC50 = 0.97 mg/L
Reported statistics and error estimates:
NOEC determined by Dunnett´s test and EC50 with probit analysis.

Applicant's summary and conclusion