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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:
1992-08-25 to 1993-01-20
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Non-GLP-guideline study. 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. No analytical confirmation.
Qualifier:
according to
Guideline:
other: 87/302/EEC page 89-94 Algal growth inhibition test
Deviations:
no
GLP compliance:
no
Analytical monitoring:
no
Vehicle:
yes
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: 2.0 g of test substance and and 18 g of a 0.4% vehicle solution (Akropal) were mixed together by means of marble-mill for about 24 hours. 1 ml of this blend were mixed and made up to 1000 ml with water achieving a concentration of 100 mg/L
- Controls: Blank control: water, vehicle control: 3.6 mg Akropal/L
- Chemical name of vehicle: alcyl-phenol-polyglycol-ether (Akropal)
- Evidence of undissolved material (e.g. precipitate, surface film, etc): at concentrations of 3.7, 11, 33 and 100 mg/L small parts of the test substance were observed on the surface of the test water .
- Concentration of vehicle in test medium: 0.4 % Akropal (stock solution)
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Strain: Green algae (Scenedesmus subspicatus)
- Source (laboratory, culture collection): Collection of algae cultures, Pflanzenphysiologisches Institut, Universitiy, Nikolausberger Weg 18, 3400 Göttingen, Germany
- Method of cultivation: according to guideline

ACCLIMATION
- Acclimation period: preculture 3 days under test conditions
- Culturing media and conditions (same as test or not): preculture under test conditions
- Any deformed or abnormal cells observed: none reported
Test type:
static
Water media type:
freshwater
Limit test:
no
Test temperature:
22 ± 2°C
pH:
7.9 - 9.8
Nominal and measured concentrations:
Nominal: 1.23, 3.7, 11, 33, 100 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: Erlenmeyer flask
- Type (delete if not applicable): stoppered with aluminium caps, on Lab-shaker
- Material, size, headspace, fill volume: 100 ml Erlenmeyer flasks filled with 50 ml test solution
- Initial cells density: 10500 cells/ml
- Control end cells density: mean cell density after 72 h per ml: 209.8
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6
- No. of vessels per vehicle control (replicates): 3

GROWTH MEDIUM
- Standard medium used: yes, according to cited guideline

TEST MEDIUM / WATER PARAMETERS
- Intervals of water quality measurement: temperature was continously measured, pH was measured at 0h and 72h

OTHER TEST CONDITIONS
- Photoperiod: continously
- Light intensity and quality: Flourescent light, approx. 8000 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: "TOA" cell counter

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3
Reference substance (positive control):
no
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Details on results:
- Exponential growth in the control: yes
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: at testconcentrations 3.7, 11, 33 and 100 mg/l small parts of the test substance were swimming on the surface of the test water after 72 hours of exposure
- Effect concentrations exceeding solubility of substance in test medium: yes
Reported statistics and error estimates:
The EbC50 values were calculated according to the maximum likelihood method, robit model (Mc Cullagh, P., Nelder, J.A., 1983: Generalized linear models, Chapman & Hall, London)

Description of key information

With high probability not toxic to aquatic algae and cyanobacteria. No toxic effects occur in the range of water solubility. 

Key value for chemical safety assessment

Additional information

In a 72 hour acute toxicity study, the cultures of Scenedesmus subspicatus were exposed to the test item at nominal concentrations of 0, 1.23, 3.77, 11, 33 and 100 mg/L under static conditions in accordance with the EEC guideline 302/87 (1987). The EbC50 values after 72 hours of exposure based on cell number were > 100 mg/L and the NOEbC values after 72 hours of exposure based on cell number were 100 mg/L. 

This toxicity study is classified as acceptable and satisfies the guideline requirements for OECD 201 toxicity study.