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Toxicity to aquatic algae and cyanobacteria

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Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
disregarded due to major methodological deficiencies
Study period:
1992-12-01 to 1992-12-04
Reliability:
3 (not reliable)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Non GLP study. Deviations from the updated OECD Guideline (adopted 2004). Only 24h exposure, vehicle use allowed testing of concentrations well above the limit of water solubility (5-7 µg/L). .The test substance did not completely dissolve. New reliable test results available (see key study).
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
Version / remarks:
1987
Deviations:
no
GLP compliance:
no
Analytical monitoring:
no
Vehicle:
yes
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
2.01 g test substance and 18 g of a 0.4% Lecithin mixture were mixed together by means of a marble-mill during about 24 hours.
1 ml of this blend were mixed and made up to 1000 ml with water achieving a test substance concentration of 100 mg/L.
- Evidence of undissolved material (e.g. precipitate, surface film, etc): yes; small parts of the test substance were swimming on the surface of the test water at all test concentrations at 0 h and at concentrations 11, 33, and 100 mg/L after 72 h of exposure. Also a small deposit was observed at test concentration 100 mg/L at h and at concentrations 33 and 100 mg/L after 72 h of exposure.
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Common name: Green Algae
- Origin: Pflanzenphysiologisches Institut, University, Nikolausberger Weg 18, D-3400 Gottingen, Germany

- Preculture: 3 d under test conditions
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Test temperature:
23 + or - 1 °C
pH:
7.8 to 8.2
Nominal and measured concentrations:
nominal: 1.23, 3.7, 11, 33, and 100 mg test substance/L
Details on test conditions:
TEST SYSTEM
- Test vessel: 100 ml Erlenmeyer flasks, stoppered with aluminium caps, on Lab-shaker
- Type (delete if not applicable): closed
- Fill volume: 50 ml test solution
- Aeration: none
- Initial cells density: 11,000 cells/ml
- Control end cells density: 1,732,000 cells/ml
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6
- No. of vessels per vehicle control: 3

GROWTH MEDIUM
- Standard medium used: yes

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

OTHER TEST CONDITIONS
- Photoperiod: continuous illumination
- Light intensity and quality: cold white fluorescent light, 120 µE/m^2 sec (approx. 8000 lux)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: Cell densities were measured at 24, 48 and 72 hours exposure on a "TOA" cell counter

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3
- Test concentrations: 1.23, 3.7, 11, 33, 100 mg/L (nominal)
Reference substance (positive control):
no
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
41 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
cell number
Remarks on result:
other: calculated according to Berkson, Jasa 48 (1953), 569-599; 95% CL: none
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
11 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
cell number
Details on results:
- Other: Strong effects of vehicle after 48h and 72h
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: yes; test substance was not fully dissolved
- Effect concentrations exceeding solubility of substance in test medium: yes
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2002-05-17 to 2002-05-24
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Version / remarks:
adopted 1984
Deviations:
no
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
Name: TK 10049
Batch No.: BV 0082899S
Purity: Approx. 98 % (commercial)
Aggregate state at room temperature: solid
Color: white to greyish
Storage conditions: at room temperature at about 20 °C, away from direct sunlight.
Analytical monitoring:
no
Vehicle:
no
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
The test organism used for the study was Scenedesmus subspicatus CHODAT, Strain No. 86.81 SAG, supplied by the Sammlung von Algenkulturen Goettingen (SAG, Experimentelle Phykologie und Sammlung von Algenkulturen, Albrecht-von-Haller-lnstitut fuer Pflanzenwissenschaften, Universitat Goettingen, D-37073 Goettingen, Germany).
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Hardness:
0.24 mmol/L (= 24 mg/L) as CaCO3
Test temperature:
23 °C
pH:
start of the test: 8.0 (test medium), 8.1 (control)
end of the test: 9.3 (test medium and control)
Nominal and measured concentrations:
100 mg/L nominal (loading rate of a filtrate of a supersaturated dispersion)
Details on test conditions:
TEST SYSTEM
- Test vessel: 50 mL Erlenmeyer flasks covered with glass dishes
- Fill volume: 15 mL
- Aeration: none
- Initial cells density: 10,000 algal cells per mL test medium (0 hours)
- Control end cells density: 870,000 cells/mL (72 hours)
- No. of vessels per concentration (replicates): 3 replicates per test concentration
- No. of vessels per control (replicates): six replicates of the control

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Culture medium different from test medium: no
- Intervals of water quality measurement: at test start and at test end

OTHER TEST CONDITIONS
- Photoperiod: continuous illumination
- Light intensity and quality: 8030 Lux (mean value), range: 7330 to 8600 Lux (minimum and maximum value of measurements)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: Small volumes of the test medium and the control (1.0 mL) were taken out of all test flasks after 24, 48, and 72 hours exposure, and were not replaced. The algal cell densities in the samples were determined by counting with an electronic particle counter (Coulter Counter®, Model ZM), with at least two measurements per sample. In addition, after 72 hours exposure, a sample was taken from the control and from the single test concentration. The shape of the algal cells was microscopically examined.
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
cell number
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
cell number
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
cell number
Details on results:
- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): no
- Effects in the range of water solubility of the substance in test medium: No

Description of key information

With high probability acutely not harmful to aquatic algae and cyanobacteria. 

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 a limit concentration of 100 mg/L under static conditions in accordance with the OECD Guideline 201 (1984).  The NOEC and EC50 values based on cell number were >= 100 mg/L. No inhibitory effects could be recorded.

A disregarded 72 hour acute toxicity study according to EEC-guideline no. 302/87 on cultures of Scenedesmus subspicatus revealed an EbC50 of 41 mg/L. The compound was solubilized with an emulsifier and parts of the compound were present as a suspension.