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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
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
GLP guideline study with concentration control analysis. The analytically determined test concentrations at the end of the experiment were generally below the limit of detection. It is therefore expected that the effect concentrations relate to the hydrolysis product(s) of the test substance.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2011
Report Date:
2011

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test substance (as cited in study report): SPP100 PISA P2a
- Description: beige to light brown crystals
- Purity (%): 98.9

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
SAMPLING FOR ANALYSIS
- Samples for possible analysis were taken from all test concentrations and the control according to the schedule below. In addition, the filter used for preparation of the test concentrations was retained for possible analysis of the residue. The method of analysis is described in the appended Analytical Report.
- Frequency: at t=0 h, t=24 h and t=72 h
- Volume: 6 ml
- Storage: Samples were stored in a freezer until analysis.
- At the end of the exposure period, the replicates with algae were pooled at each concentration before sampling.

Test solutions

Details on test solutions:
PREPARATION OF TEST SOLUTIONS
- Preparation of test solutions started with a loading rate of 100 mg/l. After a 48-hour stirring period the obtained aqueous mixture was filtered through a 0.45 μm membrane filter (rc 55, Whatman). pH of the filtrate was adjusted from 3.4/3.5 to 6.5 using 1N NaOH (Merck, Darmstadt, Germany). The lower test concentrations were prepared by subsequent dilutions of the filtrate in test medium. The final test solutions were all clear and colourless.
- After preparation, volumes of 50 ml were added to each replicate of the respective test concentration. Subsequently, 1 ml of an algal suspension was added to each replicate providing a cell density of 10^4 cells/ml.
- The test substance was not completely soluble in test medium at the loading rates prepared.

Test organisms

Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
- Strain: NIVA CHL 1
- Origin: in-house laboratory culture

STOCK CULTURE
- Algae stock cultures were started by inoculating growth medium with algal cells from a pure culture on agar. The suspensions were continuously aerated and exposed to light in a climate room at a temperature of 21 - 24°C
- Light intensity: 60 to 120 µE/m2/s
- Stock culture medium: M1 according to the Nederlandse Praktijk Richtlijn no. 6505

PRE-CULTURE
- 3 days before the start of the test, cells from the algal stock culture were inoculated in culture medium at a cell density of 1 x 10^4 cells/ml. Pre-culture was maintained under the same conditions as used in the test. Cell density was measured immediately before use
- Pre-culture medium: M2 according to OECD 201

Study design

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

Test conditions

Test temperature:
21.8 - 23.7 °C
pH:
initial pH: 6.5 - 6.8
final pH: 4.7 - 6.4
Nominal and measured concentrations:
Nominal test concentrations: 1.0, 3.2, 10, 32 and 100% of a filtered solution prepared at a loading rate of 100 mg/l
Details on test conditions:
Replicates: 3 replicates of each test concentration
6 replicates of the control
1 extra replicate of each test concentration and the control for sampling purposes
2 replicates of the highest test concentration without algae
- Test vessels: 100 ml, all-glass, containing 50 ml of test solution
- Test medium: M2
- Cell density: initial cell density of 1 x 10^4 cells/ml
- Illumination: Continuously using TLD-lamps of the type 'cool-white' of 30 Watt, with a light intensity within the range of 86 to 92 µE.m-2.s-1
- Incubation: Vessels were distributed at random in the incubator. During incubation the algal cells were kept in suspension by continuous shaking
Reference substance (positive control):
yes
Remarks:
potassium dichromate

Results and discussion

Effect concentrations
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Results with reference substance (positive control):
EC50 (72 h) 1.2 mg/L based on growth rate

Applicant's summary and conclusion