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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:
22 February 2010-25 February 2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: This study has been performed according to OECD and/or EC guidelines and according to GLP principles

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010
Report Date:
2010

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
no
Qualifier:
according to
Guideline:
ISO 8692 (Water Quality - Fresh Water Algal Growth Inhibition Test with Scenedesmus subspicatus and Selenastrum capricornutum)
Deviations:
no
Qualifier:
according to
Guideline:
other: Guidance document on aquatic toxicity testing of difficult substances and mixtures, OECD series on testing and assessment number 23, December 14, 2000.
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Name of test material (as cited in study report): 7-ADCA
- Substance type: White powder
- Physical state: Solid
- Analytical purity: 99.0%
- Lot/batch No.: D212013
- Expiration date of the lot/batch: 28 February 2011 (retest date)
- Stability under storage conditions: Stable
- Storage condition of test material: In refrigerator (2-8°C) in the dark
- Stability in water:Not indicated
- Solubility in water:0.1% (20°C)

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
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 solutions was retained for possible analysis of the residue.
Frequency: at t=0 h, t=24 h and t=72 h
Volume: 2 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.

Compliance with the Quality criteria regarding maintenance of actual concentrations was demonstrated by running a test vessel at the highest substance concentration but without algae and samples for analysis were taken at the start, after 24 hours of exposure and at the end of the test period.

Test solutions

Vehicle:
no
Details on test solutions:
The batch of 7-ADCA tested was a white powder with a purity of 99.0% and not completely soluble in test medium at the initial loading rate prepared.

Preparation of test solutions started with a loading rate of 100 mg/l applying a five-minute treatment period with ultrasonic waves followed by 2 days of magnetic stirring to reach maximum solubility of the test substance in the test medium. The resulting aqueous mixture was filtered through a 0.45 µm membrane filter (Whatman) and the clear and colourless filtrate was used as the highest test concentration. The lower test concentrations were prepared by subsequent dilutions of the filtrate in test medium.

Test organisms

Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Common name: Pseudokirchneriella subcapitata
- Strain: NIVA CHL 1
- Source (laboratory, culture collection): In-house laboratory culture
- Age of inoculum (at test initiation): 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 10E4 cells/ml.
- Method of cultivation: 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.

Study design

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

Test conditions

Hardness:
0.24mmol/l (24 mg CaCO3/l)
Test temperature:
between 23.1 and 23.9°C.
pH:
Between 6.1 - 8.1
Nominal and measured concentrations:
Nominal concentration:
0, 0.10, 1.0, 10 and 100% of a filtered solution prepared at a loading rate of 100 mg/l
Measured concentration:
Samples taken from the filtered solution prepared at a loading rate of 100 mg/l were analysed. Although the initial loading rate was not observed to be completely dissolved actual concentrations were in agreement with nominal during the test period (94-101%). No explanation for this apparent contradiction could be given. Given these analytical results effect parameters were based on the initially measured and stable concentration of 94 mg/l.
Details on test conditions:
TEST SYSTEM
- Type: open
- Material, size, headspace, fill volume: 100 ml, normal headspace, 50 ml
- Aeration: no
- Initial cells density: 10000 cells/ml
- Control end cells density: 981000 cells/ml
- No. of vessels per concentration (replicates): 6 for the highest concentration, 3 for the lower test concentrations
- No. of vessels per control (replicates): 6
GROWTH MEDIUM
- Standard medium used: yes
OTHER TEST CONDITIONS
- Sterile test conditions: no
- Adjustment of pH: no
- Photoperiod: continuous
- Light intensity and quality: TLD-lamps of the type ‘Cool-white’ of 30 Watt, with a light intensity within the range of 64 to 74 µE.m-2.s-1

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
72 h NOErC, 72 h NOEyC, 72 h ErC50, 72 h EyC50

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 10
- Test concentrations: 0, 0.10, 1.0, 10 and 100% of a filtered solution prepared at a loading rate of 100 mg/l

Results and discussion

Effect concentrationsopen allclose all
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
94 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
94 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
other: Yield
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 94 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 94 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
other: Yield
Details on results:
- Exponential growth in the control (for algal test): yes
- Effect concentrations exceeding solubility of substance in test medium: yes
No significant differences were recorded between the values for growth rate or yield at any of the test concentrations when compared to the control group.
Results with reference substance (positive control):
Potassium dichromate reduced growth rate of this fresh water algae species at nominal concentrations of 0.56 mg/l and higher.

The EC50 for growth rate reduction (ErC50: 0-72h) was 1.2 mg/l with a 95% confidence interval ranging from 0.77 to 2.0 mg/l.
The EC50 for yield inhibition (EyC50: 0-72h) was 0.44 mg/l with a 95% confidence interval ranging from 0.37 to 0.54 mg/l.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
Under the conditions of the present study with Pseudokirchneriella subcapitata, no reduction of growth rate or inhibition of yield was recorded at any of the concentrations of 7-ADCA tested.
The EC50 for both growth rate reduction (ErC50: 0-72h) and yield inhibition (EyC50: 0-72h) was >94 mg/l.
The NOEC for both growth rate reduction and yield inhibition was 94 mg/l.