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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Administrative data

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
08.10.2012 - 19.12.2013
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2013
Report Date:
2013

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Qualifier:
according to
Guideline:
ISO 8692 (Water Quality - Fresh Water Algal Growth Inhibition Test with Scenedesmus subspicatus and Selenastrum capricornutum)
GLP compliance:
yes (incl. certificate)
Remarks:
Deviation: The chemical analyses to verify test concentrations were not performed under GLP.

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
other: 51 % w/w solution in water, stabilized with X % NaOH
Details on test material:
- Substance type: Liquid
- Physical state: Light brown liquid
Specific details on test material used for the study:
Test material form: 51.0% w/w in water

PHYSICO-CHEMICAL PROPERTIES
- Boiling point: 107 °C
- Water solubility (under test conditions): > 1000 g/L
- pH 12-14
- log Pow: 1.67

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
- Concentrations: (Nominal) 0 (control); 20; 50; 100; 200; 500; 1,000 and 2,000 mg/L
- Sampling method: Samples were collected at test start, every 24 hours and at the end of the test for chemical analysis of the test product. Duplicate samples of 15 mL were collected in 20-mL plastic vials for later analysis. Only one of these samples were analysed. The spare samples were discarded after sponsor approved the report.
- Sample storage conditions before analysis: at - 20 ˚C ± 2.0˚C

Test solutions

Vehicle:
no
Details on test solutions:
A stock solution of 2,400 mg/L was prepared by weighing out 2,400 mg of the test product and dissolving it in 1 L of algal test medium. pH in the stock solutions was 9.3 and was therefore adjusted to 8.2 by adding 4 droplets of 1 M HCl. The test solutions were prepared by diluting the appropriate amounts of stock solution in algal test medium.
The test product was tested at the following nominal concentrations: 0 (control); 20; 50; 100; 200; 500; 1,000 and 2,000 mg/L.

Test organisms

Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
Clone: NIVA, CHL 1
The alga Pseudokirchnerella subcapitata is cultured at DHI under the test conditions prior to the start of the test. Algae from this culture were used in the study.

Study design

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

Test conditions

Test temperature:
23.2 ± 0.0˚C
pH:
8.0-8.1 at the beginning and 7.8-10.2 at the termination of the test.
Nominal and measured concentrations:
The results from the analysis showed a measured IBP1-Na concentration of 88-102% of the estimated nominal concentration of IBP1-Na. As the tested concentrations were maintained within ± 20% of the nominal concentrations, the statistical calculation were based on the nominal concentrations.
Details on test conditions:
TEST SYSTEM
- Material, size, headspace, fill volume: 250 mL glass flasks with wide neck, containing 100 mL of test solution
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6 (flasks with algae but no test product) + a blank of each concentration ( flasks with the test product but no algae)
Furthermore, one flask of the control and one flask of each test concentration without algae were used to collect samples for chemical analysis.

OTHER TEST CONDITIONS
- Adjustment of pH: Test media: from 9.3 to 8.2 by adding 1 M HCl
- Photoperiod: 72 hours
- Light intensity and quality: fluorescent light with an intensity of approx 60-120 μmol x m-2 x sec-1

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: Beckman Coulter Multisizer and in-vivo fluorescence, Turner TD-700 Laboratory Fluorometer

TEST CONCENTRATIONS
- Test concentrations (nominal): 0 (control); 20; 50; 100; 200; 500; 1,000 and 2,000 mg/L.
Reference substance (positive control):
yes
Remarks:
K2Cr2O7, CAS no 7778-50-9

Results and discussion

Effect concentrations
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
261 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Remarks on result:
other: (245-278) 95% confidence interval
Details on results:
- Exponential growth in the control (for algal test): yes
Results with reference substance (positive control):
- Results with reference substance valid? Yes
- EC50: 1.09 mg/L

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Remarks:
Growth rate = 1.9/day (> 1.4/day). Variation coefficient of control growth rates = 1.4 (< 5%). Mean var. coef. = 13.4% (<35%). Increase of pH > 1.5 unit from start to end for control, not considered significant. EC50 for ref. sub. = 1.09 (0.65-1.73)
Conclusions:
ErC50(72h) of the test substance, sodium O,O-diisobutyl dithiophosphate, CAS No. 53378-51-1 is 261 mg/L for Pseudokirchneriella subcapitata.
Remark: the test solution contains NaOH due to the production method.