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Ecotoxicological information

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:
21 October 2016 to 4 October 2017 (experimental start and finish dates)
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reference:
Composition 0
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Version / remarks:
2011
Deviations:
no
Qualifier:
equivalent or similar to
Guideline:
EU Method C.3 (Algal Inhibition test)
Version / remarks:
2015
Deviations:
no
GLP compliance:
yes (incl. certificate)
Test material information:
Composition 1
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Batch no.of test material: 16020201
- Expiration date of the batch: 21/03/2021
- Purity: 99.56%
- Purity test date: 01/02/2016

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Room temperature
- Stability under test conditions: No data
- Solubility and stability of the test substance in the solvent/vehicle: No data
- Reactivity of the test substance with the solvent/vehicle of the cell culture medium: No dat

Analytical monitoring:
yes
Details on sampling:
- Concentrations: Control (blank), solvent control and nominal 1.0, 1.8, 3.2, 5.6 and 10 ug/L test concentrations sampled 0, 24 and 72h
- Sample storage conditions before analysis: All samples stored frozen (<= -15oC) until analysis. On the day of analysis, test samples were thawed to room temperature
Vehicle:
yes
Remarks:
Dimethylformamide (DMF)
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A nominal 100 mg/L stock solutions in DMF (dimethylformamide) was prepared, nominal 10, 18, 32 and 56 mg/L stock solution were prepared by dilution of 100 mg/L stock solution. Test solutions were prepared by addition of 100 uL of appropriate stock solution to 1 L slowly stirring test medium. All test solutions were stirred for approximately 15 mins prior to use.
- Eluate: M2 test medium, according to OECD 201
- Differential loading: No
- Controls: The control contained blank test medium only. The solvent control contained 100 ul/L of DMF in test medium
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): DMF (dimethylformamide)
- Concentration of vehicle in test medium (stock solution and final test solution(s) or suspension(s) including control(s)): 100 ul/L
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Strain: NIVA CHL 1
- Source (laboratory, culture collection): In-house laboratory culture
- Age of inoculum (at test initiation): 3 days
- Method of cultivation: 3 days before start of the test, cells from algal stock culture were inoculated in culture medium (1 x 10 4 cells/mL) and maintained under same conditions as used in the test

ACCLIMATION
- Acclimation period: Not applicable
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Hardness:
No data
Test temperature:
Incubator maintained within 22-24oC
pH:
0h: 8.0 - 8.2
72h: 7.7 - 7.8
Dissolved oxygen:
No data
Salinity:
No data
Conductivity:
No data
Nominal and measured concentrations:
Nominal: Blank control, solvent control, 1.0, 1.8, 3.2, 5.6 and 10 ug/L
Measured (TWA): 0.85, 1.1, 1.2, 1.4 and 1.4 ug/L, respectively. Blank control and solvent control were
Details on test conditions:
TEST SYSTEM
- Test vessel: 100 mL all-glass test vessels, capped
- Material, size, headspace, fill volume: 50mL test solution per test vessel
- Aeration: No
- Initial cells density: 1.0 x 10 4 cells/mL (nominal)
- Control end cells density: 208 x 10 4 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6
- No. of vessels per vehicle control (replicates): 6

GROWTH MEDIUM
- Standard medium used: Yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Milli-RO water
- Culture medium different from test medium: No
- Intervals of water quality measurement: No data

OTHER TEST CONDITIONS
- Sterile test conditions: yes/no
- Adjustment of pH: No
- Photoperiod: 24h
- Light intensity and quality: 60 - 120 uE/m2/s (nominal) when measured range 400-700nm

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: [counting chamber; electronic particle counter; fluorimeter; spectrophotometer; colorimeter] Microscope and counting chamber
- Chlorophyll measurement: No
Reference substance (positive control):
no
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
>= 1.4 µg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
>= 1.4 µg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
biomass

Nominal concn (ug/L)

TWA concn (ug/L)

Growth rate

Yield

0-72h

% inhibition

0-72h

% inhibition

Pooled control

<LoD

1.795

-

218.4

-

1.0

0.85

1.795

0

220.3

-1

1.8

1.1

1.836

-2

246.5

-13

3.2

1.2

1.854

-3

261.8

-20

5.6

1.4

1.882

-5

286.5

-31

10

1.4

1.839

-3

250.3

-15

TWA = Time Weighted Average

Validity criteria fulfilled:
yes
Conclusions:
The ErC50 (growth rate) and the EyC50 (yield / biomass) was determined to be >1.4 ug/L (based on time weighted average measured concentrations) under the conditions of the test. Due to the very low solubility of 4,4’-(1-phenylethane-1,1-diyl)bis(heptyloxybenzene) in the test medium, concentration levels that may be toxic for algae could not be reached. The laboratory confirmed that the test item was not completely soluble in the test medium at the loading rate initially prepared.
Executive summary:

In a 72-hour toxicity study the freshwater green alga, Pseudokirchneriella subcapitata, was exposed to a range of test conditions under static test conditions in accordance with the OECD 201 test guideline and in compliance with GLP. The nominal test concentrations were a control, a solvent control, 1.0, 1.8, 3.2, 5.6 and 10 ug/L. Results were calculated on the basis of time weighted average test concentrations.

Under the conditions of the test, the ErC50 (growth rate) and the EyC50 (yield) were determined to be >1.4 ug/L, based on time weighted average test concentrations.

Due to the very low solubility of 4,4’-(1-phenylethane-1,1-diyl)bis(heptyloxybenzene) in the test medium, concentration levels that may be toxic for algae could not be reached. The laboratory study report stated that the test item was not completely soluble in the test medium at the loading rate initially prepared.

This toxicity study is considered acceptable and satisfies the guideline requirements for a short-term toxicity study to aquatic algae.

Description of key information

In a reliable (Klimisch 1) 72-hour toxicity study the freshwater green alga, Pseudokirchneriella subcapitata, was exposed to a range of test conditions under static test conditions in accordance with the OECD 201 test guideline and in compliance with GLP.

Under the conditions of the test, the ErC50 (growth rate) and the EyC50 (yield) were determined to be >1.4 ug/L, based on time weighted average test concentrations. The EC50 and NOEC values are greater than the limit of solubility of the test substance.

The test validity criteria were met and there were no significant deviations noted to affect the integrity of the study. This toxicity study is considered acceptable and satisfies the guideline requirements for a short-term toxicity study to aquatic algae.

Key value for chemical safety assessment

EC50/LC50 for freshwater algae:
1.4 µg/L
EC10, LC10 or NOEC for freshwater algae:
1.4 µg/L

Additional information