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Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

effects on growth of green algae

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From February 20 to 26, 2021

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Batch number: CN0191205
Purity: 98.3%

Analytical monitoring:

yes

Details on sampling:

Samples were taken for analysis from the freshly prepared solutions at 0 hour and the old solutions at 72 hours.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The test solutions were prepared by dilution of a stock solution. A stock solution of test item at a nominal concentration of 100 mg/L was prepared with OECD alga growth medium. 0.1003 g of test item was weighed and dissolved in 1000 mL of growth medium by magnetic stirring for about 24 hours. After magnetic stirring, undissolved test item was observed in the solution, the solution was filtered through a 0.45 μm filter membrane and the filtrated solution was used as the highest concentration (100% of 100 mg/L). Pipette 5, 16, 50, 160 mL of the filtrated solution and make up to 500 mL with OECD alga growth medium. The solutions were mixed thoroughly, resulting in test solutions at 1%, 3.2%, 10%, 32% of the saturated solution prepared at 100 mg/L.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: green alga
- Strain: Desmodesmus subspicatus
- Source (laboratory, culture collection): The stock alga was originally introduced from Institute of Hydrobiology, Chinese Academy of Sciences
- Age of inoculum (at test initiation): four days
- Method of cultivation:

ACCLIMATION
- Acclimation period: four days
- Culturing media and conditions (same as test or not): same
- Any deformed or abnormal cells observed:

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

21-24 oC

pH:

7.75 - 8.97

Nominal and measured concentrations:

nominal concentrations: 1%, 3.2%, 10%, 32% and 100% of the saturated solution prepared at 100 mg/L; measured concentrations: 0.246, 0.800, 2.22, 7.89 and 27.5 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: flask
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: 100 mL
- Aeration:
- Type of flow-through (e.g. peristaltic or proportional diluter):
- Renewal rate of test solution (frequency/flow rate): no
- Initial cells density: 5E+03 cell/mL
- Control end cells density: 3.25E+05 cell/mL
- No. of organisms per vessel:
- No. of vessels per concentration (replicates): 3 replicates
- No. of vessels per control (replicates): 3 replicates
- No. of vessels per vehicle control (replicates):

GROWTH MEDIUM
- Standard medium used: yes
- Detailed composition if non-standard medium was used:

OTHER TEST CONDITIONS
- Sterile test conditions: yes/no
- Adjustment of pH: no
- Photoperiod:
- Light intensity and quality: 4440-8880 Lux
- Salinity (for marine algae):

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: manual cell counting with microscope

TEST CONCENTRATIONS
- Spacing factor for test concentrations:
- Justification for using less concentrations than requested by guideline:
- Range finding study
- Test concentrations: 1% and 10% of the saturated solution prepared at 100 mg/L
- Results used to determine the conditions for the definitive study:

CULTURING APPARATUS
-Details on culturing apparatus used:

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol (3,5-DCP)

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 27.5 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

27.5 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 27.5 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

yield

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

27.5 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

yield

Details on results:

During the 72-hour test duration, there was no abnormal appearance of the algae observed in control replicates and replicates of each test group.
After 72 hours exposure, there was no significant inhibition of algae growth rates and yield at any concentration (inhibition < 10%). There was no significant difference in algae growth rate and growth yield between the control group and each test group (p>0.05, t-test).

Results with reference substance (positive control):

72 hour EyC50 of 3,5-DCP to Desmodesmus subspicatus was 2.0 mg/L with the 95% confidence limits 2.0 - 2.1 mg/L and 72 hour ErC50 was 2.6 mg/L with the 95% confidence limits 2.5 - 2.8 mg/L.

Validity criteria fulfilled:

yes

Conclusions:

The 72-hour effect concentration of average specific growth rate (ErCx) of and yield (EyCx) of the test item to Desmodesmus subspicatus were: ErC50 and EyC50 is greater than 27.5 mg/L, NOEC for growth rate and yield is 27.5 mg/L.

Executive summary:

An alga growth inhibition study of PF-06452787 (BOC Ketone) was conducted over a 72-hour exposure period in a static system.

The 72-hour effect concentration of average specific growth rate (ErCx) of and yield (EyCx) of the test item to Desmodesmus subspicatus were: ErC50 and EyC50 is greater than 27.5 mg/L, NOEC for growth rate and yield is 27.5 mg/L.

Description of key information

An alga growth inhibition study of PF-06452787 (BOC Ketone) was conducted over a 72-hour exposure period in a static system.

The 72-hour effect concentration of average specific growth rate (ErCx) of and yield (EyCx) of the test item to Desmodesmus subspicatus were: ErC50 and EyC50 is greater than 27.5 mg/L, NOEC for growth rate and yield is 27.5 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

27.5 mg/L

EC10 or NOEC for freshwater algae:

27.5 mg/L